Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Speciality Forums >> Science! Astronomy & Space Exploration, and Others

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | >> (show all)
Otto Piechowski
Pooh-Bah


Reged: 09/20/05

Loc: Lexington, KY
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5446758 - 09/29/12 12:56 PM

I just realized I do not know what Curiosity has been designed to detect in terms of direct evidence of life? If you know, please share!

E.g. indisputable organic chemistry? photos of microbial fossils? ?

Otto


Post Extras: Print Post   Remind Me!   Notify Moderator  
Otto Piechowski
Pooh-Bah


Reged: 09/20/05

Loc: Lexington, KY
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5446774 - 09/29/12 01:08 PM

Long before the movie Contact was made, I read what I think was Sagan's book on which Contact was made. If you read it you may recall that the "tangible" evidence of contact with extra-terrestrial intelligence was not the 18 hour blank tape, but sand in the traveler's pocket.

Anyway, I don't recall if the book had the 1 million figure or not. But that statement did show up in the movie. In the movie Jodie Foster says, " "There are 400 billion stars out there, just in our galaxy alone. If just one out of a million of those had planets, and just one in a million of those had life, and just one out of a million of those had intelligent life, there would be literally millions of civilizations out there."

Besides myself, did you catch the oddness of the math in that statement. A million of a million of a million of 400 billion is......4X10^11 divided by 10^6 is 4X10^5, 4X10^5 divided by 10^6 is .4. .4 divided by 10^6 is 4X 10^-7.

If we allow Jodie was saying, out of all galaxies, then we have 4X10^11 times 1X10^11 galaxies which equals 4X10^22 stars. 4X10^22 divided by 10^6, divided by 10^6, divided by 10^6 is 22-6-6-6 or 4X10^22-18 which works out to, what? 40,000 throughout the universe.

So (and please, correct my math) either the movie (Sagan?) is saying we come up with 40,000 intelligent civilizations throughout the universe or that there is a .00004% chance of one intelligent civilization in the Milky way (.0000004 X 100X).

Edited by Otto Piechowski (09/29/12 01:09 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5447025 - 09/29/12 03:54 PM

Quote:

Jarad, are those figures including the affect of the Heliosphere, or do we not know how exactly that boundary affects signals?



I assumed perfect transmission through vacuum (no blocking by anything). But I did forget to include the constant of 4*pi in the denominator, so it should actually be closer to 1x10^-19 watts per square mile...

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: The silence is deafening.... new [Re: Otto Piechowski]
      #5447032 - 09/29/12 03:58 PM

Quote:

Anyway, I don't recall if the book had the 1 million figure or not. But that statement did show up in the movie. In the movie Jodie Foster says, " "There are 400 billion stars out there, just in our galaxy alone. If just one out of a million of those had planets, and just one in a million of those had life, and just one out of a million of those had intelligent life, there would be literally millions of civilizations out there."




Yes, with those numbers we would only expect 0.4 planets with life per galaxy, and only 1 intelligent life per 250,000 galaxies.

But like I said earlier, we really don't know what the odds are. And we haven't looked closely enough at any other planets to spot anything other than someone nearby shining a mega-terawatt laser right at us. And there really isn't much reason to think they would be doing that, since we haven't sent out anything powerful enough for them to notice.

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
simpleisbetter
Carpal Tunnel
*****

Reged: 04/18/11

Re: The silence is deafening.... new [Re: Jarad]
      #5447173 - 09/29/12 05:41 PM

Quote:

I assumed perfect transmission through vacuum (no blocking by anything). But I did forget to include the constant of 4*pi in the denominator, so it should actually be closer to 1x10^-19 watts per square mile...

Jarad




Thanks, so basically it's just not going to happen using SETI's current search methods, so we're wasting a lot of time and money on it.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Qwickdraw
Carpal Tunnel
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: The silence is deafening.... new [Re: Otto Piechowski]
      #5447219 - 09/29/12 06:17 PM

Quote:

I just realized I do not know what Curiosity has been designed to detect in terms of direct evidence of life? If you know, please share!

E.g. indisputable organic chemistry? photos of microbial fossils? ?

Otto




Otto,

As far as I know the only instrument on board curiosity which has been designed to detect direct evidence of life are the cameras. So if we can photograph a bloom of algae or liken or an orange furry creepy crawler well, that would most likely be real evidence of life but don’t count on it.
Mars is far and away the closest model of Earth ever discovered and so far has been proven to be void of life.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Qwickdraw
Carpal Tunnel
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5447229 - 09/29/12 06:20 PM

Quote:

Quote:

I assumed perfect transmission through vacuum (no blocking by anything). But I did forget to include the constant of 4*pi in the denominator, so it should actually be closer to 1x10^-19 watts per square mile...

