Re: Axis of evil?

Marc Millis wrote:

In <1162984613.304491.32890@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> Just G. Waller
wrote:
Why are the velocity-dependent doppler shifts of the CMBR
frame-dependent?. Does it means that, at cosmological scale,
the distance between source and observer can cause doppler
shifts, as velocity can?.


Ooh, this is one of those "I should have realized that already" moments.
Duh. Now I doubt my prior mental models for what I'm toying with.

Just to check then, since I didn't even think to check for this detail
before... Does the CMBR data reflect any recessional red-shift? ... How
would one distinguish from how far away a particular CMBR photon came
from anyway to make such a determination, or are they all assumed to
come from the edge of observation? And if coming from the edge of
observation, does that mean that CMBR temperatures will rise over the
years as we are seeing farther back in time, seeing older photons from
farther away?

At this point, I know I'm asking dumb questions. With my ignorance on
this humbly exposed, please enlighten me.

Marc

I think it has to do with a suitable definition of simultaneity
of events and spacetime topology at cosmological scale.

I've already posted in this spr forum a sketch of my insight:
Humorously it's entitled
"A mole is gnawing our spacetime cheese" :)
http://www.lepp.cornell.edu/spr/2006-06/msg0074517.html

So, as a source emitting a photon and a receiver absorbing it,
are no longer simultaneous events if they were stationary at
distance r>0 when the photon was emitted, and they still remain
stationary when the photon is absorbed, a doppler redshift must
be detected produced by that distance (call it "expansion" of
the universe if you like the term).

Assume a redshift z is caused by a large distance r, between
source and observer, both at rest in a inertial frame of
reference. You always can express Hubble's law as

r / R_h = [(1 + z)^2 - 1] / [(1 + z)^2 + 1],

where R_h is Hubble's radius. Of course, r/R_h is equivalent to a v/c,
where v is a recession speed, but in this case source and observer
are at rest, and a doppler redshift z>0 still is measured because
of r>0.

"Cool ideas entertain"

.

Relevant Pages

  • Re: A Challenge to Orthodox Relativity
    ... would become less dense as velocity increased. ... line of sight or away from the observer, ... I would say no, that distance ... which definitely causes a decrease in photon density per unit of ...
    (sci.physics.relativity)
  • Re: SR vs. Emitter Theory
    ... was that the photon increase its distance at 'c' with respect to the ... the observer's frame of reference is meaningless. ... You need to know how far away the source is from the observer when the ...
    (sci.physics.relativity)
  • Re: does light travel at a straight line (2) ?
    ... so, that's the only constraint. ... so for any photon that travels at whatever weird path and speed, ... the same as any observer measuring the speed of light as c. ... PD gave a new definition of distance as: ...
    (sci.physics)
  • Re: does light travel at a straight line (2) ?
    ... so, that's the only constraint. ... so for any photon that travels at whatever weird path and speed, ... the same as any observer measuring the speed of light as c. ... PD gave a new definition of distance as: ...
    (sci.physics)
  • Re: Jeckyl wrote
    ... The change is from the viewpoint of the non-local observer. ... closure by the exterior observer would be a distance of 80 yards ... motion, ... Relativity does not demand length contraction. ...
    (sci.physics.relativity)
Quantcast