A line about entropy on wikipedia says:
"The entropy of a molecule is defined as S=K*ln(Ω) , where Ω is the number of states available to the molecule."
what does that "states available" mean?and how does it related to other definition of S, S= Q/T?
BTW,
Does the equation dS = dQ/T...
Marcus, i read the tutorial from wright last night and had some questions about it:
1. How much is H really? there are so many difference values of Hubble constant on the tutuorial...(72+/-8 km/s/Mpc, 57+/-4 km/s/Mpc, 71+/-3.5 km/s/Mpc...)
2. How come 1/H is approximately the age of...
ok, I get the other half of the picture: the light must travel further (even though it travels faster than c)
thx a lot
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well, people usually loan money to buy sailboats,don't they, so they can sail in it while trying to foot the bill...
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Or actually, wouldn't it takes more time for light to travel a distance?
Everytime the light travel a little distance, the distance left to travel expands
the unlucky photon would need to cover more distance ahead,and takes more time...
Marcus, I'm back, now waiting for offers from college.
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last night, i re-mused about the balloon model and expansion of space
(Java link:http://www.astro.ucla.edu/~wright/Balloon2.html)
On that expanding balloon,
a galaxy has a constant coordination;
only the distance between them...
Marcus, thanks so much for the answer and discussion.
i am new to PF and never expected someone would answer my questions with such details and patience
But starting from today, until to about after christmas, i'll be engaged in some college application.
Perhaps catch up more inquiry...
And another question:
the animation shows the balloon is expand OUTwards.
if the light also goes in the OUTward direction, it gets helped by the balloon expansion.
but if the light goes INward, or against the expanding direction, will the light travel a smaller distance?
the bank have a...
lol
i like that analogy
it really make sense now
'distance' itself is stretching, so light can go farther
But.. what really is 'distance'? if it can stretch longer and bigger, is it a substance?
I know ether, as a medium, was rebutted hundreds of years ago.But is the "balloon", on which...
Cool
it's clear to me now how the red shift(z) affects how light travel in space-time(Light Travel Time & Comoving Radial Distance)
but why would the expansion of space affect photons in this way?
i thought light travels in the speed of light,
and Lorentz transformation garuantee that...
WOW...like wow...
thx Marcus
but What is the Light Travel year?
if i set z=0,
Light travel year goes to 0
Comoving radial distance goes to 0
does it mean all light rays have been traveling in a 'point' for 13.666Gyr?
&
If i set z=99999999(some silly large number), or even larger, why...
If a star is 14 billion LY away, will its light ever reach earth?
if it does, the light must happened 14 billion YEARs ago, before the big bang(13.7billion years)?
Please answer in a tutorial way
thx :)