Is the relative velocity of two beams of light twice the speed of light?

The calculation of relative velocity is something that each of us knows, and the calculation of relative velocity in daily life only requires the addition of two velocities.

If we want to calculate the relative velocity of two cars, we only need to add up the speeds of the two cars, so many people think that if two beams of light move in the opposite direction, their relative velocities will be twice the speed of light after superimposing?

To be honest, there is nothing wrong with this kind of thinking, after all, the relative speed in daily life is the same thing, but this is just an "inherent idea" that human beings have been living in a state of low-speed motion, and the reason why Einstein said that "the speed of light is constant and cannot be surpassed" is because he thought of "high-speed motion".

When discussing speed, human beings always need to find a reference frame to "reference" the speed, but the speed of light "300,000 kilometers per second" does not need a reference, because when Maxwell unified electricity and magnetism, he got a formula that can directly calculate the speed of light, and because the two parameters of the formula are constants, the speed of light will not change due to the change of the reference frame.

The method of calculating relative velocity using v1+v2 in daily life is called the Galilean transform in physics, but the Galilean transform is just an approximation of the Lorentz transform, just as the law of gravitation is an approximation of the general theory of relativity.

The Lorentz transform is only valid when the speed of light is involved, and we can see from the Lorentz transform that even if both velocities are changed to the speed of light c, the final result is still c instead of 2c

However, "the speed of light cannot be exceeded" is limited to the case of carrying information, so the expansion of the universe and quantum entanglement without information, although they are faster than the speed of light, do not violate the special theory of relativity, and Einstein was not wrong.

The relative velocity of two beams of light is not twice the speed of light, as we all know, the speed of light is eternal, 300,000 kilometers per second, so the speed of light does not change due to changes in the frame of reference.

The relative velocity of two beams of light is still the speed of light, because the speed of light is the upper limit of the speed of the universe, and it cannot become faster, just like we pour two glasses of boiling water at 100 degrees together, it cannot be the same as 200 degrees.

Twice the speed of light must be very powerful, the speed of light can be said to be super fast, and it will make you disappear in an instant, and you can't find the light, such a speed is gone in the blink of an eye.

No, the speed of two beams of light is still the speed of light, and it cannot be assumed that the speed of two beams of light is twice the speed of the beam, and the speed of three beams of light is three times the speed of the beam, such an algorithm is completely wrong.

The relative velocity of two beams of light is twice the speed of light, in fact, this relative only discusses the reference problem of motion, and the speed cannot exceed this speed of light. Some things are not really about going back to the past, but about seeing the past.

Categories: Science & Engineering.

Analysis: The general law of velocity addition (i.e., the Galilei transformation) (i.e., the assumption that c+c=2c) only applies when the object is moving much less than the speed of light, c. Its essence is a simplification of the Lorentz transform.

The law of velocity addition according to the Lorentz transformation (now considered to be the absolute truth) is: u=(u'+v)/[1+u'(v/c^2)]

We can see when u'When both and v are close to c, u=(approx.) (c+c) [1+c(cc c 2)]=2c 2=c, so the above c+c=2c is wrong.

As for the law of velocity addition under the Galilei transformation, we can see that when u'When both and v are much smaller than c: u=(u'+v)/[1+u'(v/c^2)]=u'+v)/[1+0]=u'+v is simplified to the Galilian transformation.

So the Lorentz transformation does not contradict real life.

Now you get it. Wow, it's been a long time. If you don't understand it, let's look at the theory of relativity.

The speed of the other beam of light is not double, the speed of light is a normal kind of light speed, and the two of them are formed at the same time, the speed is basically the same, there is no decent difference, so their speed is the same.

No. Because two opposite beams of light, if we talk about relative velocity, then it is twice the speed of light, but its actual speed is only the normal speed of light.

No, the definition of velocity requires a frame of reference, so their relative velocity is twice the speed of light, but relative to Earth, it is still constant.

As far as this question is concerned, it seems that it is really the same thing, speed is relative, and this is the same thing in our daily life, the relative speed of trains traveling in opposite directions is the sum of the speeds of two trains. But if this is true, then isn't Einstein's theory of relativity broken? Because Einstein believed that the speed of light is the maximum speed at which an object can move.

In fact, one point that needs to be considered here is the influence of the speed of light on this relative motion, we often say that the relative velocity of two objects is the subtraction of the velocity vector of two objects, but there are still restrictions on the calculation of this relative velocity, that is, the speed of this object cannot be close to the speed of light, because when the object is close to the speed of light, then its mass and space, time will have a huge change, and this change can no longer be ignored.

