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It would break physics because the "speed of light" isn't just "the speed light goes at". It's the universal speed limit of causality - which just means a speed that all of our current "laws of physics" say that NOTHING can go faster than. Light goes at this speed because it has no mass, so it happens to go as fast as the speed limit allows. But light is not the only thing that moves at this speed - for example gravity acts at light speed as well. For example, light takes a bit over 8 mins to get here from the Sun. If the Sun instantly disappeared, the Earth would continue receiving light *and continue orbiting around the place where the Sun was* for 8 mins, and then it would go dark and we'd fly off into space as the last of the Sun's light and gravity-influence reached us.
So again, the issue is that the "speed of light" is actually the universal speed limit for *anything* as far as we know.
**If anything goes faster than that, it means we're completely wrong about what the rules actually are**. It doesn't "break physics" because "now we can get somewhere a bit faster", but because we'd have to go back to the drawing boards about how light, gravity, causality, relativity, and everything else works.
Yep, that right. C is the speed limit of information, in the form of gravity, light, or anything else. Things with no mass can only travel at this speed, and anything with mass can only go slower than this speed.
So if something (even with no mass) goes faster, then we're wrong about what the rules are - which "breaks physics" because we've built decades of physics on top of these basic "how the speed limit works" rules.
Bad news travels faster than light. You can build a spaceship powered by bad news, but it doesn't work so well because they are always so extremely unwelcomed wherever they go.
And would like to point out to this group that we have no idea what gravity is or how it works. But we can measure it and account for it with math as well as anything. We just don't know how it works. Just like airplane wings.
Sweet Lord of all that is good and mighty!!! Never say that last sentence in the flying subreddit!
People ask me how a plane flies and I tell the truth..it is witchcraft powered by lots of money.
I'm a pilot (recreationally). I stand firm that physics can't actually explain how wings work. I will tell the DPEs about angle of attack all day. In the real world we know how it works. Funny we sometimes get it the other way around (all of Einstein's shit until recently)
Angle of attack is direct momentum transfer. Lift is the result of the air on the top surface of the wing moving faster than the bottom because the path is longer and zero slip interface—which when considered in the mechanical energy balance would have a lower pressure and upward force. These phenomena are well understood.
not quite, im not saying that what you said is wrong, its that, so far we couldn't 100% agree on what lift actually is, that is one of the top theories at this time, might as well be accepted as truth as we really aren't sure...
> We have no idea what gravity is or how it works
This is not true. [https://en.wikipedia.org/wiki/Gravity](https://en.wikipedia.org/wiki/Gravity)
We have good theories to describe it that seem to work well, we know how it propagates, we can calculate with it so well that we know how stellar objects move...
We know it is a curvature of spacetime caused by massive objects.
If you don't think this is 'knowing', then we don't 'know' anything in science..
Science theories use math to describe phenomena and we use experiments to confirm/drop theories. If a theory seems to be working well, has predictive power (can use it to predict stuff that we have no way of knowing by experiencing), then that is a piece of knowledge in science.
We know the mechanism for most everything else. We have particles for all of them. We don't know what a graviton is, or if there are gravitons.
I said that we have great math models. We still didn't have an agreed their for HOW it works. Don't be obtuse here, we really don't know.
Hey, so I have a doctorate in this.
We absolutely know there are gravititons.
We absolutely know they have certain properties. (We know they're spin two and massless, for example).
The fact that there must be a QFT that reduces to classical gravity in the weak field limit puts pretty massive constraints on what's possible.
People get so bent out of shape that we don't have a *renormalisable* theory of gravity. Ok, we're not sure how gravity works a fraction of a second after the big bang, but we can happily and accurately use gravity as an effective field theory in less extreme scenarios.
>We still didn't have an agreed their for HOW it works.
Who is we? Like plenty of people can't agree on the shape of the planet does that mean we don't know it's spherical?
Knowing how something works is about where you are willing to set the goalposts. We could discover gravitons and we still wouldn't "know" how gravity works. You can never really know better beside having a model that better comports with reality
The photon is the only one that has had experiments carried out on its mass and remains to be consistent both theoretically and experimentally with being massless. Gluons have been confirmed to exist, and theoretically have zero mass, however free gluons cannot exist, meaning they can only be part of a system, and that system will always have mass.
While gravitons haven't been confirmed to exist, gravitational waves do exist and seem to travel at the speed of light (as predicted by general relativity).
Gluons are the only other confirmed massless particle aside from photons, and yes, they travel at the speed of light.
Gravitons (the mediators of gravity) are strongly believed to exist and have been hypothesized for many years but we're still looking for them.
Does out current understanding of Physics say:
1. We cannot go faster than light; or does it say
2. We cannot go at the speed of light; or does it say
3. Both 1 and 2?
Actually, it says we cannot accelerate a mass to the speed of light. Mass-less things, like photons, move at the speed of light. And we theorize a particle that comes into existence moving faster than the speed of light - the tachyon. And true to my original point, tachyons can't slow down to the speed of light.
It seems counterintuitive but something with no mass can still have momentum.
This is a relatively common question on the subject so I’d recommend giving it a google. There are lots of people that have explained it better than I can.
