what is the theory of relativity and what does it say.?

Answer 1

It basically says that if you mess around with your relatives your family tree will have no branches.

Answer 2

Let me start with Special Relativity Theory. The theory has one axiom called Principle of Relativity (PR) which says that the laws of physics must be independent of (or invariant under) the choice of inertial reference frames.

From this basic axiom, relativists build a theory first by considering two basic laws of physics, first the law of kinematics, d=vt where t is time d is distance and v is speed. The second law is called the Principle of Propagation of Light (PPL). It asserts that the speed of light is constant c.

Using d=vt and PR and PPL, one can derive Lorentz Transformation (LT) which transforms a physical phenomena from one reference frame to the other. It tells you how things look different from other inertially moving perspective.

For example, it tells you that when A is moving with speed v with respect to B and C is moving with speed u with respect to A then B will observe that C is moving with speed

v # u = (u+v)/[1+(v/c^2)u]

This relativisitc addition of speed is striking as apparently it deduces c+v=c and c+c=c. (set u and v appropriately above).
This sensational result made Einstein very famous.

The relativistic addition equation was derived from Lorentz Transformation which bans any particle to move at the speed c. LT is undefined when inter frame speed is c.

Using just d=vt and PR, one can derive yet another transformation called Gallilean Transformation (GT). As pointed out by Einstein, GT contradicts LT.

Imagine a train is runing with a constant speed. (As a slight modification of Einstein' argument for the loss of simultaneity,) Imagine lighting stike where the fromt wheel touches the rail and where the tail wheel touches the rail. According to the PR and PPL, an observer in the middle of the train observes that the lighting hits at the same time because light travels with speed c and the distances between the observer and these two point of the train which were hit by lighting is the same. But these points are also the points of the rail and so the distance between the observer and the front point of the rail keeps shrinking while the distance between the observer and the tail point of the rail keeps increasing, which makes the observer to observe that the lighting hits at different time.

By considering the case where lighting hits outside of the train, Einstein concludes that the loss of simultaneity occurs only when simultaneious events are observed from other inertial frame. The forgoing asserts that the loss of simultaneity occurs within the same inertial reference frame.

There are a lot other exciting issues regarding relativity theory. For example the General Theory of Relativity asserts as follows: Assume there is an accelerating refernce frame and a stationary reference frame. A photon in the accelerating refernce frame is under the gravitational force due to the Principle of Equality and the Pinciple of Light Bending. However this photon is also in the stationary reference frame. So, this photon is not under the gravitational force.

Consider two twins accelerate symmetrically to head each other with a constant (high) speed. When they pass each other in close distance, accoding to the relativity theory they see each other younger than himslef (due to time dilation under acceleration and inertial motion)

All of this makes relativity theory transcend our world of empirical and logical consistency. The difficulty of this theory can be readily found in a communication between Sir Arthur Eddington and his fellow physicist Ludwig Silberstein. Silberstain remarks, `Professor Eddington, you must be one of the three persons in the world who understands general relativity theory'. After a longish pause, he continues, 'Don't be modest Eddington' to which the latter replies, 'On the contrary, I am trying to think who the third person is!' (J. Waller, Einstein's Luck, Oxford University press, 2002).

However, Prof. Lawden thinks that relativity theory is readily understood by secondary school students as long as one has clear thinking. (Lawden, Elements of relativity Theory, Dover, 1985).

Answer 3

It says that time is relative to the observer and measurement as one approaches the speed of light becomes distorted. It also says that gravity affects light paths and acceleration affects time, so that people being accelerated or any object being moved in a curve (acceleration as a change in vector direction, not speed) will have time slow down - which has been shown with atomic clocks on orbiting satellites.

Answer 4

theory of relativity is the theory given by Albert Einstien which tells that nothing in this universe has absolute value except the speed of light and every physical quantities should be measured with respect to speed of light.

Answer 5

it's a theory by Albert Einstein. it refers to special relativity and general relativity.

check out these site..
http://en.wikipedia.org/wiki/Theory_of_relativity
http://www.allaboutscience.org/theory-of-relativity.htm