94bamf
professor emeritus
Reged: 12/15/08
Posts: 707
Loc: Kansas City,Mo
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So I was watching one of the "Universe" shows that I recorded with the DVR, it was about "Light speed". It was pretty entertaining, they keep talking about how light speed is the speed limit of the universe and nothing can go faster, except for expanding space, etc..
Anyway, they talked about different ideas of how one day we might break or get around the speed limit by creating a worm hole, warp drive, etc.. The main thing at the end that grabbed my attention was they made the statement, that one day we might discover that going faster than the speed of light is completely impossible, and other ideas like worm holes, warping drives(warping space) might never pan out, and we would basically have to accept the fact that traveling to other star systems is impossible. This got me thinking, because never once have I ever thought that traveling to other star systems would be impossible. I always figured we will find a way eventually, it might take a thousand years, but somehow we would find a way. I don't accept that we will never cure cancer, or any other disease, I just figure it is a matter of time and gaining the technology to do it. I pretty much think about everything like that. I never put any limits on what we as the human race can do with enough time and ever increasing technology. How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
Ken
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Telescopes:
Celestron C6 SCT on CG4 mount
Skywatcher 8 inch F/5 Newt on a GEM
Celestron 8 inch Starhopper Dob
Celestron Oynx 80ED
Celestron C130 Mak
Celestron C102HD
Binoculars:
Nikon 7x35 Action
Nikon 7x50 Action
Zen Ray Summit 10x42
Celestron 10x42 Noble
Orion 10x50 Scenix
Celestron 10x50 Noble
Pentax 12x50 PCF WP II
Celestron 15x70 Skymaster
Oberwerk 20x60
Zhumell 20x80
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Tony Flanders
Post Laureate
Reged: 05/18/06
Posts: 3469
Loc: Cambridge, MA, USA
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Quote:
How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I see no reason to believe that humans will ever travel to other stars, but there are infinite other, more meaningful things that we can do. Most of which we probably can't even imagine now.
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Tony Flanders
First and foremost observing love: naked eye.
Second, binoculars.
Last but not least, telescopes.
And I sometimes dabble with cameras.
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skybsd
professor emeritus
Reged: 02/01/08
Posts: 599
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Hi,
Very eloquently put, Tony.
You found just the right words to convey my thoughts exactly.
Regards,
skybsd
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Midnight Dan
Carpal Tunnel
Reged: 01/23/08
Posts: 2757
Loc: Brockport, NY
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Accepting limitations and growing up is probably why young people make all the discoveries! 
Seriously though, history is filled with people who said it couldn't be done only to have someone do it a few years later. Even if the speed of light can't be broken, there's the potential of suspended animation for very long trips. We don't have the technology for that either, but the point is that I personally believe we WILL get to the stars one way or another. It won't be in my lifetime, but I don't believe it's impossible.
The problem with "impossible" is that it is based on our current understanding of the general model of physics. Our recent "discoveries" of dark matter and dark energy shows that we really don't understand it all that well. The only thing "dark" means in these names is that we have no idea what the heck is happening in the phenomenon we are observing. There *could* be something called dark energy. But it is just as likely that we are simply misunderstanding some fundamental law of physics - like the speed of light. Fact is ... we just don't know.
I think there's a MUCH bigger impediment to this than the speed of light. There's no question that any potential for getting to the stars is many, many years away. Mankind has achieved the level of technology that we have because we have been around so long and have been lucky to avoid being destroyed by any number of global disasters that could have ended it all. To me, the big issue is not whether we CAN achieve travel to other stars, but whether we'll be around long enough to achieve it. Between global warming, running out of oil, overfishing the oceans, potential wars, asteroid impacts, nearby gamma ray bursts, the impending 2012 disaster (just kidding  ), etc. I'm not certain we will.
Just my 2 cents.
-Dan
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Scopes: Celestron NexStar 8SE, Orion EON 72mm ED/APO, Orion ShortTube 80
Mounts: NexStar Alt/Az GoTo, Orion Astroview (EQ3) w/single axis drive
Eyepieces: Baader Hyperion 36mm (Aspheric), 21mm 13mm, 8mm, 5mm;
Other: 2x & 3x Barlow, 0.63x Focal Reducer, Dew-not strips, DewBuster controller, SQM Meter
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94bamf
professor emeritus
Reged: 12/15/08
Posts: 707
Loc: Kansas City,Mo
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Quote:
Quote:
How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I see no reason to believe that humans will ever travel to other stars, but there are infinite other, more meaningful things that we can do. Most of which we probably can't even imagine now.
I keep reading your post, trying to think of a way to respond. All I can come up with is, I disagree..
Ken
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Telescopes:
Celestron C6 SCT on CG4 mount
Skywatcher 8 inch F/5 Newt on a GEM
Celestron 8 inch Starhopper Dob
Celestron Oynx 80ED
Celestron C130 Mak
Celestron C102HD
Binoculars:
Nikon 7x35 Action
Nikon 7x50 Action
Zen Ray Summit 10x42
Celestron 10x42 Noble
Orion 10x50 Scenix
Celestron 10x50 Noble
Pentax 12x50 PCF WP II
Celestron 15x70 Skymaster
Oberwerk 20x60
Zhumell 20x80
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bobmcg
member
Reged: 09/18/07
Posts: 53
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Travel to other stars might not be impossible in the foreseeable future because a practical method has already been proposed. Stanislav Ulam, a very creative mathematician and physicist who worked on the Manhattan Project, proposed a space ship propelled by nuclear explosions. This would allow acceleration to a large fraction of the speed of light, so trips to nearby stars could be made in a matter of years and there would be no need for suspended animation or "warps" or "worm holes". This idea cannot be tested in part due to treaties forbidding the "nuclearization" of space. See this site for a description: http://www.unmuseum.org/orionproject.htm
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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Quote:
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
Hi Tony,
With all due respect, I tend to disagree with this statement as well. I believe that the day we stop testing the boundaries of our capability is the day we lose our souls. Granted, our quest for the ever greater ability can be detrimental, but it has the potential as one of man's greatest attributes.
I have never been one for staying within the lines. 
Edited by alanon (10/31/09 03:00 PM)
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glava2005
member
Reged: 04/12/09
Posts: 89
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two major factors to concider about possible faster then light travel or space folding..
if faster then light travel is possible some other race from our or some other galaxy would have probably reached us by now in 13.7 billion years that the universe existed.
so either we are the 1st civilization to arise in our galaxy and part of the universe or faster then light travel is not possible.
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Sky-Watcher ED80
TS Astro5 mount
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earthbot1
super member
Reged: 08/27/09
Posts: 173
Loc: Central Virginia
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One day a brilliant mind will blow our current understanding away! There may be others already there, but space is a vast place.
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Nexstar 8
Meade/Celestron EPs
Bushnell 90mm Mak-Cass
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Tony Flanders
Post Laureate
Reged: 05/18/06
Posts: 3469
Loc: Cambridge, MA, USA
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Quote:
Quote:
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
With all due respect, I tend to disagree with this statement as well. I believe that the day we stop testing the boundaries of our capability is the day we lose our souls.
Quite so -- that's precisely my point!
The key to a successful and happy life is finding the *right* boundaries to be testing. If I had set out to be an Olympic athlete, I would have failed. And the harder I tried and the more I cared, the more unhappy I would have been. I was not born in the right body.
More to the point, if I had tried to be an Olympic athlete, I would have wasted my energy, and been unable to attack a whole host of other challenges. Some of which I've been successful at, others not. But if I were successful at all of them, they wouldn't be challenges.
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Tony Flanders
First and foremost observing love: naked eye.
Second, binoculars.
Last but not least, telescopes.
And I sometimes dabble with cameras.
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NerfMonkey
sage
Reged: 06/12/08
Posts: 482
Loc: NE Ohio
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Quote:
if faster then light travel is possible some other race from our or some other galaxy would have probably reached us by now in 13.7 billion years that the universe existed.
Says who? Maybe these ultra-advanced civilizations are only interested in traveling to worlds with civilizations on the same level of technology and intelligence as themselves (i.e., the ability to navigate interstellar space). Maybe we humans just aren't all that interesting to space-faring aliens.
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Mike
Zhumell 12", Oberwerk 15x70s
107 Messiers, 247 total DSOs, 6 planets, 1 comet
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lightfever
Pooh-Bah
Reged: 09/27/04
Posts: 1276
Loc: Macomb Michigan
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Quote:
so either we are the 1st civilization to arise in our galaxy and part of the universe or faster then light travel is not possible.
The universe is a big place and they may just never have come across our little corner.
I sometimes wonder what if we are the first intelligence, and the responsibility that places on us. How pitiful it would be if we destroyed ourselves or did not try to inhabit other corners of the galaxy.
And yes I think we will travel to other stars.
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Mark
Tasco 15-TE 76mm
Sky Watcher 80mm ED
AT-111 Triplet
XT8i (with Woden re-figured mirror)
Discovery 12.5" f/5 Premium DHQ (PDHQ Split-tube Dobsonian)
12.5" f/6.3 Dob (Underconstruction)
Celestron CG-5GT EQ Mount
Celestron C4 EQ Mount
"Life is not about waiting for the storm to pass, but learning to dance in the rain" unknown
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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Believing that anything is possible is a huge part of the problem as we tend to think that our follies will be fixed by future generations. "Technology will save us" is the mantra of the scientifically interested, but ignorant masses. Whether it's overpopulation or environmental and microbiological alterations, we have faith (yes, "faith") that every wrong direction we take can be easily cured by a brilliant idea.
This isn't to say that we don't want to attempt to be great and nurture the hopes and dreams of our geniuses, but to count on them to fix our mistakes is a really, really, REALLY bad bet.
In terms of faster than light travel, when you understand the great distances between celestial objects and the amount of energy it takes to accelerate even the most feeble mass to anywhere near light-speed, to realize how incredibly unlikely it will be that such travel will ever come to pass. It makes great fantasy, but to invest much time in truly believing it will come to pass is a poor use of that time.
As a matter of fact, even debating such nonsense is time I could be making some pumpkin soup, so off to the kitchen I go!  - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't.
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lightfever
Pooh-Bah
Reged: 09/27/04
Posts: 1276
Loc: Macomb Michigan
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Quote:
the amount of energy it takes to accelerate even the most feeble mass to anywhere near light-speed,
We don't yet understand what causes mass, but when this is understood it may be possible to counteract it's effect.
