- E: The speed of light is invariant!
- M: So what? A car travelling with a constant speed also has invariant speed.
- E: But the speed of light is invariant for any observer.
- M: What difference does that make?
- E: Let’s imagine that you are standing by the road with a speed radar and measure the speed of a car going with a constant speed as 50 km/h. Is that ok for now?
- M: As long as you give me the radar.
- E: Alright, now you get into another car which goes with a constant speed of 30 km/h. If you measure the previous car with the same radar once more, what speed will it show?
- M: 20 km/h of course.
- E: Ignoring the minor relativistic effects, you are absolutely correct.
- M: Smarty-pants.
- E: What if I tell you that this simple everyday logic doesn’t work for the light?
- M: What do you mean?
- E: The speed of light is invariant.
- M: For any observer?
- E: Now we are talking.
- M: Even if I travel with half the speed of light?
- E: That would be utterly difficult but even if you could, yes. You would still measure that the light has the same speed.
- M: Even if I travel with the speed of light?
- E: No, you can’t go with the speed of light.
- M: Why not?
- E: You will need infinite amount of energy.
- M: So, there is still a possibility?
- E: No!
- M: Meeh, whatever.
As I tried to explain in this probable conversation, the speed of light has a very strange feature called the invariance. It doesn’t fit into our intuition about the relative speeds of everyday objects as you already read. This feature has appeared in Maxwell’s equations first and has started the relativity era by being the main inspiration for Albert Einstein. Any person who is interested in theoretical physics cannot escape its dazzling temptation and probably tried to find reasoning about what kind of circumstances can lead light to have such a feature.
Obviously, I also did. I have written it as a Quora answer previously but this horizon analogy meant so much to me that it still guides me to reach new answers about the mysteris of the universe and it probably is much more than an analogy, so I wanted to share it once again in my blog. Here is my answer for the quora question;
What is the speed of the light?
This is a question which you will get numerous replies.
To be precise, it is the speed amount that is equal to 299279458 meters per second (Actually, the metric system now gives the definition of 1 meter as the distance covered by light in 1/299279458 seconds in vacuum. So light speed is not that many meters but meter is that many light seconds, which means it is the other way round but who cares about that).
Some will also say that it is the universal speed limit which all the electromagnetic radiation and massless particles are traveling with.
Some will add that it is the conversion factor called c which you can use to convert temporal dimension into the spatial one by multiplying the time amount with it.
Some will even say that it is not possible to reach to this speed rate for the massive objects and it is not possible to exceed it for any object.
It is also known as being measured always the same (called invariant), independent from your own speed, so this will probably also be mentioned.
But all this information is available in many sources and was discussed for the zillionth of time even in Quora, so I assume that you are not looking for these answers, otherwise you could reach them with a simple search.
Therefore, I find it reasonable to add my own non-scientific layman view on this subject hoping that it may give you or to the others some new look.
In my opinion, the key point to solve the mystery of speed of light is to understand its invariant nature. Under which circumstances will you measure the speed of something always the same, independent from your own speed. What kind of setting can cause such result? Let’s start some reasoning on our own.
If you try to catch something which is connected to your body with a length of stick which is longer than your arms, it will keep the same distance from you, doesn’t matter how much you move towards or away from it. This could be a starting point but we face the invariant speed of light phenomena with speed of any light not only with the ones which we are at their source. We face it even if it comes from distant stars. So it must be something else. What always keeps its distance from us all the time, independent from our motion?
There is one similarity between the speed of light and the horizon of the earth. If you measure the distance from the horizon and try to reduce this distance by moving towards it, doesn’t matter how much distance you have covered, how fast you move or accelerate, your distance to the horizon will always be the same. Very similar to invariant speed of light. (To make it a perfect analogy, let's assume that we are travelling in sea where there is no land in our sight, there is no wave or wind, the sky is clear and the sun is just above our head.)