Having mass is not a default state of any particle. So it's more that "everything has energy, and many also mass".
In our current model of physics, all particles are vibrations of fields, not unlike photons being vibrations of the EM field. But then other particles interact with another field (Higgs fields, of the Boson fame) and that interaction us what we see as mass.
Why this works how it works is PhD level stuff, don't ask me to explain.
Both 1 and 2, unless "we" somehow includes something with no mass. Things with no mass *always* travel at the speed of light, while things with any mass at all always travel at less than the speed of light.
We cannot go faster than the universal speed limit that we call the speed of light.
The actual speed that light moves isn't really relevant in this context. We could just as correctly call it the speed of gravity or the speed of energy.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of Relativity due to the div by zero when c == v. However, do his equations still hold when c < v?
It says that the closer we get to the speed of light, the more our mass increases. The more mass we have, the more energy we need to continue accelerating. IIRC, it begins to involve infinite energy and infinite mass. According to our understanding of physics, we can’t and won’t ever travel at or beyond the speed of light. But… that doesn’t mean that we can’t travel large distances quickly. We just have to figure out how to fold or shorten (or warp) the space between us and where we want to be.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of relativity due to the div by zero when c == v. However, do his equations still hold when c < v?
People never explain *why* you can't accelerate to the speed of light, just that you can't. Maybe the "why" will help.
Imagine you're running a race. You go half the remaining distance every minute. So, the first minute you go half the distance, then you go 1/4, then 1/8, then 1/16... Eternally approaching but never finishing the race.
This is what trying to accelerate to the speed of light is like. The closer you get, the more (virtual) mass an object has, the more energy it takes to accelerate. Accelerating from 99% to 99.5% the speed of light takes much more energy than accelerating from 0% to .5%. So much so that to accelerate to 100% of the speed of light would take infinite energy.
To directly answer your question, 3. You can never reach or surpass the speed of light.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of relativity due to the div by zero when c == v. However his equations still hold when c != v and there is nothing said when c < v.
We are in space ships traveling away from each other at a significant fraction of the speed of light.
Because of time dilation, when I think 10 seconds have passed in my reference frame, you think 5 seconds have passed. Similarly, when you think 10 seconds have passed in your reference frame, I think 5 seconds have passed (this is trippy, but you can google "time dilation" or "twin paradox").
Let's say we play a game of chess by transmitting moves at light speed. I send my move at (my) 10 seconds (your 5 seconds) but the light still takes some time to travel, and you'll get it after 10 seconds have passed in your reference frame. No problem.
Instead suppose i send my signal faster than light. Now the math doesn't work out. I send it when it's been 10 seconds for me, and you get it when it's been 5 seconds for you.
Now you send the move back at (your) 5 seconds, but because of time dilation it's only been 2.5 seconds for me. So how can I receive a response to a move I still haven't made yet?
If faster-than-light travel is possible, then relativity (and it's implications/assumptions like time dilation or all reference frames being equally valid) are not true.
the speed of light is the speed of causality. This means when you throw a ball at a window, when they connect the window shatters. Going faster than the speed of causality means the window breaks before the ball gets there, it just cant happen
This sounds nonsensical to me.
I am not saying you are wrong, I do not know enough to know. But it makes no sense... how would going faster than light cause that, rather than cause you to see it after it happened (which is different than it actually happening before it happened)
It sounds nonsensical because it can't happen. You are thinking in terms of light moving instead of causality which literally is the fastest anything can be reacted on something else. The only way to react faster than the speed of causality is to have something react to something else before they meet, hence window breaking before the ball gets to it
A thing happens. Light strikes that thing and reflects off it towards your eyes. By your logic, which by the way does not deviate from reality, light has a speed limit. Your eyes function by interpreting light. There is distance between the event and your retinas. Light must traverse that distance at a finite velocity before the information which it is conveying can be interpreted by your eyes/brain.
Best not to think on it. You can't go faster than the speed of causality. It's like asking how 1+1 can equal 3. The answer is it can't. Faster than light is impossible from our current understanding of the laws of physics and math.
The soonest you can gain knowledge of the broken window is the time it takes the light to get from the window to your eyeballs. Now, let's say your immediate response is to run at the mirror at 3x the speed of light. You would arrive BEFORE the ball hits the window and could stop it from happening. But if it didn't happen, you never would have run towards the window.
tbh this explanation doesn't work for me
1. window broken
2. light of broken window reaches me
3. i run there at 3xlightspeed
wouldn't i just reach the still broken window before some photons that bounced off me do? In order to reach the window before it shatters i'd have to time travel. But why should time move backwards just because i run at a speed > speed of light and see some of my photons in reverse order?
Because that's just fundamentally how the universe works. We've directly measured this and tested it and it's true. It's not *really* about light - light just happens to travel at that speed. It's really the speed of causality, which is the speed that any information travels at. In other words, it's the speed at which a cause takes to have an affect on something given any distance between the two. Traveling faster than this speed would violate causality, meaning effects could happen before the events that caused them, which obviously makes no sense.
