Is Light Speed is The Speed Limit of Universe?

Is Light Speed is The Speed Limit of Universe? 

Introduction

You must have seen many such characters or vehicles in science fiction films or series that can run faster than the speed of light.Such characters or vehicles not only fill us with excitement, but also make us think whether it is possible in real life also? Whether the speed of light can be achieved? It may be disappointing for many of you to know this, but the reality is that from what we have known and understood about science so far, it seems that it is impossible for us to beat the speed of light.

In this article, we will know the reasons, why we believe that it is impossible to beat the speed of light? Simultaneously, we will prove this by a simple mathemetic al equation. Now, let's start this amazing journey. 

According to science, no such object exists in this entire Universe which can run faster than the speed of light. In fact, it is not possible for any object present in this Universe to be able to travel faster than the speed of light. Albert Einstein has said that the speed of light is the speed limit of this Universe. That is, at most only the speed of light can be achieved, and that too only by a body which has no mass of its own means that it must be completely massless. Here I am only talking about the objects present in the universe, not the universe itself. Because the speed of expansion of our Universe has been more than the speed of light.

Now the question arises, Why is it so? Why any object can not travel faster than the speed of light?

Let's know through some concepts and equations.

Definition: Speed of light is defined as the speed at which light waves propagate or travel through different mediums. The value for the speed of light in a vacuum is defined as exactly 299,792,458 m/s. 

History

From ancient times, many scientists/people believed the speed of light was infinite and could travel any distance instantaneously. In the early 17th century, the  Italian physicist Galileo Galilee was among the first to try to measure the speed of light. He decided and devised an experiment in which two people with covered lanterns stood a known distance apart. One person uncovered his lantern and as soon as the other person saw the light, he uncovered his own lantern. Galileo attempted to record the time between lantern signals but was unsuccessful because the distance involved was too small and light simply moved too fast to be measured this way. Then he said that the value of the speed of light is something that is beyond my calculations. 

Now, let's understand the reason behind, why the speed of light can't be achieved? 

Reason 1st: Causality Principle

Faster than light travel is not possible because it breaks the Principle of Causality.

In easy language, Causality means the relationship between Cause and Effect. Now, if we talk about the Causality Principle, it says that the cause will always come before the effect, that is, there can be no effect without a cause, for example, if we see a broken egg on the floor, then we can say that it will be broken due to falling, that is, first the egg will fall and then it will be broken. Here the falling of egg on the floor is called Cause whereas the breaking of egg on the floor is called its Effect.

Generally, whenever we talk about the speed of light, we make a big mistake by comparing its speed to the speed of other ordinary objects. It is important for us to understand that the speed of light is actually the speed of EM wave and it is the fastest speed to spread any information in this entire Universe, that is, In a way, light is an instrument for us with which we observe this universe. This is the speed due to which time runs in order and the principle of Causality also does not break.

Understanding The Causality Principle With Examples

If the light of the Supernova explosion that occurred a year ago reaches us today, it does not mean that that explosion has happened today, it simply means that the explosion took place a year ago but its information reached us now.

If the information starts running faster than light, then the causality will break and we will be able to see the whole process in reverse order which will be like traveling time in the past.

Let's understand this a little bit better through an example, we know that no matter what the reference frame is, the light in the vacuum always travels at the same speed. Suppose you are standing in a compartment of a train that is constantly moving. There are two mirrors named A and B (as shown in the figure below) on either side of this compartment while the light bulb is in the middle of it. When you turn on this light bulb, you will see that photons will hit both mirrors simultaneously because in your reference frame the bulb, mirror, and train compartment are in a stationary state i.e. they are not moving.

Now suppose that another man is standing outside the same train compartment who is watching that train is moving. What will happen when you turn on this light from inside the compartment? How will this man see the same event? 

Let's understand that in reference to this man, mirror A is moving towards photons while mirror B is moving away from photons, due to this, in this reference frame this man will see that photons are first hit mirror A and then mirror B. That is, as your reference frame, the photons are not hit simultaneously, but if you are asked which mirror the photons are hitting first, then you will say that the photons are hitting both the mirrors simultaneously. If the question is asked by that other man, he will say that photons are hitting mirror A first and then mirror B later. Now the question is which of the two is right.

Actually, both are right and what they are seeing is not an illusion but a truth, called Relativity of Simultaneity. According to which the happenings of the common events at the same time may be different according to the different reference frames in space. 

Anyway, let's go. 

Suppose the other person can travel faster than light speed, In his reference frame, it takes less time for photons to reach mirror A and more time to reach mirror B. Then he waits for photons to hit mirror A. Until this time, the photons have not hit mirror B because mirror B  is moving away from photons, now this person moves faster than light and reaches mirror B because its speed is more than the speed of light, Now he breaks the mirror B, due to which the photons never reaches to mirror B in his reference frame. But what happened in your own reference frame? You see that mirror B is broken but how is it broken? It will be a little difficult to understand because according to you, both photons were hitting the mirror simultaneously, which means that you did not have enough time to see photons hitting mirror A first and then come and break mirror B. Because at the time when the photons were colliding with mirror A, the photons should also have collided with mirror B at the same time. There is only one way that mirror B can be broken before the photons hit it and that is that the other guy goes back in time while traveling and breaks mirror B before the photons hit both of those mirrors. But it is breaking the Principle of Causality, faster than light breaks the Principle of Travel Causality, so it is not possible. 