Jarad




Thanks, so basically it's just not going to happen using SETI's current search methods, so we're wasting a lot of time and money on it.




Exactly !


Post Extras: Print Post   Remind Me!   Notify Moderator  
Otto Piechowski
Pooh-Bah


Reged: 09/20/05

Loc: Lexington, KY
Re: The silence is deafening.... new [Re: Qwickdraw]
      #5447248 - 09/29/12 06:32 PM

Would you know if there is a microscope on Curiosity? and if so, what if magnifies and in what light?

Otto


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5447559 - 09/29/12 09:29 PM

Quote:

Thanks, so basically it's just not going to happen using SETI's current search methods, so we're wasting a lot of time and money on it.




We're not going to detect someone of our technology level and energy output. We could potentially detect someone who is much more advanced than us, if they are spending more energy than we can manage on trying to be noticed.

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
simpleisbetter
Carpal Tunnel
*****

Reged: 04/18/11

Re: The silence is deafening.... new [Re: Jarad]
      #5447577 - 09/29/12 09:47 PM

And that's where I see a flaw with the approach. Let's suppose someone were out there and just by chance decided our system looked favorable to send a hi-power directed (focused) beam message to. Based on your figures, and overcoming external EM influences, how much power would be needed to generate a burst signal to the magnitude necessary for us to detect, receive, and still be able to interpret it?

Edit - without knowing the figures, I did a bit of contemplating. Would it be safe to say the power required to generate such a directed beam signal that we might be able to detect would be greater than the power stored in a CME? I know we can't detect a CME on distant stars at present so it must be greater than that. Which means far greater than all the power stored in all the worlds nuclear weapons? That would seem a safe assumption of how much power would be needed to send a detectable, momentary, interplanetary signal, in one direction.

Edited by simpleisbetter (09/29/12 10:36 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
stephen63
sage
*****

Reged: 05/19/10

Loc: Central Pa
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5447904 - 09/30/12 03:03 AM

I googled "Minimum Discernible Signal for SETI receivers" and found an interesting paper. Curiously, table 2 uses signal levels at 10 LY. Link:
http://www.coseti.org/paper_01.htm


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: The silence is deafening.... new [Re: stephen63]
      #5448049 - 09/30/12 08:31 AM

That table assumes tightly focused laser transmission, which of course would require much less power than a non-directional signal.

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jason H.
Pooh-Bah


Reged: 11/23/07

Loc: Central Florida
Re: The silence is deafening.... new [Re: simpleisbetter]
      #5448955 - 09/30/12 06:33 PM

It's A LOT MORE difficult than most understand. I think this article might clarify things for some

http://www.setileague.org/articles/range.htm

You can run the numbers yourself with this SETI Range Calculator by pressing "Click to calculate results" and see the default values play out

http://www.satsig.net/seticalc.htm

There a 50 meter wide antenna (i.e. narrow beam-width of large scope concentrates power) transmitting at 60,000 watts at the same frequency as satellite TV only goes 22.9 light years to a receiving dish of the same size (i.e. a humongous dish.) If one changes the receive dish size to the size of one dish on the Allen Telescope Array (not built as designed BTW because of the lack of funds that some seem so concerned about) then the distance is less than 4 light years that it's detectable at that power!

Jason W. Higley


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mister T
Pooh-Bah


Reged: 02/01/08

Loc: Upstate NY
Re: The silence is deafening.... new [Re: Jason H.]
      #5448981 - 09/30/12 06:47 PM

I am curious how this might be compared to the signals we receive from the Voyager probes?

How much power do they transmit with and how "wide" of a beam do they use?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jason H.
Pooh-Bah


Reged: 11/23/07

Loc: Central Florida
Re: The silence is deafening.... new [Re: Mister T]
      #5449157 - 09/30/12 08:46 PM

Quote:

I am curious how this might be compared to the signals we receive from the Voyager probes?

How much power do they transmit with and how "wide" of a beam do they use?




Although I'm just a fan (and not pretending to be a SETI or radio scientist) a while back I had written (as there were several SETI @ home top candidates that caused me to) that Voyager II had a ~3.66 Meter High Gain Antenna (which I imagine one could make rudimentary beam-width estimates with, not knowing the actual beam form/shape and how the side lobes are.)

Back then I had come up with (but I don't remember how I did it) a beamwidth that was ~2.2 degrees at S Band and ~0.6 degrees at X Band.

I've heard several times over the years that Voyager's transmit power is only ~20 watts and at the Earth-based antennas the power received was compared to being 20 billion times smaller than the power of a watch battery or less than the energy released by a snowflake hitting the ground (although I couldn't personally back that up; it's obviously a tiny amount of energy, and my primative/ignorant calculations show that it may only be detectable to less than 1 light day away? But since Voyager 1 is only ~16 light hours away, and Voyager 2's almost 14 light hours away, I guess we'll be good-to-go for awhile with current technology.)

