In 21st Century New Physics theorethical Physisistt are Using Aeher theory to explain natural Phenomenae,Why? \nIs General Relativity Lacking as a tool.?\nSee Quantum Aether  Dynamics =Secrets of the Aether.\nJ R RedBourne= Aether theory ,He Invalidate the Universe expension theory etc..and many other theoreticfal scientists.
198895
because according to general relativity E=mc^2, so you can say that energy is a form of mass, but when you include this to the uncertainty principle it's incorrect to say that void has no energy (x & v = 0) so you have to go the other way, since there's a lot of void out there you should have the equivalent mass, and since mass is gravity we should be seeing the BIG CRUNCH right now, obviously that ain't happening, so one of the two theories must be wrong, but scientists prefer to say that both of 'em r parcially or entirely wrong
352030
They do not know how to do that.\n\nScientists do not know of any other universe or dimension, much less how to go there. They only hypothesize about such things using mathematical equations.
375801
The theory of relativity is being used in Fermi lab, U.S. to "create" either energy or new matter from energy.  Newton's laws only define motion, but they do not explain why some of the mysteries of the solar sytem or the universe occur.  With Einstein's theory, however, these mysteries become clearer.  We understand more why they occur this way and can predict how much energy is being "created" by calculating for how much matter is "lost."  Fermi lab is working to create anti-matter, combine it with matter to create energy, and utilizing the energy into more matter -- it's one of their big projects.  I'm sure they're testing for more than that, but it's the overview of what they are doing.
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To be sure, the theory has a lot of gaps.  So it's not a Law.  All's it takes is one scientifically provable discovery that doesn't fit the theory to launch a search for a new theory that will explain the new information while keeping the old proven stuff too.  A good example is Einstein's Theory of Relativity.  Newtonian Mechanics fails at extreme sizes and speeds.  Relativity so far has been able to explain all the variances found to date at those extremes, but has not been proven to be 100% valid all the time, so it's not a law yet.  If you can discover something that invalidates evolutionary theory, you'll probably win a Nobel Prize!
598607
A Grand Unified Theory of Everything cannot be explained in such fashion. I would recommend reading "Hyperspace" by Michio Kaku.
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For the aether to exist, it must have specific properties that differentiate it from other substances, right?  What are its properties?  Are they different from say a pure vacuum in space?  The experiment was a clever way to demonstrate that the earth does not move through the aether with the kind of doppler effect exhibited by a train through air, but still needed careful evaluation.  For example, the earth moves rapidly around the sun while moving even faster around the core of the galaxy.  Could the earth flatten in the net direction of motion causing at least some confusion in the experimental observations that delt with the speed of light and the length of path in various directions?  There can be many explanations for an observation, but which is best and most consistent with everything else we know let alone suspect?
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Here is the problem...\n\nThe more you study things, the more questions you have about them. Even Einstein died without fulfilling his wish to develop the unified field theory, unifying gravity with the other three known forces.
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I'd love to know what your answer is. Its actually something physics seems very confused about.\n\nAccording to GR, its masses that cause the curvature of space. Gravity isn't a force, its just masses following the path of least resistence - straight lines in curved space time.\n\nThe problem is they then try to introduce gravitons to carry what isn't really a force. Very confusing.\n\nIf we assume Einstein is right, that gravity isn't a force, but masses following curves, the real question becomes - where does mass come from?\n\nMy guess - quantum entanglement create at time zero that keeps everything in the universe interacting. I don't like the higgs bogusons theory, since that introduces yet another force carries in the terms of a, erm, massive particle that gets mass from, erm, itself...
