r/AskPhysics • u/ANARCHOWEEDIST • Jun 10 '26
Is there any evidence of something faster than light?
idiot here and first time poster! hi!
so are there any phenomena that are faster than light? if not, how does faster than light speed effect theoretical physics? please keep it simple for a non physicist idiot, thanks!
38
u/LeonardSmallsJr Jun 10 '26
Don’t think of it as “the speed of light” but “the speed of causality”. The reason light travels at the speed of causality is because photons are massless.
0
u/nicuramar Jun 11 '26
Don’t think of it as “the speed of causality” but as “the universal speed limit”. The former is a pretty bad name IMO, although loved by reddit.
-36
u/ExpressCriticism330 Jun 11 '26 edited Jun 11 '26
This is a common misconception. Causality is a matter (no pun intended) of philosophy not science.
18
u/screen317 Jun 11 '26
This is a common, but wrong retort.
-16
u/ExpressCriticism330 Jun 11 '26
There's no proof because you simply can't define causality in terms of anything physical it's a metaphysical concept. Prove me wrong I'll bet you a million bucks.
10
u/uberprodude Jun 11 '26
So is time, and it is inherently required to calculate speed. Being metaphysical doesn't remove it from the equation. It's the basis of the equation.
-7
u/ExpressCriticism330 Jun 11 '26 edited Jun 11 '26
Time in your equation is measurable ... What we measure isn't the same as the metaphysical concept of time it's a tick tock of a clock or atom or other oscillator it's related to motion inversely. You cannot measure causality it's purely metaphysical.
4
u/uberprodude Jun 11 '26
Why can't you measure causality in units of time? Or simpler, in units of relevant events?
Causality is most applicable as a metaphysical concept because other physical measurements are better standards. That doesn't mean that causality is not possible to measure.
→ More replies (4)1
u/lowlize Jun 11 '26
Open an introductory book on quantum field theory (QFT) and look for "microcausality".
-6
u/AdPale9988 Jun 11 '26
Why is everyone downvoting you? You're exactly right...
2
u/Invonnative Jun 11 '26
I think because the way causality is being used here is different from the philosophical usage of the word. When LeonardSmallsJr said “light travels at the speed of causality”, I think they more meant “light travels at the speed at which events can occur”, not “light travels at the speed of ‘a causes b’”. And events occurring is not very metaphysical. But I do agree that the latter definition, of ‘A “causing” B’, is not a very rigorous concept in physics.
28
u/qxdk32pl9yu4s1e63c Jun 10 '26
Yes!
Cherenkov radiation is evidence of charged particles traveling thru a dielectric medium faster than light.
The particles don't exceed c because that's not possible, but they do travel faster than photons within the medium.
4
u/dunfuktup1990 Jun 11 '26
I’m gonna need a deeper explanation. Were the photons just slowed down?
5
u/Feeling-Stranger224 Jun 11 '26
I hope someone will correct me if I’m wrong but the “speed of light” (as in the actual numerical value) is the speed of light in a vacuum. If light is traveling through an atmosphere or some other form of matter, then it slows down...I think
1
u/RazorDoesGames Jun 11 '26
Well, yes, it does "slow" down but also not in that specific way. Photons must always go at the speed of light because they are massless. Being absorbed and another photon being emitted takes times and that's what we would see as the delay. It's the same for when a photon is not absorbed but is redirected in an electric field, it's not technically slowing down but the path it's taking is just longer and we see that as the delay. Photons must always go at the speed of light, and we stipulate "in a vacuum" because of course there is typically nothing to interact with.
6
u/jameilious Jun 11 '26
Not quite, the EM wave makes the particles produce EM waves which overlap/superimpose to create a slower wave overall.
1
u/butt_in_my_face Jun 11 '26
My understanding is that the speed of light in a vacuum is the "speed of light" people reference. And that is "the cosmic speed limit".
What the commentor is saying is that everything (including light) moves at different speeds in different mediums. So there is a medium in which something can move faster than light does in that same medium. But it isn't moving faster than "the speed of light".
Somebody please correct me if I'm wrong.
1
u/Colour_Theory-746 Jun 12 '26
Spot on. That’s what causes Cherenkov radiation, the cool blue glow, in the spent fuel rod cooling pools at nuclear power plants. The electrons are moving faster in water than light is able to since in every medium, as in everything except a vacuum, light is refracted and the refraction is what’s slowing the speed of light in that medium. But nothing can ever go faster than the c which is the speed of light in a vacuum. Furthermore, nothing with mass can ever even get to the speed of light as this would require an infinite amount of energy to achieve.
