Mass distorts spacetime, which to an outside observer appears to change the direction light travels. The light travels in a straight line.
Gravity doesn’t alter the particle’s trajectory (or ours, for that matter). The warping of spacetime from Earth’s mass causes our movement through space to accelerate “down” at ~9.8 m/s^2
So the ghosts are in the center of the Earth, in nearly literal hell.
They would fall through the center of the earth, continue back up through the mantle, pop up momentarily to spook someone on the opposite hemisphere, then repeat the whole trip in reverse with a period of about 40 minutes.
Hm… actually are they incorporeal AND massless, or just incorporeal?
If just incorporeal, you’re right of course that initially after death they’d be falling back and forth, but over time through uneven gravity/curvature and through heat loss (stretching of unequal acceleration applied across the ghost essence, potential energy conversion, yadda), they should generally settle to the center after some time, unless there’s a maximum natural pressure of ghosts at whatever temperatures they have, so they may spread out somewhere within the crust if there are enough of them.
If they’re incorporeal AND massless, then I totally F’d up and they’d fire off at light speed as soon as they shed their mortal coil.
If the spacetime is distorted, and the light no longer appears to travel in a straight line, does that not mean that spacetime itself and the light that travels in are no longer straight?
How can a straight thing be distorted but still be straight?
It is straight in reference to the distorted spacetime.
Conventionally, a straight line is defined as the shortest path between two points, but if you take a plane that is not flat, say the surface of a ball, the shortest path between two points will be curved. But from the perspective of the two-dimensional man who lives in surface, the line is straight because it moves perfectly along his world.
Is this 2D-3D comparison supposed to be like a human-understandable analogy for a 3D-4D relationship?
I saw an explanation once about how time is the 4th dimension. They drew a line on the edge of a book. From the perspective of a single page (2D) it just looks like a dot, but because we can see many instances of that 2D representation it appears to us as a line. An individual page represents how we experience time.
Is your ball example supposed to be kind of like that because I just can’t imagine how spacetime could be a 2D thing in a 3D universe.
Well, kind of. The time dimension is a bit tricky, though – in Minkowsky space, a common way to think about spacetime, it is hyperbolic in relation to the other dimensions. In a nutshell, this means that distance is not the square root of the sum of the squares of the distances in specific dimensions, but rather of the difference. This makes it especially tricky to visualise. (I do recommend you check out this series by minutephysics, he does a great job at making it intuitive)
My analogy, therefore, doesn’t translate directly to spacetime, but it does provide a very simple 2d explanation for why straight things can act curved (even in 4d).
I think a better way of explaining it is with the idea of a shortest path, and not nessesarily a straight line. With two points in space the shortest path between them will be a straight line. If there’s a large amount of gravity tugging on space time the shortest path will be curved.
That’s called General Relativity and Reference Frames.
Start watching PBS Spacetime if you actually want to get into it.
You’re also entirely missing the point of the comment that was a joke entirely re-explaining the “reason” for ghosts ending up at the center of the Earth, which is implied by the original comment.
Well that’s just a theory, albeit good, and there’s a good chunk of modern science that refuses to marry it, so let’s not be too sure about it, shall we?
Although general relativity is highly regarded for its elegance and accuracy it is not without limitations: the gravitational singularities inside of black holes, the ad hoc postulation of dark matter, as well as dark energy and its relation to the cosmological constant are among the current unsolved mysteries regarding gravity; all of which signal the collapse of the general theory of relativity at different scales and highlight the need for a gravitational theory that goes into the quantum realm.
I really hate that people just accept these advanced theories as objective truth. It’s just the best theory we have right now, that doesn’t mean that’s how it actually works. It’s good enough that we can almost always just use the theory and get good results, but then people get all pissy when you point out that it’s still just a theory and is not without its flaws.
Massless light is still affected by gravity, though…
Mass distorts spacetime, which to an outside observer appears to change the direction light travels. The light travels in a straight line.
