Relativity Confirmed Again

[Tom.G]

A star and a black hole again confirm Relativity.

https://www.space.com/41291-relativity-revealed-milky-way-core.html

 

[jedishrfu]

Always great news to see GR working at such extreme conditions. Each confirmation makes it tougher to come up with a theory of everything but maybe it will instead direct our energies toward one theme as ideas which modify GR are dropped from the mix of possible theories.

 

[Vanadium 50]

Why (or how) is this different than the Pound-Rebka experiment? (done 59 years ago)

 

[nikkkom]

Each confirmation makes it tougher to come up with a theory of everything

I don't see why?

 

[nikkkom]

Why (or how) is this different than the Pound-Rebka experiment? (done 59 years ago)

I imagine the achievement here is mostly in the success of improvements to telescopes, AO, spectrographs and such which were necessary to raise SNR sufficiently so that valid data can be obtained in this particular difficult case. Galactic core is heavily obstructed by dust and gas.

 

[jedishrfu]

My guess is primarily because it was done at larger scales and more extreme conditions around a black hole whereas Pound Rebka was done in an Earth laboratory.

https://en.wikipedia.org/wiki/Pound–Rebka_experiment

Each new proof of GR necessarily puts a hard experimental limit on the kinds of theories that can replace it. This means that some theories that don't predict the value of the GR experiment will have to be discarded or reworked.

 

[nikkkom]

Each new proof of GR necessarily puts a hard experimental limit on the kinds of theories that can replace it.

But future quantum gravity theories are expected to differ from GR at field strengths (or curvatures, if you will) _much_ higher than even those at BH event horizons.

IOW: their predictions for events like one on this case are exactly the same as from GR. Therefore this observation does not further constrain the set of possible quantum gravity theories.

 

[jedishrfu]

I think we are in agreement here. Some of the current theories have to be or have been discarded because they failed to predict what has been measured.

This paper talks about binary pulsars (circa 2008) and how experimental results have confirmed GR and limited other alternatives to GR:

https://books.google.com/books?id=s... experiment limits alternate theories&f=false

It's not hard to imagine then that these latest GR results will do the same.

 

[nikkkom]

I think we are in agreement here. Some of the current theories have to be or have been discarded because they failed to predict what has been measured.

This paper talks about binary pulsars (circa 2008) and how experimental results have confirmed GR and limited other alternatives to GR:

https://books.google.com/books?id=sT_ICgAAQBAJ&pg=PA225&lpg=PA225&dq=GR+experiment+limits+alternate+theories&source=bl&ots=fFcBpAKvnS&sig=7XeNlFIe-Q-SQCkS7ppedB-ALc4&hl=en&sa=X&ved=2ahUKEwjTg7WisL_cAhWI7IMKHbZqAO0Q6AEwBnoECAUQAQ#v=onepage&q=GR experiment limits alternate theories&f=false

The disproved theories in question are not "theories of everything" you mentioned earlier, i.e. quantum mechanical unifications of SM forces with gravity.
They are _classical_ theories of gravity.

 

[jedishrfu]

I feel you are taking things way too seriously here. I am not a physicist and my feeling is that every theory we develop leads to a theory of everything. As we are searching for this ultimate theory of everything, our experiments help to focus our results in the right direction.

 

[Vanadium 50]

My guess is primarily because it was done at larger scales and more extreme conditions around a black hole whereas Pound Rebka was done in an Earth laboratory.

But it's not all that extreme. The acceleration due to gravity on S2 is about the same as on the surface of the moon. If you want to argue that what matters is potential, not force, you can do ~50x better with the white dwarf data.

 

[jedishrfu]

That’s a good point, I don’t have any better reason except to celebrate that we can see deeper into the center of our galaxy than before to observe GR in action.

 

[Cerenkov]

Fascinating news!

Every so often another confirmation of Einstein's theories makes headline news. To wit, LIGO's observation of gravitational waves.

But I was wondering, is there a definitive list of experiments that have confirmed GR (and SR?)...?

Thanks,

Cerenkov.

 

[jedishrfu]

Here’s some of the more famous ones:

https://en.m.wikipedia.org/wiki/Tests_of_general_relativity