- #1
RiccardoVen
- 118
- 2
Hi,
I've just started Gravitation and Inertia by Wheeler and Ciufolini. This is really a sort of trasure to me, since I was looking for something about it since when I read Einstein's relativity papers, involving Mach's principle.
The main point is really simple "Inertia here arises from mass there". I've not read carefully yet the Cauchy problem for GR, but it's depicted here everything, if "well" prepared, raises to a deterministic behaviour with GR ( which makes sense to me ).
My main ( subtle ) problem is about Mach's principle. Of course I can see it can be really well encompassed by GR, since we could think about "far stars influence" as carved within the spacetime curvature.
So, from here we can see Inertia ( or locally intertial frames, as pointed out many times in the book ) is actually influenced by the fixed stars.
So, I got two problems arising here:
1) Inertia is also defined to be the property of matter to keep its state of motion ( sorry if this is a bit rough or not matematically better defined so far ), so its propery to fight against changing in motion. This is also used in inertial frame definition, i.e. for Newton a frame in which law of inertia is valid, or for GR in which a frame is free floating.
So my doubt is: let's imagine a universe in which there are no far fixed stars. Does this mean there would be no inertia at all? Better: does a universe in which there's a just a particle ( or a couple of, in order to have an observer as well ) this particle would not keep its state of motion?
I can't believe about this, so I guess something is wrong in my reasoning above.
2) does this mean, all in all, everything is gravity? I mean, even inertia is due to gravity, from this picture.
Sorry for my noob's questions as always.
Regards thanks
I've just started Gravitation and Inertia by Wheeler and Ciufolini. This is really a sort of trasure to me, since I was looking for something about it since when I read Einstein's relativity papers, involving Mach's principle.
The main point is really simple "Inertia here arises from mass there". I've not read carefully yet the Cauchy problem for GR, but it's depicted here everything, if "well" prepared, raises to a deterministic behaviour with GR ( which makes sense to me ).
My main ( subtle ) problem is about Mach's principle. Of course I can see it can be really well encompassed by GR, since we could think about "far stars influence" as carved within the spacetime curvature.
So, from here we can see Inertia ( or locally intertial frames, as pointed out many times in the book ) is actually influenced by the fixed stars.
So, I got two problems arising here:
1) Inertia is also defined to be the property of matter to keep its state of motion ( sorry if this is a bit rough or not matematically better defined so far ), so its propery to fight against changing in motion. This is also used in inertial frame definition, i.e. for Newton a frame in which law of inertia is valid, or for GR in which a frame is free floating.
So my doubt is: let's imagine a universe in which there are no far fixed stars. Does this mean there would be no inertia at all? Better: does a universe in which there's a just a particle ( or a couple of, in order to have an observer as well ) this particle would not keep its state of motion?
I can't believe about this, so I guess something is wrong in my reasoning above.
2) does this mean, all in all, everything is gravity? I mean, even inertia is due to gravity, from this picture.
Sorry for my noob's questions as always.
Regards thanks