Re: science sense and common sense, was Re: Intelligent Design Invading Liberal Classrooms
- From: Stuart Levy <s_levy@xxxxxxxxxxxxx>
- Date: 29 Nov 2005 03:03:00 -0600
On 2005-11-26, Brian Tung <brian@xxxxxxx> wrote:
[re Big Bang thermodynamics, omitting other good stuff]
> What's more, the laws of thermodynamics are not the absolutes you seem
> to suggest they are. For one thing, energy is not even well-defined
> for strongly curved pieces of spacetime, so that the first law of
> thermodynamics cannot be exactly applied except for closed systems in
> asymptotically flat pieces of spacetime. There's no such thing, though
> very good approximations exist in laboratories. But certainly the
> initial conditions at the Big Bang are too curved to expect energy to
> behave the way "common sense" predicts it to.
>
> There are ways around this, using what are called pseudo-tensors, but as
> I understand it, their use is somewhat controversial because they don't
> transform like tensors (as their name suggests), which violates one of
> the principles of general relativity--that the laws of physics are the
> same in all reference frames. They *almost* transform like tensors...
> but not quite. So it is far from certain that we can count on the
> conservation of energy at the Big Bang; in fact, it seems almost
> certain that we cannot.
Hey, this all sounds pretty neat. I'd never heard of pseudotensors,
or the notion that energy might not be well-defined in curved spacetime.
Do you know of references, books or web pages, that might say more about
either, for a reader with some physics background but only a little GR?
Cheers
Stuart Levy
.
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