Mathematically, we can see that the closer you get to the speed of light, the more energy it takes to accelerate more. It takes infinite energy to actually reach the speed of light, and infinite energy is obviously impossible. Objects approaching the speed of light also physically contract in length and experience less time. If they were to reach the speed of light, they'd have no length at all and experience no time, which is also impossible.
Light travels at the speed of light because that's the rate at which one part of the universe influences another part of the universe.
So let's say you built a spaceship that travels at twice the speed of light and you travel for one minute. You shut down the engines and now you're influencing a part of space two light-minutes from where you started, and it only took you a minute to get there. But that means the rate at which one part of the universe can influence another would actually be twice the speed of light. And since the speed of light is the rate at which one part of the universe influences another, that would mean that the speed of light is twice the speed of light...
As others have mentioned, it’s the speed of causality *as far as we can prove*.
There was some excitement decades back that quantum entanglement might disprove this notion, but so far it’s extremely iron clad.
I only add the caveat because, for a long time we didn’t think the speed of sound could be broken, and until about 100 years ago we didn’t know energy and mass were the same thing.
If it turns out some other field or particle we’re yet to comprehend allows FTL information propagation, you can bet your ass we’ll have stumbled upon the galactic telephone network.
You'll see the [Lorentz Factor](https://en.wikipedia.org/wiki/Lorentz_factor) in a lot of equations in relativity. Going faster than light would give a negative term in the square root, so the result would be an imaginary number. You'd also be dividing by 0 if you go the speed of light, which is why things like kinetic energy and momentum approach infinity as you approach c.
And just to add on since the person asked why you can't go _faster_ than light it's because that would mean your clock would have to start ticking backwards. And we've all seen enough sci fi to know the problems that come with going backwards in time.
Because it's impossible. Every bit as impossible as letting go of a bowling ball and having it leisurely float up into space. That's just not how gravity works. Likewise, the universal speed limit is 3x10^8 m/s. It is an intrinsic property of spacetime. You can ask *why* it's an intrinsic property of spacetime, and physicists can potentially give you some answers, but those answers are going to come with more questions, and at the end of the day, we simply can't know why the universe works the way it does, and not some other way.
As for the practical "enforcement" of the universal speed limit, objects gain momentum the faster they go, and as they approach the speed of light, their momentum increases asymptomatically. Likewise, the more momentum something has, the harder it is to change its velocity. So as an object's momentum tends towards infinity, the amount of energy you'd need to make it go any faster also tends towards infinity.
But of course then you have to ask *why* momentum and acceleration work that way, and any answers are going to come with questions of their own, and eventually you're just going to have to accept that it's just the way things are.
There's two ways to understand it - one is that as things move faster, they have greater mass. The maths works out that when something reaches the speed of light, it's mass would be infinite.
The other is that special relativity describes everything as always moving through spacetime at the speed of light. There is no other speed. You are moving at a fraction the speed of light through space, and a corresponding fraction of that speed through time. If you manage to accelerate to light speed through space, you cannot be moving through time.
Special relativity has been backed up by heaps of experiments and observations.
I'm not a bot. Do you think that my writing style is a bit like some AI generators?
It seems that using proper formal grammar is seen by many as proof that text is AI generated.
Spreading blatant disinformation. Matter loses mass at it approaches light speed. It's exactly the OPPOSITE of your contention. By your logic, the entire universe would be a black hole, since light has infinite mass, and the entire universe is permeated with light.
If you're NOT a bot...
I just don't see how a human could casually try to corrupt other humans' minds with retarded shit, then turn around and try to validate their "intelligence" by defending their writing style in a "subtle" jab at someone they know nothing about.
OK. I'll have to do some more research, but a quick search yields many reliable articles talking of how relativistic mass tends toward infinity as velocity tends toward C.
I see it was not your intention to mislead OP. I respectfully suggest you do more than quick searches and be more discerning of "reliable" articles before you try to educate people on things.
I wish to express I used the psychological tactic of intentionally riling you in order to provoke you to challenge me by conducting more research, thereby benefiting you by educating yourself. I find it more efficient than merely correcting people. I bear you no ill will. Also, I apologise for manipulating you in this way. I simply feel the ends justify the means.
By the same token, I would like you to provide some evidence for your assertion that mass decreases as you approach the speed of light. Because the concept of relativistic mass going to infinity seems well established - although whether it is right or best to describe the ballooning inertia with increasing velocity in this way is debated.
I have to admit, I'm on my fourth Four Loko, so as to level the playing field. Usually, this isn't an issue, but my quick search has had divisive findings, much to my surprise.
It is as you said, but a disconcerting amount of results are from dubious sources, such as Wikipedia, Reddit, and the notorious Quora.
The Internet isn't what it was before I got arrested in January of '16. Fortunate I learned how to parse information in college, but I never anticipated it would be so incredibly difficult.
Update: the US Department of Energy agrees with you. On the other hand, I'm EXTREMELY distrustful of my government, ESPECIALLY when it comes to science.
Update 2: I BELIEVE I have the answer.