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Mark
Tasco 15-TE 76mm
Sky Watcher 80mm ED
AT-111 Triplet
XT8i (with Woden re-figured mirror)
Discovery 12.5" f/5 Premium DHQ (PDHQ Split-tube Dobsonian)
12.5" f/6.3 Dob (Underconstruction)
Celestron CG-5GT EQ Mount
Celestron C4 EQ Mount
"Life is not about waiting for the storm to pass, but learning to dance in the rain" unknown
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Wow, a lot of interesting points here in this thread.
Do you accept anything as impossible?
Yes! It is not possible that I won the lottery last year. I did not enter. Even if they gave me the money they would be doing so in error because I did not legally enter. I am comfortable with the notion that this is impossible.
If the word impossible is to have meaning then something must actually be impossible. The word is however constrained by a set of assumptions that are usually unstated.
When asked is something possible as a physicist, my answer is constrained by my understanding of physics. For example I find it amusing to tell people that I know how to build a time machine. Later I tell them that it only works in the forward direction and I have no theoretical basis for a machine to go in the reverse direction.
If I am asked if it is possible to do something as an engineer. I use a different set of criteria. No longer am I allowed to use unobtainable materials or scandalous amounts of energy. From an engineering prospective I can build a Starship Enterprise that would have many of the key features of the version D used in the TV show called TNG. However, I can find no practical way to fuel the thing. To go from stationary to c/2 would require about 80 times the mass of the ship in H2. To do a one way trip to anywhere would require 80 squared and a round trip requires 80 to the 4th power times the mass of the ship in fuel. These are not achievable by any technology I can imagine and we have not yet turned on the warp drive.
I compare this to the fate of the old NASA jet packs. Yes they work and 4 were built. We do not use them because of the fueling problem. They could only fly for about 35 seconds. The weight of the fuel must be lifted with the payload prior to use. Adding more fuel added to the weight and did not add to the flying time. A point of diminishing returns was reached and development ceased. Like my time machine the jet pack was possible but not useful.
I do not agree with the assessment of the TV show that it is impossible to get to nearby stars as I have been aware of an architecture for this for many years. I assert that solar sailing will allow a large ship to travel to a handful of nearby stars within a human life span ( 30 -40 years round trip.) One can imagine that we will do this within the next 200 years. It is certainly not impossible in principle. Neither physics nor engineering prohibits such travel.
For many years I have heard the lamentation of those who hang their hopes on some theoretical break through that will sweep away the speed of light limit. To those I suggest more reading. While the natural speed limit does make long distance travel seem to be precluded one must read the rest of the theory. The time dilation works in favor of the traveler. If one can travel near the speed of light this dilation effect slows the passage of time for the traveler relative to a stationary point such as the origin and the target. This means that our range is very much larger than we at first imagine at the expense of loss of relationships with those who do not travel.
If a 20 year old traveler takes a trip at near light speed that last for 1 year, it is possible that the travelers parents will have died of old age upon his or her return at the age of 21. In fact the world may change in some substantial way which my be displeasing to the returning traveler. This is the risk taken by the relativistic traveler. But the traveler is not prohibited by relativity from visiting the center of the galaxy. Such things are possible and the effects have been observed in the laboratory.
To the original question we do have to admit that nature seems to have handed us some fundamental limitations. We must face these. A large part of my interest in physics is about drawing lines between what nature allows us to do and what it does not. It is always possible that our understanding will change but I do not find this productive. New theories are generally developed by those who are dedicated to understanding what is there. Einstein did not just say what if measurements of c were always the same. He was responding to the observed fact that all measurements of c came out the same. He asked what else must be true if that is true. This lead him to relativity. The attitude is what is nature. Many are motivated simply by the fact that they do not like the answers we have so far. I fall among those who want to imagine everything that can be done with the understanding we now have. This is why I have little interest in new theories. I am not waiting for anything. I just would like to understand what we do have and push that to the limits.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 12939
Loc: Amargosa Valley, NV, USA
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I accept two things as impossible.
Three, actually.
1. Avoiding death.
2. Avoiding taxes.
3. Having an unmoderated debate forum that remains civil on every topic.
We've got #3 compensated for, so let's make sure this discussion stays friendly to all.
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"Since the process of science generates more mysteries than it solves, I predict that we'll never learn everything: and we'll continue to generate new ignorance at the speed of knowledge."
"S.O.E." (Sauron's Other Eye), with 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Under Construction: The "Eye of Sauron" Observatory!
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Doug76
Postmaster
Reged: 12/05/07
Posts: 5552
Loc: SE Louisiana, future Texan
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I believe accepting limitations is tantamount to quitting, and success will not come from that.
So no, I don't believe anything is impossible, given hard work and a good vision of what one is looking to achieve.
Mankind, using the wits God gave him, has time and again come up with ways to improve our lives, and ways to save us in our time in need. It seems every time we hit a threshold moment, we come through, and I expect that will keep happening, if we can keep the naysayers in check, and the do-gooder regulators.
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Doug
Truckstop Astronomer
The Universe, the light of God, in all it's majesty
6 achro refractors, 50mm-150mm
1 apo refractor, 90mm
1 SCT, 8 inch
UO Abbe Volcano Tops
Faworski Ortho's
Panoptic 24mm
Carton 100mm f/13 under construction 
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 12939
Loc: Amargosa Valley, NV, USA
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I have to both agree and disagree with Tony. First, I agree that there are certain built-in limitations in reality that we need to learn to accept if we are to make progress. I don't think those limitations are actually disadvantageous, on the contrary, they constitute "the rules of the game", that once learned, allow you to become expert at playing that game. I don't think anyone would enjoy "no rules football", in fact, if there were no rules, and no structure, it wouldn't be a playable game at all. It is the limitations imposed by nature that give the universe its structure, its complexity, and ultimately its beauty and awesomeness.
Second, I disagree that we as a species (or the descendants of this species) are prevented from traveling to the stars by these limitations. Individually, we will never do it, but there's no reason that we can't develop technology, both material and biological, that will allow us to eventually colonize the galaxy.
Faster than light travel is not required, not even near-light speed travel. Rather than challenge the laws of physics, it is perfectly possible to work within them, to allow our descendants very long lives, allow them to extract resources from asteroids and comets that they encounter along the way or at the edges of star systems, and conserve energy efficiently enough to make it to the next star system.
Traveling at a mere 1% of the speed of light would be extremely fast, yet that would allow folks to arrive at several nearby star systems within a single modern lifetime. Extended lifetimes, the ability to conserve energy along the way, and the ability to efficiently extract hydrogen energy and raw materials from icy bodies in the Oort Cloud would get us most of the way there with a relatively modest advance over today's technology.
Even if those completing the journey are a later generation than those who began it, there's no reason it can't be done by humans.
The debate comes from whether or not we would want to.
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"Since the process of science generates more mysteries than it solves, I predict that we'll never learn everything: and we'll continue to generate new ignorance at the speed of knowledge."
"S.O.E." (Sauron's Other Eye), with 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Under Construction: The "Eye of Sauron" Observatory!
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ColoHank
professor emeritus
Reged: 06/07/07
Posts: 515
Loc: western Colorado
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Quote:
The debate comes from whether or not we would want to.
We might also debate, given the ability and desire for such travel, whether we actually should. Ability and desire alone aren't an adequate justification. There are lots of things we can do that we shouldn't do.
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Questar 3.5 standard - pyrex and BB coatings
Powerguide II
8mm, 12mm, 16mm, 24mm and 32mm Brandons
modified Bogen 3030 w/ homebuilt wedge
Homebuilt Galileo scope and very large and ugly homemade tripod
other odds and ends, including iPod Touch with StarMap Pro (what a marvelous combo)...
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"Nothing exists but atoms and empty space. Everything else is opinion."
Titus Lucretius Carus 99-55 B.C.
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Joad
Wordsmith
Reged: 03/22/05
Posts: 12872
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There are even limits to the imagination: it is impossible to imagine what we cannot imagine.
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12.5 inch Portaball + Osypowski platform
LX10
Oberwerk BT100 45° binocular
Orion binoviewer + ScopeStuff extender (so it focuses at f/4.9)
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 12939
Loc: Amargosa Valley, NV, USA
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There are some things that are fundamental limits, and other things that are temporal limits. Human imagination is an evolving thing, so what we can imagine now is different than what we could imagine in the last generation. And the imagination of the next generation will be different still. I can't imagine some of the things my grandchildren will be easily able to consider. I'm not sure if that makes it impossible or just makes me primitive.
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"Since the process of science generates more mysteries than it solves, I predict that we'll never learn everything: and we'll continue to generate new ignorance at the speed of knowledge."
"S.O.E." (Sauron's Other Eye), with 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Under Construction: The "Eye of Sauron" Observatory!
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kcbridgeman
member
Reged: 03/26/09
Posts: 79
Loc: Kansas City, MO
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Quote:
Quote:
Quote:
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
With all due respect, I tend to disagree with this statement as well. I believe that the day we stop testing the boundaries of our capability is the day we lose our souls.
Quite so -- that's precisely my point!
The key to a successful and happy life is finding the *right* boundaries to be testing. If I had set out to be an Olympic athlete, I would have failed. And the harder I tried and the more I cared, the more unhappy I would have been. I was not born in the right body.
More to the point, if I had tried to be an Olympic athlete, I would have wasted my energy, and been unable to attack a whole host of other challenges. Some of which I've been successful at, others not. But if I were successful at all of them, they wouldn't be challenges.
But you'll never know whether you could have been an Olympic athlete if you choose to not try. By just saying "Reaching speeds close the the speed of light is not possible, so I'm not going to try." you have already lost the challenge. These "limits" are what drive people to find out they aren't limits, but steps towards a greater goal. Most limitations that we accept are based on what we know as fact at the present time. There have been many quotes over time about technology that at the time seemed correct, but proved to be wrong.
"Everything that can be invented has been invented."-Charles Duell, Head of the U.S. Patents Office, 1899.
“To place a man in a multi-stage rocket and project him into the controlling gravitational field of the moon where
the passengers can make scientific observations, perhaps land alive, and then return to earth – all that constitutes a wild dream worthy of Jules Verne. I am bold enough to say that such a man-made voyage will never occur regardless of all future advances.” — Lee DeForest, American radio
pioneer and inventor of the vacuum tube, in 1926. Proved wrong by Russia and Yuri Gagarin in April 21, 1961.
