rOriginally posted by obvek
I just thought of this today and it kinda stumped me, and i suddenly knew exactly where to ask it- the rhp forums.
There is no mass in space, yet scientists say that space is a few degrees above absolute zero. Correct me if I'm wrong, but it takes mass to have temperature, right? How can space be massless and still have temperature?
What the temperature of space means there is a background of
microwave radiation that would heat something very cold, say at 1
degree Kelvin, up to the tempurature of 2.73 degrees Kelvin.
It has nothing to do with mass, its just microwave radiation which
is the leftover radiation from the big bang but because the universe
has expanded to billions of light years across, this radiation has
been stretched out by the same amount, so it originally was a much
higher frequency, shorter wavelength, and thus a higher tempurature
but if you make the wavelength longer, the energy content per
packet of radiation (each wavelength) goes down. I am not sure what
the original wavelength was, ten times higher, hundreds of times,
not sure but its been measured at 2.73 degrees Kelvin.
It also doesn't matter which direction you point your antenna, its nearly
the same in all directions. Thats what won the Nobel prize for Pensias
and his buddies.