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giann_tee
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Few weeks ago a respected magazine brought some excitement with a story on missing bond between Thermodynamics and Relativity.
My question is what satisfies the definition of relativistic gas and how would that differ from single star systems with shifted spectra?
Take for example spinning galaxies that have different shifts in edges approaching or moving away from us. However we often hear the areas closer to the center to have whirls of gas - where does it count in?
Today in New Scientist there is a brief and mostly unrelated passage that says that cosmic rays are affected by the photons of CMB.
http://space.newscientist.com/article/dn12818
I guess that section is about collisions with CMB photons that seem to average the possible cosmic rays somehow.
Comments?
RELATIVISTIC THERMODYNAMICS. Einstein*s special theory of
relativity has formulas, called Lorentz transformations, that
convert time or distance intervals from a resting frame of reference
to a frame zooming by at nearly the speed of light. But how about
temperature? That is, if a speeding observer, carrying her
thermometer with her, tries to measure the temperature of a gas in a
stationary bottle, what temperature will she measure? A new look at
this contentious subject suggests that the temperature will be the
same as that measured in the rest frame. In other words, moving
bodies will not appear hotter or colder.
You*d think that such an issue would have been settled decades ago,
but this is not the case. Einstein and Planck thought, at one time,
that the speeding thermometer would measure a lower temperature,
while others thought the temperature would be higher. One problem
is how to define or measure a gas temperature in the first place.
James Clerk Maxwell in 1866 enunciated his famous formula predicting
that the distribution of gas particle velocities would look like a
Gaussian-shaped curve. But how would this curve appear to be for
someone flying past? What would the equivalent average gas
temperature be to this other observer? Jorn Dunkel and his
colleagues at the Universitat Augsburg (Germany) and the Universidad
de Sevilla (Spain) could not exactly make direct measurements (no
one has figured out how to maintain a contained gas at relativistic
speeds in a terrestrial lab), but they performed extensive
simulations of the matter. Dunkel
(joern.dunkel@physik.uni-augsburg.de ) says that some astrophysical
systems might eventually offer a chance to experimentally judge the
issue. In general the effort to marry thermodynamics with special
relativity is still at an early stage. It is not exactly known how
several thermodynamic parameters change at high speeds. Absolute
zero, Dunkel says, will always be absolute zero, even for
quickly-moving observers. But producing proper Lorentz
transformations for other quantities such as entropy will be
trickier to do. (Cubero et al., Physical Review Letters, 26 October
2007; text available to journalists at www.aip.org/physnews/select )
My question is what satisfies the definition of relativistic gas and how would that differ from single star systems with shifted spectra?
Take for example spinning galaxies that have different shifts in edges approaching or moving away from us. However we often hear the areas closer to the center to have whirls of gas - where does it count in?
Today in New Scientist there is a brief and mostly unrelated passage that says that cosmic rays are affected by the photons of CMB.
http://space.newscientist.com/article/dn12818
The problem arises because every cubic centimetre of space contains about 400 relic photons from the big bang fireball. They have little energy, but seen from the point of view of a speeding cosmic ray, they are enormously boosted in energy, becoming high-energy gamma rays. The interaction of cosmic rays with these gamma rays continually saps the very highest energy cosmic rays of energy. Therefore, we should detect none of them on Earth – but we do.
I guess that section is about collisions with CMB photons that seem to average the possible cosmic rays somehow.
Comments?
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