“A rocket will never be able to leave the Earth’s atmosphere.” — New York Times, 1936. Proved wrong by German V-2 rockets around 1946.
All of these predictions were based on common knowledge at the time they were made, but someone decide to push the envelope, and they were all proved wrong. Will I see it in our time, no. Will it happen someday, most likely, unless something either natural or man-made destroys us.
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Orion XT10/Telrad/Stellarvue F50M RACI
Numerous Eyepieces
Starry Night Pro Plus 6/Pocket PC w/Pocket Stars
Who are we? What are we? We find that we inhabit an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. ~ Carl Sagan
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Glaucus
member
Reged: 07/12/09
Posts: 42
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You can't influence what is true by not accepting it. Nature doesn't care.
That what you like and that what is true have nothing to do with each other. I find it amazing how easy it is for people to get the two tangled up.
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
Believing that anything is possible is a huge part of the problem as we tend to think that our follies will be fixed by future generations. "Technology will save us" is the mantra of the scientifically interested, but ignorant masses. Whether it's overpopulation or environmental and microbiological alterations, we have faith (yes, "faith") that every wrong direction we take can be easily cured by a brilliant idea.
Well, as a member of that scientifically interested, but ignorant, mass, I have to say that I strongly disagree with this attitude. Future generations *have* to deal with our follies; that's just plain the way it is -- would that it were not so. And I'd bet on technology instead of betting on changing human nature, every time. The former at least has a chance, but the latter just ain't gonna happen.
Quote:
This isn't to say that we don't want to attempt to be great and nurture the hopes and dreams of our geniuses, but to count on them to fix our mistakes is a really, really, REALLY bad bet.
To the contrary; this is the only bet to make. Counting on *stupid* people to fix mistakes is a nearly guaranteed recipe for failure.
In the long run, technology is our only chance. When the next extinction-level rock comes hurtling toward Earth, I'll take my chances with the geniuses who've invented space travel and some really good deflection strategies, rather than Ogg and his technology-avoiding buddies angrily shaking clubs at the sky.
Quote:
In terms of faster than light travel, when you understand the great distances between celestial objects and the amount of energy it takes to accelerate even the most feeble mass to anywhere near light-speed, to realize how incredibly unlikely it will be that such travel will ever come to pass. It makes great fantasy, but to invest much time in truly believing it will come to pass is a poor use of that time.
This sounds like a problem to be solved by geniuses and technology coming up with ways to produce those vast amounts of energy. In fact, we can already see the first faint glimmers of how that might be possible. I don't view this as "incredibly unlikely" at all, unless we follow your advice and don't invest much time in it.
Quote:
As a matter of fact, even debating such nonsense is time I could be making some pumpkin soup, so off to the kitchen I go!
I'm not a fan of pumpkin soup, but doing great things in the kitchen is one thing about which we *can* agree!
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Terry (astrotrf)
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dreamregent
sage
Reged: 04/06/09
Posts: 454
Loc: Clearwater, FL
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Quote:
Most limitations that we accept are based on what we know as fact at the present time.
Amen! I've made the same argument before but there is vehement opposition to such an assertion in many quarters... To some people, what we know today is sufficient to induce tunnel vision regarding what will be possible to discover tomorrow. How many times does it take for some branch of science to be turned on it's head before everyone accepts the fact that we are like an infant (well, maybe a 2-year-old) trying to do calculus when it comes to the universe and how it works? It might seem like humans have been here a long time but we wouldn't even register as a blip if the entire history of the universe was mapped on a radar screen at your local airport. There is no doubt that we humans have made tremendous strides over the last couple thousand years but I believe we have much, much farther to go.
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Building a f5.24 10" Dob
in an octagonal wood tube
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 25195
Loc: NE Ohio
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if faster then light travel is possible some other race from our or some other galaxy would have probably reached us by now in 13.7 billion years that the universe existed.
Wrong time frame. There could have been countless visits in the billions of years of Solar system existence. We wouldn't know unless they occurred in the tiny portion of that time in which there were people.
The numbers are just too large. For a civilization to find another out of the billions of stars within the tiny timeframe during which both civilizations exist is too much to ask.
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John C
Urban Observatory
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
To go from stationary to c/2 would require about 80 times the mass of the ship in H2. To do a one way trip to anywhere would require 80 squared and a round trip requires 80 to the 4th power times the mass of the ship in fuel.
Higgs, I don't follow this. Leaving aside for the moment how you are planning to use the hydrogen to provide propulsion, I don't understand the "80 squared" bit here. Surely if 80 ship masses accelerates the ship to c/2, then just 80 *more* ship masses decelerates it back to zero. So a round trip would require 4 times 80 ship masses, not 80 to the 4th power ...
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Terry (astrotrf)
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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You have just accepted delivery on your new Enterprise D. It is empty. The fuel to accelerate it to c/2 has 80x the mass of the empty ship. This is great. You have sufficient fuel to get to .5c. If you would like to stop relative to your start point you will need the same amount of fuel. Unfortunately you are moving at c/2 with an empty tank. The 80x fuel you need has to be on the ship when you start the trip. The makes the payload mass of the ship 81x. Thus you need 80 time the mass of the ship and the deceleration fuel to do a one way trip where you are stationary at the end of the trip. This is approximately 80^2.
Congratulation! You are now happily mingling with the people of the planet Zog but your fuel tanks are empty! Again! At the start of the trip you need fuel for all legs of the trip.
For each leg of the trip the mass of the fuel for future legs is part of the mass that must be accelerated. This results in the need for approximately 80^4 at the start of a round trip journey. And that is only a single round trip journey.
We are spoiled by our common experience with the automobile. We generally do not even consider the mass of the fuel as it is a small fraction of the mass of the car.
My greatest disappointment as I was studying for my physics degree was the realization that the speed of light limit was not the problem, it was fuel. I looked at burning interstellar hydrogen but event that was disappointing. The power generated is small in comparison to the energy required to capture the material.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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94bamf
professor emeritus
Reged: 12/15/08
Posts: 707
Loc: Kansas City,Mo
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Reading many of the responses, I am very suprised at how some people view the idea of space travel, especially people on an astronomy forum of all places. The amazing things that might be out there in space, from other forms of life, to just a greater understanding of this giant universe that we live in, is what makes me get the telescope out every night in the first place. I can't even see the point of getting the telescope out, if you don't really care about what is out there, or have a desire to explore it..
Ken
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Telescopes:
Celestron C6 SCT on CG4 mount
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InkDark
Carpal Tunnel
Reged: 10/29/07
Posts: 1837
Loc: Montreal, Canada
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Quote:
Quote:
How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I see no reason to believe that humans will ever travel to other stars, but there are infinite other, more meaningful things that we can do. Most of which we probably can't even imagine now.
I would agree 110%, but that's impossible. So I'll agree 100%.
I think that we humans tend to think that we have an unprecedented control over nature, which is a complete illusion in my opinion.
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Jimmy
If you could stop time, for how long would you stop it?
"...since that time, I have not complained about the weather one single time. I’m glad there is weather." – Alan Bean, Apollo 12
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Quote:
Reading many of the responses, I am very suprised at how some people view the idea of space travel, especially people on an astronomy forum of all places. The amazing things that might be out there in space, from other forms of life, to just a greater understanding of this giant universe that we live in, is what makes me get the telescope out every night in the first place. I can't even see the point of getting the telescope out, if you don't really care about what is out there, or have a desire to explore it..
Ken
I am sorry. I am unable to follow your response. How do people think about space travel?
As you can see from this and other threads here in the Science & Space Exploration Forum that people come to the subject from many different perspectives. Not everyone looks into a telescope for the same reasons. I do it because it is a platform for my wondering about what is out there.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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kcbridgeman
member
Reged: 03/26/09
Posts: 79
Loc: Kansas City, MO
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Quote:
Quote:
Quote:
How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I see no reason to believe that humans will ever travel to other stars, but there are infinite other, more meaningful things that we can do. Most of which we probably can't even imagine now.
I would agree 110%, but that's impossible. So I'll agree 100%.
I think that we humans tend to think that we have an unprecedented control over nature, which is a complete illusion in my opinion.
I don't this has anything to do with thinking we have unprecedented control over nature. We're not talking about changing the rules that nature abides by, we're talking about figuring out how to make the rules apply to everything. Nature says that C is a speed limit that nothing can go faster than, but there is no rule saying other things cannot attain speeds of say 99.99% of C. The only rule is you cannot go C. We may not know how to get there now, nor may we ever, but it doesn't mean it isn't possible. It's just not feasible to us at this time. I hate to quote a goofy movie, but it does put it well. From Men in Black, "Fifteen hundred years ago everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat, and fifteen minutes ago, you knew that humans were alone on this planet. Imagine what you'll know tomorrow." Excluding the alone on this planet part, I think it says it best. Just imagine what you'll know tomorrow. Just my 
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Orion XT10/Telrad/Stellarvue F50M RACI
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Who are we? What are we? We find that we inhabit an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. ~ Carl Sagan
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Mister T
sage
Reged: 02/01/08
Posts: 445
Loc: Upstate NY
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How about the effect of acceleration on the crew.
the human body cannot stand higher g forces for extended periods.
so how much does that add to the travel time?
plus we gotta decelerate gradually when we get there.
at 1 g it will take half a year to get to c/2 and half a year to slow down.
is this right??
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Tony
"After the Laws of Physics, everything else is opinion"
-Neil deGrasse Tyson
Zhumell Classic 10" Dob
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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Frankly, I'm still waiting for my flying car... - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't.
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Quote:
I don't this has anything to do with thinking we have unprecedented control over nature. We're not talking about changing the rules that nature abides by, we're talking about figuring out how to make the rules apply to everything. Nature says that C is a speed limit that nothing can go faster than, but there is no rule saying other things cannot attain speeds of say 99.99% of C. The only rule is you cannot go C. We may not know how to get there now, nor may we ever, but it doesn't mean it isn't possible. It's just not feasible to us at this time. I hate to quote a goofy movie, but it does put it well. From Men in Black, "Fifteen hundred years ago everybody knew the Earth was the center of the universe. Five hundred years ago, everybody knew the Earth was flat, and fifteen minutes ago, you knew that humans were alone on this planet. Imagine what you'll know tomorrow." Excluding the alone on this planet part, I think it says it best. Just imagine what you'll know tomorrow. Just my
You are correct. We do not know what we will discover next. For completeness I will restate the apparent limitations of nature.