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It would have been helpful if you had cited where Einstein said this.\n\nBut here's the deal...all motion is relative (which is why the theory is called the theory of "relativity")...relative to something or somethings.  Even things that seem to be perfectly still, like the tree in your front yard, are moving relative to something...relative to the sun, for example.  In other words, there is no such thing as an absolute motion relative to absolute zero velocity.\n\nWith all these motions (velocities) we have accelerations (v = at; a = v/t) that are, like their velocities, not absolute.  They, too, are relative.  So, as F = ma or F = mv^2/r = (m(v/t)^2)/r, the associated forces are relative.\n\nAs a consequence, there are forces acting on everything, even when none is readily apparent.  That tree, for example, has weight, which is one force.  But it also has a kinetic force (centripetal) due to its spin around the Earth and its revolution around the sun while on the Earth.  Then there's the motion of the solar system around the center of the galaxy, the motion of the galaxy through the universe, and the expansion of the universe itself.\n\nSo a single measured force is really the vector sum of all those other forces created by all those other motions.  So the notion that there is but a single force at work is "fictitious."  The good news is that the single force usually works in our observable world because we can ignore the effects of all those other forces.  But, alas, that is not the case in the relativistic world of near light speeds.  That is probably why Einstein would indicate what you claim he did.
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Neither,\n\nTheory is never proof so that's not it. Gravity is a weak force. M is an explanation why it is weak. Multidimensional theory is not about gravity, it's just part of it.\n\nEinstein tried to unify the fields, he failed. Many new theories came and went.... I'm not sure we 'got it' now. It is still a very unstable work in progress.
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I don't think that Mr. Hawking is through with the world of theoretical astronomy just yet. About all he has is his mind and boy does he use it. A lot of his most creative work has come to us after his 40th birthday.  Keep on thinkin' Steevo!!!!
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Hi NY NY 2\n\nQuite a hodge podge of answers above.  let me see if I can clear some misconceptions up for you:\n\nFirst, the evidence. About 8 years ago two separate independent groups announced measurements of the brightness of supernova at a redshift z=1.  (Cosmologists use redshift factor "z" to show how far away something is in space-time by designating how far light from the object is redshifted by the time it arrives at earth.  The redshift is due to the expansion of the intervening space.  Redshift z=1 corresponds to a distance where the wavelength of light has been redshifted to double its original wavelength.).  These results indicated that the universal expansion was accelerating.  Since that time the results have been confirmed, and supporting evidence was found in the detailed mapping of the microwave background.\n\nSurprisingly (you might think) it is very easy to modify the equations which describe the universe's evolution to make the expansion accelerate.  The reason for this is that Einstein originally included such a factor in his early equations.\n\nBriefly, the equations for the universe at large scale talk about gravity and pressures.  Gravity tries to collapse the universe together and pressures push it apart (roughly).  When Einstein came up with his model (1915), everyone thought the universe was static (so called "steady state"), ie it didn't change over time.  So he included a cosmological constant to counteract the collapsing action of gravity and keep the universe steady.  This cosmological constant "pushes outwards" to counter gravities inward push.  By 1928 Hubble's catalogue had convinced people the universe was expanding (not steady) and physicists realised the cosmological constant wasn't required.  Einstein called its original inclusion "his biggest blunder".  It seems that call was wrong.  :o)\n\nNow the cosmological constant is coming back.  To describe an expanding universe you stick it back in and change the values for the density of normal mass-energy and the cosmological constant, and voila - an expanding universe.  The question then becomes: what does this constant physically represent?\n\nAt present cosmologists use the term "dark energy" to refer to a number of possible culprits.  From the equations we know the properties of this dark energy very well.  Some physicists link it to action of the quantum vacuum, some label it "quintessence" (the "fifth force").  \n\nIt is *not* (as suggested above) dark matter or antimatter.  Dark matter is invoked to explain galactic dynamics: galaxies tend to rotate in a fashion which suggests they have more mass than we can actually see.  This missing mass is presumed to be dark (which is why we can't see it).  Dark matter would act like ordinary matter in Einstein's equaitons, and so can't produce an accelerated expansion.  Antimatter also behaves gravitationally like ordinary matter and so it can't be responsible for accelerated expansion either.\n\n\nHope this helps!\nThe Chicken
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There is a continuum between quantum laws and classical physics, they just haven't discovered a unified theory that expresses this continuum mathematically. Quantum laws govern all particles, and since matter is comprised of particles - naturally quantum mechanics supports material reality.\n\nuh... to "goring" - quantum mechanics does not posit that light has no mass.\n\nEinstein did not challenge all particle theory - when he said "god does not play dice with the universe" he was challenging Heisenberg's Uncertainty Principle, and quantum laws based on probability, which were subsequently validated in double-slit light experiments. So Einstein was wrong. He considered it his greatest failing as a scientist not to unify relativity with quantum laws in his lifetime.