This was the first reason why traveling faster than light is not possible. Let's know about another reason.

The 2nd Reason

If you have read our article with the title "The God particle or Higgs boson theory" then you will know that invisible fields exist everywhere in the universe, one of which is the Higgs field........

Please click above to know the 2nd reason.

The 3rd And Most Prevalent Reason

Till now we have come to know about two reasons due to which the speed of light cannot be beaten. Let us now know about the third reason which is most prevalent among the people. It is associated with the Theory of Relativity which tells us that as the speed of an object increases, its mass also increases. Many of you will say that you are wrong that the mass never increases or decreases. It is always constant. You are right, but the mass you are talking about is rest mass, that is, any object that is in rest position has the rest mass which never changes, but when an object travels at a high speed while traveling such speed,  its mass increases according to the Relativity, but as soon as it's come back to rest, then its mass again becomes the same as before, that is, as the speed of an object increases, its mass also increases. As the mass of that object increases, the more proportion it has to give energy as to accelerates it, that is, by reaching near the speed of light, the mass of that object increases to such an extent that it needs infinite energy to accelerate it and it is impossible to give so much energy. So, it is dishonest to speak of a big object. Because even an electron can never travel at the speed of light because by reaching the speed of light, its mass increases so much that the energy it needs to accelerate is not even present in the whole universe. Anything which has a mass can achieve a maximum speed of 99.999% of the light, due to this, it is also impossible for any object to have the speed of light, which has some mass of its own. So, traveling at a faster speed than light it would also be dishonest to imagine objects.

Let us now also know about one final reason that makes travel faster than light impossible, this time we will use a simple math equation to show this.

That very equation is E = mc ^ ² is a world-famous equation which you must have seen somewhere or else you may have already known about it, but you do not know that this equation is incomplete, yes heard right. This equation is made only for those objects w which you must have seen somewhere or else you may have already known about it, but you do not know that this equation is incomplete, yes heard right. This equation is made only for those objects which have some mass of their own and they are not moving from their place. If we talk about the complete equation, then it is below.  

You all must have studied Pythagoras Theorem in middle school. Now if we look at the earlier equation, it is the same as Pythagoras theorem
That is, keeping this in mind, if we draw a right-angle triangle, then it will become something like the picture below.

Let us now see when we get E = mc ^ ² by using this triangle.
By Pythagoras Theorem, we get...

              E^²=(mc2)^² + (pc) ^²               Eqn...(1)

We know that when any body is in rest then its momentum is zero, 

              i.e;        P = 0
If we put (p=0) in equation (1),we get

                           E=mc^²    (known as mass-energy equivalence) 

Now we consider the case of a massless particles, Photons... 

Putting (m=0) in equation (1),we get.... 

        i.e;             E^²=(0*c)^² + (pc)^²

        =>               E^²=(pc)^²

        =>               E    =  pc

This means that energy is equivalent to the product of momentum and speed of light only when (m=0).

Now, we can write any object's velocity in the form of
                           V   = c*(PC/E)........... equation (2)

With the help of equation (2), we can say that as the velocity of the object increases the length of side 'pc' of above the triangle also increases as shown in the figure below.

As a result, the ratio (E/pc) of sides of the triangle tends to unity. But the ratio can be maximum up to 0.9999 and it can never be unity. Because here the object's mass is not zero.
This means that the side (mc^²) can never be zero that is 'E' can never be equal to 'pc'.

The conclusion of the above discussion is that the speed of an object having some mass can never be equal to the speed of light. 

Conclusion 

Till now we have seen many ways which prove that it is not possible for us to travel at the speed of light or faster than this. We know that as the speed of an object increases, it starts to expose time dilation i.e. time starts running slowly for that. But have you ever thought that if you are light yourself then how will this world be in your eyes? 

Actually, at this speed, time will stop for you and length  contraction will happen. For example, if the light of a distant galaxy that reaches the earth today was made millions of years ago, then we feel that this light  took millions of years to reach here. But if we see it from the point of view of light, then it has not taken so long to reach the earth, it has reached the earth the very next moment of its exit from the galaxy, because time has stopped for it and the distance from that galaxy to the Earth was reduced. 

What are the effects of the traveling around the speed of light, still tells us only the Special Theory of Relativity and according to this it is impossible for us to beat the speed of light. It is possible that some more advance theory will replace it in future and make such speed possible. But so far it has not been possible to do so. Theoretically there are some concepts like Wormhole, warpdrive and Em drive through which we can beat the speed of light but unfortunately, till now it is only theories.

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