The Gravity Field and Gravitational Waves

[geordief]

i understand that the Gravity Field is static and not to be confused with Gravitational Waves which are dynamic.

 

Gravitational waves are created when there is a change in mass-energy distribution and propagate at light speed (correct?).

 

Do they have any effect on the static Gravity Field?

 

Does the energy in these Gravitational waves get distributed throughout the Gravity Field it propagates through and so do these Gravitational waves get "converted" into a new Gravity Field?

[MigL]

Gravitational waves are, in effect, changes in the gravity field.

[geordief]

Gravitational waves are, in effect, changes in the gravity field.

What does it mean to say the Gravity Field is static? Is it not changing all the time ?

 

Also ,when there is even the most minor of displacements of distribution of mass-energy in a system does that also cause Gravitational waves in exactly the same way as was detected with the recent Binary Black Hole Merger? Is is simply that the magnitude of Gravitational waves caused by such small redistributions of mass-energy in a system are entirely impossible to detect ?

 

Is it correct to say that the universe is awash with small Gravitational waves so that the local and global Gravity Fields are actually in continuous change on a vanishingly small scale?

 

They are in continuous "vibration" almost ?

 

Are the Gravitational waves that have been detected merely the ones that are large enough to have been physically detected?

[Strange]

What does it mean to say the Gravity Field is static?

 

 

I think people use it to mean that it is relatively static, to emphasise that gravity is not mediated by gravitational waves but by the state of the gravitational field.

 

 

 

Also ,when there is even the most minor of displacements of distribution of mass-energy in a system does that also cause Gravitational waves in exactly the same way as was detected with the recent Binary Black Hole Merger?

 

I think the generation of waves requires a certain sort of asymmetry. So a spinning sphere won't generate waves, for example. (The details beyond that are a bit fuzzy for me.)

 

 

Are the Gravitational waves that have been detected merely the ones that are large enough to have been physically detected?

 

Absolutely.

[geordief]

If the local Gravity Field is quivering like a jelly fish (or a blancmange) is there any way these small changes could be observed ? (by the change of behaviour of objects in the Field?)

 

Did the recent passage of Gravitational waves that actually was observed cause a permanent change in the local Gravity Field where (and elsewhere) they were detected?

 

Were those small changes measured?

 

What units would be used?(the same as for spacetime distance?)

Edited October 31, 2016 by geordief

[imatfaal]

If the local Gravity Field is quivering like a jelly fish (or a blancmange) is there any way these small changes could be observed ? (by the change of behaviour of objects in the Field?)

 

Did the recent passage of Gravitational waves that actually was observed cause a permanent change in the local Gravity Field where (and elsewhere) they were detected?

 

Were those small changes measured?

 

What units would be used?(the same as for spacetime distance?)

 

1. Why would the local gravitational field quiver like a jelly fish? Where would the mass energy be coming from / going to to cause this oscillation? Simple planets, stars, blackholes etc just have a gravitational field and do not radiate gravitational waves. To get gravitational waves that can be detected far off you need stupidly extreme events -- like two black holes spinning into each other. I have seen the g wave calculations for a normal binary star and it is a lot lot less than expected - it can simply be treated as one star at the CoM apart from if you are very close.

 

2.Yes the g waves picked up by LIGO radiated away a vast amount of energy. It was multiple solar masses worth of energy lost in seconds - it was this massive amount of energy radiated away in such a short time that allowed us to measure the waves from so far away. The overall gravitational field will have been lessened by the amount of mass energy radiated away. They lost about 5% of their mass in this event - and for the most violent portion were radiating more power than all the stars in the observable universe. And we only just picked up the signal!

 

3. How? This event happened billions of light years away and we only have the roughest clue where it happened

 

4. I think you could probably use solar masses or kilograms for the change. You had (according to predictive and reconstructive modelling) two black holes which, if memory serves, had a combined mass of 59 solar masses - they radiated away about 3 solar masses.

[geordief]

 

1. Why would the local gravitational field quiver like a jelly fish? Where would the mass energy be coming from / going to to cause this oscillation?

Simple planets, stars, blackholes etc just have a gravitational field and do not radiate gravitational waves. To get gravitational waves that can be detected far off you need stupidly extreme events -- like two black holes spinning into each other. I have seen the g wave calculations for a normal binary star and it is a lot lot less than expected - it can simply be treated as one star at the CoM apart from if you are very close.

 

2.Yes the g waves picked up by LIGO radiated away a vast amount of energy. It was multiple solar masses worth of energy lost in seconds - it was this massive amount of energy radiated away in such a short time that allowed us to measure the waves from so far away. The overall gravitational field will have been lessened by the amount of mass energy radiated away. They lost about 5% of their mass in this event - and for the most violent portion were radiating more power than all the stars in the observable universe. And we only just picked up the signal!

 

3. How? This event happened billions of light years away and we only have the roughest clue where it happened

 

4. I think you could probably use solar masses or kilograms for the change. You had (according to predictive and reconstructive modelling) two black holes which, if memory serves, had a combined mass of 59 solar masses - they radiated away about 3 solar masses.

I thought that even a minor event like 2 hands clapping (or even just moving wrt each other) would produce gravitational waves .The gravitational waves would be entirely undetectable but would still exist.

 

That is why I am surmising the the gravity field is quivering like a jelly -because gravitational waves (far too small to be detected ) are everywhere ,caused by the most minor disturbances in mass-energy distributions.

 

Am I wrong ?(about there being no limit to how weak gravitational waves can be)

Edited October 31, 2016 by geordief

[imatfaal]

I thought that even a minor event like 2 hands clapping (or even just moving wrt each other) would produce gravitational waves .The gravitational waves would be entirely undetectable but would still exist.

 

That is why I am surmising the the gravity field is quivering like a jelly -because gravitational waves (far too small to be detected ) are everywhere ,cause by the most minor disturbances in mass-energy distributions.

 

Am I wrong ?(about there being no limit to how weak gravitational waves can be)

 

Sorry - hadn't realised you were talking that small. I see no reason why a transverse oscillating masses would not produce gravitational waves in a very hypothetical sense - but the disturbances are vanishingly small and without any detail, I would guess that anything accurate enough to detect would be absolutely swamped by noise (from residual particles in strong vacuum to quantum background). If something is theoretically impossible to detect can you really say it is there? For instance, I would think that the slight imbalance of charge inherent in the human body and between hands would produce far larger readings in emr than the g waves