Gravitational Waves: Impact & Effects on Gravity

[roineust]

When a gravitational wave passes through a location in space, what is the magnitude of equivalent gravity that it produces at that location?

Or rather, is it correct to say that gravity can influence gravitational waves but gravitational waves can't influence gravity?

 

[jbriggs444]

When a gravitational wave passes through a location in space, what is the magnitude of equivalent gravity that it produces at that location?

Or rather, is it correct to say that gravity can influence gravitational waves but gravitational waves can't influence gravity?

Gravitational waves are gravity.

 

[Vanadium 50]

You've asked this question here and here and here.

All three ended up locked. I don't see any reason a fourth would have any different outcome.

 

[roineust]

You've asked this question here and here and here.

All three ended up locked. I don't see any reason a fourth would have any different outcome.

Sorry, but i don't understand from your reply the answer to my question.

 

[roineust]

Gravitational waves are gravity.

If they are the same, how do i calculate the equivalent gravity force as measured on earth, not at the origin of the wave, of the most powerful gravitational wave that passed through LIGO, since the start of its operation?

 

[Ibix]

If they are the same, how do i calculate the equivalent gravity force as measured on earth, not at the origin of the wave, of the most powerful gravitational wave that passed through LIGO, since the start of its operation?

Gravity is not a force. The force from both the static(ish) gravitational field of the Earth and from gravitational waves is zero. The force you feel standing on the Earth is the electromagnetic interaction between your feet and the floor.

 

[roineust]

Gravity is not a force. The force from both the static(ish) gravitational field of the Earth and from gravitational waves is zero. The force you feel standing on the Earth is the electromagnetic interaction between your feet and the floor.

And a gravitational wave causes changes in this electromagnetic interaction between my feet and the floor?

 

[Ibix]

Yes, in principle, although it would depend on the polarisation and direction of the wave. Bearing in mind that the peak strain of the LIGO detection events was 10^-22 or something of that order, it would be indetectable.

 

[pervect]

When a gravitational wave passes through a location in space, what is the magnitude of equivalent gravity that it produces at that location?

Or rather, is it correct to say that gravity can influence gravitational waves but gravitational waves can't influence gravity?

Gravitational waves don't produce gravity in the sense I think you mean. There are several ways of explaining them. I'm going to pick the way I most often think of them, which is to say they are produced by tidal gravity.

If you have a circular array of test masses, you can think of the wave as making the test move as per the image below, taken from a wiki article, https://en.wikipedia.org/w/index.php?title=Gravitational_wave&oldid=978704658#Effects_of_passing.

There are other ways of thinking about this topic, but this is one of the simplest.

The motion in the image is enormously exagerated. I haven't seen a numerical calculation, but the quote below from google might give you some idea:

At its most sensitive state, LIGO will be able to detect a change in distance between its mirrors 1/10,000th the width of a proton!

 

[roineust]

Yes, in principle, although it would depend on the polarisation and direction of the wave. Bearing in mind that the peak strain of the LIGO detection events was 10^-22 or something of that order, it would be indetectable.

Does there exist an astronomical reason to reject a possibility, that not only gravitational waves in the order of magnitude of 10^-22 are prevalent through the universe, but also gravitational waves of a much bigger order of even 10^-11 are prevalent through the universe?

Wouldn't an Earth array of superconducting gravimeters (10^–11 m·s^-2 ), be able to triangulate very big gravitational wave incidents in the sky?

Are LIGO like devices designed in such a way, that if a 10^-11 order of magnitude gravitational wave incidents had occurred, they would have been able to detect them?

 

[PeterDonis]

how do i calculate the equivalent gravity force

You can't. Gravitational waves are not waves of "gravity force". They are waves of tidal gravity. Just as you were told in the three previous threads that @Vanadium 50 referenced.

Gravitational waves are gravity.

Tidal gravity, yes. Not "gravity force".

 

[PeterDonis]

Does there exist an astronomical reason to reject a possibility, that not only gravitational waves in the order of magnitude of 10^-22 are prevalent through the universe, but also gravitational waves of a much bigger order of even 10^-11 are prevalent through the universe?

The strength of a gravitational wave at the detector is not a fixed number. It depends on how far away you are from the source. If you are asking whether it is likely that any sources of gravitational waves are close enough to Earth so that the waves they produce will have order of magnitude $10^{-11}$ when detected on Earth, I think the general opinion is that that is very unlikely.

(10^–11 m·s^-2 )

Where are you getting this from and what do you think it means? (Hint: the strength of a gravitational wave at the detector, for example the $10^{-22}$ number that is sometimes quoted for LIGO's sensitivity, is a dimensionless number; it does not have units of acceleration.)

 

[roineust]

You can't. Gravitational waves are not waves of "gravity force". They are waves of tidal gravity. Just as you were told in the three previous threads that @Vanadium 50 referenced.
Tidal gravity, yes. Not "gravity force".

That was close to my first question in this thread:

Tidal gravity direction and strength can not be changed by gravity force, no matter how strong and in what direction that gravity force is applied? And the other way: Gravity force direction and strength can not be changed by tidal gravity, no matter how strong and in what direction that tidal gravity is applied?

 

[Ibix]

Earlier LIGO-like devices were less sensitive and did not pick up anything. So highly prevalent strong gravitational waves seems unlikely. What would be the source, apart from anything else?

Wouldn't an Earth array of superconducting gravimeters (10^–11 m·s^-2 ), be able to triangulate very big gravitational wave incidents in the sky?

I did not say 10^-11ms^-2. I was talking about strains - fractional length changes.

The problem with measuring your proper acceleration is that you can't isolate your sensor from the Earth because you are actually measuring the contact force between the Earth and the sensor. So you can't isolate it from the vibrations of earthquakes, or a truck driving down the street. So any gravitational wave signal will be lost in hugely stronger local noise.

Tidal gravity direction and strength can not be changed by gravity force, no matter how strong that gravity force is? Gravity force direction and strength can not be changed by tidal gravity, no matter how strong that tidal gravity is?

Gravity is not a force. It's very difficult to know how to answer your questions because you don't seem to accept the underlying framework in which they can be answered.

Yes, a passing gravitational wave does, in principle, affect the reading on a weighing scale. No, this is not a practical means of detecting them. Yes, in principle, gravitational waves may be lensed by static(ish) gravitational fields, but we do not have detectors of sufficient precision to see this and the events that produce detectable waves are too short lived for us to detect such effects even if that were not the case.

 

[Vanadium 50]

Gravity is not a force. It's very difficult to know how to answer your questions because you don't seem to accept the underlying framework in which they can be answered.

Sad, but true. Even to the point of changing units on your answer, like turning a strain into an acceleration.

 

[PeterDonis]

Tidal gravity direction and strength can not be changed by gravity force, no matter how strong and in what direction that gravity force is applied? And the other way: Gravity force direction and strength can not be changed by tidal gravity, no matter how strong and in what direction that tidal gravity is applied?

There is no such thing as "tidal gravity direction and strength"; tidal gravity is not a vector. It's a tensor.

There is no such thing as "gravity force"; gravity is not a force in GR.

Your questions cannot be answered because, as @Ibix has already pointed out, you don't appear to grasp the underlying framework. That being the case, there is no point in continuing this discussion.

Please let me know if this should be a new thread

It will be in a moment. This thread is closed.