The theory asserts that objects with a non-zero rest mass may not achieve c. If you wish to invest the energy you my accelerate such objects arbitrarily close to c. This is routinely done in particle accelerators.
The theory also asserts that massless object may propagate at c and only c under all conditions. This is why all measurements of the speed of light produce the same answer without regard to the speed of the source or the detector.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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FAB
Stargeezer
Reged: 08/06/04
Posts: 2499
Loc: Blythe, CA USA
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Do I find anything impossible? Yes, returning unfrozen toothpaste to its tube, or turning an orange inside out without breaking the skin.
Seriously, there's a word that describes faith without reason and logic. The TOS, however. prohibits going there. Nonetheless, I have a mindless faith that mankind, if the species survives, will one day journey outward. Man will somehow become a starfaring species.
FAB
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Floie
10.0" Hardin Dob
6.0" Konus Refractor
3.0" Celestron Tabletop Newtonian
10X50 Binoculars
Amscope T490A Trinocular Compound Microscope
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http://home.earthlink.net/~blhtvl
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Quote:
How about the effect of acceleration on the crew.
the human body cannot stand higher g forces for extended periods.
so how much does that add to the travel time?
plus we gotta decelerate gradually when we get there.
at 1 g it will take half a year to get to c/2 and half a year to slow down.
is this right??
In my Enterprise D example you have correctly noticed that I have ignored the impact on the crew. My point is I will not build one until I can figure out how to fuel it.
In fact if I were to design such a thing it would be based upon the Discovery architecture from 2001. A spinning section for 1g living space with lesser used areas in zero g.
I am a proponent of solar sailing as the architecture of choice for nearby interstellar travel. I have not seen the numbers in Decades but as I recall it basically takes a 1 kilometer class rock from the asteroid belt and retrofits it as a colony ship. Lots of room for a crew of 1000 with large parks and other amenities.
The thickness of the rock provides radiation and meteoroid shielding. The living areas must always face way from the direction of travel. A large solar sail would provide a modest acceleration for on the order of a year when combined with a Solar momentum exchange one would get to nearby stars in on the order of 15 to 20 years.
I have not seen this analysis since I was in collage and can not duplicate the work at this time. The calculations is complicated by the variation in solar flux during the acceleration. This is the only architecture that provides the potential to gain speeds of tenths of c. In this architecture the accelerations are low and the crew would experience zero g with a small drift.
In the Enterprise version one would want to limit the acceleration to human sustainable levels with the impacts to travel time that you have computed.
Disclaimers:
Please operate your Enterprise D safely! Remember that many of its features are complete fantasy and do not actually work.
If you choose to build a kilometer class colony ship please remember to stay in the shadow of the rock. Never look directly forward. Also be careful with that momentum exchange with the sun as a careless traveler may place the ship into a situation where the gravity of the sun greatly exceeds the thrust available from the solar sail.
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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HiggsBoson
Pooh-Bah
Reged: 02/21/07
Posts: 1118
Loc: Kal-li-fornia
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Quote:
Frankly, I'm still waiting for my flying car... - j
http://www.terrafugia.com/
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Michael
ATM: 6" F/9 Newtonian Travel Scope
ATM: 12.5" F/4.5 Real Soon Now...
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Michael A. Earl
vendor- Canadian Satellite Tracking and Orbit Research
Reged: 11/17/08
Posts: 1113
Loc: Brockville, Ontario, Canada
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Yes, I do accept that some things are impossible, however, I do not think that we have found these yet.
The only method of determining impossibility is trying something an infinite amount of times. I don't have time for that.
Yes, there are limitations on humanity but we have not found them yet. Every time we think of a limitation, someone proves it wrong. Previously mentioned space travel, moon landing, interstellar probes, climbing Mount Everest, etc.
Is interplanetary habitation possible? The only way to know is to try: many times. I do believe something will eventually take hold and flourish, not without many failures however.
There are so many examples of predictions on our limitations that have been proven wrong, that I am convinced that most predictions about our future limitations will be just as wrong when the truth is unfolded.
I still am amazed that I can keep my entire music collection in an area the size of a cassette box.  How can anyone talk about limitations at a time like this?!?
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Michael A. Earl - Vendor
Canadian Astronomy, Satellite Tracking and Optical Research
www.castor2.ca
Celestron NexStar 11 GPS
Celestron NexStar 8i SE
SBIG ST-9XE CCD
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 5672
Loc: Inner Solar System
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Quote:
Quote:
How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I couldn't disagree more.
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- Rick
14" LX200GPS
Dyslexics Untie!
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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Quote:
Quote:
Frankly, I'm still waiting for my flying car... - j
http://www.terrafugia.com/
Well that's depressing...
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
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ColoHank
professor emeritus
Reged: 06/07/07
Posts: 515
Loc: western Colorado
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Our physiological limitations are the greatest stumbling block to human inter-stellar travel. So let's leave human travelers and their appetites and frailties (including lack of longevity) out of the equation, and instead send a fleet of probes that employ those propulsion technologies deemed most likely to succeed. The greatest challenge then will be to ensure that someone on Earth will still be around umpty years/decades/centuries/millennia from now with the interest, commitment and wherewithall to monitor the probes' transmissions when they finally approach their destinations. What we're most likely to learn from these little experiments is that travel to even the nearest extra-solar planetary system will take so long that succeeding generations of mankind will have forgotten about the launches or long-before judged the endeavor inconsequential by the time the missions are presumed to end.
For now, I'm going to worry more about whether I-70 will be open so the kids and their families can drive over the Rockies from Denver for Thanksgiving. At only 265 miles, the trip isn't measured in light years, but it can be extremely problematic at this time of year -- even with proven propulsion and navigation systems.
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Questar 3.5 standard - pyrex and BB coatings
Powerguide II
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modified Bogen 3030 w/ homebuilt wedge
Homebuilt Galileo scope and very large and ugly homemade tripod
other odds and ends, including iPod Touch with StarMap Pro (what a marvelous combo)...
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"Nothing exists but atoms and empty space. Everything else is opinion."
Titus Lucretius Carus 99-55 B.C.
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Jarad
Post Laureate
Reged: 04/28/03
Posts: 4327
Loc: Atlanta, GA
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Quote:
I am a proponent of solar sailing as the architecture of choice for nearby interstellar travel. I have not seen the numbers in Decades but as I recall it basically takes a 1 kilometer class rock from the asteroid belt and retrofits it as a colony ship. Lots of room for a crew of 1000 with large parks and other amenities.
There was a book that used this concept to visit a nearby star. I think it was called "The Sparrow". Good book - light on science, heavy on philosophy, but interesting.
Quote:
Disclaimers:
Please operate your Enterprise D safely! Remember that many of its features are complete fantasy and do not actually work.
If you choose to build a kilometer class colony ship please remember to stay in the shadow of the rock. Never look directly forward. Also be careful with that momentum exchange with the sun as a careless traveler may place the ship into a situation where the gravity of the sun greatly exceeds the thrust available from the solar sail.
I hate it when my solar sailboat falls into the sun. Especially when I left my sunblock SPF50,000,000 at home...
Jarad
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Well, considering that we have the technology NOW to send probes to other stars (but not the money to do so), I would say that calling interstellar travel impossible shows ignorance to the current state of technology, and likely future advances. With advances in nuclear fusion, space access, materials, biology, computers, radiation hardening, agriculture- we WILL have the technology to send humans on a long duration voyage in a hundred years or so. We DO NOT have to violate light speed to do this! Personally, I believe that FTL travel is PROBABLY impossible, but there is no way to tell until we discover more about physics.
Lemme go through some points in more detail.
One thing that makes it very narrow-minded to say that we will never travel to stars is the assumption that stars will always be far away. In the short term, yes, but stars will get alot closer to us than a measely 4 light years over the next couple million years. Will we survive that long? Who knows, but still... there will come a point when a star is pretty nearby.
Another thing that makes it narrow-minded to say humans will never spread to other stars is the assumption that future humans will live with today's biological limitations. We will not. Genetics, medicine, biological technologies are all advancing quite nicely, with no end in sight. In the future, it is almost certain that we will be able to do at least one of the following things:
-Stop aging
-Go into suspended animation or some other low metabolism mode
-Grow humans automatically from DNA on reaching a distant star after a thousand year voyage
Another point that persons who claim interstellar travel to be impossible fail to consider is the progress of computer technology. While silicon-based computer technology is finally reaching some limits, quantum computing looks quite possible. Quantum computers will be many orders of magnitude better than silicon computers. After the advent of quantum computers (assuming they will be perfected, and will be as powerful as predicted) it is my professional opinion that true artificial intelligence will become possible.
So what does true artificial intelligence have to do with interstellar travel? Quite alot, actually. The possibilities are endless. For example, humans may not be smart enough to figure out how to travel between stars, but our computers might be. Artificial intelligence machines could tend the human infants grown on-site from DNA after a 10,000 year voyage.
Nuclear energy advances- We are already able to harness the power of fusion in an uncontained environment (a "fusion" bomb, though that's a misnomer as most energy in a fusion bomb comes from fission, but I digress). A fusion rocket engine need not be contained either. Also note that with today's nuclear technology, we can get to the stars already with an unmanned probe.
Space access- an interstellar craft would many WAY bigger than anything that we can currently launch. It would have to be built in space. We are already getting good experience building stuff in space. Future advances in space access, such as a space elevator (which requires possibly carbon nanotube materials technology) would greatly help.
So lets talk about some ways of getting to the stars. Right now, two viable methods exist:
Light sail
Nuclear propulsion
Light sails would probably be a bit slower, but they are possible. You would need a light source much brighter than the sun to power it- a nuclear-powered very high energy laser on the moon would do the trick. Unfortunately, it might be a one-way trip, as stopping would be quite difficult.
Nuclear propulsion- nuclear bombs were already proposed to power a spacecraft, and it looks like they would work. Other methods have been proposed, like an "antimatter catalyzed nuclear fusion" or some such, which basically uses SMALL amounts of antimatter to help nuclear fusion along. Antimatter is getting more accessable as time goes on, so this doesn't seem all that impossible. You wouldn't need much, as the antimatter is NOT used to propel the craft, just to help the fusion reactions take place.