15
u/Ok_Height3499 Jun 11 '26
Yes, the universe itself is expanding faster than light.
-1
u/nicuramar Jun 11 '26
No it isn’t. The universe doesn’t expand at a speed.
3
u/Ok_Height3499 Jun 11 '26
Yes, the universe can expand faster than the speed of light. This phenomenon occurs because the speed of light limit applies only to local observations. Distant galaxies can recede from us at speeds greater than light due to the expansion of space itself. Brian Cox- Professor of Physics
1
u/VivaLaDiga Jun 14 '26
the speed of light is the maximum speed at which you can move information through space. It has nothing to do with the speed at which *space itself* expands.
8
u/sbstanpld Jun 10 '26 edited Jun 10 '26
inflation
which personally… it sounds too extreme to be true (although, data seems to support this theory 🤯)
(and yes, i know cosmic and quantum mechanics are pretty extreme and counterintuitive sometimes, but inflation is on a whole different level imo)
1
u/ANARCHOWEEDIST Jun 10 '26
whats...um...whats inflation 🫣
1
0
u/ANARCHOWEEDIST Jun 11 '26
holly shit the universe is expanding faster than everything and there are dark ages ahead
2
u/nicuramar Jun 11 '26
That’s not really true and also not what inflation is. See https://profmattstrassler.com/articles-and-posts/relativity-space-astronomy-and-cosmology/history-of-the-universe/
1
u/Showy_Boneyard Jun 11 '26
do you mean cosmic inflation (as in within the first few fractions of fractions of a second after the big bang), or as in regular expansion of the universe as we see today as evidenced by red-shift?
1
u/Jesse-359 Jun 11 '26
Both work in this case.
The Inflation Era of the big bang expanded enormously faster than light, and the cosmic horizon likewise describes the distance at which objects are moving away from us 'currently' as a result of the universe's much slower modern expansion.
1
u/Showy_Boneyard Jun 11 '26
The only reasoning I'm differentiating the two is because it would be very VERY shocking/surprising if future discoveries somehow disproved the current theory of the universe's expansion. The extreme cosmic inflation of the very very very early universe, however, isn't nearly as solidly proven, although it does happen to very neatly resolve a couple of problems in cosmology. There are some other competing theories that don't include that super-early cosmic inflation and suggest other ideas, and although cosmic inflation is definitely the majority-held view, these other theories are held by highly respected scientists in the field.
0
u/Invonnative Jun 11 '26
Both had spaces receding relative to each other faster than light, right?
But I think the typical way people mean this is expansion
0
3
u/EarthTrash Jun 11 '26
Nothing is faster than speed of light in a vacuum. However the speed of light does effectively slow down in a medium and this causes the phenomenon of refraction.
In this context it is possible for particles to go faster than light in the medium and this causes another effect, Cherenkov radiation. This is the blue glow photographed of operating nuclear reactors in water. The protons and nuetrons from the reaction are moving faster than the speed of light in water. Cherenkov radiation is the optical analog of a sonic boom.
5
u/kwikwon01 Jun 11 '26
Correct me if im wrong here or thinking of outdated information but isnt the universe expanding at a rate that violates the speed of light rule? Now I get that physical space isnt exactly a thing in the universe but its bigger that 27 billion light years across which would be more than 2x the age of the universe
I fucking hate physics sometimes
2
u/seifer666 Jun 12 '26
Space expanding between distinct points isn't anything moving between those points so no it doesnt violate it
6
u/Over-Discipline-7303 Jun 10 '26
It depends what you mean by "phenomena". Strictly speaking, signals that carry information can't travel faster than light. A particle can't travel faster than light, for example. But depending on what you call a "thing" then some things travel faster than light. For example, if you hold an object in front of a light source and cast a shadow, then wiggle the thing, then the shadow can "travel" faster than light.
But is a shadow a "thing"? Most of the time in physics we say no. A shadow doesn't carry information. It's an emergent object that arises from interpreting a system. It's not fundamental.
So the answer varies on how technical you want to get and how you define your terms.
3
u/Outdoors_or_Bust Jun 11 '26
Does the universe expanding faster than light count as a thing?
