What is the main difference between special and general theory of relativity?
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In simpler words: special theory of relativity is just a special case of the general theory!\n\nGeneral theory of relativity deals with accelerated frames of reference. In other words when we have the 'acceleration not equal to zero' (e.g. gravitational acceleration), we use general theory. That is why this is mainly a 'theory of gravity'. One special case for this can easily be when acceleration = 0, and that is the case of special relativity! This is the basic difference between the two theories.\n\nThe other differences could be seen in the postulates of these two theories:\nSpecial theory of relativity postulates:\n1. A frame of reference moving with a constant velocity (i.e., no acceleration) with respect to an inertial frame, is also an inertial frame.\n2. Speed of light in vacuum remains constant in all inertial frames of reference.\n\nGeneral theory of relativity postulates:\n1. In an accelerated frame of reference (with respect to an inertial frame) the spacetime is warped. \nOr, Gravity warps spacetime. \n2. In an accelerated frame of reference (with respect to an inertial frame) the time is dilated. \nOr, Gravity dilates time.\n\n***\nInertial frames: A given region (or coordinate system) where Newton's laws are valid.\nSpacetime: The region in space and time.\nWarped: Distorted\nDilated: Slowed down.
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probably your teacher drives to school in a car that can reach relativistic speed ( a good fraction of c)\n\nnow seriously :  in our every day life time and space can very well be considered independent, you can separate them with a high level *very very high) of accuracy. These effects of Special and General Relativity are negligible in the world around us.\n\nThat's why all students of Physics still begin their study with Newtonian mechanics and all engineers here on earth do not apply relativity formulas where space and time are interdependent
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Actually there is only theory of relativity: Einsteins general relativity. Special relativity explains only movement of bodies without acceleration. Most people belive that is everything relative but it isn't, there is an absolute spacetime. Einsteins relativity differs from Gallilean only in the fact that Gallilean take space and time to be separeted. Because of this important difference and the fact the speed of light is top speed comes the difference in calculation.
811313
I believe it is expanding.  The speed og light, c, is the cosmic speed limit for objects or radiation within spacetime.  Spacetime itself can (hypothetically) expand faster than c, though what the limit to this might be I don't know.  Special relativity is not violated since there is no object being accelerated.
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Gravity is the force of attraction between massive particles. Weight is determined by the mass of an object and its location in a gravitational field. While a great deal is known about the properties of gravity, the ultimate cause of the gravitational force remains an open question. General relativity is the most successful theory of gravitation to date. It postulates that mass and energy curve space-time, resulting in the phenomenon known as gravity.\n\nGravity is acceleration.  means that (if the mass is unvarying) there must be a force that causes a mass to accelerate. For a rocket ship, that is the rocket engine. For the earth, it is the compression of the mass between something on the surface of the earth and the earth's center of mass. The acceleration is in relation to spacetime in that the weight one feels is one's resistance to deviating from one's path in spacetime. The same holds true in the rocket ship except that a rocket engine supplies the force to accelerate an occupant from his spacetime path. There is no difference between the weight he feels because of gravity or the rocket.
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there is a important factor that appears in the theory of relativity:\nit's called "gamma" (we use the greek letter usually).\nFor a body moving with the velocity v, we have \ngamma=1/squareroot(1-v^2/c^2) , where c is the velocity of light.\nas you can check, as v increases (but always being lower than c), gamma becomes bigger and bigger, tending towards infinity as v tends to c. You can also check than when v=0, gamma=1.\n\nIn non relativistic theory, the mass of a rod for example is called "m" and its length "L". In the point of view of the rod, m and L are constant. For an outside observer also...\nBut what the theory of relativity shows is that for the outside observer, the mass and length of a rod moving with a velocity v is no more m and L, but gamma*m and L/gamma.\nThus, if the velocity is much smaller than c (everyday experience), gamma~1 and nobody can see the difference, if the velocity increased a lot, gamma->iinfinity, and thus the mass also tends towards infinity and the length tends towards 0...  for the outside observer!    If you are the rod, your velocity compared to yourself is 0, so your "own gamma" is 1 and your length and mass, in YOUR point of view, is constant.\n\nthe theory of relativity shows that "basic" things such as the length, the mass (and even the time between two events) of an object depends on the observer. \n\nI hope I've been a bit helpful. Go on with your reading, don't be afraid if you do not understand everything at the first and even the tenth reading, that comes with experience...