Finally, there is the space-ark concept- a slow-moving space craft that is very large and has a self-sustaining ecosystem and human population. We live on one of these already. The question is, how small can we make an artifical space ark. Can we make it small enough to be practical?
Anyway, just my thoughts on the subject. Right now, money and motivation are keeping us from lauching stuff into interstellar space. For good reason too- at this point, the huge amount of money that would be required to make an interstellar probe would be far better spent on science that needs to be done, and on issues here on earth.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
Edited by tatarjj (11/02/09 05:20 PM)
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moynihan
Carpal Tunnel
Reged: 07/22/03
Posts: 1604
Loc: Wisconsin
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Interesting thread.
I myself do not know if traveling past, or faster than, the speed of life is "impossible", in the absolute, dictionary sense of the word. At our current level of knowledge it does seem to be the case. So for operant reasons I accept it as a biogeophysical limit.
Of course, there are currently speculative ideas on not going faster than the speed of light, but rather getting around it, so to speak (worm holes, etc.).
But, two things;
1. If we cannot obtain a velocity in excess of that of light, interstellar travel/exploration/settlement is not ruled out. It would just take a really long time. It would then be a political/social question, not really a technology one.
2. Working partially in the area of (suject verboten in forum, therefore not stated) I have to consider biogeophysical constrants that are "real", in that for given a goal, they bound the potential solution space. So yes, I can think of something being literally impossible. But the goals are rarely impossible,though some ways of acheiving them are.
A mundane, non-work example; i accept that absent augmenting my morphology (an ultralite)i cannot fly under my own power on this planet.
As the sci-fi writer Phillip K. Dick said, "Reality is what is left, when you stop believing."
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"Gosh, you've... really got some nice toys here"
Dual mount/ambient temperature Hominid Widefield Photon Collectors®
Pleistocene™ ˝ watt Wetware Integration Unit.
entia non sunt multiplicanda praeter necessitatem
Edited by moynihan (11/02/09 05:33 PM)
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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tatarjj wrote:
Quote:
... (a "fusion" bomb, though that's a misnomer as most energy in a fusion bomb comes from fission, but I digress).
Can you provide a reference for this?
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Terry (astrotrf)
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kcbridgeman
member
Reged: 03/26/09
Posts: 79
Loc: Kansas City, MO
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Quote:
tatarjj wrote:
Quote:
... (a "fusion" bomb, though that's a misnomer as most energy in a fusion bomb comes from fission, but I digress).
Can you provide a reference for this?
Is this maybe a reference to the fact that it takes a fission bomb inside of of a fusion bomb to produce the x-rays that are needed to create the high temperatures and pressure needed to initiate fusion? The fusion of the lithium deuteride then induces fission of the urianium-238. This fission causes the bomb to explode, so I guess the process could be considered mainly fission, but I would consider it a moot point.
How fusion bomb works.
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Orion XT10/Telrad/Stellarvue F50M RACI
Numerous Eyepieces
Starry Night Pro Plus 6/Pocket PC w/Pocket Stars
Who are we? What are we? We find that we inhabit an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. ~ Carl Sagan
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Thanks, kcbridgeman, for the reference. The claim was that most of the *energy* in a fusion bomb actually comes from fission -- and that's the reference I'd like to see.
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Terry (astrotrf)
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Glaucus
member
Reged: 07/12/09
Posts: 42
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If you want humans to colonize other planets why sent the bags of water?
You would only sent a few nanobots. They then would build stuff that would build stuff that would build the factory that turns DNA into human. You can sent information through photons. So you wouldn't even sent a chip containing the data you need.
Even if you don't have nanotechnology you can just sent DNA. Yeah, it has some challenges. But I bet the space ship carrying just human DNA will overtake the ship carrying frozen bodies. The question is if the late arrivals will be unfrozen.
And unless it takes billions of years, travel time isn't really important. Only issue is the star of your destination blowing up. If you are sending stuff to other galaxies and it takes a billion years then that's not a problem either. Once you arrive you can pick a good destination system. And if that what you are sending is below a gram it doesn't take much energy to get reasonably close to light speed. Basically 100% of your mass will be fuel. And no issue of accelerations either. And when a civilization has nano technology I bet they can just build a cannon and shoot the 1 gram probe to a good fraction of light speed. So no need to carry fuel.
Edited by Glaucus (11/04/09 08:35 PM)
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kcbridgeman
member
Reged: 03/26/09
Posts: 79
Loc: Kansas City, MO
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Orion XT10/Telrad/Stellarvue F50M RACI
Numerous Eyepieces
Starry Night Pro Plus 6/Pocket PC w/Pocket Stars
Who are we? What are we? We find that we inhabit an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. ~ Carl Sagan
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groz
Pooh-Bah
Reged: 03/14/07
Posts: 1075
Loc: Duncan, BC
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Quote:
Future advances in space access, such as a space elevator (which requires possibly carbon nanotube materials technology) would greatly help.
Space elevator is a great concept for a science fiction book, and in the fiction book, where you can ignore some realities, it works well. But, if you have actually studied the concept, you would understand why it's self defeating.
First, we need the actual cable. That cable has to be built from impossiblium. Yes, I know, the hypsters talk a lot about carbon tubes, but, they dont quite understand the actual engineering problems. The tubes may well be able to be refined to the point they can withstand the tensile forces of the cable weight, but, then they wont be able to withstand the compression forces of the crawler thingies gripping them. To deal with that, we need re-inforcement, and that re-inforcement adds more mass to the cable, which increases the tensile forces. This becomes a circular problem, which wont solve. Now, once you do think you have it solved, consider now the real compression forces that have to be withstood. Surface area of a few thousand miles long, by some measureable diameter, with all these heavy crawler thingies hanging off it. It's to big a cumbersome to maneuver out of the way when there's an incoming particle arriving at 20,000 mph + in velocity, so, it's going to have to withstand the impact, without breaking, and dropping the little crawlie thingies trying to climb up to orbit. Hmm, the strenght of materials problem just got even tougher, and, we haven't yet visited the stability problems of this long slender cable touching the ground on one end, a couple miles up it's being exposed to wind velocities regularily in the 200mph range, and, it's got to stay still so the crawlie things dont fall off.
Now, lets look at the crawlie things, they sort of suffer the same problem as the enterprise D references much earlier in this thread, gotta power them. BUT, there is a distinct advantage, since they are more or less localized, we can beam power up from the base in some fashion. That doesn't require use of an element that falls between impossiblium and nogotany in the periodic table, that's just an engineering problem, that can be solved with todays technology and a few truckloads of money tossed in for good measure. So, assuming we toss the truckloads of money at the power problem for the crawlie things, and solve that one, then we are still stuck trying to figure out just what they will crawl up, or are we???
If we have the ability to beam the energy into the climbers that is required for them to do the climb, and we dont have anything for them to climb, that's an EASY problem to deal with. We rip off the stupid gripper gadgets, replace with wings, and voila, we have self contained little climbers that can fly circles above the energy source, and climb right on up there without the silly cable.
As a whole, the space elevator concept requires two problems to be solved, one of them very hard, and the second comparatively easy. But, the solution to the easy one, negates the need for the solution to the hard one. So, the space elevator will never happen, there's no point to it. Figure out how to provide an unlimited energy source to the lifting vehicle in a way that it's not 95% of the starting mass, and, you no longer need the silly cable for it to climb.
And, as another thought, since we have now figured out how to send unlimited quantities of energy to a vehicle in transit, then it's time to go back and re-visit that Enterprise D concept. It doesn't need 80x vehicle mass in fuel anymore, we will just send it the energy it needs on a similar beam, problem solved...
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
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tatarjj wrote:
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... (a "fusion" bomb, though that's a misnomer as most energy in a fusion bomb comes from fission, but I digress).
Can you provide a reference for this?
Is this maybe a reference to the fact that it takes a fission bomb inside of of a fusion bomb to produce the x-rays that are needed to create the high temperatures and pressure needed to initiate fusion? The fusion of the lithium deuteride then induces fission of the urianium-238. This fission causes the bomb to explode, so I guess the process could be considered mainly fission, but I would consider it a moot point.
How fusion bomb works.
It is not a moot point, as a "fusion" bomb gets most of its energy yield from fission. What the fusion process does is produce ALOT of high speed neutrons. These neutrons are so plentiful that they ensure that a much higher quanity of the fissile material in the "fusion" bomb actually undergoes nuclear FISSION. The U-238, normally inert, unders alot of fission as well. Remember, FISSION is caused by a neutron hitting the nucleus of an unstable atom. More neutrons = more fission, and fusion produces ALOT of neutrons. So basically, what happens is this:
1) Explode first stage of the weapon, fission bomb
2) Fission bomb causes fusion of deuterium and tritium
3) High speed neutrons cause highly efficient fission of fissile material, including normally non-fissile material (U-238)
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Look, I didn't bring up the space elevator as a central point to my arguement, it was just PART of it. I think it is POSSIBLE we may some day get it. I am DOUBTFUL it will ever be built, but I'm not about to sign off on it as being impossible as you are. If they can prove that it is a physical impossibility that any material can be strong enough to work as a space elevator cable due to some fundamental limit in the laws of physics, only THEN will I say it's impossible.
You mentioned something that reminded me of those laser-powered rockets they were looking at... what's the status of those?
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
Edited by tatarjj (11/05/09 03:04 AM)
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Thanks, kcbridgeman, for the reference. The claim was that most of the *energy* in a fusion bomb actually comes from fission -- and that's the reference I'd like to see.
Here's one, pay attention to page 5.
http://www.progressive.org/images/pdf/1179.pdf
Note that if half of the energy came from U-238 alone, that isn't even counting the first fission stage of the weapon, and then, any remaining fissile material in that first stage that gets split by neutrons from the fusion process.
Also wikipedia, while definately not the most reliable source, has information on this too:
http://en.wikipedia.org/wiki/Thermonuclear_weapon
Maybe if you follow wikipedia links to their sources, you can verify for yourself. Tell me what you find, I'd like to hear it. There's not much information about this topic out there you know...
While none of these sources are perfectly reliable, you have to understand that's all the general public has to go on. The government sure isn't going to tell us.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
Edited by tatarjj (11/05/09 03:32 AM)
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Thanks, tatarjj, for the references -- interesting reading, for sure.
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Terry (astrotrf)
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Shadowalker
Unpretentious Rocket Scientist
Reged: 11/23/04
Posts: 3537
Loc: Poplarville, MS, USA
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Space elevator is a great concept for a science fiction book....
