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Published by Karnuvap 09-29-2008
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Should we debate this or provide answers?|
#2
By
modest
on
09-29-2008
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| Re: Night Sky I also suspect Karnuvap knows the answer, but this is the Q & A forum, so... This is known as Olbers' paradox. Proposed by... German astronomer Heinrich Wilhelm Olbers. If the universe is infinitely old and infinitely large then a person might expect every line of sight (everywhere they look in the sky) to end at a star. This would make the sky (day or night) about as bright as the sun in every direction. Of course, big bang theory has a finite age placed on our universe and has it expanding (which puts a finite size on the visible universe) thus the paradox is resolved  ~modest |
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Last edited by modest; 09-29-2008 at 05:27 AM.
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#4
By
litespeed
on
11-23-2008
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| Re: Night Sky Flat or Curved - The Long Answer Recent experiments seem to show the universe is flat and hence infinite, even if it DID begin in a big bang. The experiment apparently sent lazer beams out in such a way as to create a triangle with some third 'constructed' side out in space. The goal was to measure the total angles and see if they added to 180 degrees, indicating flat, or some other sum that would indicate the universe is curved, hence finite. An analogy would be triangles drawn on an uninflated baloon with 180 degrees total angle, then the baloon blown up and a different total is observed, changing as the baloon gets larger and larger, always approaching 180 degrees, but never reaching that number. The recent experiment is not considered definitive, however, because the universe might be curved so little that we do not have instruments sensitive enough to measure it. Anyway, I am skeptical infinities exit in our universe, including the universe itself, as well as singularities in black holes. The apparent absence of infinite cosmic rays and/or microwave background radiation seem to support this. Another possibility I have not seen discussed is this: infinite universe with finite mass. Finally, even if the universe is infinite with infinite mass [postulating some mechanism to keep infinite cosmic rays from killing us], our visible part of the universe DOES seem to have a finite mass. Accordingly, if our part of the universe continues to expand at an increasing rate the entire issue is moot. This is because all the fussible matter will eventually get used up in dieing stars, and the entire, currently visible place will go dark. The remaining heavy elements in planets, neutron stars etc will simply continue to speed away from each other in the dark. |
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Last edited by litespeed; 11-23-2008 at 06:11 AM.
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#6
By
theblackalchemist
on
11-23-2008
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| Re: Night Sky Can we also add that the sky *could* have been white? and when the universe was created, it started m o v i n g a w a y ? Does this also mean that before the big crunch, the universe's sky will be again white?? TBA |
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#7
By
litespeed
on
11-23-2008
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| Re: Night Sky Dear Alchemist According to the big bang theory the universe was, for a few hundred thousand years, too dense for light to exist. Then electomagnetic radiation suddenly sprung into existence. At that time there would have been lots of light, as you mention. Background microwave radiation is the residue of this event. Further, all of astonomy recently suffered one of those once in a lifetime "ooops" moments. Specifically, experimental evidence is overwhellming the universe is expanding at an INCREASING rate. Accordingly, the generations old arguement of whether universe expansion is slowing down enough to reverse course to create a 'crunch' is now moot. At least until some other 'big ooops' moment trips everyone up once again. Well. Fool me once, shame on you. Fool me twice, shame on me. It is important to realize ALL THESE THINGS are and have been theories based upon data accumulated up until that time. And we have several billion more years till OUR star gets cranky. Quote:
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#8
By
ossium70
on
11-26-2008
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| Re: Night Sky i actually recently read a book with this quote in it. now before i answer with an idea as to why this quote may be wrong. i would like to touch on the idea of a universe that is not infinite. Does it wrap in on itself? if so wouldn't the light from a single star itself eventually eluminte the universe... for example no matter which direction you look you would see the star coming from every position since every direction eventually returns to the same location. you have to take into account that the universe is big and we are not the center of it so the light takes off and we see it now, but as it travels in other directions it takes much longer for it to reach us but it eventually will. Do this millions upon millions upon millions of times more and the combining light of every star should eventually light up the sky's. NO? This idea can go much more indepth but i am simple stating the basics.. |
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Last edited by ossium70; 11-26-2008 at 07:14 PM.
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