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Albert Einstein's theory of relativity, or simply relativity, refers specifically to two theories: special relativity and general relativity. As a field of study, relativity also includes metric theories of gravitation in which special relativity applies locally.\nThe term "relativity" was coined by Max Planck in 1908 to emphasize how special relativity (which at that time was the only relativity theory) uses the principle of relativity.\nAlbert Einstein's 1905 paper "On the Electrodynamics of Moving Bodies" introduced the special theory of relativity. Special relativity considers that observers in inertial reference frames, which are in uniform motion relative to one another, cannot perform any experiment to determine which one of them is "stationary". This is known as the principle of relativity. While this principle was not new to Albert Einstein's work, he found that including electromagnetism in this principle required a new formalism with many surprising consequences. In particular, it required the speed of light in a vacuum to be the same for all these observers, regardless of their motion or the motion of the source of the light.\nOne of the strengths of special relativity is that it can be derived from only two premises:\n·The laws of physics are the same in any inertial frame of reference. This means that the laws of physics observed by a hypothetical observer traveling with a relativistic particle must be the same as those observed by an observer who is stationary in the laboratory. \n·The speed of light in a vacuum is constant (specifically, 299,792,458 meters per second). \nGeneral relativity was developed by Einstein in the years 1911 - 1915. General relativity is a geometrical theory which postulates that the presence of matter "curves" spacetime, and this curvature affects the path of free particles (and even the path of light). It uses the mathematics of differential geometry and tensors in order to describe gravitation without the use of the force of gravity. This theory considers all observers to be equivalent, not only those moving with uniform speed.\nhttp://en.wikipedia.org/wiki/Theory_of_relativity
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There isn't an easy explanation, though it isn't that hard either.  \n\nThe whole idea of special relativity is that all motion is relative to the speed of light and that nothing with mass can travel that speed.  So, in answer to your first two questions, the speed of the light in both directions is still the same as it would be if you were standining still.  \n\nWhat Einstein proved was that there are no fixed points in space, but that space and time are constantly streching and contracting to accomodate the fixed speed of light.  The important thing to understand is that distances of space and lengths of time are different depending upon your relative motion.  I hope that begins to answer your question.
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a speeding object slows down in time due to gravity not speed. that's why steins general theory was also trying to tell us. that gravity slows time.
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I don't think we understand either well enough at this point to answer the question. They are both singular in that they both are regions where General Relativity predicts its own breakdown, and as such requires us to come up with new physics to understand them. \n\nThe prediction of these singularities in both cases was shown by the beautiful mathematics discovered by Roger Penrose and Steven Hawking. \n\nNote the following Quote by physicist Lee Smolin.\n\n"It may be conjectured that each black hole of our universe leads to such a creation of a new universe and that, correspondingly, the big bang in our past is the result of the formation of a black hole in another universe." Lee Smolin\n\nOne of the reasons Lee Smolin comes up with this idea is that the constants that our universe is based on seems to be tuned to the production of Black Holes.  That is if you take the fundamental physical constants which we measure and tweak them, you get a reduction in the formation of Black Holes. This he argues is an indication that the birth of baby universes such as our own is directly connected with the existence of Black Holes.\n\nBut to know if there is a direct connection between black holes and baby universes, as Smolin has speculated, is well beyond our current understanding of physics. And the anthropic type arguments that Smolin makes could have other reasons for being true. Our universe is likely fine tuned for our existence for example, and the Black Holes just come along for the ride as it were.
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Your question can be answered with the following quote.  Basically the difference is in the fact that gravitational acceleration is proporationally the the two objects being studied, whereas inertial aceleration refers cheifly to a single object being accelerated without regard to another mass.\n\nQuestion\n\nWhat is the difference between the inertial and gravitational mass?\n\nAsked by: Raminder\n\nAnswer\n\n1) Inertial mass. This is mainly defined by Newton's law, the all-too-famous F = ma, which states that when a force F is applied to an object, it will accelerate proportionally, and that constant of proportion is the mass of that object. In very concrete terms, to determine the inertial mass, you apply a force of F Newtons to an object, measure the acceleration in m/s2, and F/a will give you the inertial mass m in kilograms. \n\n2) Gravitational mass. This is defined by the force of gravitation, which states that there is a gravitational force between any pair of objects, which is given by \n\nF = G m1 m2/r2 \n\nwhere G is the universal gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between them. This, in effect defines the gravitational mass of an object. \n\nAs it turns out, these two masses are equal to each other as far as we can measure. Also, the equivalence of these two masses is why all objects fall at the same rate on earth.
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Relativity consists of two parts, namely Special and General Relativity.\n\nSpecial Relativity : Two postulates\n\nPostulate 1. The Principle of Relativity\nThe laws of physics are the same in all inertial frames of reference.\n\nNo coordinate system which is in absolute rest. All motion with constant speed is relative and any coordinate system moving with constant speed (relative to the "fixed stars") is called an inertial coordinate system (or inertial frame [of reference]). \nTwo inertial frames A and B are moving with constant speed  relative to each other. An observer at rest in A will say that objects at rest in B are moving with respect to A. On the other hand, an observer at rest in B will say that it is the objects at rest in A that are moving with respect to B. Motion is relative!\n\nPostulate 2. The Constancy of Speed of Light in Vacuum\nThe speed of light in vacuum has the same value c in all inertial frames of reference.\n\nSimultaneity \n    One of the most important concepts in special relativity is the one of simultaneity. Two physical events that occur simultaneously in one inertial frame are only simultaneous in any other inertial frame if they occur at the same time and at the same place. Time is relative!\n\n\nGeneral Relativity\n\nIn short, it is a theory in which gravity is described by saying that space and time are dynamics quantities that can curve in response to the effects of matter and can in turn alter the behavior of matter.