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New ideas and concepts in science have always been considered moving toward "psudo-science" until the ability to prove the new theory was achieved.  Finding a way to prove string theory, or anything else on the quantum level will be man's biggest challange, and we won't get there without philosophy.
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There is no such thing as an aether. It is an old myth stemming from a misunderstanding among radio talk-shows.\n\nThere is also no such thing as mass-curvature, as it is not possible to describe as a dimension, and therefore have no curvature. If you are referring to the curvature in space that mass creates, then you have asked nothing.
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Quintessence was discovered by two groups which looked at distant supernova. By seeing how bright the supernova were they were able to estimate how far away they were. This was used to plot the relationship between distance and redshift that can be used to show how fast the universe is expanding.\n\nWhat they found instead, was that the universe is accelerating. That is, the rate and which the universe is expanding today is more than it was a billion years ago, and  in a billion years from today the rate of expansion will be even faster.\n\nThe name "quintessense" is used for various models of the vaccum energy which drive the acceleration of the rate of expansion. The term was chosen because it sound nice and mysterious, it has no connection with any Earth-Fire thing. They could have called it "Peanut Butter" and nothing would have changed in the mathematics - which is what counts.\n\nIf you're interested in science, like it sounds you are, I would strongly recommend reading more about it, and just enjoy the very strangeness of it. Engage with people on message boards. It is extremely difficult to make a major, ground-breaking contribution to physics even with a PhD and research experience. It is basically impossible to do so without one. \n\nI don't mean to be condensending, its just that there were, and still are, a lot of crank theories out there based on a few ideas which may or may not be wrong, but which ignore the VAST amount of experimental data there is about the universe we live in.\n\nYou don't want to fall into the trap of being a crank, or quack. Trust me, I've seen it. (When a post-doc at a big state university.)
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Laney, first of all allow me to say that I'm incredibly glad and pleasantly surprised to hear of your genuine interest in this field.   You are to be truly commended for your intellectual courage and abilities.  ...But to address your question, there are in fact thousands of great explanatory/layman-type books out there on Quantum Mechanics, Field Theory, Gravity, Philosophy, Reality, and associated topics like cosmology, etc.  Some of them even dating back to the mid 70's, that nonetheless are still wonderful reads.  ...Theoretical physics at the level that we are talking about here, though, is unfortunately a seven-headed exotic mathematical monster that is not even accessible to most physicists, much less the lay person.   Having said that, and as you know, there have been courageous attempts by talented physicist like Brain Greene (and many others before and after him) to make our latest theoretical/scientific visions of the physical world/universe available to the general public.   ...Since you mentioned that you are NOT mathematically inclined, but did enjoy Greene's The Elegant Universe, the first thing that came to my mind (and the book that I would recommend most) was in fact Greene's newer work called "The Fabric of the Cosmos: Space, Time, and the Texture of Reality" - in case you haven't read it yet.    \n\nAmong some of the other more recent titles worth mentioning also are:\n\nThe Great Beyond - by: Paul Halpener (A very nice book)\n\nThe Cosmic Landscape - by: Leonard Susskind\n\nHiding in the Mirror - by: Lawrence M. Krauss\n\nThe Road to Reality - by: Rofer Penrose\n\nA First Course in String Theory - by: Barton Zwiebach (This is a very nice book but a lil' more mathematically oriented than you might enjoy - let's say undergraduate physics level) \n\nI also highly recommend:  The Five Ages of the Universe - by: Fred Adams\n\nThat should keep you busy for a while - Good Reading!  ;-)