Why Is Heat Distribution Unequal in the Expanding Universe?

[csrichie]

I ran across this on a website. The problem is, because heat spreads out slower than light, when the big bang explodes and expands at the speed of light then there should be unequal heat regions all over the universe. But this is not true according to observation. Why is this so?

 

[pervect]

I ran across this on a website. The problem is, because heat spreads out slower than light, when the big bang explodes and expands at the speed of light then there should be unequal heat regions all over the universe. But this is not true according to observation. Why is this so?

The standard explanation is inflation. The problem is known as "the horizon problem". See for instance http://www.astro.ucla.edu/~wright/cosmoall.htm (I'll provide a short quote to point out the specific applicable section).

Any event that influences the temperature of the CMB that we see on the left side of the sky must be within the left-hand yellow region. Any event that affects the temperature of the CMB on the right side of the sky must be within the right-hand yellow region. These regions have no events in common, but the two temperatures are equal to better than 1 part in 10,000. How is this possible? This is known as the "horizon" problem in cosmology.

Inflation

The "inflationary scenario", developed by Starobinsky and by Guth, offers a solution to the flatness-oldness problem and the horizon problem.

The "flatness-oldness" problem (i.e. why omega is close to one) is also explained by inflation.

 

[Chronos]

That does not make any sense to me, csrichie. Heat is transferred by kinetic and photonic energy, according to current theories. The speed of transfer is interrupted by molecules jostling for a more stable position in the grand scheme of things.

 

[Phobos]

... when the big bang explodes and expands at the speed of light ...

Note that the Big Bang was not like a conventional "explosion" (it was, in part, the rapid expansion of all space) Also, it didn't expand at the speed of light (at least, not for more than an instant as you'll see from pervect's info about the inflationary period). Also note that there are observable variations in the cosmic microwave background radiation.