How is General Relativity and String Theory conected?
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Very simply put, string theory (now most often called "M" theory) is an attempt to unite quantum physics with relativity; we hope that by doing so we can develop a set of equations that will tie together the four fundamental forces of nature. The direct relationship of three of those forces have been linked, but gravity so far remains the "outsider."
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According to string theory, the strings are the universe's \nelemental material. They vibrate in different ways and can\njoin and break apart to form different elemental particles\nthat make up the universe. The strings exist in 11\ndimensions: time, which physicists consider a dimension, and\n10 spatial dimensions. Four of those dimensions are the ones\nwe are familiar with, three spatial dimensions plus time.\nThe other dimensions may be so small they're invisible to\ncurrent detection equipment and are only known to exist because they leave a "footprint" of where they have been.
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It hasn't been completely accepted, but it is widely believed to be the correct direction to go.  They are still trimming the fat, and many of the theories will never be tested as we can not experience some things that occur in the extra dimensions that we can not see, according to string theory.  (Theory is not accepted as fact, its a theory)
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That previous answer is wrong.  The reconciliation between classical physics and quantum mechanics is intrinsic to quantum mechanics itself.  One thing we require of quantum mechanics is that, in the limit of large quantum numbers, we recover classical mechanics.  Schrodinger, Ehrenfest and some others demonstrated from the outset that quantum mechanics does indeed give rise to classical mechanics in such a limit.\n\nString theory is, rather, an attempt to reconcile the general theory of relativity with the standard model for particle physics.  For the most part, string theory is an attempt to do two things: 1) Provide a quantum theory of gravity 2) Provide an account of physics which explains both gravity and the standard model of particle physics (when dealing with particle physics at our current level of understanding, we have to introduce the effects of gravity by hand.  The standard model of particle physics and the general theory of relativity are completely separate theories right now).\n\nBefore going further, it's probably a good idea to make sure that everyone understands what a dimension is.  Think of a piece of thread with a black dot painted on it somewhere.  To find that dot, I really only need to know how far it is from the end of the thread in inches.  It requires one number to find anything on a piece of thread, so we say that the thing is one dimensional.  A piece of paper has length and width, so it's two dimensional.  To find something on a cube, for example, I need 3 coordinates.  Finally, if I were to ask you to meet me for dinner, I'd need to supply you with a location (which takes 3 numbers) and a time (which is another).  At first appearance, our universe seems to be 4 dimensional.\n\nIn string theory, we define something called a Planck length by taking the sqaure root of the quantity obtained by multiplying the gravitational constant by Planck's constant and then dividing by the cube of the speed of light.  We actually know all three of these, and we obtain something like 1.61 x 10^(-33)cm as the Planck length.\n\nNow, once the mathematics behind the central hypothesis of string theory have been developed, we can actually derive values for the gravitational constant.  As a strange artifact of the mathematics, this value changes based off of how many spatial dimensions the universe is made out of.  There is no comparing, for example, a four dimensional gravitational constant to a five dimensional constant because their units are different.  We can, however compare Planck lengths, which always carry units of centimeters.  I'll come back to this in a second.\n\nIn order for this superstring business to work, someone had to work out the way they vibrate.  For whatever reason, they use the Ramanujan function to do this, and it spits out the number 10 as the number of dimensions required for string vibrations.  As for your question, the 11 dimensions were part of a previous theory (called supergravity), and it has since been roundly disproven.  The current developments of string theory call for 10 dimensions.\n\nThe problem is the Planck length... it's one we get out of four dimensional spacetime, not 10 dimensional spacetime.  If string theory is right, then somehow our universe is 10 dimensional, and looks 4 dimensional.  How can this be?\n\nThink of a cardboard tube, but one that's actually hundreds of miles long.  Up close, you need two numbers to tell where a small dot of ink might lie on the surface of this tube.  From far away, though, you wouldn't really be able to distinguish between a tube and a very thin piece of string, and you'd begin to talk only about where something lies with respect to the end of the tube, and you'd only need one number.  It's possible that space has this kind of topology, with several small dimensions, and that's why it looks 4 dimensional, but might actually have more dimensions than that.\n\nThere is no experimental verifi
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i string theory is just cool as it integrated all the basic forces of nature and is attempt to bring everything in physics under 1 theory. but like all theories, it has its draw backs.