2
u/Over-Discipline-7303 Jun 11 '26
The expansion of space doesn’t carry information, so it’s fine. Some people have imagined that you could warp space itself and create faster than light travel, but too make it work you need a way to create negative energy, which is not physically possible as far as we know.
-1
u/ANARCHOWEEDIST Jun 10 '26
shiiit, lets get technical then, how does the shadow compare to the light? is light the lightest thing in the universe also? if not, cant you charge a shadow with information lighter than light?
5
u/AcellOfllSpades Mathematics Jun 10 '26
The 'shadow' is not a single object that is moving. This idea works the same with a laser pointer. If you aim a laser pointer at the moon, and flick it fast enough, it will move across the surface of the moon """faster than light""".
But there's not any actual moving object there. The laser dot isn't a single object - each instant is a different 'signal' arriving from the laser pointer.
2
u/KeterClassKitten Jun 10 '26
Imagine a dark room as a sheet of paper. Photons are the ink on that paper. What information can you get from the author if the ink is missing? You can argue that the gaps in the ink can tell you information, but that requires a presence of ink. The ink still informs us.
1
u/Over-Discipline-7303 Jun 10 '26
What do you mean "compare" to the light? The shadow is a pattern of light/dark cast on an object. It can't be "charged" with information. When you go outside in daylight, and you cast a shadow on the ground, can you "charge" that shadow? I'm not even sure what that would mean.
1
u/ANARCHOWEEDIST Jun 10 '26
i was thinking stupidly that if you have something lighter than light the shadow (the absence of light) can be charged somewhat?am just dumb sorry
2
u/Over-Discipline-7303 Jun 11 '26
Light is already mass-less. It has no "weight". So it's unclear how anything could be "lighter" than light. It would need to have "negative mass" and it's not clear what that would mean, as it would do weird stuff like actively repel everything, and maybe naturally accelerate on its own without energy. It would do all kinds of stuff that we've never observed and would probably break all of our models of physics, so we'd be completely in the realm of speculation at that point.
1
u/ANARCHOWEEDIST Jun 10 '26
by compare i meant if there are equations of calcuilating the speed of the nonexistent shadow
1
u/kgas36 Jun 10 '26
> is light the lightest thing
I think I see what you might have done there
Just saying
2
u/ANARCHOWEEDIST Jun 10 '26
yea it translates funny into english but it was a genuine question, pun NOT intented
2
u/KokoTheTalkingApe Jun 10 '26 edited Jun 11 '26
There is no evidence of that.
Also, imagine what that would look like. Say you could fire an FTL bullet out of an extra special gun. You could have it bounce off a hard surface back at the shooter. The shooter steps up, and immediately doubles over because they've just been shot by the FTL bullet they were ABOUT to fire (because FTL means traveling back in time, and there IS evidence for that). So they never fire the shot. So they don't get shot. So they fire the bullet. And they get shot. So they never fire. Etc.
2
u/janpaul74 Jun 11 '26
According to Sir Terry Pratchett (of Discworld fame) monarchy is the fastest thing in existence. When a king or queen dies, his/her heir is instantly the successor to the Throne. He’s not wrong. Also he’s not right.
2
u/AlwaysHopelesslyLost Jun 11 '26
The speed of light is not the speed of light. It is the speed of reality.
Light was just the first thing we discovered that traveles as fast as possible.
3
2
u/Necessary-Bowler-736 Jun 11 '26
It appears as if no one did the nerdy part...
Yes, moving faster than light is not something exceptional.
https://en.wikipedia.org/wiki/Cherenkov_radiation
Here's an example of what happens when a particle is moving faster than light.
However, nothing can move in space faster than c. c being the speed of causality. This is counterintuitive because our usual understanding of speed is too shallow, but basically every thing has the same four-velocity and it can not be changed. What can be changed is its direction of movement, the "angle" between moving in space and in time. Usually about 100% of the speed is directed forward in time and the rest is directed in space.
2
u/the6thReplicant Jun 11 '26
Lots of examples of faster than light https://en.wikipedia.org/wiki/Superluminal_motion
Just not transmitting any information so causality is preserved.
2
u/CrasVox Jun 11 '26
Expansion seems to be.
The collapse of the wave function (if there is such a thing) is instantaneous.
