Most Precise Test Yet of Einstein's Gravitational Redshift

[circumpolar]

A nice experiment demonstrating that gravity changes the flow of time, just like the great man said it would.

ScienceDaily (Feb. 18, 2010)
http://www.sciencedaily.com/releases/2010/02/100217131125.htm

Holger Müller says:
"If we used our best clocks, with 17-digit precision, in global positioning satellites, we could determine position to the millimeter," he said. "But lifting a clock by 1 meter creates a change in the 16th digit".

:eyepop:

[astroron]

Thanks, all very mind bending.

[Jarvamundo]

Cool.... Now if only the pesky Quasars (http://www.iop.org/EJ/article/1538-4357/553/2/L97/015104.html) would conform! conform! conform! sigh...

[sjastro]

The article deals with the issues of cosmological redshift not gravitational redshift.

The irony is that if the observed redshift of a quasar is gravitational rather than cosmological, then quasars are much closer to us in which case the lack of time dilation takes care of itself.
(The article does however dismiss this as a possibility).

Regards

Steven

[Jarvamundo]

heheh... sigh... and they remain relatively pesky

hmm Would both be connected by frame transformation?

[sjastro]

No.

Cosmological redshift is a based on single universal frame of reference. The frame itself undergoes expansion, objects in the frame remain stationary (unless subject to gravity from neighbouring objects).

The time dilation for quasars is based on the distance of the quasar from the observer. The time dilation is calculated using the Lorentz transformation from special relativity.

Gravitational redshift is a direct consequence of the equivalence princple which says there is no difference between a stationary frame in a gravitational field and an accelerated frame moving in a gravity free field.
A photon moving in an accelerated frame will be observed to have a Doppler shift. In the stationary frame the photon will have the same Doppler (gravitational) shift if the strength of the field equals the acceleration of the frame in a gravity free field.

Regards

Steven

[xelasnave]

I lifted this from the article linked to above....


There would appear to be three possible explanations for the lack of a time dilation effect in quasar light curves, all of which conflict with broad consensus in the astronomical community. First, time dilation might not in fact be a property of the universe, which would effectively mean that the universe was not expanding. Apart from the overwhelming support for the big bang theory, the direct measurements of time dilation quoted above strongly argue against this. The second possibility is that quasars are not at cosmological distances. This is an argument that was hotly disputed in the 1970s, with an emerging consensus favoring cosmological distances. This has subsequently been strongly confirmed by studies of quasar host galaxies at high redshift. The third possibility is that the observed variations are not intrinsic to the quasars but caused by some intervening process at lower redshift, such as gravitational microlensing. Although this idea has been strongly argued (Hawkins 1996), there is an opposing view that variations in quasars are dominated by instabilities in the central accretion disk. The reality of this mode of variability in active galactic nuclei is supported by detailed observations of Seyfert galaxies (Peterson et al. 1999) and gravitationally lensed quasars (Kundi et al. 1997), where the presence of intrinsic variations cannot be in doubt. The debate centers on whether this mechanism is responsible for the long-timescale large-amplitude variations that dominate the power spectra discussed in this Letter.

I like the first possibility:D

alex

[Jarvamundo]

updated paper Dec 2009 from Hawkins with a larger sample set http://adsabs.harvard.edu/abs/2009ASPC..413...24H.. seems Hawkins is moving towards the micro lensing solution...

"The main result of this paper is that timescale measures of a large sample of quasar light curves do not show the effects of time dilation."
"The lenses are most plausibly primordial black holes"
"This implies a population of compact lensing bodies sufficient to account for the dark matter"

Looking at the list of abstracts from other papers, from the same publication (http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?bibcode=2009ASPC..413&d b_key=ALL&sort=BIBCODE&nr_to_return =500&data_and=YES&toc_link=YES) it seems those other alternatives are still being explored by many.



Also... Thanks Steven,
So in short?
Gravitational Redshift = The frame is accelerated
Cosmological Redshift = The frame is expanded

[sjastro]

To be more precise Cosmological Redshift is based on the expansion of the observable Universe's frame of reference.

Accelerated frames of reference move in space-time. The Universe's frame of reference is the expansion of space-time itself.

Thanks for the interesting articles.

Steven

[Jarvamundo]

Yep got it, cheers Steven

Interesting indeed!... US$65 gets you the volume http://aspbooks.org/a/volumes/table_of_contents/?book_id=463

Now the question... more astro kit, or a bunch of papers... depends on cloud cover really? heheh