Gravitational Double Slit

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drag

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Greetings !

I see that my original thread called "Uncertain Gravity?"
did not get the attention that I hoped it would (a level
at least sufficient to answer the question I'm now separately
posting here).

So, the question:
What does modern physics say about the double slit experiment
where a gravitational wave detector is placed near a slit
instead of an EM wave detector (or a nuclear detector since
the weak and strong forces have been included in later theories
that deal with them based on the quantum approach) ?
(And if you don't know that, then - what do you think ?)

Thanks ! :smile:

Live long and prosper.
 
Don't know what 'current science' says, but if I recall it properly a gravitational wave detector is being built in the US, it is called LIGO for Large Interferometry Gravitational Observatory, and if I recall again correctly, it is rather huge, (Mile{s} long) not something that you could place in a lab behind the double slit experiment, if that is the one you talking about.

Otherwise, sorry to take up your time. My 2 ¢


EDIT SP!! x 2
 
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FZ+

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I don't quite understand this. How do you diffract gravity waves if as far as we know there is no way to shield from gravity or change it's rate of propagation?
 

jeff

Science Advisor
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Originally posted by drag
What does modern physics say about the double slit experiment
where a gravitational wave detector is placed near a slit...
Since gravity couples to everything, it seems unlikely that a consistent TOE could be constructed that allows gravity to escape governance by the quantum rules that govern everything else. For this reason, such theories haven't been pursued. In fact, the converse issue of what the implications of quantization are for GR, and in particular, for the principle of equivalence and diffeomorphism invariance is a common worry.

The problem of diffeomorphism invariance doesn't lend itself well to you're question, but I have seen the issue of the equivalence principle dealt with in terms of, for example, particles diffracted by a "gravitational grating". However the results of such gedanken experiments don't throw the equivalence principle into doubt.
 
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LURCH

Science Advisor
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Originally posted by FZ+
I don't quite understand this. How do you diffract gravity waves if as far as we know there is no way to shield from gravity or change it's rate of propagation?
Well, that is the sticky in the wicket, no? Perhaps the two slits could be in a berrier of Bose-Einstein Condensate (if these are shown to "block" gravity, which I find hard to accept).
 

drag

Science Advisor
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Greetings !

jeff, thanks for your response. :smile:
Could you, please, tell us a bit more about what
"diffeomorphism invariance" is and how exactly the
equivalence principle is related here (for the poor
hobbyists amongst us, like me ).
Originally posted by FZ+
I don't quite understand this. How do you diffract gravity waves if as far as we know there is no way to shield from gravity or change it's rate of propagation?
But you can alter the course and shape of the wave, right ?

So, suppose you have a nutron going through a slit and you send
a gravity wave. The nutron itself also bends space-time so
the wave should be somehow affected by it in the above manner
(I guess ).

The question is, will this "detection" collapse the WF ?
If not, what will it detect ? And will this mean that
we can get around the HUP through GR and find out what
that QM "mess" is all about ?

Live long and prosper.
 
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in a low gravity limit it is possible to construct a quantum field theory of gravitons - whether this is valid or not remains to be tested - so if a single graviton was diffracted through some version of the double slit experiment, it would act "exactly like a photon" in a similar experiment.

As stated above, it might be possible to set up refractive barriers that allow slit like experiments to b e conducted.

Joe
 

drag

Science Advisor
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Greetings !
Originally posted by Andersen
in a low gravity limit ...
What do you mean by "low gravity limmit" ?
And why is that ?
Originally posted by Andersen
As stated above, it might be possible to set up refractive barriers that allow slit like experiments to b e conducted.
Actualy, I'm just asking about the theory of what will happen.
Like I said before - I don't think that such an experiment will
be practicly possible any time soon (and that's probably
an understatement :wink:). But, if someone got an idea on
how to do it - go right ahead and tell us ! :smile:

Live long and prosper.
 

FZ+

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[Oopsey.... What was I thinking?]
 
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drag

Science Advisor
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Originally posted by FZ+
Gravity having an effect on gravity? Hmm.. certainly a novel idea...
Can this be tested somehow?
I'm not certain what precisely is the problem here.
This is not a novel idea at all.

Live long and prosper.
 
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Originally posted by drag
Greetings !

What do you mean by "low gravity limmit" ?
And why is that ?

Actualy, I'm just asking about the theory of what will happen.
Like I said before - I don't think that such an experiment will
be practicly possible any time soon (and that's probably
an understatement :wink:). But, if someone got an idea on
how to do it - go right ahead and tell us ! :smile:

Live long and prosper.
my recollection of the details is fuzzy - but:
at low enough gravity you can neglect nonlinearities, and then vibrations in space time obey equations analogous to light - which are then amenable to quantization as per the standard methods of QM -> gravitons.

It is possible that a gravitational version of an einstein ring (big GW source behind massive object could yeild some sort of interfenernec epattern in GW's - not positive how you could measure the pattern with ligo though

Joe
 

drag

Science Advisor
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Any other opinions on this ? :smile:
 

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