A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Research
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Speedometer



 
 
Thread Tools Display Modes
  #1  
Old December 10th 17, 10:34 PM posted to sci.astro.research
jacobnavia
external usenet poster
 
Posts: 105
Default Speedometer

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]]
  #2  
Old December 11th 17, 07:52 AM posted to sci.astro.research
John Heath
external usenet poster
 
Posts: 13
Default Speedometer

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]]
  #3  
Old December 21st 17, 10:53 PM posted to sci.astro.research
Edward Prochak
external usenet poster
 
Posts: 3
Default Speedometer

[[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]]
  #4  
Old December 21st 17, 11:10 PM posted to sci.astro.research
Richard D. Saam
external usenet poster
 
Posts: 240
Default Speedometer

[[Mod. note -- I apologise for the delay in processing this article.
It arrived in my moderation queue on 2017-12-19, just before an
extended power/internet outage at my location.
-- jt]]

On 12/11/17 12:52 AM, John Heath wrote:

There is movement in the CMB

Check me.

Yes, there is apparent movement in the CMB.
The Milky Way is moving at approximately 627 km/s
(at our solar system position 276 degree galactic longitude,
30 degree galactic latitude)
with respect to the photons of the Cosmic Microwave Background (CMB).
This has been observed by satellites
such as COBE and WMAP as a dipole contribution to the CMB,
as photons in equilibrium at the CMB frame get blue-shifted in the
direction of the motion and red-shifted in the opposite direction.
and also: the solar system is orbiting galactic center
at about 217 km/sec which is essentially additive
(217 + 627) or 844 km/sec relative to CMB dipole rest frame.
and also: the earth has a velocity of 30 km/sec around the sun.
The CMB 'hot spot' or 'wind origin' (+3.5 mK above the present CMBR
2.729 K) is in constellation Leo at essentially the celestial equator:
http://aether.lbl.gov/www/projects/u2/

RDS
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 11:24 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.