Why doesn't the temperature in outer space get lower than 3 degrees Kelvin?

Question

As you know, its very cold in outer space. Scientists can create temperatures to less than one millionth of a degree above absolute zero--millions of tiomes colder than in outer space! Yet the temperature in outer space doesn't get colder. It could, but something is keeping that from happening. Any ideas?

I just discovered that because the temperature doesn't get lower than 3 degrees Kelvin is because the heat from the Big Bang keeps outer space from getting any colder. Do you believe this?

Answer 1

That's the microwave background radiation from the big bang. As space continues to expand, it will get colder and colder. Brrrrrrrrr.

Answer 2

In the laboratory, scientists use special techniques to extract heat and reach temperatures very close to absolute zero, but in nature an object can only cool off by losing its heat to something colder. The microwave background left over from the Big Bang is at 3K. Objects in space can't get any colder than that because if they did, the microwave radiation would warm them up.

Most parts of space receive enough radiation from stars to make the equilibrium temperature higher than 3K.

Answer 3

The solar winds keep the few particles that are out there moving VERY slowly, so it doesn't get much lower than 3 degrees Kelvin. It has been getting colder since the Big Bang, but nowadays we cannot notice any significant change because it's happening so slow

Answer 4

Actually the temperature of space is 2.753 Kelvin.

Answer 5

This is based on calculations that assume the the cosmological red shift is a Doppler effect. Here is a very good history of this topic:
http://www.dfi.uem.br/~macedane/history_of_2.7k.html

Keep in mind that Nernst calculated this temperature to be 0.75 K, and others have calculated it to be as high as 7 K.