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Is it theoretically possible that one day a gravitational wave detector will be developed, that is sensitive enough to detect gravitation at the order of magnitude that an Earth like planet has?
So it is correct to ask questions this way?Vanadium 50 said:I predict that this will end up becoming an argument about what "theoretically possible" means.
This would be ~1000000000000000000000000000000000000 times weaker than a BH merger.
In the words of Jim Carey, "So you're telling me there's a chance!"
As always at PhysicsForums, it's best to post a link to the reading you have been doing about gravitational waves, and do as much of the calculation as possible to show whether it would be possible/reasonable to do this detection.roineust said:So it is correct to ask questions this way?
I guess, but it would still be best if you addressed the missing parts of your OP that I already mentioned, and said quantitatively why what you want to discuss is superior to the current approaches in the search for Exoplanets. Thanks.roineust said:Should i ask the motivating question behind the initial question or is it already totally clear what i am about to ask?
So after presenting links and calculations (as @berkeman said) I think the question becomes whether it is theoretically possible to practically detect ... (etc.)roineust said:So it is correct to ask questions this way?
So i was supposed not to ask the "theoretically possible" continuation question, after you gave the quantitative answer to the initial question?Vanadium 50 said:You got a quantitative answer, and somehow it's not good enough. I predicted that this will end up becoming an argument about what "theoretically possible" means. And we seem to be on that path, given that a quantitative answer is somehow unsatisfactory.
roineust said:So i was supposed not to ask the "theoretically possible" continuation question
Vanadium 50 said:I predict that this will end up becoming an argument about what "theoretically possible" means.
So by writing "theoretically possible" you did not mean physics theory but argument theory?Vanadium 50 said:And away we go!
Yes.roineust said:Is it theoretically possible that one day a gravitational wave detector will be developed, that is sensitive enough to detect gravitation at the order of magnitude that an Earth like planet has?
roineust said:So by writing "theoretically possible"
roineust said:Oh, no it has nothing to do with exoplanets it has to do with general relativity equivalence principle:
If such a detector had existed, wouldn't it make the equivalence principle not correct?
No.roineust said:If such a detector had existed, wouldn't it make the equivalence principle not correct?
How is that different in principle from current gravitational wave detectors? So in your opinion a detector that can detect black holes and neutron stars is compatible with the equivalence principle, but one that detects planets is not?roineust said:As much as i understand, if such a detector would have existed, then a claim that says that there is no experiment that can tell the difference between a gravitational field of a certain strength and non-gravitational constant acceleration, that causes equal acceleration to that gravitational field, will be a not correct claim.
Dale said:Yes.
Without him specifying like @berkeman suggested I think it's pointless to draw conclussions or even discussing equivalence principle etc. ...berkeman said:As always at PhysicsForums, it's best to post a link to the reading you have been doing about gravitational waves, and do as much of the calculation as possible to show whether it would be possible/reasonable to do this detection.
You did post this in the technical forums, after all, not the General Discussion forum...
That is not quite what the EP claims. The EP claims that “there is no experiment that can tell the difference between a [ constant] gravitational field of a certain strength and non-gravitational constant acceleration” within a sufficiently small region of spacetime, one that is small enough that the tidal effects that distinguish a gravitational field from non-gravitational constant acceleration are negligible.roineust said:there is no experiment that can tell the difference between a [constant] gravitational field of a certain strength and non-gravitational constant acceleration
You do realize that gravitational waves are not simply the result of there being a gravitational field? You need something like a mass accelerating to produce them. With the BH detection, the GW radiation was produced by the holes spiraling in on each other. While an Earth-like planet can produce GWs, it would be due to its orbit around its star. In that case, an Earth-like planet orbiting a star like our Sun, at a similar distance, would generate GWs at a power of just 200 watts. These waves could have a frequency of 1 cycle per year, and a wavelength of 1 light year.roineust said:As much as i understand, if such a detector would have existed, then a claim that says that there is no experiment that can tell the difference between a gravitational field of a certain strength and non-gravitational constant acceleration, that causes equal acceleration to that gravitational field, will be a not correct claim.
Nugatory said:because if we’re detecting gravitational waves we aren’t working with a constant gravitational field.
These are my words, which you have reused while changing their meaning, if the answer to the preliminary question was no, would it still be false pretense?Vanadium 50 said:Those are your words. Words #3 and #4 of this thread.
roineust said:If such a detector had existed, wouldn't it make the equivalence principle not correct?
Is the equivalence principle defined in such a way that it is experimentally non-falsifiable?PeterDonis said:No. The equivalence principle is only valid over regions of spacetime that are small enough that tidal gravity is not detectable. Gravitational waves are waves of tidal gravity, so if a gravitational wave is detected, then by definition the region of spacetime involved is not small enough that tidal gravity is not detectable.
Of course it's falsifiable: drop two masses off the Leaning Tower of Pisa and have one hit the ground before the other because it's made of (hypothetical) material that accelerates twice as fast under gravity as normal matter. If you repeat the experiment in a closed box you could then tell whether you were accelerating in empty space (the masses "fall" at the same rate) or at rest on a planet (they fall at different rates).roineust said:Is the equivalence principle defined in such a way that it is experimentally non-falsifiable?
For example: the region is defined to always be smaller than the area that any future equipment will be able to measure?
Not sure this helps the OP.Ibix said:... it's made of (hypothetical) material that accelerates twice as fast under gravity as normal matter...
It's a heuristic to help form an intuition about how the theory works, not part of the theory itself, so it's not clear what it would mean to "falsify" it. We don't use it in those problems in which it does not help us form that intuition - which is another way of saying that it doesn't have much of anything to do with gravitational waves.roineust said:Is the equivalence principle defined in such a way that it is experimentally non-falsifiable?
roineust said:Is the equivalence principle defined in such a way that it is experimentally non-falsifiable?
DaveC426913 said:Is it falsifiable without invoking physics-defying materials?
Have a look at an analogous principle:roineust said:Is the equivalence principle defined in such a way that it is experimentally non-falsifiable?
For example: the region is defined to always be smaller than the area that any future equipment will be able to measure?
DaveC426913 said:Have a look at an analogous principle I just made up.
It's not the best analogy, granted. The point is that the Equivalence principle doesn't have a minimum resolution, below which it's not valid. That seems to be what the OP thinks.PeterDonis said:It's not analogous. Your "principle" is a tautology, since part of the definition of a sphere is that it has the same radius at every point on it.
The EP is not a tautology; it is not a logically necessary proposition.
DaveC426913 said:the Equivalence principle doesn't have a minimum resolution, below which it's not valid