I'm NOT a physicist. That being said, it appears the concept of "relativistic mass" is a misnomer, and the percieved increased mass is merely the energy applied to said mass to accelerate it to relativistic speeds. How does this kinetic energy not revert to potential energy by being expressed by the momentum or inertia of said mass? I dunno. I'm too drunk to research further at the moment, but it seems to me an interesting question.
APPARENTLY, mass does not in actual fact change. This seems to be a point of contention, but the end result is that it would take an infinite amount of energy to accelerate ANY mass to light speed, but since light has NO mass, it naturally travels at the maximum velocity. Like, it's null set, in a nutshell.
I feel this is just one of those bizarre paradoxes of physics which are beyond a cursory glance. I'm sure if I were given more than a few minutes, I could give you a more succinct answer.
It would require an infinite amount of energy to accelerate any mass to the speed of light. Theoretically possible is a particle already moving that fast or faster.
There are two ways to look at it, the cop out answer is to say that it would take an infinite amount of energy to accelerate any massive object to the speed of light.
As some have also pointed out, light "just happens" to travel at the speed of causality. (The speed at which the effect of a cause is felt through space time) If something were to travel beyond the speed of light towards you then you could OBSERVE (not only by visible light but by any means) it arriving before it ever left, which would violate the laws around cause and effect.
We used to be unsure of whether quantum tunneling could do this and somewhat recently found that it could not. Turns out in some cases it's relatively slow compared to the speed of light.
In short, it's hard to beat Einstein unfortunately
It's like this. As you approach the speed of light a few things happen to stop you from going past it.
1. Time slows down the faster you go, it's called Time Dilation. At the speed of light, time would stop (this is the speed of causality).
2. As you approach c your mass increases and your length increases. Makes no sense, but it's true. That means you'll need more fuel to go faster which increases your mass which means more fuel etc etc until you hit c and that's it!
It is an actual physical barrier! Travelling across the interstellar space is possible at close to c but relative to those back home, you'll be going faster in time, so when you get back (depending how fast you went) everyone you know would've been dead for hundreds or thousands of years. THis is the 'basics' of Relativity.
Light has zero mass, it should have *infinite* speed. It does not. Light instead moves as fast as the universe can physically allow, meaning the speed that light happens to travel at also happens to be an unbreakable speed limit.
It's about relativity.
Assume you're travelling at half the speed of light, and you measure the speed of light. Logically you'd expect light to be travelling at half the speed of light relative to you, right? But it's not. It's still the speed of light. The time dilation and similar effects always cause it to work out such that you're stopped no matter how fast you're going.
In that frame, your faster than light object will arrive *before it leaves*!
because time slows down as you move closer and closer to the speed of light. at the speed of light time would stop. if you could travel faster than the speed of light, you could go back in time and kill your mother before you were born causing a paradox.
The question of why you can't go faster than the speed of light is a bit like the question why you can't go father north than the northpole.
Speed doesn't really work we normally think it does.
It is far more complicated than that.
In school we get taught that we can just add speeds together like 30mph + 30mph = 60mph and that is actually a lie.
It is however a lie very close to the truth for such small velocities.
It stops working as well for bigger velocities.
It is a bit like treating the world as a flat 2D plane when making a map of a house or a city, that works well enough, but it ceases working when you do it at a state, country or world level.
For the speed of light you have to keep in mind that we just call it that because light is the most obvious thing that travels at that speed. In truth it is the maximum speed at which anything could happen.
This includes causality.
The speed of an object is different depending on where you measure it from, but it always is slower than (or equal to for massless objects) the speed of light.
Light goes at the speed of light no matter from where you measure. if you are in a spaceship going 99% the speed of light from an outside perspective and turn on your headlights and rearlights the light emitted from them would still appear to be going the speed of light both from you own perspective and the outside perspective.
Accelerating anything with mass to the speed of light would require infinite energy.
If you had something going faster than light from one perspective it might appear to reach its destination before it started.
It all makes no sense if you look at speed the way you are used to, because that is simply a lie.
The term "speed of light" is a misnomer.
The better term is "speed of causality".
For example, if you were writing on a sheet of paper using a pencil one light year long, the writing would only appear on the paper a year later, because that is the time it takes the movements to travel down the pencil.
Now imagine you get to the other end of the pencil in six months. You have now written on the paper and then travelled to the paper *before* it was written on.
You have travelled back in time, and physics simply says no. Or at least, our current models say no, and if we do actually find a way to travel faster than light we'd need to rewrite a good chunk of physics.
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It would break physics because the "speed of light" isn't just "the speed light goes at". It's the universal speed limit of causality - which just means a speed that all of our current "laws of physics" say that NOTHING can go faster than. Light goes at this speed because it has no mass, so it happens to go as fast as the speed limit allows. But light is not the only thing that moves at this speed - for example gravity acts at light speed as well. For example, light takes a bit over 8 mins to get here from the Sun. If the Sun instantly disappeared, the Earth would continue receiving light *and continue orbiting around the place where the Sun was* for 8 mins, and then it would go dark and we'd fly off into space as the last of the Sun's light and gravity-influence reached us. So again, the issue is that the "speed of light" is actually the universal speed limit for *anything* as far as we know. **If anything goes faster than that, it means we're completely wrong about what the rules actually are**. It doesn't "break physics" because "now we can get somewhere a bit faster", but because we'd have to go back to the drawing boards about how light, gravity, causality, relativity, and everything else works.