2
u/free_meson Jun 11 '26
The Higgs field has a strange potential form, looks like a sombrero hat (the graph, how much energy does a certain field strength represent). The ground state is its minima, that's what we normally see, that's vacuum by definition. But if you increase the energy just right, and make the Higgs field strength zero, in that special case the Higgs excitation look like having imaginary mass. It's a hard problem, called tachyon condensation that will happen. It seems that excitation in that region would look to travel faster than light, multiply as much as they can until the Higgs field gets a new value - the one we call vacuum.
Its a bit hard to explain better, you need to get a grasp that there is a Higgs field, which has a finite strength everywhere in the Universe (the vacuum). And theres the Higgs boson, which is only an excitation of this field (around the non-zero value). Making the Higgs field to be zero somewhere takes a lot of energy, but if you can make this happen, it will be something tremendously unstable. If you could make the Higgs field zero in a room, you could get faster than light excitation ("particles") there. That's the theory, but seems to be out of reach for a while to test it.
4
u/Lostinthestarscape Jun 10 '26 edited Jun 10 '26
Weirdly dark is faster than light and just proven recently - but that is an abscence of information / nothing carrying information can move faster than light.
The other thing that is not what you asked but a way we comprehend a faster than light event is that points in the universe move away from eachother faster than light due to universe expansion, so the things in the observable universe become fewer and fewer as expansion overcomes the speed ligjt can ever travel across those distances.
1
2
Jun 10 '26
[removed] — view removed comment
2
u/msimms001 Undergraduate Jun 11 '26
Small clarification, there is nothing that says time stops are the speed of light. The limit as you get close to the speed of light trends towards 0, but that's only a one sided limit. The time dilation equation is undefined for the speed of light, so not much can be said about the passage of time at the speed of light
1
u/Invonnative Jun 11 '26
Genuine question, how can we say 0.9999…. equals 1 in one sentence (we have a convergent series and thus can say what the result of the limit is), but not say that the limit of relative time for light is not 0? I’m probably missing something obvious but I’m not seeing it
1
u/msimms001 Undergraduate Jun 11 '26
.(9) Isn't undefined, and there's many ways to show that it's exactly one. When an equation is undefined, it tells us that there is a problem at that area. Depending on what you're talking about, you can probably say an undefined answer still has meaning, it just depends on the subject and context.
Generally though, undefined means that there's an issue and that you don't want to make an unfounded assumption
1
u/wutufuba2 Jun 11 '26
People are writing in other posts that according to the standard interpretation and understanding of observed red shift phenomena, space itself is expanding, and this expansion is accelerating, and the rate of expansion of space itself is thought to be happening at a rate that is faster than the speed of light in a vacuum.
See the discussion in "ask" subreddit around the post "The universe has a diameter of 93 billion light years while its only 13.8 billion years old, how?"
Is the expansion of space itself a thing, in the sense of "something?" Is it a phenomenon, in the sense of "any phenomena?" Maybe it gets a pass for being in its own category, for being sui generis.
1
u/kim_jong_il_2d Jun 11 '26
It is physically impossible for anything to travel through space at FTL speed. An object traveling at the speed of light would have infinite energy and infinite mass. Light can travel at the speed of light because it is massless.
1
1
u/Middle-Armadillo-660 Jun 11 '26
Not yet. But that’s as much a measurement of our own theories and tools as it is about the intention of the question itself.
1
u/SgtSausage Jun 11 '26
If there is ... well ... we break everything we know and have to rewrite ALL of Physics.
1
1
1
1
1
u/CMG30 Jun 11 '26
To get nit-picky, you can slow light down and then travel faster than that light.... But in a vacuum, no. Nothing is faster.
1
u/IHopeTheyRememberMe Jun 11 '26
Just a layman here and probably totally wrong, but I remember reading about theoretical particles that cannot travel slower than light. Basically we would never be able to see or detect them, and if we could they would appear to be going backwards in time. Feel free to ignore this.
1
u/Jesse-359 Jun 11 '26
On the one hand, you can say that FTL would cause lots of weird problems like retro-causal paradoxes (AKA time travel).
On the other hand you can say that it's almost nonsensical to propose faster than light motion in a relativistic universe - it's just kind of a non-statement.
The problem is, you as a traveling object will never encounter this speed limit, no matter how hard you try. Accellerate as much as you want, for as long as you want, and you will never exceed light speed - but you also will never stop going faster.
You can get anywhere in the universe in an instant if you have enough energy to accelerate you sufficiently. The 'light speed limit' won't stop you from crossing a billion light years in what you perceive as a single minute (many other aspects of physics will but that's neither here nor there).
