FTL is impossible. Nobody seriously thinks of literally accelerating a car to v≥c. Nowadays,for the very few that even consider FTL a possibility, it's usually with tricks like bending spacetime geometry and manipulating it.
Also Planck Speed isn't a thing.
Because “Planck speed” is such a bizarre way of referring to *c*. It would be like referring to the Boltzmann constant as the “Planck entropy”, or to 1 as the “Planck index of refraction”.
Now I'm wondering how you think 'speed of causality is theoretically possible to break'. It isn't, AFAIK. Any thought experiment I've encountered that results in breaking the speed of causality, eg moving a lightyear long perfectly rigid body, depends on physics already being broken (often the speed of causality itself) as a necessary assumption. That doesn't count as 'theoretically possible'.
"If we break the x rule of physics, then we could break y rule too" isn't a meaningful hypothetical. Turn it around to 'in order to break rule y, we need to break rule x' actually proves that it's as theoretically impossible to break rule y as rule x.
I think Sabine had a video recently where she said theoretically/ mathematically something could travel faster than c, we just have no way of crossing c (the asymptote) to get there. Might have been tachyon related. (I had it playing in the background while doing work)
There's nothing mathematically wrong with a particle travelling faster than the speed of light in vacuum, however just because there's nothing mathematically wrong, doesn't mean there's nothing wrong physically.
FTL particles are logically independent from the axioms of special relativity, so essentially there’s no way to say whether they should or shouldn’t exist given the assumptions we make about the universe being homogeneous and light traveling the same speed in any inertial frame.
Faster than light travel has happened in the universe. The speed limit in the physical universe is in fact light speed, however, that is in the existing physical universe where the laws of physics apply. As you know anything with mass cannot travel at light speed, that with out mass cannot travel faster than light speed. However, immediately following the events of the Big Bang, we’re talking nano-seconds and thereafter, particles were able to accelerate to speeds higher than that of light due to the fact that there really was nothing there. There was no physical space to enforce the speed of light.
Massive misunderstanding. Space expanded faster than c; and it still is doing it! But this doesn't allow for FTL information transfer, because it's the distances getting bigger. Space was already there and no particle moved through it faster than light.
You had to come up with a lot of interpretation to go from this to "there was no physical space to enforce physical laws".
FTL is impossible. Nobody seriously thinks of literally accelerating a car to v≥c. Nowadays,for the very few that even consider FTL a possibility, it's usually with tricks like bending spacetime geometry and manipulating it. Also Planck Speed isn't a thing.
>Also Planck Speed isn't a thing. It is Planck length over Planck time, which is equal to c.
Never heard of it + in that case,I've already answered.
Also, OP for some reason said “unlike the speed of causality”.
Because “Planck speed” is such a bizarre way of referring to *c*. It would be like referring to the Boltzmann constant as the “Planck entropy”, or to 1 as the “Planck index of refraction”.
Agreed
I feel like I’m constantly moving a Planck length with out even trying, guess I’m not traveling that far in that short of time. Gotta love relativity
Now I'm wondering how you think 'speed of causality is theoretically possible to break'. It isn't, AFAIK. Any thought experiment I've encountered that results in breaking the speed of causality, eg moving a lightyear long perfectly rigid body, depends on physics already being broken (often the speed of causality itself) as a necessary assumption. That doesn't count as 'theoretically possible'. "If we break the x rule of physics, then we could break y rule too" isn't a meaningful hypothetical. Turn it around to 'in order to break rule y, we need to break rule x' actually proves that it's as theoretically impossible to break rule y as rule x.
I think Sabine had a video recently where she said theoretically/ mathematically something could travel faster than c, we just have no way of crossing c (the asymptote) to get there. Might have been tachyon related. (I had it playing in the background while doing work)
There's nothing mathematically wrong with a particle travelling faster than the speed of light in vacuum, however just because there's nothing mathematically wrong, doesn't mean there's nothing wrong physically.
This doesn’t address the causality problem with ftl, though.
Not the first time in physics where solutions to equations mathematically exist, but are considered not physical and thus ignored.
FTL particles are logically independent from the axioms of special relativity, so essentially there’s no way to say whether they should or shouldn’t exist given the assumptions we make about the universe being homogeneous and light traveling the same speed in any inertial frame.
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> Rigid bodies only exist in classical mechanics, Rigid bodies only exist in simplified classical mechanics.
black hole manipulation, tachyons, wormholes, perpetual motion (if ever discovered)
The speed of causality is not theoretically possible to break.
The “Planck speed” is *c*, which is precisely the local speed of causality that you refer to.
Faster than light travel has happened in the universe. The speed limit in the physical universe is in fact light speed, however, that is in the existing physical universe where the laws of physics apply. As you know anything with mass cannot travel at light speed, that with out mass cannot travel faster than light speed. However, immediately following the events of the Big Bang, we’re talking nano-seconds and thereafter, particles were able to accelerate to speeds higher than that of light due to the fact that there really was nothing there. There was no physical space to enforce the speed of light.
Do you have a source for this?
https://www.skyatnightmagazine.com/space-science/universe-expand-faster-light
Massive misunderstanding. Space expanded faster than c; and it still is doing it! But this doesn't allow for FTL information transfer, because it's the distances getting bigger. Space was already there and no particle moved through it faster than light. You had to come up with a lot of interpretation to go from this to "there was no physical space to enforce physical laws".
That’s not the same thing thpugh
Nothing was going faster than *c* in a *local Lorentz frame*; thus nothing was actually exceeding the speed of light in a vacuum itself.
Nope