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# Re: absolute velocity, cosmology, special relativity

• From: Jack Uretsky <jlu@HEP.ANL.GOV>
• Date: Tue, 20 Feb 2001 22:18:35 -0600

Hi all-
Well, John gives one way of formulating the question. But prior
to discovery of CBR there was no "preferred" reference frame in the
universe. Now there is. Larry asks, what are the consequences of this
new fact. This might turn out to be a profound question. Arons touches
other postings on this subject.
Regards,
Jack

On Mon, 19 Feb 2001, John S. Denker wrote:

At 04:43 PM 2/19/01 -0700, Larry Smith wrote:
Does the detection of our absolute motion through the heavens relative to
the cosmic background radiation (by noting different temperatures in
different directions) violate the postulates of special relativity?

No.

Is the cosmic background radiation "the" absolute fixed reference frame?

No.

===================================

Let me reformulate the question, to see if I understand the intent:
Special relativity says the physical laws should not depend
on the reference frame, so how come we have this physical
observation that _does_ depend on the reference frame?

When stated that way, the question practically answers itself: There is a
distinction between the physical LAWS and the physical OBSERVATIONS.

There are two main ways this can happen:

to symmetrical laws, the result will (in general) be asymmetric. But the
laws are still symmetric.

asymmetry will develop. That is, sometimes a high-symmetry question has a
lower-symmetry answer. This is called "spontaneous symmetry breaking".

As a concrete illustration: A blindfolded person throws a marble into a
roulette wheel. The wheel is symmetric. The probability of landing in any
given cell is symmetric; it is uniformly 1/N. Yet the solution is not
symmetric; you will not observe 1/Nth of a marble in each cell; you will
find the whole marble in a definite cell. The resulting wheel+marble
system will be asymmetric.

We can quibble over whether this result requires any discernible
macroscopic asymmetry in the initial conditions.
-- To one way of looking at it, the wheel is a "noise amplifier" whose
behavior depends on unobservable ultramicroscopic details of the initial
conditions.
-- OTOH since these details are unobservable, another equally valid way
to look at it is that the symmetry breaking "just happens".

Any physical observation that could have "just happened" doesn't tell us
anything about the physical laws. Our proper motion through the local
background radiation is IMHO firmly in the "just happened" category.

The directionality of the background radiation is no more a threat to
special relativity than, say, the directionality of sunlight. The sun just
happens to be there.

==========

The flip side of this is that it is great fun to look for things that
couldn't have "just happened" and try to use them to infer something about
the physical laws. The asymmetrical decay of neutral Kaons is in this
category.

--
While [Jane] Austen's majestic use of language is surely diminished in its
translation to English, it is hoped that the following translation conveys
at least a sense of her exquisite command of her native tongue.
Greg Nagan from "Sense and Sensibility" in
<The 5-MINUTE ILIAD and Other Classics>