But there is also one problem with this analogy. The example we have given is a displacement based one (distance to horizon) and the one we seek for similarity is velocity based (light speed). Let’s replace every displacement related terms in our first sentence with the velocity based ones in our scenario and see if it fits. Check the below version with the parenthesis and replace them with the bold ones to see the equivalence.
There is one similarity with the horizon of the earth (speed of light). If you measure distance (speed) from (of) horizon (light) and try to reduce this distance (speed) by moving towards it, doesn’t matter how much distance (speed) you have covered (gained), your distance to (speed from) the horizon (speed of light) will always be the same.
So, it seems like it works. This tells me that, if we somehow change our displacement based perception with the velocity based one, in a sense that, if we can take the time derivative of our reality and start to replace the distances with velocity (just like the photons do) maybe, only maybe then we can relate with this example.
Let’s take it a bit further and go into the details of the horizon analogy. If this analogy fits well, then the speed of light shall fit to the other features of the horizon, as well. What are the other features of the horizon? Horizon is actually an illusion created by the intersection of 2 dimensional earth surface with the 3 dimensional space. So if our analogy is correct, then this definition should also fit to speed of light.
Yes, somehow it does. But to see that, we need to change our perception again. You know that if you take the time derivatives of displacement again and again, you will reach to the concepts of velocity, acceleration, jerk, jounce etc. after each derivation (taking its integrals will lead you to absement, absity, abseleration etc., too but it will only make the subject more complicated. So, I will pass that part for now). That means all these concepts are related. Actually they are the same phenomenon derived! from each other. And the common thing among them is time, which is often related with the speed of light. It is not possible to explain all the details here now but if you put all of these and many other thoughts together, you can reach to a conclusion that there is a motion based connection between dimensions, speed of light being the border between them. So according to that, any phenomenon around us which has a constant speed motion (like electromagnetic radiation) has 1 more (4) spatial dimension in addition to the ones that we perceive. You can also take that further and say that any constant acceleration phenomenon has even 1 higher number of (5) spatial dimension than that. If you don’t find out any similar things around you, just think about the gravity causing a constant acceleration all the time. It is also known that the mass is usually referred as the 5th dimension. I don’t know how far can you take this idea since I couldn’t see its limit yet but seems like you can take it further.
If you finally can start to see things around you with those glasses, you will also start to see speed of light differently and your restrictions about speed of light will become different, too. Knowing that it is a horizon, an intersection between the dimensions, you are only able to perceive everything around you up to that speed. Your perception cannot reach beyond it just like the horizon of the earth doesn’t allow us to see beyond it (That can also point out to us that there is a curvature in our universe. But this one is between all spatial dimensions, not limited within the 3 spatial ones that we can perceive). You can keep going towards horizon as much as you want but your distance will stay the same. Similarly, you can increase your speed as much as you want. You can physically pass well beyond that amount defined as speed of light but when you measure the speed of any light around you (like your distance to horizon) you will always get the same value. (This is not my assumption. Any physicist will tell you that it is possible to keep accelerating as long as you have the energy needed for that. They only interpret your speed rate differently and tell you that it will never reach to speed of light. This is due to space-time limiting our perception with horizon of speed of light. After all, what will be your reference at that speed rate? You will keep measuring the speed of any light with the same rate. And that is the same light which lets you to see all the other stars, planets, etc around you which could be a reference to define your own speed. With lack of a good reference, how can you tell what your speed is? This is just like watching an illusion shown to us by the greatest magician of the universe. He is always hiding all the clues away from us. Seems like we are helpless to see beyond that illusion.)
This type of thinking will also tell you that the light and all other electromagnetic radiation are having 4 spatial dimensions as I’ve said before. Just like any intersection between n dimensional object and a n-1 dimensional one, we can only perceive its projection in our 3 dimensional space. This prohibits us from discovering the light’s whole nature. That is also the case with the mass and we cannot perceive the fundamental parts of it since there are barriers made of speed of light between us and them, hiding their big picture. What we see is only the thickness of that big picture’s paper which is its intersection with our dimension.
With this point of view, speed of light is not a feature of the light itself nor a universal speed limit but is the horizon between the curved dimensions of our universe.
