On Sunday, December 10, 2017 at 4:34:35 PM UTC-5, jacobnavia wrote:
Imagine this:

You are jogging and want to know your speed.

Easy. Measure the CMB from all directions, and you will see that the CMB=

becomes bluer in the direction you are moving to, and redder in the
direction you are moving from.

Is such an instrument possible?

In principle of course. The software in the quantum computer inside the
device calculates the speed of the earth rotation, movement of the
earth, the sun, the galaxy, etc. And subtracts all that giving you a
terse reading of 5.2 Km/hour.

Besides the small engineering problems :-)


does the CMB give us an absolute frame of reference?

[[Mod. note -- The CMB gives us a reference frame in the manner the
author describes. Whether or not it's appropriate to call this reference
frame "absolute" is a different matter. So far as we know the laws of
physics don't operate any differently in that frame vs any other frame.
E.e., we know of no experiment which can distinguish such a reference
frame without "looking out the window" at the outside universe. So
the CMB frame is a property of the universe as a whole, but is not a
property of the local laws of physics.
-- jt]]

There is movement in the CMB so the data would be more like a bell
curve where the average would be a ball park number for a absolute
frame of reference. As to the laws of physics being the same for
all frames of reference? That statement is consistent with measurements
made so far with a focus on so far. Future measurements could paint
a different story as technology proceeds with more accurate test
equipment and economical ways to get into space.

[[Mod. note -- The original postewr did say "In principle of course",
which I think can be interpreted as assuming very precise measurements.
And if we take an all-sky average (i.e., choose the reference frame
in which the CMB has no dipole moment) that averages over the spatial
variation in the CMB.
-- jt]]