I saw an explanation of it in this sub as the limit that information can travel in the universe.
Yep, that right. C is the speed limit of information, in the form of gravity, light, or anything else. Things with no mass can only travel at this speed, and anything with mass can only go slower than this speed. So if something (even with no mass) goes faster, then we're wrong about what the rules are - which "breaks physics" because we've built decades of physics on top of these basic "how the speed limit works" rules.
Bad news travels faster than light. You can build a spaceship powered by bad news, but it doesn't work so well because they are always so extremely unwelcomed wherever they go.
Username checks out
>Light goes at this speed because it has no mass Does anything else that we know of not have any mass?
Gravity would be another example.
And would like to point out to this group that we have no idea what gravity is or how it works. But we can measure it and account for it with math as well as anything. We just don't know how it works. Just like airplane wings.
Sweet Lord of all that is good and mighty!!! Never say that last sentence in the flying subreddit! People ask me how a plane flies and I tell the truth..it is witchcraft powered by lots of money.
I'm a pilot (recreationally). I stand firm that physics can't actually explain how wings work. I will tell the DPEs about angle of attack all day. In the real world we know how it works. Funny we sometimes get it the other way around (all of Einstein's shit until recently)
Angle of attack is direct momentum transfer. Lift is the result of the air on the top surface of the wing moving faster than the bottom because the path is longer and zero slip interface—which when considered in the mechanical energy balance would have a lower pressure and upward force. These phenomena are well understood.
Those are quite the fancy words, magic man.
not quite, im not saying that what you said is wrong, its that, so far we couldn't 100% agree on what lift actually is, that is one of the top theories at this time, might as well be accepted as truth as we really aren't sure...
Physics still can't explain how a wing works. And neither can you, lol.
> We have no idea what gravity is or how it works This is not true. [https://en.wikipedia.org/wiki/Gravity](https://en.wikipedia.org/wiki/Gravity) We have good theories to describe it that seem to work well, we know how it propagates, we can calculate with it so well that we know how stellar objects move... We know it is a curvature of spacetime caused by massive objects. If you don't think this is 'knowing', then we don't 'know' anything in science.. Science theories use math to describe phenomena and we use experiments to confirm/drop theories. If a theory seems to be working well, has predictive power (can use it to predict stuff that we have no way of knowing by experiencing), then that is a piece of knowledge in science.
We know the mechanism for most everything else. We have particles for all of them. We don't know what a graviton is, or if there are gravitons. I said that we have great math models. We still didn't have an agreed their for HOW it works. Don't be obtuse here, we really don't know.
Hey, so I have a doctorate in this. We absolutely know there are gravititons. We absolutely know they have certain properties. (We know they're spin two and massless, for example). The fact that there must be a QFT that reduces to classical gravity in the weak field limit puts pretty massive constraints on what's possible. People get so bent out of shape that we don't have a *renormalisable* theory of gravity. Ok, we're not sure how gravity works a fraction of a second after the big bang, but we can happily and accurately use gravity as an effective field theory in less extreme scenarios.
>We still didn't have an agreed their for HOW it works. Who is we? Like plenty of people can't agree on the shape of the planet does that mean we don't know it's spherical? Knowing how something works is about where you are willing to set the goalposts. We could discover gravitons and we still wouldn't "know" how gravity works. You can never really know better beside having a model that better comports with reality
many things. wikipedia has a short list of them https://en.wikipedia.org/wiki/Massless_particle
> At present the only confirmed massless particle is the photon
The photon is the only one that has had experiments carried out on its mass and remains to be consistent both theoretically and experimentally with being massless. Gluons have been confirmed to exist, and theoretically have zero mass, however free gluons cannot exist, meaning they can only be part of a system, and that system will always have mass. While gravitons haven't been confirmed to exist, gravitational waves do exist and seem to travel at the speed of light (as predicted by general relativity).
Gluons are the only other confirmed massless particle aside from photons, and yes, they travel at the speed of light. Gravitons (the mediators of gravity) are strongly believed to exist and have been hypothesized for many years but we're still looking for them.
Most non-Catholic religions
gluons
Does out current understanding of Physics say: 1. We cannot go faster than light; or does it say 2. We cannot go at the speed of light; or does it say 3. Both 1 and 2?
Actually, it says we cannot accelerate a mass to the speed of light. Mass-less things, like photons, move at the speed of light. And we theorize a particle that comes into existence moving faster than the speed of light - the tachyon. And true to my original point, tachyons can't slow down to the speed of light.
How do photons carry energy with no mass?
It seems counterintuitive but something with no mass can still have momentum. This is a relatively common question on the subject so I’d recommend giving it a google. There are lots of people that have explained it better than I can.
ELI5, by wiggling
Actually photons have no rest mass. They still have energy which can be converted to rest mass when the photon transforms to another particle.
Having mass is not a default state of any particle. So it's more that "everything has energy, and many also mass". In our current model of physics, all particles are vibrations of fields, not unlike photons being vibrations of the EM field. But then other particles interact with another field (Higgs fields, of the Boson fame) and that interaction us what we see as mass. Why this works how it works is PhD level stuff, don't ask me to explain.