- M: So what? A car travelling with a constant speed also has invariant speed.
- E: But the speed of light is invariant for any observer.
- M: What difference does that make?
- E: Let’s imagine that you are standing by the road with a speed radar and measure the speed of a car going with a constant speed as 50 km/h. Is that ok for now?
- M: As long as you give me the radar.
- E: Alright, now you get into another car which goes with a constant speed of 30 km/h. If you measure the previous car with the same radar once more, what speed will it show?
- M: 20 km/h of course.
- E: Ignoring the minor relativistic effects, you are absolutely correct.
- M: Smarty-pants.
- E: What if I tell you that this simple everyday logic doesn’t work for the light?
- M: What do you mean?
- E: The speed of light is invariant.
- M: For any observer?
- E: Now we are talking.
- M: Even if I travel with half the speed of light?
- E: That would be utterly difficult but even if you could, yes. You would still measure that the light has the same speed.
- M: Even if I travel with the speed of light?
- E: No, you can’t go with the speed of light.
- M: Why not?
- E: You will need infinite amount of energy.
- M: So, there is still a possibility?
- E: No!
- M: Meeh, whatever.
As I tried to explain in this probable conversation, the speed of light has a very strange feature called the invariance. It doesn’t fit into our intuition about the relative speeds of everyday objects as you already read. This feature has appeared in Maxwell’s equations first and has started the relativity era by being the main inspiration for Albert Einstein. Any person who is interested in theoretical physics cannot escape its dazzling temptation and probably tried to find reasoning about what kind of circumstances can lead light to have such a feature.
Obviously, I also did. I have written it as a Quora answer previously but this horizon analogy meant so much to me that it still guides me to reach new answers about the mysteris of the universe and it probably is much more than an analogy, so I wanted to share it once again in my blog. Here is my answer for the quora question;
What is the speed of the light?
This is a question which you will get numerous replies.
To be precise, it is the speed amount that is equal to 299279458 meters per second (Actually, the metric system now gives the definition of 1 meter as the distance covered by light in 1/299279458 seconds in vacuum. So light speed is not that many meters but meter is that many light seconds, which means it is the other way round but who cares about that).
Some will also say that it is the universal speed limit which all the electromagnetic radiation and massless particles are traveling with.
Some will add that it is the conversion factor called c which you can use to convert temporal dimension into the spatial one by multiplying the time amount with it.
Some will even say that it is not possible to reach to this speed rate for the massive objects and it is not possible to exceed it for any object.
It is also known as being measured always the same (called invariant), independent from your own speed, so this will probably also be mentioned.
But all this information is available in many sources and was discussed for the zillionth of time even in Quora, so I assume that you are not looking for these answers, otherwise you could reach them with a simple search.
Therefore, I find it reasonable to add my own non-scientific layman view on this subject hoping that it may give you or to the others some new look.
In my opinion, the key point to solve the mystery of speed of light is to understand its invariant nature. Under which circumstances will you measure the speed of something always the same, independent from your own speed. What kind of setting can cause such result? Let’s start some reasoning on our own.
If you try to catch something which is connected to your body with a length of stick which is longer than your arms, it will keep the same distance from you, doesn’t matter how much you move towards or away from it. This could be a starting point but we face the invariant speed of light phenomena with speed of any light not only with the ones which we are at their source. We face it even if it comes from distant stars. So it must be something else. What always keeps its distance from us all the time, independent from our motion?
There is one similarity between the speed of light and the horizon of the earth. If you measure the distance from the horizon and try to reduce this distance by moving towards it, doesn’t matter how much distance you have covered, how fast you move or accelerate, your distance to the horizon will always be the same. Very similar to invariant speed of light. (To make it a perfect analogy, let's assume that we are travelling in sea where there is no land in our sight, there is no wave or wind, the sky is clear and the sun is just above our head.)
But there is also one problem with this analogy. The example we have given is a displacement based one (distance to horizon) and the one we seek for similarity is velocity based (light speed). Let’s replace every displacement related terms in our first sentence with the velocity based ones in our scenario and see if it fits. Check the below version with the parenthesis and replace them with the bold ones to see the equivalence.