Gravity doesn’t alter the particle’s trajectory (or ours, for that matter). The warping of spacetime from Earth’s mass causes our movement through space to accelerate “down” at ~9.8 m/s^2
So the ghosts are in the center of the Earth, in nearly literal hell.
They would fall through the center of the earth, continue back up through the mantle, pop up momentarily to spook someone on the opposite hemisphere, then repeat the whole trip in reverse with a period of about 40 minutes.
Hm… actually are they incorporeal AND massless, or just incorporeal?
If just incorporeal, you’re right of course that initially after death they’d be falling back and forth, but over time through uneven gravity/curvature and through heat loss (stretching of unequal acceleration applied across the ghost essence, potential energy conversion, yadda), they should generally settle to the center after some time, unless there’s a maximum natural pressure of ghosts at whatever temperatures they have, so they may spread out somewhere within the crust if there are enough of them.
If they’re incorporeal AND massless, then I totally F’d up and they’d fire off at light speed as soon as they shed their mortal coil.
But light isn’t a particle it’s a wave. I mean, just look at it… Oh… Forget it. It’s a particle.
It’s neither a particle nor a wave, it’s a photon.
A zebra is neither a horse nor a tiger, though it shares properties with both.
It was a joke – it behaves as a wave until you observe it; then it collapses into a particle.
If the spacetime is distorted, and the light no longer appears to travel in a straight line, does that not mean that spacetime itself and the light that travels in are no longer straight?
How can a straight thing be distorted but still be straight?
It is straight in reference to the distorted spacetime.
Conventionally, a straight line is defined as the shortest path between two points, but if you take a plane that is not flat, say the surface of a ball, the shortest path between two points will be curved. But from the perspective of the two-dimensional man who lives in surface, the line is straight because it moves perfectly along his world.
Is this 2D-3D comparison supposed to be like a human-understandable analogy for a 3D-4D relationship?
I saw an explanation once about how time is the 4th dimension. They drew a line on the edge of a book. From the perspective of a single page (2D) it just looks like a dot, but because we can see many instances of that 2D representation it appears to us as a line. An individual page represents how we experience time.
Is your ball example supposed to be kind of like that because I just can’t imagine how spacetime could be a 2D thing in a 3D universe.
Well, kind of. The time dimension is a bit tricky, though – in Minkowsky space, a common way to think about spacetime, it is hyperbolic in relation to the other dimensions. In a nutshell, this means that distance is not the square root of the sum of the squares of the distances in specific dimensions, but rather of the difference. This makes it especially tricky to visualise. (I do recommend you check out this series by minutephysics, he does a great job at making it intuitive)
My analogy, therefore, doesn’t translate directly to spacetime, but it does provide a very simple 2d explanation for why straight things can act curved (even in 4d).
Here is an alternative Piped link(s):
this series
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I’m open-source; check me out at GitHub.
I think a better way of explaining it is with the idea of a shortest path, and not nessesarily a straight line. With two points in space the shortest path between them will be a straight line. If there’s a large amount of gravity tugging on space time the shortest path will be curved.
That’s called General Relativity and Reference Frames.
Start watching PBS Spacetime if you actually want to get into it.
You’re also entirely missing the point of the comment that was a joke entirely re-explaining the “reason” for ghosts ending up at the center of the Earth, which is implied by the original comment.
Well that’s just a theory, albeit good, and there’s a good chunk of modern science that refuses to marry it, so let’s not be too sure about it, shall we?
Edit: Wikipedia summarises it nicely:
Edit: Also highly recommend this read: https://plato.stanford.edu/entries/quantum-gravity/
I really hate that people just accept these advanced theories as objective truth. It’s just the best theory we have right now, that doesn’t mean that’s how it actually works. It’s good enough that we can almost always just use the theory and get good results, but then people get all pissy when you point out that it’s still just a theory and is not without its flaws.
I had to search for a bit but I finally found this !science_memes@mander.xyz post: https://mander.xyz/post/3197041