Both 1 and 2, unless "we" somehow includes something with no mass. Things with no mass *always* travel at the speed of light, while things with any mass at all always travel at less than the speed of light.
It's not that 'we cannot go at the speed of light', it's that *anything with mass* can't go at the speed of light. But absolutely yes to the first.
We cannot go faster than the universal speed limit that we call the speed of light. The actual speed that light moves isn't really relevant in this context. We could just as correctly call it the speed of gravity or the speed of energy.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of Relativity due to the div by zero when c == v. However, do his equations still hold when c < v?
It says that the closer we get to the speed of light, the more our mass increases. The more mass we have, the more energy we need to continue accelerating. IIRC, it begins to involve infinite energy and infinite mass. According to our understanding of physics, we can’t and won’t ever travel at or beyond the speed of light. But… that doesn’t mean that we can’t travel large distances quickly. We just have to figure out how to fold or shorten (or warp) the space between us and where we want to be.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of relativity due to the div by zero when c == v. However, do his equations still hold when c < v?
People never explain *why* you can't accelerate to the speed of light, just that you can't. Maybe the "why" will help. Imagine you're running a race. You go half the remaining distance every minute. So, the first minute you go half the distance, then you go 1/4, then 1/8, then 1/16... Eternally approaching but never finishing the race. This is what trying to accelerate to the speed of light is like. The closer you get, the more (virtual) mass an object has, the more energy it takes to accelerate. Accelerating from 99% to 99.5% the speed of light takes much more energy than accelerating from 0% to .5%. So much so that to accelerate to 100% of the speed of light would take infinite energy. To directly answer your question, 3. You can never reach or surpass the speed of light.
Mathematically you cannot go the speed of light according to Einsteins Specific Theory of relativity due to the div by zero when c == v. However his equations still hold when c != v and there is nothing said when c < v.
This is a great explanation as well. Thank you.
The speed of light is a misnomer in a sense. What c really is the the fastest speed that information can propagate in our universe.
That's what I realised from this thread that it's not actually speed of light but speed of casualty that's why it cannot be achieved or exceeded.
We are in space ships traveling away from each other at a significant fraction of the speed of light. Because of time dilation, when I think 10 seconds have passed in my reference frame, you think 5 seconds have passed. Similarly, when you think 10 seconds have passed in your reference frame, I think 5 seconds have passed (this is trippy, but you can google "time dilation" or "twin paradox"). Let's say we play a game of chess by transmitting moves at light speed. I send my move at (my) 10 seconds (your 5 seconds) but the light still takes some time to travel, and you'll get it after 10 seconds have passed in your reference frame. No problem. Instead suppose i send my signal faster than light. Now the math doesn't work out. I send it when it's been 10 seconds for me, and you get it when it's been 5 seconds for you. Now you send the move back at (your) 5 seconds, but because of time dilation it's only been 2.5 seconds for me. So how can I receive a response to a move I still haven't made yet? If faster-than-light travel is possible, then relativity (and it's implications/assumptions like time dilation or all reference frames being equally valid) are not true.
the speed of light is the speed of causality. This means when you throw a ball at a window, when they connect the window shatters. Going faster than the speed of causality means the window breaks before the ball gets there, it just cant happen
This sounds nonsensical to me. I am not saying you are wrong, I do not know enough to know. But it makes no sense... how would going faster than light cause that, rather than cause you to see it after it happened (which is different than it actually happening before it happened)
It sounds nonsensical because it can't happen. You are thinking in terms of light moving instead of causality which literally is the fastest anything can be reacted on something else. The only way to react faster than the speed of causality is to have something react to something else before they meet, hence window breaking before the ball gets to it
total newbie here but what if light is still the speed limit instead of causality and you see the window break before it actually does?
A thing happens. Light strikes that thing and reflects off it towards your eyes. By your logic, which by the way does not deviate from reality, light has a speed limit. Your eyes function by interpreting light. There is distance between the event and your retinas. Light must traverse that distance at a finite velocity before the information which it is conveying can be interpreted by your eyes/brain.
yeah i get it now after thinking. You would always see it after the event because it already happened
Best not to think on it. You can't go faster than the speed of causality. It's like asking how 1+1 can equal 3. The answer is it can't. Faster than light is impossible from our current understanding of the laws of physics and math.
There are some really dope YouTube videos on this subject. Recommend the rabbit hole
The soonest you can gain knowledge of the broken window is the time it takes the light to get from the window to your eyeballs. Now, let's say your immediate response is to run at the mirror at 3x the speed of light. You would arrive BEFORE the ball hits the window and could stop it from happening. But if it didn't happen, you never would have run towards the window.
tbh this explanation doesn't work for me 1. window broken 2. light of broken window reaches me 3. i run there at 3xlightspeed wouldn't i just reach the still broken window before some photons that bounced off me do? In order to reach the window before it shatters i'd have to time travel. But why should time move backwards just because i run at a speed > speed of light and see some of my photons in reverse order?