There is one similarity with the horizon of the earth (speed of light). If you measure distance (speed) from (of) horizon (light) and try to reduce this distance (speed) by moving towards it, doesn’t matter how much distance (speed) you have covered (gained), your distance to (speed from) the horizon (speed of light) will always be the same.
So, it seems like it works. This tells me that, if we somehow change our displacement based perception with the velocity based one, in a sense that, if we can take the time derivative of our reality and start to replace the distances with velocity (just like the photons do) maybe, only maybe then we can relate with this example.
Let’s take it a bit further and go into the details of the horizon analogy. If this analogy fits well, then the speed of light shall fit to the other features of the horizon, as well. What are the other features of the horizon? Horizon is actually an illusion created by the intersection of 2 dimensional earth surface with the 3 dimensional space. So if our analogy is correct, then this definition should also fit to speed of light.
Yes, somehow it does. But to see that, we need to change our perception again. You know that if you take the time derivatives of displacement again and again, you will reach to the concepts of velocity, acceleration, jerk, jounce etc. after each derivation (taking its integrals will lead you to absement, absity, abseleration etc., too but it will only make the subject more complicated. So, I will pass that part for now). That means all these concepts are related. Actually they are the same phenomenon derived! from each other. And the common thing among them is time, which is often related with the speed of light. It is not possible to explain all the details here now but if you put all of these and many other thoughts together, you can reach to a conclusion that there is a motion based connection between dimensions, speed of light being the border between them. So according to that, any phenomenon around us which has a constant speed motion (like electromagnetic radiation) has 1 more (4) spatial dimension in addition to the ones that we perceive. You can also take that further and say that any constant acceleration phenomenon has even 1 higher number of (5) spatial dimension than that. If you don’t find out any similar things around you, just think about the gravity causing a constant acceleration all the time. It is also known that the mass is usually referred as the 5th dimension. I don’t know how far can you take this idea since I couldn’t see its limit yet but seems like you can take it further.
If you finally can start to see things around you with those glasses, you will also start to see speed of light differently and your restrictions about speed of light will become different, too. Knowing that it is a horizon, an intersection between the dimensions, you are only able to perceive everything around you up to that speed. Your perception cannot reach beyond it just like the horizon of the earth doesn’t allow us to see beyond it (That can also point out to us that there is a curvature in our universe. But this one is between all spatial dimensions, not limited within the 3 spatial ones that we can perceive). You can keep going towards horizon as much as you want but your distance will stay the same. Similarly, you can increase your speed as much as you want. You can physically pass well beyond that amount defined as speed of light but when you measure the speed of any light around you (like your distance to horizon) you will always get the same value. (This is not my assumption. Any physicist will tell you that it is possible to keep accelerating as long as you have the energy needed for that. They only interpret your speed rate differently and tell you that it will never reach to speed of light. This is due to space-time limiting our perception with horizon of speed of light. After all, what will be your reference at that speed rate? You will keep measuring the speed of any light with the same rate. And that is the same light which lets you to see all the other stars, planets, etc around you which could be a reference to define your own speed. With lack of a good reference, how can you tell what your speed is? This is just like watching an illusion shown to us by the greatest magician of the universe. He is always hiding all the clues away from us. Seems like we are helpless to see beyond that illusion.)
This type of thinking will also tell you that the light and all other electromagnetic radiation are having 4 spatial dimensions as I’ve said before. Just like any intersection between n dimensional object and a n-1 dimensional one, we can only perceive its projection in our 3 dimensional space. This prohibits us from discovering the light’s whole nature. That is also the case with the mass and we cannot perceive the fundamental parts of it since there are barriers made of speed of light between us and them, hiding their big picture. What we see is only the thickness of that big picture’s paper which is its intersection with our dimension.
With this point of view, speed of light is not a feature of the light itself nor a universal speed limit but is the horizon between the curved dimensions of our universe.