Several good ones have been written. In Ben Bova's book (Mercury, iirc), one was constructed. Which fell down - sabotage (again, iirc). Caused a man-made disaster the entire circumference of the earth along the equator.
Anyway, that's not the point. As an under graduate a student selected as a seminar topic the physics of Ringworld. Some of you may remember Larry Niven's Ringworld, where a ring the diameter of earth's orbit is constructed around a star as a habital land mass, providing orders of magnitude more surface area than a planet.
Anyway, my classmate analyzed the forces such a structure would have to endure. Answer? not able to be built with any known material. And that didn't even address the stability issues - of which there would be plenty for a 50,000mile high tower.
Of course this was in the 70s, before the current plentiful supply of Impossibilium.
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Tom Nicolaides
http://www.first-light.org
My evil self is at that door, and I have no power to stop it
-- Dr. Edward Morbius
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Shadowalker
Unpretentious Rocket Scientist
Reged: 11/23/04
Posts: 3537
Loc: Poplarville, MS, USA
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Here's one i don't think is impossible, but has been devilishly difficult to obtain. That's Single Stage to Orbit.
All rockets launching payloads are either staged or have strap-on boosters that fall away during ascent. The reason is chemical propulsion hasn't enough energy to lift the necessary mass of a single stage vehicle.
For years we've been investigating ways to do it - many of which required large amounts of impossibilium, the salient properties being light weight and high strength.
Some of you might remember the X-33 program. It was to be a 1/3 scale of a reusable single stage to orbit space plane. To reduce weight a carbon fiber fuel tank was designed and tested. I worked that test program. We filled it with liquid hydrogen and pressure cycled it. Short answer: it leaked. A lot. Project mangement decided to go to an aluminum tank. Not long after that the program was canceled.
To reduce weight on the Shuttle, ways to reduce the weight of the external tank were looked at. How do we do it, they asked? Well, lithium's a light metal, they answered. Let's mix it with Aluminum and see what happens. So they did. Hence the invention of Mystery Metal - the Aluminum-Lithium light weight external tank. A variation of Impossibilium, this one turned out to be Possibilium.
I have a picture somewhere of that X33 tank on the test stand somewhere. I'll dig it out.
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Tom Nicolaides
http://www.first-light.org
My evil self is at that door, and I have no power to stop it
-- Dr. Edward Morbius
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 5672
Loc: Inner Solar System
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Quote:
Several good ones have been written. In Ben Bova's book (Mercury, iirc), one was constructed. Which fell down - sabotage (again, iirc). Caused a man-made disaster the entire circumference of the earth along the equator.
That's just what happened in K. Robinson's "Mars" trilogy. Makes you wonder how good an idea it even is to begin with.
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- Rick
14" LX200GPS
Dyslexics Untie!
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Michael A. Earl
vendor- Canadian Satellite Tracking and Orbit Research
Reged: 11/17/08
Posts: 1113
Loc: Brockville, Ontario, Canada
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You would only sent a few nanobots. They then would build stuff that would build stuff that would build the factory that turns DNA into human. You can sent information through photons.
Is this the definition of a perpetual motion machine? 
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dreamregent
sage
Reged: 04/06/09
Posts: 454
Loc: Clearwater, FL
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space elevator
There's a new article about this subject and NASA's little contest this week in the Mojave Desert on CNN.com. Actually, I think the most interesting part of the article is the last paragraph. It's a quote from Arthur C. Clarke.
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"Every revolutionary idea seems to evoke three stages of reaction," Clarke once said. "They may be summed up by the phrases: One, it's completely impossible. Two, it's possible, but it's not worth doing. Three, I said it was a good idea all along."
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I've read the first two arguments a number of times on this very forum...almost word for word. I'm sure that one day I'll be reading the third phrase as well. You can read the full article HERE.
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Building a f5.24 10" Dob
in an octagonal wood tube
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Glaucus
member
Reged: 07/12/09
Posts: 42
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Quote:
Is this the definition of a perpetual motion machine?
http://en.wikipedia.org/wiki/Nanobots
Edited by Glaucus (11/05/09 07:07 PM)
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llanitedave
Humble Megalomaniac
Reged: 09/26/05
Posts: 12939
Loc: Amargosa Valley, NV, USA
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Those may be the three possible reactions, but I'd be willing to bet there are plenty of those ideas that never get beyond step one or two. Therefore, you rarely hear about them.
If it gets to step three, then it's incorporated into confirmation bias.
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"Since the process of science generates more mysteries than it solves, I predict that we'll never learn everything: and we'll continue to generate new ignorance at the speed of knowledge."
"S.O.E." (Sauron's Other Eye), with 16" Royce conical mirror: A permanent work in progress.
10" Homebuilt dob, old Coulter mirror
Under Construction: The "Eye of Sauron" Observatory!
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
Quote:
space elevator
There's a new article about this subject and NASA's little contest this week in the Mojave Desert on CNN.com. Actually, I think the most interesting part of the article is the last paragraph. It's a quote from Arthur C. Clarke.
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"Every revolutionary idea seems to evoke three stages of reaction," Clarke once said. "They may be summed up by the phrases: One, it's completely impossible. Two, it's possible, but it's not worth doing. Three, I said it was a good idea all along."
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I've read the first two arguments a number of times on this very forum...almost word for word. I'm sure that one day I'll be reading the third phrase as well. You can read the full article HERE.
Excellent quote. History has shown that if something is not explicitly disallowed by the laws of physics, it is foolhardy to dismiss it as impossible. You guys telling me that space elevators are impossible would be telling me, if the year was 1909, that flying to the moon is impossible. Just because something cannot be done with today's technology, or is incredibly hard, doesn't make it impossible.
Yes, I know that we do not have a full picture of physics yet, but look at some examples. People said we would never fly, even when their laws of physics known to them at their time didn't explicitly disallow flying. They said we would never make it to the moon, even though any mid 1800s chemist could have calculated that it was possible to pack enough chemical energy into a small enough place to escape earth's gravity.
Is a material strong enough to serve as a space elevator cable physically possible? I haven't seen any physical law that says it isn't. So no one should say that it will NEVER be done. If you do, you risk getting quoted and laughed at in, fifty, one hundred, two hundred years 
Oh by the way, here's what wikipedia says about a space elevator on Mars:
"A Martian tether could be much shorter than one on Earth. Mars' surface gravity is 38% of Earth's, while it rotates around its axis in about the same time as Earth.[44] Because of this, Martian areostationary orbit is much closer to the surface, and hence the elevator would be much shorter. Exotic materials might not be required to construct such an elevator. However, building a Martian elevator would be a unique challenge because the Martian moon Phobos is in a low orbit, and intersects the Equator regularly (twice every orbital period of 11 h 6 min). A tether on Phobos may assist in journeys between Earth and Mars."
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
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Frankly, I'm still waiting for my flying car... - j
http://www.terrafugia.com/
Well that's depressing...
I just checked out their web site -- what do you find depressing about this?
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Terry (astrotrf)
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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Quote:
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Frankly, I'm still waiting for my flying car... - j
http://www.terrafugia.com/
Well that's depressing...
I just checked out their web site -- what do you find depressing about this?
That's not the flying car that's been just around the corner for the past sixty years. That's just an airplane with fold-up wings!
I want George Jetson's car! - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't.
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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It seems that the closer that someone is to a field of study, the better they understand the base nature of the limitations involved. While "impossible" is a 100% word that most scientists are not going to touch, many can be comfortable with the 99.99% chance of something not happening.
The less you know about something, the more open the possibilities are. That's the nature of ghost, UFO and Bigfoot sightings, horoscopes, paranormal activities and conspiracy theories.
The world of the ignorant is a fantastic place. It's just not real.
There's real beauty is in understanding limitations as they show the structure of our universe by defining its edges. Once an edge is known, then you look for a workaround! - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't.
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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Quote:
Once an edge is known, then you look for a workaround! - j
I like this statement. Knowledge of a limitation by one direct means like faster than light travel should not stop mankind from going to the stars. Perhaps other methods of doing so will be feasible in the future. Just because c cannot be reached or exceeded does not mean we are stranded. It merely takes the will to do some thing, and we are capable (I believe) of finding a way to start moving humanity to other stars.
Let us consider for a moment that a true doomsday is coming soon. I do not mean the 2012 junk, but a hypothetical situation that states the earth will die in 100 years. It isn't important to know how this will happen, but make it that it is an unavoidable end where our technology is not capable of saving our planet. What then? Do we sit down, and start writing our epitaph? Do we just party like its 2199?
I don't think so. I think we should spend the rest of our time doing what we can to send out a best effort colonization to another world. Whatever that method or methods are, I know that I would be much happier trying to do something to assure that humanity survives.
I know that this is a hypothetical senario, but total annihilation brings up a major difference in how one looks at the situation.
1. It removes the "who pays for it" attitude. Suddenly the ritual stuff called money becomes religated back to its original intent, and not worshiped as it is now. A dollar, or an ounce of gold or whatever becomes worthless unless it can be used to support the colonization efforts. So cost is no longer a debate.
2. I realize that humanity is hardly humane , but I do believe that there is a lot of thing worth preserving about our culture. Our art, our music, are part of what is worth saving, but the attributes of mankind are far more than that. The concepts of humanity like love, heroism, brotherhood, self sacrifice for others, and yes even our dreams and aspirations are, in my opinion, worth striving to insure their existence. So colonization becomes a moral imparative in my opinion.
Given the above hypothetical situation, I think that we could most assuredly work around the seemingly impossible stumbling blocks, and accomplish the task of space colonization. If faced with ultimate destruction, I believe that we would find a way given some amount of time to prepare, or perhaps we would at least die trying. This brings up another issue. I believe that if we did just give up and not at least try to move out into the cosmos then we deserve to go extinct. If all we do is stick our heads in the sand then what good are we? If man does not at least keep up the effort to survive then what does that say about us?
Here today, (in our present reality) the fact that we are blind to what might happen tomorow much less in a 100 or 1,000 yrs doesn't make the situation any different. Earth *IS* ultimately doomed over the course of time. We don't know when. We don't know how, but this place is not going to be here forever. Yes. We may even prolong the inevitable by pushing a few asteroids, and meteors away, but sooner or later this planet will have its number come up.