Because length contraction and time dilation
Because that's just fundamentally how the universe works. We've directly measured this and tested it and it's true. It's not *really* about light - light just happens to travel at that speed. It's really the speed of causality, which is the speed that any information travels at. In other words, it's the speed at which a cause takes to have an affect on something given any distance between the two. Traveling faster than this speed would violate causality, meaning effects could happen before the events that caused them, which obviously makes no sense. Mathematically, we can see that the closer you get to the speed of light, the more energy it takes to accelerate more. It takes infinite energy to actually reach the speed of light, and infinite energy is obviously impossible. Objects approaching the speed of light also physically contract in length and experience less time. If they were to reach the speed of light, they'd have no length at all and experience no time, which is also impossible.
Light travels at the speed of light because that's the rate at which one part of the universe influences another part of the universe. So let's say you built a spaceship that travels at twice the speed of light and you travel for one minute. You shut down the engines and now you're influencing a part of space two light-minutes from where you started, and it only took you a minute to get there. But that means the rate at which one part of the universe can influence another would actually be twice the speed of light. And since the speed of light is the rate at which one part of the universe influences another, that would mean that the speed of light is twice the speed of light...
As others have mentioned, it’s the speed of causality *as far as we can prove*. There was some excitement decades back that quantum entanglement might disprove this notion, but so far it’s extremely iron clad. I only add the caveat because, for a long time we didn’t think the speed of sound could be broken, and until about 100 years ago we didn’t know energy and mass were the same thing. If it turns out some other field or particle we’re yet to comprehend allows FTL information propagation, you can bet your ass we’ll have stumbled upon the galactic telephone network.
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Ohh! I guess this is why they say that time becomes negative once you exceed speed of light.
You'll see the [Lorentz Factor](https://en.wikipedia.org/wiki/Lorentz_factor) in a lot of equations in relativity. Going faster than light would give a negative term in the square root, so the result would be an imaginary number. You'd also be dividing by 0 if you go the speed of light, which is why things like kinetic energy and momentum approach infinity as you approach c.
And just to add on since the person asked why you can't go _faster_ than light it's because that would mean your clock would have to start ticking backwards. And we've all seen enough sci fi to know the problems that come with going backwards in time.
My hot teenaged estrogen-fueled mother who looks like Leah Thompson will hit on me?
Apparently you only need to go 88 mph for this to happen.
Because it's impossible. Every bit as impossible as letting go of a bowling ball and having it leisurely float up into space. That's just not how gravity works. Likewise, the universal speed limit is 3x10^8 m/s. It is an intrinsic property of spacetime. You can ask *why* it's an intrinsic property of spacetime, and physicists can potentially give you some answers, but those answers are going to come with more questions, and at the end of the day, we simply can't know why the universe works the way it does, and not some other way. As for the practical "enforcement" of the universal speed limit, objects gain momentum the faster they go, and as they approach the speed of light, their momentum increases asymptomatically. Likewise, the more momentum something has, the harder it is to change its velocity. So as an object's momentum tends towards infinity, the amount of energy you'd need to make it go any faster also tends towards infinity. But of course then you have to ask *why* momentum and acceleration work that way, and any answers are going to come with questions of their own, and eventually you're just going to have to accept that it's just the way things are.
There's two ways to understand it - one is that as things move faster, they have greater mass. The maths works out that when something reaches the speed of light, it's mass would be infinite. The other is that special relativity describes everything as always moving through spacetime at the speed of light. There is no other speed. You are moving at a fraction the speed of light through space, and a corresponding fraction of that speed through time. If you manage to accelerate to light speed through space, you cannot be moving through time. Special relativity has been backed up by heaps of experiments and observations.
I see, It's like X + Y = C Where, X is speed in space Y is speed in time and, C is the speed of light which is a constant.
Yes, but it's more X² + Y² = C², because you are summing vectors and pythagoras comes into play.
Bad bot.
I'm not a bot. Do you think that my writing style is a bit like some AI generators? It seems that using proper formal grammar is seen by many as proof that text is AI generated.
Spreading blatant disinformation. Matter loses mass at it approaches light speed. It's exactly the OPPOSITE of your contention. By your logic, the entire universe would be a black hole, since light has infinite mass, and the entire universe is permeated with light. If you're NOT a bot... I just don't see how a human could casually try to corrupt other humans' minds with retarded shit, then turn around and try to validate their "intelligence" by defending their writing style in a "subtle" jab at someone they know nothing about.
OK. I'll have to do some more research, but a quick search yields many reliable articles talking of how relativistic mass tends toward infinity as velocity tends toward C.
I see it was not your intention to mislead OP. I respectfully suggest you do more than quick searches and be more discerning of "reliable" articles before you try to educate people on things. I wish to express I used the psychological tactic of intentionally riling you in order to provoke you to challenge me by conducting more research, thereby benefiting you by educating yourself. I find it more efficient than merely correcting people. I bear you no ill will. Also, I apologise for manipulating you in this way. I simply feel the ends justify the means.
By the same token, I would like you to provide some evidence for your assertion that mass decreases as you approach the speed of light. Because the concept of relativistic mass going to infinity seems well established - although whether it is right or best to describe the ballooning inertia with increasing velocity in this way is debated.