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Here is the most complete explanation I've found (and no, "God did it" is not an explanation).\n\nAccording to string theory, there are ten spacial dimensions (plus one for time).  A dimension is simply a direction (Left-Right, Up-Down, Forward-Back, etc.).  Before the time of the Big Bang, all of them were extremely small with virtually no room for matter to move around.  Seven of them are still that way today.\n\nAt the time of the Big Bang, the natural quantum fluctuations dictated by quantum mechanics caused the three spacial dimensions I mentioned above to expand very slightly.  Although gravity always attracts particles together over the enormous physical distances we can see today, when all matter is compressed together in one tiny point it causes gravity to become REPULSIVE.  This is shown by the equations of string theory.\n\nWith all matter in one location pushing against each other, the three dimensions that were slightly stretched were forced to expand outward extremely rapidly.  This is what we now refer to as the Big Bang.
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I would highly recommend the last answer. BRIAN GREENE's\nThe Elegant Universe. Great Book, I read it and it explains a lot in real English. Also check out his other book, which is also a great book on string theory its call "The fabric of the Cosmos"(great title!), a little more complex but highly usefull. Or if you hate to read, then buy the Nova special on string theory, which is hosted by Brian Greene (the author). He is one the lead string theorists. Mabye the next Einstein? (Possibly). I would watch the movie first. Then read the book, you would understand the material better with visuals.
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Sometimes, when people cannot fathom or answer an issue, they turn to blind faith for that answer.  That is not the scientific approach and, carried to extremes, such blind faith can lead to the Dark Ages when very little was done to advance mankind's knowledge.\n\nThat being said, string theory can lead one to conjecture about the pre-big bang.  (I like your "big suck" idea by the way.)  String theory conjectures the possibility of parallel null universes, devoid of observable mass-energy as we know it.  Then, according to the theory, two of these big nothings collide.  Since they have an eternity to do it in, one can even show (using simple probability) at least one such collision is likely over an infinity (eternal) number of attempts.\n\n(If the concept of two "nothings" colliding gives you a headache, join the crowd.  Nothing, however, is only nothing in our limited four dimensional observable universe.  String theory goes up as high as eleven dimensions; so if these null universes exist in these higher dimensions, they would seem to be nothing to us because we cannot see beyond four dimensions.)\n\nSo two null universes collide.  When they do, the collision releases a lot (I mean A LOT) of energy (and mass, its all a jumble in the beginning).  That released energy-mass is what we on Earth now call the "big bang."\n\nThe last part of your question, re another big bang in our universe, is also a possibility according to string theory.  There is no reason to limit our null universe to just one collision with another null universe.  We can say "at least" one collision, because we live in one of the results.  \n\nBut there could very well be others, where our null universe has collided with other null universes, and not necessarily the one our null collided with to create the observable universe we live in.  Which brings up the possibility that other observable universes in our null universe might be totally different from our own.
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Wow! You do not ask for much do you...This is a very complicated question to answer...and frankly NO ONEyet fully understands how to answer it. \n\nAccording to Einstein's theory of General Relativity, which is our premier way of explaining how gravity works, there is no formal distinction between the description of what a gravitational field is, and what space-time is.\n\nEssentially, space is what we refer to as 3 of the 4 dimensions to a more comprehensive entity called the space-time continuum, and this continuum is itself just another name for the gravitational field of the universe. If you take away this gravitational field...space-time itself vanishes! \n\nTo ask where space comes from is the same as asking, according to general relativity, where this gravitational field came from originally, and that gets us to asking what were the circumstances that caused the Big Bang itself. We don't really know.
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You should read Brian Greene's books \n\nThe Elegant Universe\nand \nThe Fabric of the Cosmos\n\nThe Elegant Universe wil explain his work on string theory.
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Currently String theory is the most accuret theory, and does as well as Quantum and Relativity, but it can also work with what we know of a black hole.
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There are two major theories of modern physics: Quantum Mechanics and General Relativity. Both work well, with QM being applicable to atomic and smaller sizes, and GR to large (Solar size, galaxy size, etc.) things.\n\nThe major question in physics today is: how do we combine QM and GR so that they are two aspects of one larger theory. This postulated theory is usually called a Unified Theory or Theory of Everything or something like that. String theories are attempts to do this (so far all are still incomplete).\n\nThe major difference between QM and GR is that nn QM energy comes in discrete levels (all way to small for us to notice). However in GR space-time is continious. So it is not instantly clear whether space-time is continous or quantized in a unified theory.\n\nFor consistency between these space quantization would have to be on extremely small scales. This would almost certain occur (if it did) at distances called the Planck length, which is ~ 10^-33 cm. (This is about one billion trillion times smaller than an atomic nucleus.)\n\nQuantization of time would then be the interval for light to cross this distance, about 10^-43 seconds. It is because of a lack of a unified theory that physicists can't say anything about the conditions of the universe before 10^-43 seconds after the Big Bang. (Of course that is still pretty good.)\n\nThe short answer is: no one knows, but the scale of quantization would have to be much, much smaller than any known elementary particle.
