What is the principal of special relativity ?

Answer 1

The principle of relativity is this: "The motions of bodies included included in a given space are the same among themselves, whether that space is at rest or moves uniformly forward in a straight line." In other words, if you are in an enclosed space, say a spaceship, and the spaceship is moving in a straight line at uniform speed, you won't be able to tell by experiments inside the spaceship that it is moving (as long as you don't look outside the spaceship.

That is the principle of relativity, and the quote above is not from
Einstein; it is from Isaac Newton. That's right, the principle of relativity was not discoverd by Einstein; it was discovered by Newton 200 years earlier.

Einstein's Special Theory of Relativity, published in 1905, makes a slight correction to Newton's formulas. Newton assumed that mass was a constant. For example, in Newton's Second Law: F = d(mv)/dt, where m stands for "mass." Einstein discovered that mass increases with velocity. Einstein's Special Theory of Relativity gives the corrected term for mass, specifically, the mass of an object equals the rest mass of the object divided by the square root of [1 minus (the object's velocity squared divided by the speed of light squared)]. Einstein also added the fact that, although mass varies with velocity, the speed of light is a constant.

That is the Special Theory of Relativity. In this theory Einstein corrected Newton's equations for systems travelling at uniform speed in a straight line -- in other words, for systems not undergoing any acceleration.

In the General Theory of Relativity, Einstein provided the math necessary to deal with any type of motion, including acceleration and non-linear motion, as well the effects of gravity (which turns out to be equivalent to acceleration).

What both the General and Special Theories of Relativity teach us is that there is no universal frame of reference. Measurements you take involving time and motion depend on your frame of reference (i.e. someone moving relative to you will get different results from his measurements than you). Further, they teach us that no frame of reference is special; one frame of reference is as good as another. More precisely, all frames of reference are equivalent. Einstein proved this equivalence by providing the equations necessary to translate measurements taken in one frame of reference to those taken in any other frame of reference. He showed that all frames of reference are precisely, mathematically equivalent. In fact, Einstein wanted to call his theory The Theory of Equivalence instead of the Theory of Relativity.

So that's it for relativity: take Newton's Laws (and Newton's princile of relativity), add in the knowledge that mass varies with velocity and the speed of light is a constant, and correct the equations to take this into account. Simple, isn't it?

Answer 2

In simplest terms, special relativity is the theory of what happens when objects move at velocities approaching the speed of light. Unusual effects include distortions in the perception of time and physical dimensions, as well as the equivalence of time and energy.

Answer 3

a million. No. alterations contained in the curvature of spacetime propagate at c. 2. Spacetime. 3. Like some thing else, the creature's arm can't flow swifter than c, as measured regionally by skill of the creature.

Answer 4

In short, it established the relationship between time, distance and the universal speed of light to all observers.
It also established the relationship between mass and energy.

Obviously, the star of this theory became the famous equation: E=MC2.