[[Mod. note -- I apologise for the delay in processing this article.
It arrived in my moderation queue on 2017-12-18, just before an
extended power/internet outage at my location.
-- jt]]

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]]

I have one problem with using CMB as a reference frame:
Where is coordinate (0,0,0,0)? IOW where is the origin?

Ed

[[Mod. note -- Physics is translation-invariant so you can pick any
spatial point you want and use that as your spatial origin.

In cosmology there is a preferred time coordinate, which puts t=0
at the big bang. See
https://en.wikipedia.org/wiki/Chrono...f_the_universe
for a general discussion.
-- jt]]