EMPulse
How to work out the difference between how much energy/radiation the Sun emits per second and how much energy the sun absorbs/receives per second from all the incoming energy/radiation from all the stars? And not forgetting the suns gravitational field is focusing/bending the incoming energy/radiation onto it.

PS. wonder if this could make the universe stay in thermal equilibrium...
PS. if the suns gravity bends incoming radiation, how does it affect our view of space from earth? And have we compensated for it when we determine the distance of objects in space?
Confused1
The temperature of space is about 2.7 Kelvin

From:- http://en.wikipedia.org/wiki/Sun
The (effective) temperature of the surface of the Sun is about 5,700K

Here is a black body radiation calculator:-
http://www.spectralcalc.com/blackbody_calc...r/blackbody.php

What does the calculator thingy tell you about the ratio of energy arriving to energy leaving the Sun?

-C2.
Confused1
The thing tells us that
from space the Sun gains about :-
3.01355e-06 W/m2
5.98581e+07 W/m2

So the loss of energy to space is about 10,000,000,000,000 times greater than the energy it receives back.

-C2.

QUOTE
PS. wonder if this could make the universe stay in thermal equilibrium...

it kinda is. (nobody as yet knows whether there will be expansion forever or contraction etc)
brucep
QUOTE (Matador+Jan 25 2012, 08:23 PM)

it kinda is. (nobody as yet knows whether there will be expansion forever or contraction etc)

Guth's inflation predicts the spatial geometry of the universe is flat and the WMAP experiment confirmed that prediction.
thanks. made me look it up myself. yes been confirmed to within 0.5% error
im a few years behind lol.

what are the implications of that. Ω = 1

wait let me read up on it.

ok -

* described by euclidean space
* geometry Flat (obviously)
* its ultimate fate is the same as that of an open universe
* can have zero TOTAL energy

Robittybob1
QUOTE (brucep+Jan 27 2012, 07:37 AM)
Guth's inflation predicts the spatial geometry of the universe is flat and the WMAP experiment confirmed that prediction.

I find statements like that really confusing for there is nothing flat about the Universe. "Flat' seems to mean something other than what I think of as flat.
Take a flat sheet of paper and roll it into a tube it is still flat!
So what shape is the Universe if it is flat?
I see what robbity is getting at.

edit:

its to do with the dimensional geometry. dont look at it froma 3d perspective.

hope that help
AlexG
The problem is that the word 'flat' has a couple of different meanings.

When speaking of GR, flat means that the geometry of space is Euclidian. A triangle always adds up to 180 degrees, and parallel lines never intersect.

When speaking of cosmology, flat means that the attraction of gravity is just balanced by the cosmological constant, and the universe will continue to expand.

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