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Einstein’s Special Theory of Relativity started with two postulates: 1) that the laws of physics are observed to be the same in any non-accelerated reference frame and 2) that the speed of light (c) is observed to be the same for all observers.\n\nThe first assumption isn’t too worrisome, but the second seems trickier.  It’s certaonly not intuitively obvious, but it makes sense from both a theoretical and an observational perspective.  Observational because the Michelson-Morley experiment (and others) detected no change in the velocity of light when measured from a moving frame of reference; theoretical because Maxwell’s Equations yield a specific value for the velocity of light.\n\nWhen Einstein considered Maxwell’s Equations, he realized that they don’t allow for a “standing wave” solution, which is what a light wave would look like if you were travelling at the speed of light.  So he already sensed there would be a problem with travelling at very high speeds.  Indeed, when you re-work the addition of velocities, it comes out to be not simple addition, but a fraction that never gets larger than c.  \n\nThus, in the photon-photon collision you describe, each photon would “see” the other one travelling toward it with a velocity c.  (Although measuring velocities from a photon’s perspective is a little non-intuitive; you have to take the limit of the aforementioned addition formula, which causes some trepidation.)\n\nOh, and the ten-dimensional idea is just one among many…  No way yet to prove (or disprove) that one.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
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I am trying to give just a brief idea about these questions. Actual explanations need a lot of space. In any case, one can easily search the internet for these things.\n1. Special theory of relativity was combined with quantum mechanics to produce a new branch of physics called 'relativistic quantum mechanics'. This was done mainly by Dirac. He considered the wave functions of particles moving with very high velocities, and used Lorentz transformation equations in his mathematics. He considered also the imaginary (complex) solutions to the basic equations of motion (such as the Schrodinger equation, for example). The main contribution of this 'unification' was the theoretical discovery of anti-particles (which was varified later on from the experimental discovery of positrons).\n2. The 'unification' of general theory of relativity and quantum mechanics leads to the branch called 'quantum gravity'. The basic problem with this unification is the matching of length scales at which these two theories work. Quantum mechanics is designed and valid for subatomic length-scales, whereas, the general theory of relativity, which is the theory of gravity, deals with massive objects and large (astronomical) length-scales. Presently, scientists are looking for a suitable wavefunction for the universe, which is expected to provide information about the universe in the same way as the wavefunction of an electron gives many information about it.\n3. Feynman reconstructed almost the whole of quantum mechanics and electrodynamics in his own way, deriving a way to analyze atomic interactions through simple diagrams (now known as Feynman diagrams), a method that is still used widely. QED was the theory to which Feynman diagrams were first applied. For his work on quantum electrodynamics, Feynman was one of the recipients of the Nobel Prize in Physics for 1965, along with Julian Schwinger and Shin-Ichiro Tomonaga.\n\nI would also like to comment on the answers given by other users, such as Smart prash: \n1. In question 1 the user is asking about Dirac's relativistic quantum mechanics, and not about Bohr's elementry quanrum mechanics.\n2. Please don't get confused. Quarks are not coloured at all (how can they be?). Colour of a quark is just one of the many quantum numbers that is used in a way to number them in terms of their different energies. Moreover, the question is about QED (quantum electrodynimics), and the colour quantum number is a concept from QCD (quantum chromodynamics).
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You've confused the statement of the theory. Let two observers be in the same inertial reference frame with two synchronized watches. One observer accelerates in a negligibly small amount of time to some fraction of the speed of light relative to the other observer. The latter observer will be called O1 and the moving observer O2. \nO2 will measure the time in 01's reference frame to be going *slower* than the time in his frame. Likewise, O1 will measure the passage of time in 02's frame to be going *slower* than in 01's frame (the half-life of particles "increases" depending on their speeds). In other words, given two events A and B that always occur t seconds apart in O, they will occur at some separation T > t when measured from O'. The same will occur if O' is switched with O in the sentence above.\nQuestions like this usually come from confusing the relativity of simultaneity. Remember that in relativity, there are no two events that are simultaneous with respect to all inertial frames. \nI recommend you check out the text "Spacetime Physics" by Wheeler et al.
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The theory of everything is the Holy Grail of physics, which would be a scientifically verifiable and verified theory to reconcile the contradictions between relativity and quantum mechanics.  Currently, QM is used for the very small (particle physics) and relativity is used for the very large (astronomy and cosmology), but somewhere in between they become inconsistent.
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Quantum mechanics has no problems with special relativity.  \nIt is with only gravity and general relativity that there is a problem.  The problem is that no one fully understands how gravity works on a small scale.  On the other quantum mechanics is really hard to do on a large scale.  It is only in some extreme cases do the two clash.  As far as I know time is not the problem.\nIt is that in physics ever theory has its limits, which is why we eventually find a more complete theory to replace it as a knowledge increases.