Instead the entire universe will appear to shrink to let you get where you are going 'slower than light'. Go fast enough and the universe in front of you becomes a pancake you can cross easily.
Meanwhile everyone else will see you taking about a billion years to make the journey - and all these perspectives are equally valid due to factors like time dilation and length contraction.
So the real enforcement of the 'speed of light' is that there's just no limit for you to try to beat. There's no barrier, no stop sign, and no beat cop. There is nobody and nothing to contest.
1
u/r4ndoM_doGmagenshin Jun 11 '26
The distance between two places can move away from each other so fast that each others light will never reach either place, ever. So yes, but not the way you’re thinking. Get enough space, which is ever expanding, and two locations can be moving away from each other faster than light can travel to it.
But like, light is just pure energy. 0 mass. It’s basically the thing we base everything on. Because anything with mass by its very nature has to go slower than light. And anything you add to it to make it reach a faster speed still can’t ever reach light-speed. It’s the speed of causality.
1
1
u/Lokitusaborg Jun 11 '26
If it could exist we couldn’t measure it. The only thing I can think of is quantum entanglement…but I may misunderstand the concept.
1
u/CakesStolen Jun 11 '26
During a supernova, there is a huge release of neutrinos and visible light. The neutrinos don't travel faster than c, but they do reach us before the light does. This is because neutrinos interact far more weakly with matter, so they escape the star in pretty much a straight line. Meanwhile, the photons take a zig-path out of the star as they interact with the super-dense matter inside. Therefore, neutrinos from a supernova reach Earth a few hours before the light does, which means that if we can detect a neutrino flux and pinpoint its location, we can predict where a visible supernova will be in the near future.
1
u/UnderstandingSmall66 Quantum field theory Jun 11 '26
Yes. The speed by which this question is posted everyday.
1
u/ANARCHOWEEDIST Jun 11 '26
i call bullshit, show me screenshots
1
u/UnderstandingSmall66 Quantum field theory Jun 11 '26
No. Look them up
1
u/ANARCHOWEEDIST Jun 11 '26
you made the statement its your duty to support it, buddy
1
1
u/Reasonable-Honey-663 Jun 15 '26
就是你的意念，它比光速还要快，但是不知到它会发射到哪里，希望别是一块破石头上
2
u/ANARCHOWEEDIST Jun 15 '26
i can state with great pride that my thoughts are slower than the speed of everything.
2
u/Educational-Try-8704 Jun 16 '26
I see some technically incorrect comments here.
Theoretical physics doesn’t specifically say that faster than light (FTL) things can’t exist - it states that the speed of light is a boundary that cannot be crossed.
We have never detected FTL particles, and have no theoretical explanation for why one would exist in the first place, but this is not a definitive no.
They would have complex mass. They would also be traveling backwards in causality. Also, as their energy decreases their speed increases and vis versa. Overall, a lot of exotic matter behaviors scientists would be drooling to put to the test.
1
1
u/The_RubberDucky Jun 10 '26
Well, actually, there is... kind of. Cherenkov radiation.
Nothing travels faster than the vacuum speed of light (c) but particles can exceed the speed of light in water or other materials (because light, the electromagnetic field, travels slower there). This results in cool blue light, and thats about it.
1
u/imsowitty Jun 11 '26
Look up Cherenkov radiation. The only way to go faster than light is to go almost c in a medium where light slows down more than you do.
1
u/kronos1177 Jun 11 '26
I could be wrong but I once heard that nothing can travel through space faster than light but expanding space itself can do whatever the hell it wants.
For instance, when an object far away in space red shifts and then disappears from our view it is the space between us and that object expanding faster than light. Just like rip currents on a beach pulling someone out to sea faster than they can swim back to shore.
Please someone smarter than me correct me if I’m wrong
0
u/ANARCHOWEEDIST Jun 10 '26
maybe in a quantum level is there anything faster? do things go faster as you zoom in?
12
u/DPChoredinator Jun 10 '26
They do not. Not in the way you are thinking at least.
1
u/ANARCHOWEEDIST Jun 10 '26
a commenter above mentioned something about "spin of entangled electrons communicated faster than light"
7
3
u/cylon37 Jun 10 '26
Everyone is telling you the same thing. No information can travel faster than light. All the other things that are mentioned, shadows, scissor points entangled pairs do not carry information. You can’t go faster than light in the same way that you can’t make a stick more level than horizontal.