This may also be of interest

http://www.space.com/6014-seti-signal-detectors-allen-telescope-array-light-faint-fiducials.html

and this one I found tonight that had a lot of info that was radio telecom specific for Voyager

http://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf


Jason W. Higley

Edited by Jason H. (09/30/12 10:23 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jason H.
Pooh-Bah


Reged: 11/23/07

Loc: Central Florida
Re: The silence is deafening.... new [Re: Jason H.]
      #5449360 - 09/30/12 10:56 PM

Just adding, I saw this one

http://www.unmannedspaceflight.com/index.php?showtopic=6924

where the guy says of the Voyager's that the "Signal strength for both is down to around -160dbm through the Network's big 70-metre antennas."

I believe that's in the femtowatt range? (or the quadrillionth [ten-to-the-minus-fifteen] of a watt range?)

Jason W. Higley


Post Extras: Print Post   Remind Me!   Notify Moderator  
Otto Piechowski
Pooh-Bah


Reged: 09/20/05

Loc: Lexington, KY
Re: The silence is deafening.... new [Re: Jason H.]
      #5449943 - 10/01/12 10:39 AM

I believe I am correct in asserting the position taken here on the issue of intended and unintended communications with extra-terrestrial intelligence is:

1. It has not happened.
2. It makes sense it has not happened for "this" reason, or for "that" reason.
3. Such communication may happen sooner rather than later, man happen later rather than sooner, or may never happen.

Might I suggest we put aside the issue of communication, intended or otherwise, and now turn our thoughts and words to the issue of transportation.

a. Do we agree there is no evidence of extra-terrestrial intelligence having visited us human persons?

b. How could such transportation occur? Within the possiblities of the technologies we think are real and likely? Within imaginary but possible technologies of the future?

c. How likely is it that such beings will come to us?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: The silence is deafening.... new [Re: Otto Piechowski]
      #5450140 - 10/01/12 01:20 PM

Quote:

a. Do we agree there is no evidence of extra-terrestrial intelligence having visited us human persons?




I agree with this. Some people obviously disagree (watch any UFO show or movie), and it may come down to what you think qualifies as "evidence", but I don't think there has been any physical evidence sufficiently strong to stand up to peer review thus far.

Quote:

b. How could such transportation occur? Within the possiblities of the technologies we think are real and likely? Within imaginary but possible technologies of the future?




Within currently understood technology, something along the lines of the book "Footfall" is possible. In that book aliens came to earth using a multi-generational ship along the lines of a Bussard ramjet at sublight speeds. Their primary weapon against us was basically dropping rocks from orbit (simple, yet effective).

With imaginary technologies, pick your SF book or movie of choice, or create your own. Hard to narrow that one down...

Quote:

c. How likely is it that such beings will come to us?




Well, working from our N of 0 on this one, we have no real way to guess. The most I will say is "unlikely".

If you want me to narrow it down further, I would say "less likely than us finding other life", since we at least know for sure that we exist, and us discovering other life would include non-intelligent and non-technological ones like bacteria under the ice of Europa, which should be mor ecommon than technologically advanced intelligent life. But them finding us requires that other intelligent life exists, is nearby enough to detect us, has developed tech well in advance of our own such that they can travel here, and is interested enough in coming here to spend the effort to do so.

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
Otto Piechowski
Pooh-Bah


Reged: 09/20/05

Loc: Lexington, KY
Re: The silence is deafening.... [Re: Jarad]
      #5450188 - 10/01/12 01:51 PM

Jarad,

Is it possible there is more likely a chance of being visited by extra-terrestrial intelligent civilizations then being communicated with by them. I know...intuitively...it sounds like a silly question. But, let's run with it, if we can at all.

Let's us assume in both cases there are the same number of intelligent civiilzations spread throughout the galaxy.

Otto


Post Extras: Print Post   Remind Me!   Notify Moderator  
llanitedave
Humble Megalomaniac
*****

Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: The silence is deafening.... [Re: Jarad]
      #5450189 - 10/01/12 01:51 PM

Spending the effort is the real hurdle. It's not that the technology needs to be exotic -- we're really not that far from having the requisite technology ourselves. The problem is that implementing it is horrendously expensive, both energetically and in physical resources.

They'd have to really, really want to come here, and frankly the surface of the Earth doesn't offer any physical materials that couldn't be had much more cheaply and conveniently by mining the comets.

The cost/benefit equation just doesn't add up, and that's a completely different thing than the Drake equation.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | >> (show all)


Extra information
2 registered and 3 anonymous users are browsing this forum.

Moderator:  LivingNDixie, FirstSight, JayinUT 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 19860

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics