Why does light move at the speed of light?
(Approx. Trans. - see approx. Trans. At the end of the post)
Why does light move at the speed of light? Why he just does not stand still? What sets it in motion (especially so fast)?
')
Everything and everywhere, simply by the fact of its existence, “moves” with the speed of light (which actually has nothing to do with light). Yes, this also applies to you. Right now.
People generally perceive the "universe" as a "space", something separate from "time", and frankly, they are wrong. Space and time are not separate things. The universe is made of "space-time", just like that, without a space. You are probably accustomed to the fact that “year” is a unit of time, and “light year” is a unit of distance, that is, they are different things; but from the point of view of physics, this is absolutely the same thing (well, of course, depending on what type of physics you do).
In our everyday life, we proceed from the fact that movement is a certain distance (space) that has been overcome in some time. However, if we decided that this is the same thing, our definition of movement suddenly becomes complete nonsense. “I walk a kilometer for every kilometer I walk” - some kind of nightmare!
It turns out that everything works like this - everything in the Universe “travels” through spacetime with a constant “speed”, which I will further refer to as s, for brevity. Do not forget, “movement” in space-time does not make sense, therefore nothing can be “faster” or “slower” than anything else. Everything passes around a kilometer within a kilometer, so here.
However, we see with our own eyes that different things around us have different speeds. The reason for this is the awesome fact that space and time are orthogonal (with this beautiful word I try to say “at the right angle to each other”). For example, in the same sense, the north and east are orthogonal (perpendicular) - you can go exactly north for any length of time, and this will not affect your movement to the east or west.
Just as you can move to the north, while not moving east, you can move in time without moving in space. But even steeper is the fact that you can move in space in such a way that it does not affect your “position” in time.
I think that you are now (like me) sitting and looking at the screen. This means that you are not particularly traveling in space. And since you have to travel in space time with a constant speed c, this means that all your “movement” is spent in the direction of time.
By the way, this is why the famous time dilation takes place. An object that moves very quickly (relative to you) moves in space, but since it also moves in space time at a constant speed, it has to move more slowly in time to compensate (again from your point of view).
Even more surprising, the light does not move at all in time. It is a bit difficult to explain, but in short, this is due to the fact that it has no mass.
Something that does not move in space, but which has mass, may have energy. This is the meaning of the formula E = mc ^ 2. Light has no mass, but it definitely has energy. If we apply the mass of light to E = mc ^ 2, we get 0, which is meaningless, because light has energy. Therefore, the light can never be still.
Moreover! The light is never fixed as to anything. Since, like everything else in the Universe, it travels through spacetime with speed c, then all this “spacetime speed” must be in the “direction” of space, and nothing remains for a while.
So, the light moves with speed c. It is not by chance that this speed is often defined as "the speed of light in a vacuum." In fact, this is the speed with which everything moves everywhere and everywhere. It just so happened that the light with this speed moves precisely in space, because it has no mass.
By the way, here you can answer another frequently asked question - why can nothing move faster than light, and why things “material” (having mass) cannot move at the speed of light. Since everything “moves” in space-time at a constant speed c, nothing can overcome this speed in space. And no, traveling back to the past will not help.
Also, since objects with a mass can be "fixed" with respect to something (for example, themselves), they always have to move in time at least a little. This means that they cannot move in space as fast as light. Then they would have to move in space time faster than speed c, which is impossible.
So, if the light does not move through time, only through space, why then does it not move instantly? After all, we know for sure that the light needs some time to fly from the Sun to the Earth.
It is very difficult (if at all possible) to adequately describe the flow of space and time from the point of view of a photon. We can say that photons do not "feel" time, although this sounds strange. Although we have no reason to worry about their feelings.
It takes some time for the light to move from one place to another, because its speed is finite relative to anyone who watches it. Do not try to imagine “what sees the light around you,” we can only imagine “what the one who sees the light sees.” We cannot (at least at this stage of development) discuss how the world "perceives" the world; this most likely does not make sense.
(Approx. Lane - I will not resist the temptation to present myself as a photon. It turns out that the photon, from the point of view of itself, flies away from the Sun and flies to Earth at the same time instant. In general, everything is one time moment because something not at all).
A slightly silly question, but does all this mean that if something moves through space, it will age more slowly, because its movement through spacetime will be slower with respect to everything around it something?
Yes it is! Congratulations, now you understand what time delay means. A very correct remark about "relative to everything around."
Didn’t we manage to stop the light in the crystals and all that?
We managed to launch a photon inside a special crystal that absorbed it. Having done this, the crystal vibrates in a special way that encodes information about the photon (color and all that). After some time, the crystal emits a new photon, with the same properties as previously absorbed, because the vibrations “stored” these properties.
Nowhere at this time we stopped the photon. Roughly speaking, we killed him, and then cloned him.
This important discovery, for example, allows us to use optics in IT. We know how to transmit information with the help of light, but it is impossible to store such information, unless you spend time converting it into electricity.
Why does light move at the speed of light? Why he just does not stand still? What sets it in motion (especially so fast)?
')
Everything and everywhere, simply by the fact of its existence, “moves” with the speed of light (which actually has nothing to do with light). Yes, this also applies to you. Right now.
