Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Inserting dark energy where push is needed to make the universe expand at the rate it does help in building on higher level theories and hypothesis, but I was wondering, how many people actually believes there is such a force compared to simply not understanding gravity and other "normal" forces completely?
The same with dark matter - it makes the maths work out nicely in predicting or reversing the rotation of galaxies, and in this sense use it by all means, but really - don't you think it's just a matter of we're not entirely understanding gravity and other physics at such huge scales? Einstein fine tuned a lack in Newtons' theories on gravity on a stellar scale, maybe theres more finetuning needed for a galactic scale?
It just sounds like another string theory...
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
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Pess
Brackets
Reged: 09/12/07
Posts: 1752
Loc: Toledo, Ohio
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Quote:
Inserting dark energy where push is needed to make the universe expand at the rate it does help in building on higher level theories and hypothesis, but I was wondering, how many people actually believes there is such a force compared to simply not understanding gravity and other "normal" forces completely?
The same with dark matter - it makes the maths work out nicely in predicting or reversing the rotation of galaxies, and in this sense use it by all means, but really - don't you think it's just a matter of we're not entirely understanding gravity and other physics at such huge scales? Einstein fine tuned a lack in Newtons' theories on gravity on a stellar scale, maybe theres more finetuning needed for a galactic scale?
It just sounds like another string theory...
The trouble with string theory is that the theory itself can be modified an infinite number of ways to account for just about anything.
Also at this point it has no predictive value for anything that can be directly tested.
Dark energy and dark matter sound like cool names but basically they are just the nomenclature assigned to describe observations of invisible mass & an anti-gravitational effect observed in the cosmos.
You could just as easily called them the Mickey Mouse and friends effect.
Since mass-stuff is the only known thing that produces a gravity field and since we don't have a clue the nature of exactly what this unobservable (so far) extra mass-stuff is...the term 'Dark Matter" almost applies itself.
Pesse (Isn't String Theory a way to help remember stuff while on an errand?) Mist
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12" RCX400
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Custom Wyorock focuser for refractor
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Todays Quote: "A friend will bail you out, but a great friend is the one next to you who thought your idea to drill through the bilge was inspirational!"
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Ok, so you see it too as an effect and not necessarily something real. There seem to be a lot of effort going into finding Mickey Mouse and friends in stead of improving our understanding of gravity!
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
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jayscheuerle
Carpal Tunnel
Reged: 01/16/06
Posts: 2843
Loc: S. Philadelphia, PA
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I believe we're in the dark when it comes to completely understanding energy and matter. Does that count?
As long as we're asking questions and looking for answers, we have to have some sort of name to refer to these effects. I like that "dark" is used as it accurately reflects our ignorance right now. I wouldn't be surprised if in the future, if confirmed, these names will have some scientists' surname tagged to them.
Dark Chocolate, Dark Beer, Dark Energy and Dark Matter. It's all good.  - j
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12" Green Goblin (trusser w/Protstar secondary and OWL refigured primary)• 6" f/5 Eero2 ball-scope • 6" f/5 Frankenscope • Garrett Optical 10x50 binos • Edmund 8" yoke-mounted red-tube reflector • Edmund 6" GEQ red-tube reflector (on loan to Dad)
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Skyquest XT8 • NexSTar 8i • Eeroscope 6" f/5 ball(sacrifice was not in vain) • Vixen ED80sf • Edmund red-tube 4.25" f/10 • Edmund Astroscan
Facts are stubborn things.
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Yes, but I feel we're searching in the wrong place. Should not be looking for something invisible or energetic floating in space, but study gravity itself.
For instance, one of the missions of the LHC is to create dark matter. Rather look for the Higgs bozo. I mean bozon.
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
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HiggsBoson
professor emeritus
Reged: 02/21/07
Posts: 734
Loc: Kal-li-fornia
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I am new to mirror making. Many of my friends ask me why I use glass rather than metal for mirrors. They ask why I grind by hand. Some say that it is not possible to get a smooth accurate surface by hand grinding. Others suggest that I should mold a mirror.