When an object approaches the speed of light, then the mass of the object increases, time slows down, and space is distorted, and in this case, it makes no sense to calculate the relative velocity. Because of the influence of this time and space factor, the speed at this time can be regarded as absolutely stationary.

Why do you say that, when the speed is close to the speed of light, time will infinitely tend to be stationary, and when the speed of light is completely reached, then time is completely stationary, that is, the time of the two beams of light is stationary, and the time is stationary, then the relative velocity of the two beams of light is 0.

When approaching the speed of light, the theory of relativity is used, not Newtonian mechanics, and it is not necessary to bring Newton's worldview into the understanding of the theory of relativity, because then it would be impossible to understand what the theory of relativity is talking about. This is because the worldview of relativity and Newton's worldview are different, in the theory of relativity, space-time are mutually influencing and not independent, and space-time can be bent and will be affected by motion. To put it bluntly, a centimeter or a second may be different for people in different frames of reference.

Judging from the current development of science, the speed we already know is the speed of light, which is also the fastest speed in the universe that we know.

Speaking of relative velocity, we have to mention the theory of relativity, the theory of relativity for us, has been more subversive of some of our traditional thinking, after all, in our traditional thinking, time is absolute, that is, the absolute view of time and space proposed by the lamp at that time, but from the overall framework of relativity, time and space are relative, but because of some of our inherent traditional thinking for a long time, it has formed a deep-rooted thought in our brains, so it has caused the current result, Even though sometimes we force ourselves to think about problems with some concepts of relativity, most of the time we can't help but use the thinking mode of time and space to consider some deeper problems, some physics problems.

Due to the continuous change of some reference frames of the theory of relativity, many people lose themselves in the process of changing the frame of reference, which is equivalent to digging a hole for themselves and then jumping down again.

In fact, the relative velocity of two objects, we do not need to take into account any frame of reference, and in our ordinary life, we are based on ourselves as a reference, to consider some problems, and this is no problem, after all, for the environment we are in at this stage, we do not need to consider so accurate, and because we live in a low-speed world, we can use Galileo's transformation to meet the accuracy, there is no need to use the transformation of Luolongchi, because Luolongchi transformation, It is mainly used in the relative velocity of the sub-light world, but then again, in fact, the Galileo change is an approximate value of the Dolontz transform, and now in the continuous development of science and physics, in fact, we have found some things that exceed the speed of light, but they cannot be completely explained or applied by reasonable experiments.

From a scientific point of view, it is indeed possible for two objects close to the speed of light to move opposite each other, but this is only based on theoretical technology. There is no way to confirm the actual aspect.

The relative velocity must exceed the speed of light, because the relative velocity of two objects moving close to the speed of light is twice the original speed.

The speed of light will be exceeded because the relative velocity of two objects traveling opposite each other is doubled.

If you want to measure the motion of an object, you must have a stable reference, and if the system changes to a frame of reference, its motion state may be different. But from the point of view of light, you have to change a frame of reference, and it is not impossible to make its relative speed exceed the speed of light, but this speed is relativeIt's not that the speed of this light is moving faster than the speed of light, it's that you change the frame of reference, and in a different way of defining it, it's faster than the speed of light.

The speed of two opposing beams of light is not twice the speed of light. Because the speed of light is absolute, and an object in motion cannot be used as a reference, the speed of light is unsurpassable and does not form twice the speed of light.

That is true. If it is two beams of light in opposite directions, then the relative velocity between them is twice the speed of light.

No. Because the speed of light is absolute, and moving objects generally cannot be used as a reference, it is not twice the speed of light.

The ordinary relative velocity is when the velocity is very low relative to the speed of light, for example, A and B are moving relative to each other, with the direction of A's velocity being positive, and let A's velocity be v1 and B's velocity being -v2, then the velocity of A relative to B is v1+v2

But when the speed is close to the speed of light, the above no longer holds. Rather, it is used.

Einstein's relativistic velocity formula:

v=(v1-v2) [1-(v1v2 c 2)] You will find that when either of the velocities of A and B is c, no matter what the velocity of the other is, the final relative velocity is calculated as c, so their relative velocity is the speed of light.

Explanation: c is the speed of light, the ultimate velocity of an object, which cannot be exceeded.