Recent content by jaketodd

I thought if it's like a rubber sheet, it might deform like a rubber sheet. Is differential geometry a good start to understanding how it really behaves? Thanks

Does it hold true enough that there are radial wrinkles in spacetime around a gravitating object, like in this picture of a flexible material being pushed down on at the center? Thanks

I'd like to start with: Does the rubber sheet analogy still hold true enough? Or is there really no visualization (it's all mathematical constructs)? Does this picture analogy hold at all here? With the curved geodesics influencing the paths of things. Thanks!

Like I said, I realize I'm splitting hairs. But it's still kind of interesting. I did not know inertial reference frames larger than one point were an idealization until today, for example. Sorry to those that already knew that.

But you said spacetime is curved everywhere in the universe. Wouldn't that make it impossible to define any region of two or more points as inertial? A line between any two points would always traverse spacetime curvature. I guess I'm splitting hairs. Sounds like the relativistic velocity...

Ok, sorry.

So then technically, since spacetime is curved everywhere in the universe, then it's always impossible, in-practice, to use the relativistic velocity addition law for any two points, anywhere? I meant the invariance of the speed of light, even for light emanating from something moving faster...

But the fabric of the universe is expanding even in tiny localized regions, right, i.e. dark energy? And even without dark energy, isn't the expanding universe also expanding in more localized regions, just not as uniformly as the universe as a whole? (Because all regions are expanding...

So the curved spacetime surrounding the spaceship prevents "linking" the reference frame of the spaceship to an observer outside the Alcubierre drive region via the relativistic velocity addition law? If so, reference frames are linked using that law if you can draw a line between them that...

If magnetic fields, currently attainable by humans, are much stronger than the ones required for impacting spacetime geometry affecting the expansion of the universe, then why can't we influence much more localized spacetime geometry with magnetism? Thanks

Quotes from Cosmic magnetism, curvature and the expansion dynamics: "Most interestingly, the coupling between magnetism and geometry implies that even weak fields have a significant impact if the curvature contribution is strong." "The energy scales involved vary from ∼ 100 MeV at the QCD...

Inside the warp bubble/for the spaceship described by Alcubierre, the spacetime is flat. So, therefore, wouldn't that be compatible to an observer, in a local inertial frame/no curvature difference between reference frames? If so, and if Alcubierre is right, wouldn't that throw a wrench in...

So, in non-locally inertial reference frames, you can see something go faster than light? Is curved spacetime, which one example is what Alcubierre describes, the only way to see someone go faster than light, or can you ever see someone go faster than light without spacetime curvature/gravity...

Moderator's note: This was originally posted in another thread but has been spun off. "It is shown how, within the framework of general relativity ... motion faster than the speed of light as seen by observers outside the disturbed region is possible." The warp drive: hyper-fast travel within...

You're trying to put words in my mouth, and are just plain rude.