People generally perceive the "universe" as a "space", something separate from "time", and frankly, they are wrong. Space and time are not separate things. The universe is made of "space-time", just like that, without a space. You are probably accustomed to the fact that “year” is a unit of time, and “light year” is a unit of distance, that is, they are different things; but from the point of view of physics, this is absolutely the same thing (well, of course, depending on what type of physics you do).
In our everyday life, we proceed from the fact that movement is a certain distance (space) that has been overcome in some time. However, if we decided that this is the same thing, our definition of movement suddenly becomes complete nonsense. “I walk a kilometer for every kilometer I walk” - some kind of nightmare!
It turns out that everything works like this - everything in the Universe “travels” through spacetime with a constant “speed”, which I will further refer to as s, for brevity. Do not forget, “movement” in space-time does not make sense, therefore nothing can be “faster” or “slower” than anything else. Everything passes around a kilometer within a kilometer, so here.
However, we see with our own eyes that different things around us have different speeds. The reason for this is the awesome fact that space and time are orthogonal (with this beautiful word I try to say “at the right angle to each other”). For example, in the same sense, the north and east are orthogonal (perpendicular) - you can go exactly north for any length of time, and this will not affect your movement to the east or west.
Just as you can move to the north, while not moving east, you can move in time without moving in space. But even steeper is the fact that you can move in space in such a way that it does not affect your “position” in time.
I think that you are now (like me) sitting and looking at the screen. This means that you are not particularly traveling in space. And since you have to travel in space time with a constant speed c, this means that all your “movement” is spent in the direction of time.
By the way, this is why the famous time dilation takes place. An object that moves very quickly (relative to you) moves in space, but since it also moves in space time at a constant speed, it has to move more slowly in time to compensate (again from your point of view).
Even more surprising, the light does not move at all in time. It is a bit difficult to explain, but in short, this is due to the fact that it has no mass.
Something that does not move in space, but which has mass, may have energy. This is the meaning of the formula E = mc ^ 2. Light has no mass, but it definitely has energy. If we apply the mass of light to E = mc ^ 2, we get 0, which is meaningless, because light has energy. Therefore, the light can never be still.
Moreover! The light is never fixed as to anything. Since, like everything else in the Universe, it travels through spacetime with speed c, then all this “spacetime speed” must be in the “direction” of space, and nothing remains for a while.
So, the light moves with speed c. It is not by chance that this speed is often defined as "the speed of light in a vacuum." In fact, this is the speed with which everything moves everywhere and everywhere. It just so happened that the light with this speed moves precisely in space, because it has no mass.
By the way, here you can answer another frequently asked question - why can nothing move faster than light, and why things “material” (having mass) cannot move at the speed of light. Since everything “moves” in space-time at a constant speed c, nothing can overcome this speed in space. And no, traveling back to the past will not help.
Also, since objects with a mass can be "fixed" with respect to something (for example, themselves), they always have to move in time at least a little. This means that they cannot move in space as fast as light. Then they would have to move in space time faster than speed c, which is impossible.
So, if the light does not move through time, only through space, why then does it not move instantly? After all, we know for sure that the light needs some time to fly from the Sun to the Earth.
It is very difficult (if at all possible) to adequately describe the flow of space and time from the point of view of a photon. We can say that photons do not "feel" time, although this sounds strange. Although we have no reason to worry about their feelings.
It takes some time for the light to move from one place to another, because its speed is finite relative to anyone who watches it. Do not try to imagine “what sees the light around you,” we can only imagine “what the one who sees the light sees.” We cannot (at least at this stage of development) discuss how the world "perceives" the world; this most likely does not make sense.
(Approx. Lane - I will not resist the temptation to present myself as a photon. It turns out that the photon, from the point of view of itself, flies away from the Sun and flies to Earth at the same time instant. In general, everything is one time moment because something not at all).
A slightly silly question, but does all this mean that if something moves through space, it will age more slowly, because its movement through spacetime will be slower with respect to everything around it something?
Yes it is! Congratulations, now you understand what time delay means. A very correct remark about "relative to everything around."
Didn’t we manage to stop the light in the crystals and all that?
We managed to launch a photon inside a special crystal that absorbed it. Having done this, the crystal vibrates in a special way that encodes information about the photon (color and all that). After some time, the crystal emits a new photon, with the same properties as previously absorbed, because the vibrations “stored” these properties.
Nowhere at this time we stopped the photon. Roughly speaking, we killed him, and then cloned him.
This important discovery, for example, allows us to use optics in IT. We know how to transmit information with the help of light, but it is impossible to store such information, unless you spend time converting it into electricity.
Translator's note.
You have just read (or missed) the translation of this post here on reddit , more precisely, the responses of user corpuscle634 . Being very far from the topic of a post (I am a designer), I, however, simply could not help but share this text with the community. Accordingly, here I must observe the necessary formalities, such as: write about errors in a personal, an amateur translation, the moped is not mine, and all that.
If you, like me, this post caused a “massive lightbulb moment”, and you want to continue, here's another from mathematics - A Visual, Intuitive Guide to Imaginary Numbers
May space be with you!
Source: https://habr.com/ru/post/237071/
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