For the first time in history man is capable of actually doing the seemingly impossible like space travel. This was only reached by the hard work, sweat, and aquired knowledge of those before us that dreamed big. Are the accomplishments of space travel and colonization hard? You can bet your bippy! Are they impossible? Only if we choose to sit on our collective buttocks, and not keep striving to advance.
So "Once an edge is known, then you look for a workaround!" works for me. No matter what the goal, that statement is true as long as the outcome is valued enough.
ADD ON:
All too often I hear folks dwell on the "what we can't do" list of things. I agree that c is the law. That is not what I am saying here. What I am getting at is that we should focus on what we can do. I do not think that just because we know of some limitations that we have exhausted our possibilities. We have only ventured out of the caves into what is possible in my opinion. We should focus on what is plausible. Yes knowing what isn't viable is extremely important. It keeps us on the right path to succeed by saving a lot of trial and error. OK... Let's work out what we can do.
Edited by alanon (11/06/09 02:45 PM)
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Shadowalker
Unpretentious Rocket Scientist
Reged: 11/23/04
Posts: 3537
Loc: Poplarville, MS, USA
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"Nothing is impossible for the person who doesn't have to do it." --- Tom Nicolaides
Okay, maybe my quoting myself is a bit pretentious. To be honest, it doesn't really reflect my beliefs on this subject. I use that quote when my wife tells me that building her a new greenhouse wouldn't be all that hard
Aside from the things that are tautologically impossible I believe very few things are.
When a problem is encountered, when something looks impossible we can't really know if it is unless we try it. For example, the Space Elevator. Groz makes a very convincing case. However, anyone who's serious about building such a thing will know and understand the argement. He will see those problems and use his ingenuity to find ways around them, solve them, develop other approaches - in short, think "outside the box." (I hate that expression, btw).
You see, I don't have to build a Space Elevator, so it's trivial to me
An endeavor that requires collective resources is going to look insurmountable for a lot of reasons, most of which have little to do with the technical feasibility or difficulty. A really large endeavor takes a shared commitment and vision to overcome the really difficult problems.
Alanon's Asteroid would provide that shared commitment. Hopefully there will be a less disastrous reason.
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Tom Nicolaides
http://www.first-light.org
My evil self is at that door, and I have no power to stop it
-- Dr. Edward Morbius
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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Well said, Shadowalker. I use the doomsday senario to make a point. It eliminates the arguments of cost, and of the "put it off till later" crowd. By giving man no choice, I would assume that his chances of achieving his grasp for the stars would greatly improve.
Unfortunately, we tend to only get off our derrieres once a problem is eminant. In reality, the only real reason that got us into the serious space race to start with was the threat that Sputnik posed to us. We figured that to not ramp up to meet the technological advances of a political adversary would lead to trouble for our side. The rest of the space accomplishments like the Appolo missions was mainly just to one-up the other guy.
Lets face it... We have nearly stopped dead in the water as far as manned space flight. We are not interested as a whole to foot the bill in these times. No threat is perceived so it sits on the back burner. 
EDIT:
By dead in the water I mean in the near future. We are ultimately left without a vehicle once the shuttle is done. Also, it looks as though there is a real threat to even moving forward with the Constellation projects.
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Alanon the Wizard (a literary character, not the organization)
Dan
12.5" Obsession #1531
WO 98mm FLT (aluminum tube)
WO ZenithStarII 80mm ED
Coronado PST Ha
Edited by alanon (11/06/09 03:36 PM)
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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Unfortunately, we tend to only get off our derrieres once a problem is eminent.
And THAT will most likely be our downfall. We don't do 10 year plans, much less 100 year plans. 30 years ago, we had a major energy crisis. What did we do? We went from tiny Pintos and Gremlins to Navigators and Escalades. The evidence behind our affecting climate change is stronger than ever, but since gas prices have dropped, nobody really cares and there's a perception that the argument has weakened because of a cooler summer or two. Population soars, stretching resources thin, and we push it off to being a problem with the Chinese and Indian populations. Our collective tombstone is destined to read "I guess we should have paid attention to that".
Yes, one day the Earth will be uninhabitable. One day, the last star will burn out too. It all comes down to the timescale which you're comfortable concerning yourself with. In terms of the next 100 to 500 years, our ventures into space (much less approaching light-speed) are relatively irrelevant. Energy, food, population, disease, pollution, social conflict, water... those are going to be knocking on the door of emergency much sooner than the perceived necessity of setting up an outpost on Mars. For every brilliant mind working on a solution will be ten million happily ignorant folks going about their daily business. Same as now. Deterioration happens slowly and most people won't even notice things getting worse. They'll just hear the tales about the "good old days" from their grandparents. Like when dark skies were everywhere.
Quote:
It's not impossible. I used to bullseye womp rats in my T-16 back home, they're not much bigger than two meters.
My impossible quandary is to design a 16" f/4.5 that transports in the trunk of a Ford Focus, cools down quickly, stores in a dust-proof 1'x2'x2' container, sets up in 5 minutes, is front-side collimatible, liftable by one person, and tracks (among all other premium dob qualities). Nothing impossible to it. Just difficult. No robbing Peter to pay Paul. Something Dave Bonandrini would recommend, but Ross Sackett would put in his living room.
That's not only something I can do in my lifetime, but within the next year. It will require more work than worry and more action than anticipation, but I'll end up with more satisfaction than soliloquy. - j
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Fight indignorance!
The Green Goblin - 12" of dobsonian excellence!
The PortaBowl-a $100 4.5" f/8 ball-scope YOU can build!
Eero2-a 6" f/5 ball-scope you probably can't.
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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Hi Jay,
I totally agree that the energy, environmental, and agricultural issues are of a top priority. They are of utmost importance. HOWEVER... This does not mean that we have to stop all human endeavor to fix those. We are capable of doing more than one thing at a time.
EDIT:
I wasn't yelling however. It was just that way for emphasis.
Edited by alanon (11/06/09 04:52 PM)
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groz
Pooh-Bah
Reged: 03/14/07
Posts: 1075
Loc: Duncan, BC
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Groz makes a very convincing case.
I think you guys all missed the real point on the space elevator concept. Space elevator consists of two major problems, the 'hard' one of building the wire / whatever, then the much easier one of 'powering the climber gadgets'. But, once you solve the 'power the climbers' problem, you will discover, that same power method can power _anything_, and, you can use it to power free-flying 'climbers'. So, solving the easy part of the space elevator, removes the need for a solution to the hard part. Just power free flying lifters with whatever mechanism was invented to power the wire climbers, and, voila, you no longer _need_ the wire.
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dreamregent
sage
Reged: 04/06/09
Posts: 454
Loc: Clearwater, FL
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Quote:
It seems that the closer that someone is to a field of study, the better they understand the base nature of the limitations involved. While "impossible" is a 100% word that most scientists are not going to touch, many can be comfortable with the 99.99% chance of something not happening.
I've noticed this as well...but I've also noticed these are often the same people with the worst case of tunnel vision when it comes to innovation. Sometimes, I think the experts get so caught up in discovering every nook and cranny of the last plateau reached that they forget there is still more mountain to climb. What's discovered on the next plateau often causes revisions (and, sometimes, outright refutations) of what was found on the last one. It has been so since the beginning of what we call science. A cursory glance at the history of science will confirm this. Many scientists have made pronouncements that seemed profound for their times but have ultimately proved faulty. Their theories and "laws" of how things work get revised and refined as time goes on and more information becomes available. This still happens today and I strongly suspect there is a 100% chance it will continue to happen well into the future. However, that doesn't stop anyone from making some sort of profound discovery tomorrow and then a pronouncement that this is "the way it is." A 100 years later, "the way it is" becomes "the way we thought it was." Such is the nature of the sciences.
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Building a f5.24 10" Dob
in an octagonal wood tube
Edited by dreamregent (11/06/09 06:49 PM)
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Shadowalker
Unpretentious Rocket Scientist
Reged: 11/23/04
Posts: 3537
Loc: Poplarville, MS, USA
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Quote:
I think you guys all missed the real point on the space elevator concept. ....
I thought I got it. The hard part is building the tower. The somewhat easier part is find a way to lift the compartment that ferries passengers and cargo. Takes energy and if we solve that problem we wouldn't need to tower.
My simple mind comes up with a counterweight system - like an elevator. Surely a cable long enough could be fabricated? Could be powered electrically from the ground. Sure, we're talking about thousands of miles, but I would think we could transmit electrical power that far?
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Tom Nicolaides
http://www.first-light.org
My evil self is at that door, and I have no power to stop it
-- Dr. Edward Morbius
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groz
Pooh-Bah
Reged: 03/14/07
Posts: 1075
Loc: Duncan, BC
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solve that problem we wouldn't need to tower.
Cmon tom, step outside of your box for a little bit, put on your engineers cap, and get out the slide rule.
New problem for you. We are now building a lifter (you have a little experience with these). Unlimited energy available from outside the vehicle, it'll be beamed up using whatever mechanism the space elevator folks figure out for beaming power up to thier climbers.
Your problem, now, design a vehicle that can utilize that energy, and climb on up out of the atmosphere. It's essentially a rocket (you know about those), that doesn't need to carry fuel. But, there's a twist now, the energy we have comes in a form that doesn't burn readily. My initial thoughts are along this line. First stage propulsion modelled after a ramjet, air intake, then apply the energy in some manner (aka, we are replacing the combustion chamber with some other means of applying the energy), then exhaust of highly acclerated air. This is essentially the same problem you work at in the work-a-day world, with one little twist. This vehicle doesn't need to carry fuel. How much easier can the life of a rocket scientist get? A vehicle with an unlimited energy supply, and the fuel adds zero mass to the all up liftoff mass....
But, you know what, I got a sneaking suspicion you will _still_ come up with a two stage final configuration. Stage one will take advantage of aerodynamics and that abundant source of reaction mass called 'atmosphere', while stage two will have to work some other way....
Then again, with unlimited energy available, maybe we can figure out how to work against earths magnetic field, and, do away with reaction mass altogether......
My point being, once that energy source is under control, there's a lot of different ways to use it, and, the wire hanging down from space is probably the _least likely_ to end up being a practical application.
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jayscheuerle
Post Laureate
Reged: 01/16/06
Posts: 4071
Loc: S. Philadelphia, PA
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So if your space elevator is propelled by a super-strong laser beaming microwaves to it so that it can climb up a tether, then why not just use 10 lasers so that it can just power itself up through the atmosphere? OR 100? OR 1000?
