What is Albert Einstein's 'General theory of relativity'?

Answer 1

Einstein's Theory of Relativity proposes that gravity, time, energy and matter are all tied together. Changes in one affect the others. Each must be viewed relative to the others. Among other effects it supposes that:

1. The faster you go the slower time passes. If you put a clock on a fast rocket which eventually curves around and meets you, the clock will be running "slow" against a standard clock that you kept with you. Strangely enough an observer on the moving rocket would see his clock acting normally and the stationary clock as moving faster.

2. The faster you go, the shorter an observer standing still would see you. The reduction of length happens in the direction you are traveling. Anyone moving at the Hugh sped would see his length staying the same.

3. Energy and mass are equivalent and can be swapped one for the other at a rate shown in Einstein's famous equation (E = mc2). This can be shown to demonstrate that the faster you go the massier (heavier) you get. That is another math heavy story.

Humorists have made light of the definitions of the Theeory (e.g. Einstein once said," ... It's like when you sit next to a pretty girl for one hour, and it feels like an minute, as opposed to when you sit on a hot stove for one minute, and it feels like an hour. That is relativity.") mainly because understanding it cannot be done in anything but math-speak.

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General relativity is a theory of gravitation developed by Einstein in the years 1907-1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion: In other words an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics. This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and momentum within it.

Some of the consequences of general relativity are:

• Time goes more slowly at lower gravitational potentials. This is called gravitational time dilation.
• Orbits precess in a way unexpected in Newton's theory of gravity. (This has been observed in the orbit of Mercury and in binary pulsars).
• Even rays of light (which have zero mass) bend in the presence of a gravitational field.
• The Universe is expanding, and the far parts of it are moving away from us faster than the speed of light. This does not contradict the theory of special relativity, since it is space itself that is expanding.
• Frame-dragging, in which a rotating mass "drags along" the space time around it.

Technically, general relativity is a metric theory of gravitation whose defining feature is its use of the Einstein field equations. The solutions of the field equations are metric tensors which define the topology of the spacetime and how objects move inertially.

Answer 2

The Theory of Special Relativity merely states that the speed of light is constant, while the Theory of General Relativity states that gravity and acceleration are equivalent. All other parts of the theories of relativity are derived from these two statements.

Answer 3

General relativity or the General theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1915/16. It unifies special relativity and Newton's law of universal gravitation, resulting in a theory in which gravity is a property of the geometry of space and time.

In special relativity if one human were to stand on earth, and another human were to go into space and travel at the speed of light for 40 years, and come back to earth, the man that stayed on earth would be forty years older. The man who was in space would have not aged. This is because when you travel faster in the three dimensions of space, you "travel" slower in time. For example, if you needed to get to the other side of the road the fastest way to go is straight in one dimension. But if you go in a diagonal it'll take longer since you're sharing two dimensions. Similar, since time is a dimension, if you have to travel faster in space you'll go slower in time because you're sharing dimensions.
Light goes really fast, and it also bends. Therefore, if you go the speed of light, you live longer.

Answer 4

If an object is moving with velocity v comparable to velocity of light (c), relative time in the moving frame slows down.

It is given by formula t'=t*(1-sqrt(v*V/C*C)) ----------- (1)

Let us consider two guys having watches made of same company,same make, showing same timings. Let one of the person is standing out side a rocket, other person get in to rocket. Suppose, the rocket starts moving exactly at 5 pm with velocity = 0.9 C (where C is velocity of light). Let the rocket travels some distance and comes back to same place with same velocity (0.9 C). when it reaches near the person standing outside, the person standing out side watches his watch showing the time 6.40 pm (after 100 minutes). But the watch of the person who traveled in the rocket shows the present time as 5.45 pm. !!!

The above example can explain that time is relative. Inside the moving frame, (rocket in this case) the time slows down. i.e heart beat, watch, physical activities, everything slows down. ( Imagine slow motion movie).

This is the simple explanation of theory of relativity. This theory also tells that velocity of light is maximum possible velocity by which any particle can move. No one can exceed velocity of light.

lets go for another example.

If you are traveling in a vehicle with velocity 3 m/sec. if you throw a marble with velocity 2 m/sec at forward direction, the person on the land tells that marble is moving with velocity 5 m/sec (3+2=5). this is velocity w.r. t. stationary frame (land).

Suppose, if vehicle is standing, the person in land having velocity detector will tell light (photon) from headlight of vehicle is moving with velocity C. Suppose,vehicle is moving with large velocity. The person on land having velocity detector will tell light from headlight of vehicle (photon) is moving with velocity C only. i e, in every frame of reference velocity of light remains constant.

The above equation (1) is derived from two brilliant Fundamental Postulates given by GREAT Scientist Albert Einstein.

1. All the laws of physics have the same form for all co-ordinate systems moving with constant relative speed to one another.

2. The velocity of light in vacuum is a constant, independent not only of the direction of propagation but also of relative velocities of the source and the observer.

Answer 5

Einstein's theory of General Relativity describes the connection between matter and energy (e = mc2) and the relationship of gravity to time, and the way that matter, energy, space and time are all affected by travel at high velocity. It presents a profoundly different understanding of how the universe works, as compared to the previously dominant model known as Newtonian Mechanics.

Answer 6

There are two theories, and they state lots of different things - that things like time, space, and mass are affected by velocity, and by gravity. Better read an introduction, for example in the Wikipedia article: http://en.wikipedia.org/wiki/Theory_of_Relativity

Answer 7

E=MC2 Energy equals Mass times Speed-Of-Light times it again