Those who have not studied mirror making are completely unaware of why I should proceed as I do. It is easy for them to find fault just due to the fact that they have not looked at the problem. The procedures I use have been developed by trial and error over decades. It is unlikely that someone who has not considered or studied mirror making is going to find an obviously better way just by thinking about it for 5 minutes.
Similarly, science is done using a procedure called the Scientific Method. The results and speculations you see in print are the results of years of study and decades of developments building upon earlier work. I suggest that someone who has not followed this progression of work would not easily understand why the current consensus has been developed and is in a poor position to criticize it.
At there edge of science there must be speculation. One wrong speculation leads to another. The outcome of experiments naturally eliminates the wrong ones. But without the publication of wrong postulate and the discussion that follows the process of probing and error and correction can not move forward.
Dark matter is a specific postulate that would explain a particular observation. The postulate has testable consequences and about 2 years ago a photo was taken that appears to show a separation between baryonic mater and dark matter in a collision between galaxies. The photo shows baryonic matter of a galaxy in one position and gravitational lensing of light from behind the collision in a different position. The separation of the two is consistent with expectations that dark matter would not be slowed by the collision as much as the baryonic matter.
Rather than simply declare the silliness of the dark matter postulate, perhaps you could explain this observation using some other postulate?
The universe has been observed to expand. Einstein’s general relativity predicted this expansion prior to its observation. Einstein thought that this was silly and made what he called the biggest blunder of his career by changing the math to eliminate the expansion. This is typical of what happens when humans do physics based upon what they think is silly rather than follow the scientific method. GR carries a built in prediction of the expansion that has been observed and therefore does not require modification to explain it. The error here is giving this feature a separate name. The expansion is inherent feature of the current best description of gravity.
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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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Pess
Brackets
Reged: 09/12/07
Posts: 1752
Loc: Toledo, Ohio
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I'm all for understanding gravity better. If you know how to go about that feel free to speak up.
Gravity has come full circle. Before it was a 'force' like any other. Then Einstein made it a geometric consequence of mass distorting the fabric it sits in. Now we are back to describing gravity as a distinct 'force' perhaps leaking out of other, folded up, dimensions.
Our current theories of the universe are mere weak approximations until gravity is 'folded in'. (ouch! bad pun!)
Newton had all the theory we needed until Relativity completely reshaped the landscape which was again reshaped by quantum mechanics.
I think we are overdue for anther shake-up. Although it can be argued that Einstein's eureka moment was aberrantly early along the evolutionary time line of theoretical physics development.
As an aside, I just submitted my patent for a FTL radio.
It works like this:
1) Create a tiny black hole with a particle accelerator.
2) This black hole evaporates in a wash of Hawking radiation.
3) Since Hawking radiation arises from Virtual particles pulled from the vacume energy of the universe, quantum probability means that they can be anything and posses any energy (even negative energy and mass). The group of particles with negative energy & mass are termed tachyons.
4) Just like a regular radio set can alter ambient electrons into an ordered pattern a radio or TV receiver can decipher, a (yet to be developed) radioset next to the evaporating blackhole can order these newly created tachyons as they streak away at FTL speeds.
5) A receiver elsewhere in the universe can detect these tachyons and decipher the pattern just as a traditional radio captures radiating electrons and deciphers their pattern into displayable radio and television broadcasts.
Pesse (Hello grandma? I just wanted to call and talk to you before you died tomorrow.) Mist
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Fantastic Patent!!
..but risky dont you think? Wouldnt the tiny blackhole hit the ground like a million tonnes of bricks and then start making its way to earths core, after which things get worse... ?
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
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Pess
Brackets
Reged: 09/12/07
Posts: 1752
Loc: Toledo, Ohio
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Quote:
Fantastic Patent!!
..but risky dont you think? Wouldnt the tiny blackhole hit the ground like a million tonnes of bricks and then start making its way to earths core, after which things get worse... ?