At a certain point, we think that "okay, the laws of physics allow it", but harvesting the energy, though physically possible, may still be a daunting task. Just because something works in sound theory doesn't mean it works in day to day reality. - j
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Fight indignorance!
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ColoHank
professor emeritus
Reged: 06/07/07
Posts: 515
Loc: western Colorado
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Some of these posts are beginning to sound like, "If we had any eggs, we could have ham and eggs, if we had any ham."
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Questar 3.5 standard - pyrex and BB coatings
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Shadowalker
Unpretentious Rocket Scientist
Reged: 11/23/04
Posts: 3537
Loc: Poplarville, MS, USA
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Quote:
Cmon tom, step outside of your box for a little bit, put on your engineers cap, and get out the slide rule....
Oh geez, you gonna make me think? Okay, let's use some easy numbers. Let's say our payload's mass is 1000 kg - about the capacity of a typical elevator. We want to hoist our payload to geosynchronous altitude - abpout 42,000km. Because all the faring and housing is counterweighted, all we need concern ourselves with is the payload mass.
Now, a typical elevator might use a 100hp motor and hoist such a load 1 meter per second. So this elevator, assuming no stops in the lingerie department, would take 42,000,000 seconds to get there. A year and some change and we can release our comm satellite to beam porn to all of North America.
Now, we probably want to go faster. Assuming reciprocity holds, we should be able to use a 1000HP motor to make it go ten times as fast. A 10,000 HP motor and we can get there in about 4 days.
At about 1 KW per horsepower, that certainly doesn't seem excessive.
Obviously I'm missing something. Maybe my engineer's hat. I have one here somewhere. I wore it last when I presented my son his diploma. A mechanical engineer, but he can be forgiven for that.
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Tom Nicolaides
http://www.first-light.org
My evil self is at that door, and I have no power to stop it
-- Dr. Edward Morbius
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
I think you guys all missed the real point on the space elevator concept. Space elevator consists of two major problems, the 'hard' one of building the wire / whatever, then the much easier one of 'powering the climber gadgets'. But, once you solve the 'power the climbers' problem, you will discover, that same power method can power _anything_, and, you can use it to power free-flying 'climbers'.
Unless, of course, the wire itself becomes part of the solution to powering the climber gadgets.
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If we have the ability to beam the energy into the climbers that is required for them to do the climb, and we dont have anything for them to climb, that's an EASY problem to deal with. We rip off the stupid gripper gadgets, replace with wings, and voila, we have self contained little climbers that can fly circles above the energy source, and climb right on up there without the silly cable.
If we "beam" power to the climbers, will it be more efficient to have the climbers use that power to physically climb a cable, or use that power to "fly" somehow? And how would such a climber use the beam power to fly outside the atmosphere (or, for that matter, above, say, 20 miles)?
I don't think it's a foregone conclusion that beam-powering the climbers obviates the need for the cable.
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Terry (astrotrf)
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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I think we should spend the rest of our time doing what we can to send out a best effort colonization to another world.
Alanon, I agree with you. But something *I* accept as impossible is getting most of humankind to agree with us on this.
In the first place, if it won't happen for 100 years, nearly everyone will be content to ignore the problem for at least 50 years and perhaps 75. There will also be a large segment of folks who argue that we should do nothing and meekly accept our fate. Another large segment of folks will argue that we should do nothing because a miracle will save us at the last second (and some of these will go on TV to claim that this miracle won't occur unless you send them money -- call 1-800-DOOMSDAY and give generously). And another segment will argue that we shouldn't send humans into space; we should instead send a robot tending a bag of water filled with blue-green algae.
Then there'll be the folks who go to court to stop the projects to save humanity or prevent the disaster because of the environmental damage the projects would cause, particularly if it became necessary to drain a wetland, dam a river, cut down a tree, or build a power plant.
The real losers will be the folks who always say that the money could be *so much better spent* on <insert their favorite cause here>; they'd be hard-pressed to maintain that claim any longer (though some would undoubtedly try).
Then, the day before it happens, they'll all look at us and say, "Why didn't you *do* something?" My response at that point would be, "What for?"
(Yeah, I woke up surly this morning. Why do you ask? )
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Terry (astrotrf)
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InkDark
Carpal Tunnel
Reged: 10/29/07
Posts: 1837
Loc: Montreal, Canada
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How depressing would it be to one day just accept that we can't travel the stars? I could never accept that..
I don't find the idea depressing at all; quite the contrary. Reassuring, if anything.
Accepting one's limitations and learning to make the best of them is called "growing up." Without limitations, we would all be lost souls.
I see no reason to believe that humans will ever travel to other stars, but there are infinite other, more meaningful things that we can do. Most of which we probably can't even imagine now.
I would agree 110%, but that's impossible. So I'll agree 100%.
I think that we humans tend to think that we have an unprecedented control over nature, which is a complete illusion in my opinion.
I don't this has anything to do with thinking we have unprecedented control over nature. We're not talking about changing the rules that nature abides by, we're talking about figuring out how to make the rules apply to everything. Nature says that C is a speed limit that nothing can go faster than, but there is no rule saying other things cannot attain speeds of say 99.99% of C. The only rule is you cannot go C. We may not know how to get there now, nor may we ever, but it doesn't mean it isn't possible. ...
Although it is true that we don't know the limits, I think that we should expect that there are limits. If someone was to ask if we will eventually be able to downsize our bodies to the size of elementary particles and navigate through the quantum world, most of us, if not all, would find the question pretty silly. Of course we would never think that it is possible. So why do we "feel" that we can conquer vast distances?
Our bodies are struggling with the physical world everyday. If we fall from tiny heights we get injured, our bodies are getting oxidized by the same oxygen that we breath,...even our cars rust and ware out. We cope with nature but it is not easy. This let me think that this world is not « made » for us, so limits are expected and probably real. This is of course only my opinion.
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Jimmy
If you could stop time, for how long would you stop it?
"...since that time, I have not complained about the weather one single time. I’m glad there is weather." – Alan Bean, Apollo 12
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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Hi Terry,
You do bring up a very valid observation of things as they are , and quite probably as they would be in my hypothetical senario. I would, however, hope that at least the ratio of folks willing to do the work needed to save mankind would increase.
You did miss one group though... Those are the ones who will refuse to believe that the inevitable disaster really exsists. You know the kind. The "what energy crisis" or "what moon landing" crowd? They are alway a great addition to the throng of naysayers.  
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Alanon the Wizard (a literary character, not the organization)
Dan
12.5" Obsession #1531
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5025
Loc: Mobile, Alabama, USA
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I think someone will find a way around the light barrier before they can convince a cat it's on the right side of a door.......
Taras
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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
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Two curious cats
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
You did miss one group though... Those are the ones who will refuse to believe that the inevitable disaster really exsists. You know the kind. The "what energy crisis" or "what moon landing" crowd? They are alway a great addition to the throng of naysayers.
You are quite right; how could I possibly have forgotten the "it's all a government conspiracy" crowd?  
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Terry (astrotrf)
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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From what I understand from the laser powered rockets, we cannot drive them into orbit on just laser power alone. This is because these craft require a dense atmosphere. What would be more likely is a laser-powered craft that ignited a rocket motor once it got high enough so that the lasers were no longer accelerating it.
As far as "oh lets remove the cable"! from the space elevator, I see it unlikely as removing the need for the cable. Why? Well, the crawler needs something to crawl against, of course. Beaming power up to the crawler does not automatically eliminate the need for the cable. A rocket would have to expend energy just to HOVER, but a crawler would expend none just to hang on the cable not moving.
More likely, the space elevator will not be built because it is either too costly, too hard, impossible, or we simply find a better way of getting into space, maybe like a laser powered first stage and then a small chemical second stage rocket.
Another reason the space elevator might not happen is that we're polluting space with no end in sight, and a cable would be very vulnerable to space debris.
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John T.
Austin, TX
25" f/4.2 Dob
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8X56 Binos
Edited by tatarjj (11/07/09 11:46 PM)
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astrotrf
professor emeritus
Reged: 09/30/07
Posts: 703
Loc: Rodeo, NM
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Quote:
From what I understand from the laser powered rockets, we cannot drive them into orbit on just laser power alone. This is because these craft require a dense atmosphere. What would be more likely is a laser-powered craft that ignited a rocket motor once it got high enough so that the lasers were no longer accelerating it.
And the problem with *that*, of course, is that now you've got to hoist all of that rocket fuel off the ground, along with the craft and its payload.
Crawling up a cable looks like the best idea to me, too.
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Terry (astrotrf)
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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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Another major problem with long-haul manned space exploration that is not likely to be solved anytime soon is that of radiation exposure. Until someone comes up with a way to provide lightweight yet effective shielding from highly energetic ionizing radiation, it is not clear that even manned interplanetary exploration would be safe.
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Kobayashi
sage
Reged: 07/10/08
Posts: 375
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Quote:
I think you guys all missed the real point on the space elevator concept. Space elevator consists of two major problems, the 'hard' one of building the wire / whatever, then the much easier one of 'powering the climber gadgets'. But, once you solve the 'power the climbers' problem, you will discover, that same power method can power _anything_, and, you can use it to power free-flying 'climbers'.
I think you're missing the whole point of a space elevator. The purpose of the tower/wire is to provide something to push (or pull) against. Pulling yourself up a rope is far more efficient than pushing yourself against thin air. Climbing a ladder to the 2nd floor is easy; flying a human-powered helicopter to the same height is so difficult that nobody has done it yet.
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-- Ken Kobayashi
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moynihan
Carpal Tunnel
Reged: 07/22/03
Posts: 1604
Loc: Wisconsin
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...I use the doomsday senario to make a point. It eliminates the arguments of cost,...
That would still be argued about  
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"Gosh, you've... really got some nice toys here"
Dual mount/ambient temperature Hominid Widefield Photon Collectors®
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alanon
Nobody tells me anything
Reged: 06/29/07
Posts: 2611
Loc: Las Vegas
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That is funny, moynihan. Unfortunately it is true though. There are a lot of folks that I know that I think would take their cash to the grave with them rather than spend it. 
I should change that line to. It would minimize as much as possible the money issue.
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Alanon the Wizard (a literary character, not the organization)
Dan
12.5" Obsession #1531
WO 98mm FLT (aluminum tube)
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