On 10/08/15 18:06, Alastair McDonald wrote:
"RedAcer" wrote in message
...
On 10/08/15 16:53, RedAcer wrote:
On 10/08/15 15:12, Alastair McDonald wrote:
"RedAcer" wrote in message

The hotter body will cool anyway whether the colder body is there or
not. The radiation from the colder body means that the hot body will
cool more slowly that it would have done if the cold body weren't
there.
It is not 'cold' radiation as you keep insisting. It does not cool the
hot body, it warms it up.(I'm assuming no background bodies or source
of
radiation)

There is always background radiation of one type or another. Think
about
it. You are either surrounded by walls, or by the earth and sky, or by
cosmic background radiation. Describe a real situation where it does not
exist.

We are all trying to explain some physics to you. The way that it's done
(in any physics class/book) is to concentrate on the salient features of
interest in the system and ignore/minimise other 'smaller' effects.
Assume we doing the experiment out in space where the CMBR is at 2.3K.
Let the cold body be at 200K and the hot at 300K. OK.
Terms of in the SB equation are proportional to T^4 and so can easily be
ignored in a first approximation.

Last sentence not very clear, should be:-
"Terms in the SB equation are proportional to T^4 an so the CMBR can
ignored in a first approximation."

You are making the same mistake as Alan LeHun in the Four Question thread.

You have not got a two body system. It is a three bodies when you include
the CMBR. In that case the main source of cold radiation is the coldest
body - the CMBR. It is not the cooler of the two bodies. If you then
approximate the CMBR, which is the source of the cold radiation, to zero,
then of course the cold radiation does not exist. But that is because you
have approximated it to zero. You can't just approximate numbers to zero,
particulary if they are divisors, which of course they aren't in this case.

I think you have a bit more to learn before you try to teaching me.

Cheers, Alastair.



Clearly you do not understand physics. Write the SB equations for this
system and show how big the CMBR is compared to to the bodies at 200 and
300 K. Do the calculations with and without it.
hint 2^4 = 16
200^4 = 1,600,000,000
Before you start read this.
https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
You are on your own now.