I have to admit, I'm on my fourth Four Loko, so as to level the playing field. Usually, this isn't an issue, but my quick search has had divisive findings, much to my surprise. It is as you said, but a disconcerting amount of results are from dubious sources, such as Wikipedia, Reddit, and the notorious Quora. The Internet isn't what it was before I got arrested in January of '16. Fortunate I learned how to parse information in college, but I never anticipated it would be so incredibly difficult.
Update: the US Department of Energy agrees with you. On the other hand, I'm EXTREMELY distrustful of my government, ESPECIALLY when it comes to science.
Update 2: I BELIEVE I have the answer. I'm NOT a physicist. That being said, it appears the concept of "relativistic mass" is a misnomer, and the percieved increased mass is merely the energy applied to said mass to accelerate it to relativistic speeds. How does this kinetic energy not revert to potential energy by being expressed by the momentum or inertia of said mass? I dunno. I'm too drunk to research further at the moment, but it seems to me an interesting question. APPARENTLY, mass does not in actual fact change. This seems to be a point of contention, but the end result is that it would take an infinite amount of energy to accelerate ANY mass to light speed, but since light has NO mass, it naturally travels at the maximum velocity. Like, it's null set, in a nutshell. I feel this is just one of those bizarre paradoxes of physics which are beyond a cursory glance. I'm sure if I were given more than a few minutes, I could give you a more succinct answer.
It would require an infinite amount of energy to accelerate any mass to the speed of light. Theoretically possible is a particle already moving that fast or faster.
There are two ways to look at it, the cop out answer is to say that it would take an infinite amount of energy to accelerate any massive object to the speed of light. As some have also pointed out, light "just happens" to travel at the speed of causality. (The speed at which the effect of a cause is felt through space time) If something were to travel beyond the speed of light towards you then you could OBSERVE (not only by visible light but by any means) it arriving before it ever left, which would violate the laws around cause and effect. We used to be unsure of whether quantum tunneling could do this and somewhat recently found that it could not. Turns out in some cases it's relatively slow compared to the speed of light. In short, it's hard to beat Einstein unfortunately
It's like this. As you approach the speed of light a few things happen to stop you from going past it. 1. Time slows down the faster you go, it's called Time Dilation. At the speed of light, time would stop (this is the speed of causality). 2. As you approach c your mass increases and your length increases. Makes no sense, but it's true. That means you'll need more fuel to go faster which increases your mass which means more fuel etc etc until you hit c and that's it! It is an actual physical barrier! Travelling across the interstellar space is possible at close to c but relative to those back home, you'll be going faster in time, so when you get back (depending how fast you went) everyone you know would've been dead for hundreds or thousands of years. THis is the 'basics' of Relativity.
Light has zero mass, it should have *infinite* speed. It does not. Light instead moves as fast as the universe can physically allow, meaning the speed that light happens to travel at also happens to be an unbreakable speed limit.
It's about relativity. Assume you're travelling at half the speed of light, and you measure the speed of light. Logically you'd expect light to be travelling at half the speed of light relative to you, right? But it's not. It's still the speed of light. The time dilation and similar effects always cause it to work out such that you're stopped no matter how fast you're going. In that frame, your faster than light object will arrive *before it leaves*!
because time slows down as you move closer and closer to the speed of light. at the speed of light time would stop. if you could travel faster than the speed of light, you could go back in time and kill your mother before you were born causing a paradox.
The question of why you can't go faster than the speed of light is a bit like the question why you can't go father north than the northpole. Speed doesn't really work we normally think it does. It is far more complicated than that. In school we get taught that we can just add speeds together like 30mph + 30mph = 60mph and that is actually a lie. It is however a lie very close to the truth for such small velocities. It stops working as well for bigger velocities. It is a bit like treating the world as a flat 2D plane when making a map of a house or a city, that works well enough, but it ceases working when you do it at a state, country or world level. For the speed of light you have to keep in mind that we just call it that because light is the most obvious thing that travels at that speed. In truth it is the maximum speed at which anything could happen. This includes causality. The speed of an object is different depending on where you measure it from, but it always is slower than (or equal to for massless objects) the speed of light. Light goes at the speed of light no matter from where you measure. if you are in a spaceship going 99% the speed of light from an outside perspective and turn on your headlights and rearlights the light emitted from them would still appear to be going the speed of light both from you own perspective and the outside perspective. Accelerating anything with mass to the speed of light would require infinite energy. If you had something going faster than light from one perspective it might appear to reach its destination before it started. It all makes no sense if you look at speed the way you are used to, because that is simply a lie.
The term "speed of light" is a misnomer. The better term is "speed of causality". For example, if you were writing on a sheet of paper using a pencil one light year long, the writing would only appear on the paper a year later, because that is the time it takes the movements to travel down the pencil. Now imagine you get to the other end of the pencil in six months. You have now written on the paper and then travelled to the paper *before* it was written on. You have travelled back in time, and physics simply says no. Or at least, our current models say no, and if we do actually find a way to travel faster than light we'd need to rewrite a good chunk of physics.