I think you’ve got SR wrong, obv. Maybe because you’re not imagining changes of reference frame to mix time and space coordinates for far-away places? Here’s a lorentz transform gif, showing how events (spacetime points) change when you change velocity : https://i.stack.imgur.com/O4OnL.gif The points move along these hyperbolas. So “length-contracting” your way to alpha centauri looks like moving a point that is in your future lightcone but very far away, until it’s directly in your future direction (you’ll go straight there in free-fall).
The reason you can’t use this to set an absolute reference frame is because the lorentz transformation effect moves things in both time and space, in a way that means the “present distance” (in the way that you think is the present in your reference frame) will be smallest precisely when you are stationary relative to it (i.e. when it’s a vertical line in a spacetime diagram). This means that if there are two different stars out there moving at different velocities, the longest distance to them will be measured at different velocities.
Look at that lorentz transform gif again, but try to pick out diagonal lines of points with your eye! Diagonal lines are moving objects. Watch what happens to all sorts of diagonal lines, particularly their “present distance” along the x-axis.
The other thing I’d argue against here is drawing too much from the copernican principle. Not thinking our scale is special doesn’t have to mean we have strong evidence that all scales are the same—we could be equally virtuous copernicans just be being uncertain about the laws of physics at different scales in a symmetrical way. Then if we do experiments and see differences at different scales, we can update that uncertainty to learn about the world.
I think you’ve got SR wrong, obv. Maybe because you’re not imagining changes of reference frame to mix time and space coordinates for far-away places?
What’s entertaining is that I’d say this is basically a (considerable) rephrase of my criticism of the way people generally handle special relativity. So I am completely in agreement here if we’re talking about “my model of the way other people model special relativity”.
So “length-contracting” your way to alpha centauri looks like moving a point that is in your future lightcone but very far away, until it’s directly in your future direction (you’ll go straight there in free-fall).
This, right here, is incredibly frustrating, because I think this is exactly what I’m referring to by velocity-as-rotation-in-time. The direction an object moves is, from its perspective, the future; it is the direction of time. “Moving a point that is in your future lightcone” is rotating which direction “time” points at, until “time” points at, for example, Alpha Centauri.
Except relativity; from your perspective it is the rest of the universe whose time is rotating, and it is Alpha Centauri’s future which is pointed, partially, at you; your future is still pointed firmly in the direction of time itself, since obviously you can’t move. The speed at which you move, or rather the speed at which Alpha Centauri moves towards you, is determined by the angle between Alpha Centauri’s future cone and your own. (That is, the more Alpha Centauri’s future cone is pointed at time, rather than at you, the slower it moves in space, and the faster it moves in time).
The reason you can’t use this to set an absolute reference frame is because the lorentz transformation effect moves things in both time and space, in a way that means the “present distance” (in the way that you think is the present in your reference frame) will be smallest precisely when you are stationary relative to it
I don’t understand what you mean by present distance; do you mean distance in a unified concept of space and time? (I handle this particular problem in my crackpot nonsense by insisting that the time dimension is spacelike in proportion to velocity, sort of; so the distance “lost” to length contraction is regained in some portion of the distance-in-time becoming distance-in-space. If that makes sense. Is this analogous to this concept?)
The other thing I’d argue against here is drawing too much from the copernican principle. Not thinking our scale is special doesn’t have to mean we have strong evidence that all scales are the same—we could be equally virtuous copernicans just be being uncertain about the laws of physics at different scales in a symmetrical way. Then if we do experiments and see differences at different scales, we can update that uncertainty to learn about the world.
I think I can break the claim down into a weak version, and a strong version:
The weak version: “Every scale will have laws of physics.”
The strong version: “Every scale will have the same laws of physics.”
I’m pretty sure even the weak version rules out quantization, since if there is quantization, then there is a scale below which nothing meaningfully exists.
Well, you sure weren’t falsely advertising :)
I think you’ve got SR wrong, obv. Maybe because you’re not imagining changes of reference frame to mix time and space coordinates for far-away places? Here’s a lorentz transform gif, showing how events (spacetime points) change when you change velocity : https://i.stack.imgur.com/O4OnL.gif The points move along these hyperbolas. So “length-contracting” your way to alpha centauri looks like moving a point that is in your future lightcone but very far away, until it’s directly in your future direction (you’ll go straight there in free-fall).
The reason you can’t use this to set an absolute reference frame is because the lorentz transformation effect moves things in both time and space, in a way that means the “present distance” (in the way that you think is the present in your reference frame) will be smallest precisely when you are stationary relative to it (i.e. when it’s a vertical line in a spacetime diagram). This means that if there are two different stars out there moving at different velocities, the longest distance to them will be measured at different velocities.
Look at that lorentz transform gif again, but try to pick out diagonal lines of points with your eye! Diagonal lines are moving objects. Watch what happens to all sorts of diagonal lines, particularly their “present distance” along the x-axis.
The other thing I’d argue against here is drawing too much from the copernican principle. Not thinking our scale is special doesn’t have to mean we have strong evidence that all scales are the same—we could be equally virtuous copernicans just be being uncertain about the laws of physics at different scales in a symmetrical way. Then if we do experiments and see differences at different scales, we can update that uncertainty to learn about the world.
I try to be accurate.
What’s entertaining is that I’d say this is basically a (considerable) rephrase of my criticism of the way people generally handle special relativity. So I am completely in agreement here if we’re talking about “my model of the way other people model special relativity”.
This, right here, is incredibly frustrating, because I think this is exactly what I’m referring to by velocity-as-rotation-in-time. The direction an object moves is, from its perspective, the future; it is the direction of time. “Moving a point that is in your future lightcone” is rotating which direction “time” points at, until “time” points at, for example, Alpha Centauri.
Except relativity; from your perspective it is the rest of the universe whose time is rotating, and it is Alpha Centauri’s future which is pointed, partially, at you; your future is still pointed firmly in the direction of time itself, since obviously you can’t move. The speed at which you move, or rather the speed at which Alpha Centauri moves towards you, is determined by the angle between Alpha Centauri’s future cone and your own. (That is, the more Alpha Centauri’s future cone is pointed at time, rather than at you, the slower it moves in space, and the faster it moves in time).
I don’t understand what you mean by present distance; do you mean distance in a unified concept of space and time? (I handle this particular problem in my crackpot nonsense by insisting that the time dimension is spacelike in proportion to velocity, sort of; so the distance “lost” to length contraction is regained in some portion of the distance-in-time becoming distance-in-space. If that makes sense. Is this analogous to this concept?)
I think I can break the claim down into a weak version, and a strong version:
The weak version: “Every scale will have laws of physics.”
The strong version: “Every scale will have the same laws of physics.”
I’m pretty sure even the weak version rules out quantization, since if there is quantization, then there is a scale below which nothing meaningfully exists.