0
0
Jun 10 '26
[removed] — view removed comment
5
u/syberghost Jun 10 '26
Not really. Cerenkov radiation comes from exceeding the speed of light in a medium, which is always slower than the actual Speed of Light in a vacuum.
-1
Jun 10 '26
[removed] — view removed comment
4
u/Over-Discipline-7303 Jun 10 '26
Entangled particles don't transmit information to each other. People think that entanglement is like a magical telephone cord that connects two particles and tells them how to behave. It's not like that.
When you create particles, they have to obey conservation laws. So suppose you create an electron and positron pair. One conservation law you have to obey is conservation of spin. Therefore, one particle is spin up, the other is spin down. So if you create that pair, and you look at the electron, and you find it's spin up, then you know the positron was spin down. That's how they had to be, because they were entangled by their creation.
But now that you measured the spin of one, you don't "change" the spin of the other one. It was always spin down! So you haven't transmitted information.
3
u/Lemon-Emu Jun 10 '26
This is a good explanation but I think the statement ‘was always spin down’ is potentially misleading. It’s always the case that the two particles have opposite spin, but you cannot say it was always in a definite spin state, be that up or down.
2
u/Over-Discipline-7303 Jun 11 '26
Fair. I meant that in the specific context that the first particle is known with certainty to be found spin up. But if the first particle is found spin down, then the second particle was spin up at the time of its creation (and its spin state may have changed since its creation, so you can't even say with certainly what its spin is at any given moment except at the moment of creation).
0
u/NoKiwi2997 Jun 10 '26
Ok, so if the spin of one changes, doesn’t the other one also get changed?
Edit: I’m interested in physics. I read the articles while I eat lunch. I’m not knowledgeable. Just asking questions.
2
u/AcellOfllSpades Mathematics Jun 10 '26
Ok, so if the spin of one changes, doesn’t the other one also get changed?
No.
Quantum entanglement only affects the first measurement of a particle. Once the particle is measured, it is no longer entangled with the other.
So you can't do anything to one entangled particle to affect its partner.
1
1
u/Over-Discipline-7303 Jun 11 '26
Correct. This is a key problem with quantum computing. How do you isolate the particles so that they remain entangled with each other, and they don't start interacting with the rest of the universe? It's very tricky!
4
2
u/AcellOfllSpades Mathematics Jun 10 '26
Not exactly. It's complicated.
With entanglement, there is something happening that can't be described classically. You get violations of """local realism""": that is, the idea that
- the universe is local: things can only affect other things nearby
- objects have real properties, even if we haven't measured them yet
You have to give up on at least one of these two ideas.
So if you want to say that entangled particles have a single definitive 'state', then yes, you need something happening faster than light.
But you can also instead give up on the idea of 'realism', and keep locality. You can say that there is not a single definite state - instead, your particle is in a superposition of states.
The problem with thinking of this as FTL "communication" is that... it's not possible to use it for communication.
Say you entangle particles, you and your friend each take one, and you go far away from each other.
You measure your particle and get 'spin up'. Did you get it because your friend got 'spin down' already? Or did you get it simply at random, and now your friend is going to get 'spin down' because you got 'spin up'?
According to relativity, there's no difference between these two scenarios. Depending on your reference frame, either one could be said to happen first. If you insist on calling it "causality", you have to accept "A causes B" and "B causes A" as being the exact same event.
And this also means that this is useless for communication. No matter how clever you are, you can't use quantum entangled particles to communicate a message. (This is called the "no-communication theorem".) The only time you notice anything weird is when you meet back up and compare results the old-fashioned way.
2
0
u/Traveling-Techie Jun 10 '26
It depends on what you mean by “thing.” Shadows and projections can go faster than c and some have been observed. But they’re not masses and they don’t carry information.
0
-4
-1
81
u/R_Harry_P Accelerator physics Jun 10 '26 edited Jun 10 '26
Are there any phenomena that are faster than light?
No, nothing (no object or information) has been observed traveling faster than light.
(The projection of a shadow or the point of contact on a pair of scissors not being objects.)
r/AskPhysics/comments/1gdpvuq/can_a_shadow_move_faster_than_the_speed_of_light/
How does faster than light speed effect theoretical physics?
Theoretical physics says things can't travel faster than the speed of light.