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String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics. For this reason, string theories are able to avoid problems associated with the presence of pointlike particles in theories of physics. Studies of string theories have revealed that they predict not just strings, but also higher-dimensional objects.\n\nThe basic idea is that the fundamental constituents of reality are strings of energy of the Planck length (about 10-35 m) which vibrate at resonant specific frequencies[1]. Another key claim of the theory is that no measurable differences can be detected between strings that wrap around dimensions smaller than themselves and those that move along larger dimensions (i.e., physical processes in a dimension of size R match those in a dimension of size 1/R). Singularities are avoided because the observed consequences of "big crunches" never reach zero size. In fact, should the universe begin a "big crunch" sort of process, string theory dictates that the universe could never be smaller than the size of a string, at which point it would actually begin expanding.\n\nInterest in string theory is driven largely by the hope that it will prove to be a theory of everything. It is a possible solution of the quantum gravity problem, and in addition to gravity it can naturally describe interactions similar to electromagnetism and the other forces of nature. Superstring theories include fermions, the building blocks of matter, and incorporate supersymmetry. It is not yet known whether string theory will be able to describe a universe with the precise collection of forces and matter that is observed, nor how much freedom to choose those details that the theory will allow. String theory as a whole has not yet made falsifiable predictions that would allow it to be experimentally tested, though various special corners of the theory are accessible to planned observations and experiments. Hence critics of string theory occasionally remark that the theory "... is not even wrong," quoting a quip attributed to Wolfgang Pauli.\n\nWork on string theory has led to advances in mathematics, mainly in algebraic geometry. String theory has also led to other theories, supersymmetric gauge theories, which will be tested at the new Large Hadron Collider experiment.
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Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. It is considered one of the most promising candidate theories of quantum gravity. Superstring theory is a shorthand for "supersymmetric string theory" because unlike bosonic string theory, it is the version of string theory that incorporates fermions and supersymmetry.\n\nThe deepest problem in theoretical physics is harmonizing the theory of general relativity, which describes gravitation and applies to large-scale structures (stars, galaxies, super clusters), with quantum mechanics which describes the other three fundamental forces acting on the microscopic scale.\n\nThe development of a quantum field theory of a force invariably results in infinite (and therefore useless) probabilities. Physicists have developed mathematical techniques (renormalization) to eliminate these infinities which work for the electromagnetic, strong nuclear and weak nuclear forces, but not gravity. Thus the development of a quantum theory of gravity must come about by different means than were used for the other forces.\n\nThe basic idea is that the fundamental constituents of reality are strings of the Planck length (about 10−35 m) which vibrate at resonant frequencies. The tension of a string (8.9×1042 newtons) is about 1041 times the tension of an average piano string (735 newtons). The graviton (the proposed messenger particle of the gravitational force), for example, is predicted by the theory to be a string with wave amplitude zero. Another key insight provided by the theory is that no measurable differences can be detected between strings that wrap around dimensions smaller than themselves and those that move along larger dimensions (i.e., effects in a dimension of size R equal those whose size is 1/R). Singularities are avoided because the observed consequences of "big crunches" never reach zero size. In fact, should the universe begin a "big crunch" sort of process, string theory dictates that the universe could never be smaller than the size of a string, at which point it would actually begin expanding.
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The Four fundamental components in the string theory are  gravity, electromagnetism, and the weak and strong nuclear forces.\n\n  The impact of the string theory on observance of gravitational law allowed for the standard physics model to describe the effects of gravity in the world of quanta.
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In the Standard Model, quarks, electrons and the like are considered to be pointlike. This gives problems at short distances where for instance the electromagnetic force between two of them becomes infinite.\n\nThe basic idea of stringtheory is that the fundamental constituents of matter are strings of a length of order of 10^35 m which vibrate at specific frequencies. However, the simplest string theories give more problems then they solve and consistent theories requires more then four dimensions. \n\nMembranes take the idea even further.  The particles are represented by vibrating surfaces and higher dimensional objects.
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"M" Theory is one current attempt at a Grand Unification Theory which reconciles the differences between Quantum Mechanics and General Relativity.  It is impossible to predict what applications could come from such a theory; it would certainly allow us to explain many, many things about our physical world that we do not understand now.  Such a theory may be a long way off, however.