A dark universe?

[weeman]

I posted a reply in the thread 'Fate of the Universe' under Space, Science and Astronomy, talking about how the universe may go dark if it continues to expand for billions to trillions of years from now. <br /><br />It got me thinking. If space became so vast that we could no longer see light from any other galaxies, would it change beliefs of future civilizations here on Earth?<br /><br />It is theorized that if the expansion of space continues to speed up, all galaxies in the universe will become so redshifted that they will no longer be detectable. <br /><br />The universe will officially go dark.<br /><br />So, hypothetically speaking, if the only visible matter in the universe were within the Milky Way (assuming it still exists!), would it create new beliefs with advanced peoples that exist on Earth in the far, far future? <br /><br />If all that these people could see are the stars within the Milky Way, then to them, that would be the entire universe. They would make theories, calculations, and assumptions on how the universe came to be (the universe being just the Milky Way). They would have no idea that billions of other galaxies exist out in the rest of the universe at incredibly vast distances.<br /><br />This topic may have some material in it that fits better in 'Phenomena' or 'Science Fiction', but I think that there is a lot of plausible science within this idea <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[kyle_baron]

<font color="yellow"><br />If all that these people could see are the stars within the Milky Way, then to them, that would be the entire universe. They would make theories, calculations, and assumptions on how the universe came to be (the universe being just the Milky Way). They would have no idea that billions of other galaxies exist out in the rest of the universe at incredibly vast distances.</font><br /><br />I would agree with that assessment. Information gets lost over eons of time, due to wars, major catastrophies, etc. <br /> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[kelvinzero]

Was an article about that recently.<br /><br />http://uplink.space.com/showthreaded.php?Cat=&Board=sciastro&Number=713282

 

[vandivx]

point is it very likely won't happen, nature doesn't work on the principle of runaway scenarios and some would be scientific evidence put forward is just that - a would be, it will in all likeness turn up to be wrong sooner or later<br /><br />I don't think we have correct picture of the universe at all for any conclusion made these days to be believable, I mean how anybody can seriously claim anything when the issues of DM & DE are still outstanding, clearly our understanding of nature is grossly lacking to say the least<br /><br />still considering it at face value on your terms, if some cataclysmic thing happened and humankind had to start again from trees and caves and galaxies receeded past the point of visibility from the point of view of our instruments today... you are like that guy who said in 18th century that everything was invented and physics is at an end, if those apes climbed from the trees down, whos to say they wouldn't get not only to our place in science but much further at which point they would discover those galaxies despite their great distances? <br /><br />you could say mankind were in that position you outline only some hundred of years back - they had no instruments to see galaxies and their beliefs were shaped accordingly - and so what, development went on and Galileo or who it was ground his lens and that's how it started LOL<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

Universe fades away.None to see.

 

[dragon04]

<font color="yellow">So, hypothetically speaking, if the only visible matter in the universe were within the Milky Way (assuming it still exists!), would it create new beliefs with advanced peoples that exist on Earth in the far, far future?</font><br /><br />In your scenario, the re-discovery of the CMB would create a very puzzling problem. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[trumptor]

The way I'm understanding what weeman is trying to say is that looking wayyyy into the future when all the galaxies but our own have through expansion reached the point of receding faster than "c" which would in turn leave any civilization in that time period to only be able to see our galaxy. Nomatter what type of telescope they develop it wouldn't help since everything would be receding at faster than "c". How would they be able to see the background radiation? How would they deduce that vacuum energy is out there? To them it would seem that we live in a static universe with the Milky Way/Andromeda? being its only galaxy.<br /><br />Looking at speedfreak's link it explains everything.<br /><br />I guess first of all we'd have to assume that the universe will be forever expanding at an increasing rate. I think its really interesting to wonder what intelligent life during those days would see. I would also wonder if there have maybe been other key events in our universe's past that are undetectable to us now and some long gone civilization was wondering the same thing about our time.<br /><br /> <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[alokmohan]

We are moving faster than c?What exacly you mean?

 

[trumptor]

I don't mean that the galaxies are moving apart at faster than c through space, but that space itself is expanding at an increasing rate causing the galaxies to eventually recede from us at faster than the SOL. And that would mean that the light they emit would never get to us making them invisible to us. <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[SpeedFreek]

Yes it is an interesting idea, that future civilisations may have no clue that space is expanding.<br /><br />Interestingly, recession at the speed of light or above does <b>not</b> mean we will not see those galaxies - indeed, we observe galaxies that recede at the speed of light and always have done. The dark universe scenario happens when the expansion rate is many magnitudes higher than now, i.e. things are receding at the speed of light at far closer distances than currently. The current "hubble distance" where objects recede at light speed it around 9.5 billion light years away. It would have to be only 200 million light years (closer than andromeda) before we stopped being able to observe any new information about andromeda.<br /><br />(In fact, it's not quite as simple as that. If an object is receding at c, its light still makes its way towards us through its local space, which is hardly expanding at all - it is only the cumulative effect of the expansion over the entire distance that causes a galaxy to recede at c or more. It is more a case of how fast new space is being created (the acceleration of expansion) that stops or delays us from seeing that object). <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[vandivx]

there is an argument that you can imagine there is some planet halfway btw the far off galaxies that we supposedly can't see because they are beyond horizon... well, the planet halfway btw there and here can certainly see those galaxies and if they can at their position, so can we because we can see the halfway positioned planet and receive the signals that they can receive, its just that the signal will be weak but it can never dissapear like shutting down light in room...<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[weeman]

<font color="yellow"> It would have to be only 200 million light years (closer than andromeda) before we stopped being able to observe any new information about andromeda. </font><br /><br />Isn't Andromeda 2.5 million ly away? Or am I wrong? Are you suggesting that the distance where the universe goes black is less than 200 million ly or 2.5 million ly? <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[SpeedFreek]

Sorry about that, you are correct <img src="/images/icons/smile.gif" /><br /><br />The distance would need to be 2 million light years, not 200 million. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[alokmohan]

You are right.