Re: Why is the Speed Of Light Constant?


sal wrote:
On Sat, 25 Feb 2006 15:41:51 -0800, JanPB wrote:

bornto@xxxxxxxx wrote:
There's too many topic's here for me to read to try to find a "right"
answer to this question so here is my post:

I've been trying to research the properties which define the speed of
light for a spacetime frame. Anyways I can't find any explanation. Yet
all I keep seeing is that light being this constant speed.

We don't know why the speed of light is constant just like we don't know
why 3D space is (more or less) Euclidean or why there are 3 dimensions,
and so on.

Akshully .... I've read something recently that suggests that we (well,
somebody someplace) may have a handle on why there are 3 dimensions, not
4, not 2.

Perhaps you read it here:
http://hyperphysics.phy-astr.gsu.edu/HBASE/forces/isq.html or here:
http://arxiv.org/abs/physics/0204034

It's based on the good old Anthropic Principle again, which is a
little bit of a copout (since it's kind of equivalent to the assumption
that there are an infinite number of universes which cover all possible
configurations). In this case, it is quite possible that
sufficiently complex structures to allow the formation of life could not
exist in universes with fewer _or_ _more_ than 3 dimensions. So, since
we're constrained to exist in a universe where there can be life, we
_must_ find ourselves in a 3-d universe.

For 2 dimensions the problems of creating life are pretty obvious. I've
read that there are also problems with .. um... enclosures, maybe, and
chemical bonds, surely, in 4 dimensions and higher, but I can't recall
what little I've read and I certainly can't cough up a proof of it. None
the less I thought it was an interesting hint, however dimly perceived and
ill-defined.

<< Note that space-time cannot be regarded as a straightforward
generalization of Euclidian 3-space to four dimensions, with time
as the fourth dimension. The distribution of signs in the metric
ensures that the time coordinate x^4 is not on the same footing as
the three space coordinates. Thus, space-time has a non-isotropic
nature which is quite unlike Euclidian space with its positive definite

metric. >>
http://farside.ph.utexas.edu/teaching/jk1/lectures/node13.html

Sue...




Some say that's all there is to it. Others say spacetime is a different
thing than space and while one can philosophically squeak by leaving the
Euclidean properties of space without justification, the same cannot be
done with spacetime.

It's a difficult debate because we are now at the crossroads (quantum
mechanics and general relativity are not reconciled) and it's not even
clear the very concept of spacetime survives.

--
Nospam becomes physicsinsights to fix the email
I can be also contacted through http://www.physicsinsights.org

.

Relevant Pages

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