There are 2 theories of relativity, the special theory & the general theory.
The Special Theory of Relativity says that all constant motion is relative; you can’t be moving in an absolute sense. There’s no way to show that you’re “really” moving. It also says that the speed of light (c) appears to be the same to everyone, even if they’re moving. From these 2 facts, the theory then shows that as you move faster, a person who is not moving with you, will (1) see your length shrink, (2) see your time slow down, & (3) see your mass increase. That’s pretty amazing. The theory then shows that E=mc2. It also implies that time is the 4th dimension & that space-time is the best way to look at things.
The General Theory says that gravity and acceleration are the same thing. For example, in a falling elevator, you feel no gravity, and in a rocket that’s accelerating, it creates gravity that pushes you down. Also, the theory says the best way to understand gravity is to think of it as the bending of space-time. The sun bends space-time around it, and the planets go around the sun because they are trying to go in as straight a path as they can in this bent space-time. This description of gravity has been shown to be better than Isaac Newton’s.
2007-09-29 05:06:44
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answer #1
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answered by Anonymous
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Special Relativity:
Einstein's Postulates
Principle of Relativity (First Postulate): The laws of physics are the same for all inertial reference frames.
Principle of Constancy of the Speed of Light (Second Postulate): Light always propagates through a vacuum (i.e. empty space or "free space") at a definite velocity, c, which is independent of the state of motion of the emitting body.
General Relativity:
What Does General Relativity Mean?
For an analogy to general relativity, consider that you stretched out a bedsheet or piece of elastic flat, attaching the corners firmly to some secured posts. Now you begin placing things of various weights on the sheet. Where you place something very light, the sheet will curve downward under the weight of it a little bit. If you put something heavy, however, the curvature would be even greater.
Assume there's a heavy object sitting on the sheet and you place a second, lighter, object on the sheet. The curvature created by the heavier object will cause the lighter object to "slip" along the curve toward it, trying to reach a point of equilibrium where it no longer moves. (In this case, of course, there are other considerations -- a ball will roll further than a cube would slide, due to frictional effects and such.)
This is similar to how general relativity explains gravity. The curvature of a light object doesn't affect the heavy object much, but the curvature created by the heavy object is what keeps us from floating off into space. The curvature created by the Earth keeps the moon in orbit, but at the same time the curvature created by the moon is enough to affect the tides.
Proving General Relativity
All of the findings of special relativity also support general relativity, since the theories are consistent. General relativity also explains all of the phenomena of classical mechanics, as they too are consistent. In addition, several findings support the unique predictions of general relativity:
2007-09-29 04:10:30
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answer #2
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answered by Rod Mac 5
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This is much too big a topic to be answerable here! To begin with, there are two theories of relativity: the Special and the General theories. The first deals with objects moving at constant speed and the second covers objects that are accelerating. You really must get hold of a book and read it!
By the way, the well-known equation E = Mc^2 is NOT Einstein's theory of relativity as many respondents seem to think.
2007-09-29 03:04:51
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answer #3
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answered by clausiusminkowski 3
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Planck's (love the name btw) explanation is perfection, so there's nothing more I can really add - except two analogies that might help.
Special relativity: imagine that you are in a car, and I am standing beside the road watching you approach. You are travelling at 50mph, and as you pass me you throw me a ball that's travelling at 20mph. We can calculate fairly simply that the true velocity of that ball is 70mph - in the car it was already travelling 50, you added another 20 with the force that you used to throw it.
Yes? But what's extremely weird is that the light coming from the headlights on your car behaves in an entirely different way. No matter what speed you are or aren't travelling, light will zoom away from you at exactly the same rate. If you are in motion, you do not add on the 50mph that you are already travelling, and when you stop, you do not subtract it.
So, this tells us that light (in a vacuum, provided it is unimpeded) travels at exactly the same rate no matter who is watching or how fast they are travelling.
