Special Theory of Relativity
Patent Clerk in the year 1905, a published his science paper which changed the science and perspective of the whole world. Special Theory of Relativity is the something that is going to blow your mind.
He elegantly explained how space and time are interrelated and gave us amazing insights about moving at the speed of light. It introduced us to the cosmic limit of the speed of an object. What happens if we travel at the speed of light? This theory explains how space and time are linked for the objects moving at a constant velocity.
Constant velocity is also the main difference between special and general relativity. When we talk about special relativity we take into account the objects moving with constant velocity whereas in general relativity we talk about a motion which is not constant velocity motion.
The move from constant velocity motion to accelerated motion, it turns out, brings in an understanding of the force of gravity. Einstein realised that by including a generalized motion that would include accelerated motion; he could get an understanding of the force of gravity in terms of warps and curves. Now let us talk about some very important corollaries of special relativity. One of the most famous equations in physics comes from special relativity.
The special theory of Relativity's E=mc^2 means—“Energy equals mass times the speed of light squared”. It shows that energy and mass are interchangeable: they are different forms of the same thing.
Fastest velocity ever known is the speed of light. As an object moves, its mass also increases. Near the speed of light, the mass is so high that it reaches infinity, and would require infinite energy to move it, thus capping how fast an object can move. Light contains photons whose rest mass is zero that's why light is able to travel with that speed of light.
Time and space are interchangeable or we can say they are two sides of a coin. So when we move through space, some of the motion can be thought of as being “diverted” into motion through time( and vice-versa), we always move through time, when we are at rest we move only through time but when we move through space also, some of our motion through time is diverted towards space and so the time is less than it should be or we can say time is “dilated”. Thus, the dimension of space and time affect each other, and both space and time are thus relative concepts. This revolutionary idea also helps in better understanding of simultaneity but we will come to that later. The concept of time dilation is one of the most fascinating ideas in physics. A Strange conclusion from Einstein’s work is that time moves relative to the observer. An object in motion experiences time dilation, meaning that time moves more slowly when one is moving than when one is at rest.
Therefore, a person moving, ages more slowly than the one at rest. Merely, are able to say that “moving clocks run slower than those at rest”. How? Well as I have explained above that when we move through space some of our motion is diverted from time to space, and time moves slow. For a person moving, time would move normally for him but when observed from a different inertial frame which is at rest it would appear to be moving slowly. This becomes extremely apparent at speeds approaching the speed of light. Imagine a 15-year-old travelling at 99.5 per cent the speed of light for five years( from his perspective). When he would get back to Earth, according to NASA, he would be only twenty years old. His twin on Earth, however, would be 65 years-old. This is also called “Twin Paradox”. So, when astronaut Scott Kelly spent nearly a year aboard the International Space Station in 2015-2016, his twin brother Mark Kellyaged a little faster than Scott. To some extent, are able to say that the quicker or faster you go, the slower you age and therefore slimmer you're. The reason it is not noticeable in everyday life is that we move with velocity much smaller than the speed of light. The nearer the speed of an object approaches the speed of light, the more warped lengths and time intervals tend to become. The time dilation sounds much theoretical but it has practical applications as well. Its practical explanation is GPS
Lorentz factor
The Lorentz factor or Lorentz term is the factor by which time, length, and relativistic mass change for an object while that object is moving. So if an object is moving with velocity c, we put its velocity in the equation which gives us the factor of how much it will be affected by its velocity. When this velocity v is equal to c, we can clearly observe from the equation that γ → ∞ (which means, γ will approach to infinity). So, we can assume that travelling at the speed approaching the speed of light would hypothetically enable the time travel into future, as time slows down for the speeding object in order to “prevent” the cosmic speed restriction of the speed of light. A corollary of all this is that, if it were possible to exceed the speed of light, then we could go back in time ( it is shown in the tv series The Flash), although some scientists believe that some as yet undiscovered law of physics may intervene to prevent such paradoxes. Actually, special relativity does not forbids the existence of particles that can travel at speed faster than the light, and there's theoretical sub-atomic particle known as Tachyon, which might spend its life travelling faster than the speed of light, however, it's still hypothetical.
Another corollary of the special relativity is ‘Simultaneity or Relativity of simultaneity’. It states that one person's interval of space is not the same as another person’s, and time runs at a different speed for a different observer. Simply you can say that if two events occur simultaneously in an inertial frame then it is not necessary they will occur simultaneously in another inertial frame (the idea that, events that appear to happen at the same time for one person may happen at a different time for another person). The idea of space-time plays an important role in its understanding, we know space and time are interchangeable and how. The idea becomes even more clearly when we consider that our picture of the moon is actually what the moon was like 1,1-4. seconds ago( the time light takes to reach earth from the moon), our picture of the Sun is actually how it looked 8 and-a-half minutes ago, and by the time we see an image of Alpha Centauri, our nearest star system, it is already4.3 years old. We can therefore never know what the universe is like at this particular time, and the universe is clearly not a thing that extends just in space, but in space-time. Therefore we can say that time is experienced individually. There is no time, there are times! Due to the relativistic effects of the concept of time dilation, our idea and understanding of “now” is, therefore, something of an imaginary concept, one which we as humans have devised for ourselves, but for which nature itself has no real use. The physicist does not regard time as “passing” or “flowing” and time is not a sequence of events which happen: the past, present and future is just there, laid out as space-time. The ‘Twin Paradox’ mentioned earlier is the perfect example of this. Therefore, as Einstein remarked, “For us physicists’, the distinction between past, present and future is only an illusion, however persistent”.
Einstein’s theory of relativity introduced us with some of the most important underlying theories of modern physics which opened new doors of possibilities to explore for us. SO what do you think about Einstein’s special relativity?
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