Nope.
Blackholes evaporate via the Hawking radiation which carries away their energy (mass).
The smaller the blackhole, the faster the evaporation rate.
Microscopic blackholes would vanish in a splash of Hawking radiation.
In fact we could be making blackholes in the lab in the very near future when the Large Hadron Collider comes online.
Pesse (A Man-made Black Hole that destroyed the Earth would really suck big time!) Mist
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12" RCX400
WILLIAM OPTICS 110mm APO ZENITH STAR refractor
Custom Wyorock focuser for refractor
SBIG ST2000XM
CFW-10
Astrodon Series I LRGB
Douglas Schwan DC
Befuddled visual observer, bewildered astrophotographer, bemused tinkerer.
Purveyor of cognitive dissonance.
Todays Quote: "A friend will bail you out, but a great friend is the one next to you who thought your idea to drill through the bilge was inspirational!"
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Mike Casey
Postmaster
Reged: 11/11/04
Posts: 5855
Loc: Pasadena CA
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The existence or nonexistence of Dark Energy and/or Dark Matter is not dependent on whether one believes in the existence or nonexistence of Dark Energy and/or Dark Matter.
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Mike (tVA)
"The series of weapons tests had fused the sand in layers, and the pseudo-geological strata condensed the brief epochs, micro-seconds in duration, of thermonuclear time." ~ J. G. Ballard
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Mike K
sage
Reged: 04/01/07
Posts: 418
Loc: Central Texas
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Quote:
..but risky dont you think? Wouldnt the tiny blackhole hit the ground like a million tonnes of bricks and then start making its way to earths core, after which things get worse... ?
See here.
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Clear skies,
Mike K.
30°31" N 97°44" W, LP: Red
Observe: Once or twice a week back yard, once a month under dark skies
Favorites: Globulars, planets, face-on spirals
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Quote:
The existence or nonexistence of Dark Energy and/or Dark Matter is not dependent on whether one believes in the existence or nonexistence of Dark Energy and/or Dark Matter.
Of course.
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
Celestron NexImage Webcam
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Quote:
See here.
Yikes. There's enough square root and sigma symbols in that pdf to re-assure me!
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
Celestron NexImage Webcam
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My Jupiter|My Company
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Pess
Brackets
Reged: 09/12/07
Posts: 1752
Loc: Toledo, Ohio
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Quote:
The existence or nonexistence of Dark Energy and/or Dark Matter is not dependent on whether one believes in the existence or nonexistence of Dark Energy and/or Dark Matter.
Something exists which exerts an observable influence on the universe.
As long as these observations can be trusted not to be observational artifacts, it really doesn't matter what we call their cause.
Pesse (Personally, I prefer Deity joke #7) Mist
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12" RCX400
WILLIAM OPTICS 110mm APO ZENITH STAR refractor
Custom Wyorock focuser for refractor
SBIG ST2000XM
CFW-10
Astrodon Series I LRGB
Douglas Schwan DC
Befuddled visual observer, bewildered astrophotographer, bemused tinkerer.
Purveyor of cognitive dissonance.
Todays Quote: "A friend will bail you out, but a great friend is the one next to you who thought your idea to drill through the bilge was inspirational!"
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HaleBopper
sage
Reged: 01/14/08
Posts: 216
Loc: Great White North
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HiggsBoson, you make some excellent points. I think the best we "non-pros" can do is read up on the subject matter and try to understand why certain theories are put forth. Whether we choose to accept what we read is another case. Bottom line, results obtained through scientific experimentation, and scrutiny, trump all feelings and opinions.
Having said that, as a non-pro, I don't really have a hard time accepting the dark matter idea. It's not new. Fritz Zwicky in the 1930s postulated its existence. Through the years, evidence mounted in support of that notion.
As for dark energy, although not settled, it's just my personal belief that it will be proven. For instance Einstein showed mathematically that gravity depends not only on mass and energy, but also on pressures exerted. Gravity can be repulsive as well as attractive. The cosmological constant, if it turns out to be correct, exerts an overall repulsive force. Is this correct? Who knows, maybe it's wrong after all...
