Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.physics.relativity > #597743

Re: Atomic Clocks and ℎ: Can changes in ℎ explain observed frequency changes?

Show all headers | View raw

Aether Regaind wrote:

> Thomas 'PointedEars' Lahn:
>> Aether Regaind wrote:
>> 
>>> Atomic clocks are based on measuring a particular, very sharp,
>>> transition frequency in atoms of a heavy alkali element (Cs/Rb). So, in
>>> effect, they are based on Bohr's frequency relation:
>>>
>>> ΔE = ℎ*f
>> 
>> That was _Planck_‘s idea (in 1900, confirmed by Einstein in 1905), not
>> Bohr’s.
>>  
>>> An alternate explanation for the observed frequency changes in atomic
>>> clocks,
>> 
>> Cite any such observed frequency changes.
> 
> See any of Neil Ashby's thorough papers on GPS, eg.:
> RELATIVITY IN THE GLOBAL POSITIONING SYSTEM
> https://pubmed.ncbi.nlm.nih.gov/28163638/

The original publication is actually available via 

<https://link.springer.com/article/10.12942/lrr-2003-1>

as redirected to by

<https://doi.org/10.12942/lrr-2003-1>.

I know this treatise very well (I frequently cite it here when the next – or 
always the same – crackpot comes along and claims “t' = t”.  Therefore I 
know that you have either not read it or completely misunderstood it.

There is no noticable frequency shift in an atomic clock during its 
operation *where it is* for millions of years.  That is why such a clock is 
so precise and that is why it is used not only on the ground for 
applications like NTP, but also for GNSS-based time services.

The frequency shift that you have misunderstood is one that arises from the 
geometry (the curvature) of spacetime: If we choose the time measured (by 
atomic clocks) on the ground as the proper time (principle of relativity: 
there is no preferred reference frame), we find that more proper time 
elapses on a GPS/any GNSS satellite, and is thus measured by the atomic 
clock on board, in any given interval of ground proper time.

That also means that the satellite’s sending frequency has to be *adjusted* 
(decreased) to appear *from the ground* as the expected (standard) 
frequency.  Otherwise the observed frequency would be too high.

I point you in particular to the section “Relativistic Effects on Satellite 
Clocks”:

| The first two constant rate correction terms in Eq. (34) have the values:
| 
| […] ((35))
| 
| The negative sign in this result means that the standard clock in orbit is
| beating too fast, primarily because its frequency is gravitationally
| blueshifted. In order for the satellite clock to appear to an observer on
| the geoid to beat at the chosen frequency of 10.23 MHz, the satellite
| clocks are adjusted lower in frequency so that the proper frequency is:
| 
| [1 − 4.4647×10⁻¹⁰] × 10.23MHz = 10.22999999543 MHz. ((36))
| 
| This adjustment is accomplished on the ground before the clock is placed 
| in orbit.


PointedEars
-- 
Q: What happens when electrons lose their energy?  
A: They get Bohr'ed.

(from: WolframAlpha)

Back to sci.physics.relativity | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Atomic Clocks and ℎ: Can changes in ℎ explain observed frequency changes? Aether Regaind <AetherRegaind@invalid.com> - 2022-12-16 17:20 +0000
  Re: Atomic Clocks and ℎ: Can changes in ℎ explain observed frequency changes? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2022-12-17 02:00 +0100
    Re: Atomic Clocks and ℎ: Can changes in ℎ explain observed frequency changes? Aether Regaind <AetherRegaind@invalid.com> - 2022-12-17 18:40 +0000
      Re: Atomic Clocks and ℎ: Can changes in ℎ explain observed frequency changes? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2022-12-17 23:01 +0100
  Re: Atomic Clocks and „€0 Can changes in „€ explain observed frequency changes0 Mikko <mikko.levanto@iki.fi> - 2022-12-18 11:34 +0200

csiph-web