Now, to work out the speed of anything you would divide distance by time taken - and Einstein realised that if speed does not change, something else must. And he postulated that it is time that changes (relative to an observer).
This essentially means that the faster you (or anything) travels the more time will appear to slow down to anyone watching your progress. If you are on a train, and I am sitting on the platform, and I watch you coming past at, say, 80% the speed of light - I would notice if I looked in the window that you were moving quite sluggishly and any clocks on the wall would be moving slower than my watch. It would be a bit like watching a video slowed down. But, you wouldn't notice anything different at all - it would all be entirely normal from your perspective. But if you happened to look out at me, it would be me that was moving slowly and sluggishly etc. There is, therefore, no way whatsoever to know which one of us is actually speeding and which one is stationary - it's all relative.
General relativity: this is all about the inextricable way in which space and time are bound up together, and how gravity is a product of this.
Envisage spacetime as a rubber sheet stretched between two people. In the middle rests a cannonball, which causes the sheet to sag a bit. If a third person takes a smaller ball and rolls it across the sheet it will try to move in a straight line as Newton's law of motion predicts, but will be drawn into the dip made by the bigger ball.
That, essentially is how gravity works - large bodies of mass (like the sun) cause a dip in spacetime which attracts smaller bodies (like the earth).
:-)
2007-09-29 06:18:46
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answer #4
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answered by Hello Dave 6
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Basically, the special theory of relativity takes note of the fact that the speed of light is the same for all observers, no matter how fast they are going, or in what direction.
From this, Einstein figured out that there is no such thing as "absolute" position or speed. All speeds are relative to something. He also figured out that mass and energy can be converted into each other.
2007-09-29 02:50:03
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answer #5
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answered by morningfoxnorth 6
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The original theory of relativity was not E=mc^2 which was a formula developed by Henri Poincare 1n 1901.
The Abert Einstein theory of relativity stemmed out of Galileo 's Principle of Relativity which Einstein Adopted to formulate his Theory of special relativity.
Einstein Relativity theory is based on two postulates;
Postulated #1=The speed of light is constant in local space irrespective of the motion of the source.
Postulate #2 =All inertial frames of references are equivalent.
General relativety is a theory of invariance which Henri Poincare also had formulated which Eintein had used for the Theory of General Relativity.
The theory is basically based on what Einstein called the equivalency Principle.
The Principle of Equivalency states that Inertial acceleration and gravitational acceleration are equivalent.
The formulation of General relativity led to Einstein 's Field Equations which represented another way of defining Newtons law of Universal gravitation.
2007-09-29 03:47:08
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answer #6
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answered by goring 6
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at the start, your estimate of 10 years if way, way off. somebody else has provided the respond for you even though it does not take a genius to choose that in case you travelled at 50% the fee of sunshine, a distance of a million mild 12 months might take 2 years to traverse, so needless to say vacationing at 70% will take even much less time. Relativity is all approximately "frames of reference" or perspectives. once I say the journey at 50% of sunshine speed takes 2 years, I recommend 2 years from the perspective or reference physique of an observer on the earth. To the pilot of the spaceship, the journey could have been shorter in his or her reference physique because of the time dilation outcomes of specific relativity. traveling at 70% mild speed might consequence in a extra significant dilation result. which you will answer your question, an observer on the earth does not see the deliver traveling slowly. they might see it traveling at 70% the fee of sunshine.
2016-10-20 07:17:44
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answer #7
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answered by giardina 4
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Which theory would that be?
Special relativity or general relativity?
2007-09-29 02:46:41
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answer #8
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answered by Oregon 3
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simple answer from einstein was"when u sit with ur girlfriend 1 hour fells like a minute....when ur on a hot stove a minute is like an hour" relativity at its simplicity...
2007-09-29 03:05:39
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answer #9
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answered by bad g 1
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e=mc^2
energy = mass X speed of light squared
2007-09-29 02:39:55
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answer #10
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answered by Anonymous
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