When we talk about relativity, actually, we are talking about two theories: the general theory of relativity and the special theory of relativity. Both were presented by scientist Albert Einstein at the beginning of the 20th century.. Like any new explanation, this one also arose from an unanswerable question: how to combine Maxwell’s electromagnetism and Newtonian mechanics.
The two theories of relativity determined the foundations of modern physics and thanks to them we can better understand the functioning of the universe , as well as the structure of space and time.
Contrary to popular belief, Einstein was not awarded the Nobel Prize for the theory of relativity, but for the photoelectric effect, an experiment that demonstrated why light could extract electrons from a metal. Theory of Relativity
His main contribution was the correlation of gravity and the dimensions of space-time.
This correlation can be explained by the tendency to maintain a state of motion, something that occurs when an elevator accelerates or decelerates due to the force of inertia.
According to this theory, space and time are closely related. The structure of both is dynamic and not static as previously believed. In this way, space-time could be deformed according to the applied velocity. This new idea is precisely what underlies the concept of relativity.
Briefly, general relativity theory explains that the curvature of spacetime is determined by the amount and type of energy involved in spacetime. In turn, the curvature of spacetime affects the way energy flows through space.
This theory arose after addressing two fundamental questions: what would happen if an object traveled at the same speed as light? and could we see the light stopped or at a slower speed? Theory of Relativity
To answer these questions, Einstein presented four arguments:
1) Depending on the speed of an object, its mass increases. Thus, one cannot exceed the speed of light, since increasing the object’s speed must proportionally increase the energy to move more mass, to the point where it requires infinite energy.
2) Time and space expand. In this way, for the speed of light to be the same, seeing it standing still or approaching it, it is necessary that space-time expands in relation to its speed.
3) Time is not absolute and there is no simultaneity. Everything is relative to the eye of the beholder that perceives it. What may seem like a second to someone can seem like a year to someone else if its gravitational mass and velocity varies. Theory of Relativity
4) Mass is a form of energy. Energy is equal to mass by squared acceleration.