In a nut shell, this is what I gather from reading Brain Greene's "The Fabric Of The Cosmos." He does a good job explaining the physics to the "masses" without invoking the complicated math. Given that these theories involve a lot of complicated math, I think we can appreciate that it's not an easy thing to explain to the general interested public. Many of us simply take it on faith. Either way, it's very interesting reading and I recommend it. Just know that you'll probably have read it about 10 times to fully understand the material as written. I'm only on the 4 th reading 
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8" SCT CG5 mount
Canon Digital Rebel 400
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Dipole
sage
Reged: 12/21/06
Posts: 398
Loc: Right behind you
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Dark matter/energy is just a step, like a place holder in a book.
We have a theory of gravity that works up to a point. We get to that point and we start seeing observations that don't fit our model. So we need to adjust the model to fit observations.
The new model requires "dark matter" and "dark energy" to provide a solution that meshes the theory to the observation.
Now we are at the next step... finding out if we are on the right track! Today there are several experiments in the works to try and detect dark matter and energy. If they succeed yippee. If not then we know the "dark" solution to the problem is not correct and we need to pursue other ideas.
Most theories fall apart but open the door for other ideas and that's where the real science comes in!
So does dark matter or dark energy exist? Yes, as a way to express something we don't yet understand.
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Sorry Michael I missed your post earlier - I saw something about lens making and thought I was on the wrong forum! 
Of course, I'm totally aware that I'm just skimming the very top of a very deep and academic field and thanks to the stunning work done by professionals, we can look at the results and draw our own conclusions.
Therefore I'm wondering if someone else out there had the same idea as I. Perhaps I came over ignorant! 
As for the colliding galaxy picture, I could postulate that some unkown properties of gravity from normal matter cause the specific lensing at that specific position. It could have something to do with gravitational waves or a type of wake caused by the normal matter passing through. However, I know precious little about this example so I'm afraid you've got me there!
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
Celestron NexImage Webcam
7mm SWA 58° Plössl
My Jupiter|My Company
Edited by Taqyon (07/11/08 04:54 PM)
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Quote:
As for dark energy, although not settled, it's just my personal belief that it will be proven. For instance Einstein showed mathematically that gravity depends not only on mass and energy, but also on pressures exerted. Gravity can be repulsive as well as attractive. The cosmological constant, if it turns out to be correct, exerts an overall repulsive force. Is this correct? Who knows, maybe it's wrong after all...
This I can live with - that it's a repulsive force generated from gravity. Feels right 
Quote:
In a nut shell, this is what I gather from reading Brain Greene's "The Fabric Of The Cosmos." He does a good job explaining the physics to the "masses" without invoking the complicated math. Given that these theories involve a lot of complicated math, I think we can appreciate that it's not an easy thing to explain to the general interested public. Many of us simply take it on faith. Either way, it's very interesting reading and I recommend it. Just know that you'll probably have read it about 10 times to fully understand the material as written. I'm only on the 4 th reading
Sounds like an excellent read, will look it up!
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
Celestron NexImage Webcam
7mm SWA 58° Plössl
My Jupiter|My Company
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HaleBopper
sage
Reged: 01/14/08
Posts: 216
Loc: Great White North
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I think you'll enjoy it. There are lots of books out there on the subject but I found his book quite good.
When you do read it, start up another thread. It should make for some fine discussion!
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8" SCT CG5 mount
Canon Digital Rebel 400
Kodak Easyshare 2.0 Megapixels
5, 8, 13, 17, 21, 24mm Orion Stratus
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Taqyon
sage
Reged: 06/17/08
Posts: 211
Loc: Cape Town, South Africa
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Hehe, I'm just deciding between the hard copy or the audible..
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Hein du Plessis
8" Skywatcher Collapsible Dobsonian
Celestron NexImage Webcam
7mm SWA 58° Plössl
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