Gravitational redshift

[Peron]

Does gravitational redshift happen to Jupiter? if so, has anyone ever detected it?

 

Thanks.

[insane_alien]

yes it happens, i don't know if anyone has bothered to do much checking.

 

we know it happens to earth(otherwise GPS would be less accurate than a sextant) and we test it out and detect it every second of every day.

[swansont]

IIRC Kopeikin's experiment to measure the speed of gravity did so, though possibly indirectly. There's controversy over whether he actually measured the speed of gravity, but he did measure the Shapiro delay, which depends on the gravitational time dilation.

[Peron]

yes it happens, i don't know if anyone has bothered to do much checking.

 

we know it happens to earth(otherwise GPS would be less accurate than a sextant) and we test it out and detect it every second of every day.

 

You mean Gravitational time dilation. What does GPS have to do with gravitational redshift?

 

In physics, light or other forms of electromagnetic radiation of a certain wavelength originating from a source placed in a region of stronger gravitational field (and which could be said to have climbed "uphill" out of a gravity well) will be found to be of longer wavelength when received by an observer in a region of weaker gravitational field. If applied to optical wave-lengths this manifests itself as a change in the colour of the light as the wavelength is shifted toward the red (making it less energetic, longer in wavelength, and lower in frequency) part of the spectrum. This effect is called gravitational redshift and other spectral lines found in the light will also be shifted towards the longer wavelength, or "red," end of the spectrum. This shift can be observed along the entire electromagnetic spectrum.

 

http://en.wikipedia.org/wiki/Gravitational_redshift

 

Does it happen to Jupiter? and has anyone measured it?

[Martin]

You mean Gravitational time dilation. What does GPS have to do with gravitational redshift?

 

Everything. The GPS satellites are up higher than we are. They carry atomic clocks. These atomic clocks run faster than clocks on the surface of the planet, which are deeper down in the gravitational potential well.

 

Being deeper in gravitational potential slows clocks and also the vibrations of lightwaves by the same factor. That is called gravitational redshift.

 

 

 

Does it happen to Jupiter? and has anyone measured it?

I think Swansont already told you yes and yes. There was a measurement involving Jupiter gravity and (indirectly) time. I'm not at all clear about the details.

Maybe you could take the name Swansont gave you, and look up his papers, and see if there was something. Try to find something on your own before asking again.

Just go to arxiv.org, select "search" and type in the author's name.

http://arxiv.org/

*selects search and gets* http://arxiv.org/multi?group=grp_physics&%2Ffind=Search

*types Kopeikin and gets* http://arxiv.org/find/grp_physics/1/au:+Kopeikin/0/1/0/all/0/1

 

Ooops, I got curious myself and did a search for Kopeikin and found this 2003 paper

http://arxiv.org/pdf/gr-qc/0310059

Plus there are a lot of followup papers from 2003 thru 2005.

 

But basically, Peron, you should know how to follow up on your own, if somebody gives you a lead. You are obviously plenty smart and capable to do this. And if you try and need additional help be absolutely welcome to ask, but try first.

Edited October 4, 2009 by Martin

[insane_alien]

as martin says, gravitational redshift must be accounted for when communicating with the satellites. the satellite sends out signals at a certain frequency and if you tuned the reciever to exactly that frequency you wouldn't get the signal. if you change the frequency apropriately using gravitational redshift equations then it is trivial to communicate with the satellite.

 

also, gravitational redshift and gravitational time dilation are different facets of the same thing.