How does Gravitational Mass work?

[MigL]

Trying to consider one common original 'now' is similar to considering an original spatial singularity.
GR's applicability has boundries.

[geordief]

1 minute ago, MigL said:

Trying to consider one common original 'now' is similar to considering an original spatial singularity.
GR's applicability has boundries.

Yes I see that.

[Mordred]

6 hours ago, geordief said:

If the Earth (or any body or collection of bodies) undergoes changes  such as loss -ie redistribution of all the ice in the world , would that cause any  change to its the gravitational field? (say measured from the Moon

If you change the mass distribution of a body then you will get changes in a gravitational field however some of those changes such as you described would average out. For example the polar ice would become water but the overall mass wouldn't change  so locally on Earth you can measure the changes but from the Moon you wouldn't be able to measure the distribution change.

[geordief]

12 minutes ago, Mordred said:

If you change the mass distribution of a body then you will get changes in a gravitational field however some of those changes such as you described would average out. For example the polar ice would become water but the overall mass wouldn't change  so locally on Earth you can measure the changes but from the Moon you wouldn't be able to measure the distribution change.

But you would from the space station,would you?

So the measurable difference would extend a small distance from the body?

Is there a  general boundary for any body beyond which  the internal  redistribution of mass  becomes completely unmeasurable and within which it is measurable?

[Strange]

15 minutes ago, geordief said:

But you would from the space station,would you?

Not sure about the space station, but it can certainly be measured by satellites, for example: https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_Explorer

 

[Mordred]

I seriously doubt you would notice at the space station for the scenario provided. The range one can detect changes would vary depending on the overall mass distribution and the amount of change.

Think of it this way from the space station the mass of the Earth seems uniform. However one can measure variations in g from various points on the Earth's surface 

Cross posted with Strange evidently it is plausible to get some anistrophy measurements 

(Lol guess that can happen when you make educated guesses instead of calculating lol )

Edited December 15, 2019 by Mordred

[studiot]

1 hour ago, geordief said:

But you would from the space station,would you?

So the measurable difference would extend a small distance from the body?

Is there a  general boundary for any body beyond which  the internal  redistribution of mass  becomes completely unmeasurable and within which it is measurable?

I don't think the space station is equipped for gravimetric surveys (which is what you are asking about)

But several satellites have been put up for this purpose over the decades.
Their resolution is certainly fine enough to measure such changes.

No there is no boundary.
Astromomers have had several successes and made several discoveries due to measuring high gravity activity/changes at great distance eg by neutron stars and black holes.