What Did the Universe Look Like from the Big Bang to Now?

[SeventhSigma]

I am asking for a sort of "artists rendition" of what the universe looked like from the Big Bang onward -- what our universe would have "looked like" over time to a theoretical observer.

I've seen plenty of pics like http://en.wikipedia.org/wiki/File:WMAP_2010.png and plenty of animations that depict the Bang as a large explosion/expansion, but I want to know what it might have actually looked like. Would there be sound? What would it actually look like in terms of color/appearance/etc? What did it look like before stars/galaxies were formed? What did the Bang itself "look like"?

I've always wondered this but have never found a source that gave any sort of definitive answer. Thanks!

 

[Chalnoth]

I am asking for a sort of "artists rendition" of what the universe looked like from the Big Bang onward -- what our universe would have "looked like" over time to a theoretical observer.

I've seen plenty of pics like http://en.wikipedia.org/wiki/File:WMAP_2010.png and plenty of animations that depict the Bang as a large explosion/expansion, but I want to know what it might have actually looked like. Would there be sound? What would it actually look like in terms of color/appearance/etc? What did it look like before stars/galaxies were formed? What did the Bang itself "look like"?

I've always wondered this but have never found a source that gave any sort of definitive answer. Thanks!

Well, it would look completely and utterly uniform. The deviations in temperature from place to place were, at the time the CMB was emitted, one part in one hundred thousand. Before that, the deviations were even less (though it didn't matter because you couldn't see very far before that anyway). But it would have looked like perfect thermal radiation that was cooling. Once the universe got cool enough to be visible (before that it'd be dominated by gamma rays and x-rays), it'd look rather blue or violet, and steadily shift towards the red. Once the universe looked quite red, at around 3000K temperature, the CMB was emitted, at which point it'd get steadily redder and darker until the stars turned on some time later.

But was there sound before the CMB was emitted? Yup!
http://scienceblogs.com/startswithabang/2009/09/listening_to_the_big_bang.php

 

[Chronos]

We have a pretty good idea what the universe looked like back to the surface of last scattering [CMB] - as chalnoth noted . Our knowledge of what it looked like before that is theoretical. We draw inferences from the CMB and galactic distibutions, suggesting matter has always been uniformly distributed. But, with that knowledge comes an enigma. Our math falls apart for conditions around e-43 seconds after the big event - leaving the possiblity of a bounce, or creation event. As I consider singularities as unphysical mathematical artifacts, the bounce conjecture appears logical. Perhaps a human would serve us better in comparison. We can extrapolate a human back to a biological singularity - but we know that is absurd. Our ideas about the origin of the universe may be equally absurd.

 

[Chalnoth]

We have a pretty good idea what the universe looked like back to the surface of last scattering [CMB] - as chalnoth noted . We have little idea how it looked before that. We draw inferences from the CMB and galactic distibutions, suggesting matter has always been uniformly distributed. But, with that knowledge comes an enigma. Our math falls apart for conditions around e-43 seconds after the big event. That leaves us with the possiblity of either a bounce, or creation event. As I consider singularities as unphysical mathematical artifacts, the bounce conjecture appears to be the only logical alternative.

A bounce still seems highly unlikely to me. Until it's demonstrated that the very strong inhomogeneities (likely including many black holes) that would occur in the collapsing phase are smoothed-out by the bounce, I'm going to remain highly skeptical on this one.

 

[SeventhSigma]

What does it mean to say that it looked uniform?

Would it look like as shown in this video at 3:03?

http://www.youtube.com/watch?v=KMQk6MveZOE&feature=related

I'm just really trying to understand what it would have actually looked like.

 

[Chalnoth]

What does it mean to say that it looked uniform?

Would it look like as shown in this video at 3:03?

http://www.youtube.com/watch?v=KMQk6MveZOE&feature=related

I'm just really trying to understand what it would have actually looked like.

Well, no. Those warm and cool spots only differ in temperature by about one part in one hundred thousand. So you couldn't actually see those. At the time the CMB was emitted, you'd just see a rather reddish light that looks, to the eye, the same in every direction.

 

[SeventhSigma]

So instead of blackness, discrete gas forms, stars, etc, we would see pure redness in every direction?

 

[Chalnoth]

So instead of blackness, discrete gas forms, stars, etc, we would see pure redness in every direction?

Basically, yes, though the color changed with time (progressively redder as the universe expanded. There wouldn't have been anything else to see until much later, when stars started to form.

 

[SeventhSigma]

So this redness would phase out into gas forms against blackness and eventually into the stars that led to the fusion of heavier elements?

 

[Chalnoth]

So this redness would phase out into gas forms against blackness and eventually into the stars that led to the fusion of heavier elements?

Well, not quite. Once the plasma became a gas, it was transparent. So all that you could see at that time would be the CMB. But the CMB progressively became redder and redder.

At the same time, the areas where there was a bit more matter started to collapse in on themselves. Eventually this collapse led to the formation of the first galaxies.