I was watching a PBS Nova special on the universe and string theory and they said that instead of the atoms containing quarks, instead they contain these strings.  Can they prove that quarks exist?  If so, the documentary says that quarks are not point particles like they thought but rather these strings?  Why can't they prove strings exist?
123350
By using particle collisions, it is possible to show that there is *something* inside of protons, for example. These 'somethings' have the properties that the theorists predict that quarks will have. Furthermore, the theoretical predictions made by the quark models (such as decay rates, reaction cross sections, etc) are in agreement with what is actually seen in the accelerators. This is why we say that quarks exist even though nobody has seen an isolated quark (and there are good theoretical reasons why we may never see one).\n\nOn the other hand, the strings in string theory are *incredibly* small, which means we need very high energies to probe them. No particle accelerator that we have right now will produce these energies. Also, the strings are what would describe the nature of the quarks, not show they don't exist. The question is whether they are point particles or extended to some (small!) degree.
530485
Because a 1 dimensional string solves many of the problems associated with 0 dimensional point particles of the Standard Model.\n\nGuys, M-Theory isn't different from string theory, it just combines all the string theories into one.  There are actually many string theories and superstring theories.....
175127
You would have to be able to take a base measurement on the number of quarks that is associated with gravity in an area observed and tell over time if there is a gain or loss of quarks from the base measurement.\n\nP.S.\nThere is no way in the world that the current technology can even begin to do this provided that we would have to agree that // universes exist.
556042
dont mind "feel good", he has no idea what he is talking about.\nWe assume, and the theories predict that singularities exist.\nThe existance of black holes, nutron stars and the like\nshow what the theory predict, and so we can assume that the theories are correct.\na singularity is really not a single point, it does have size(sort of). However that size is not measured the same way we measure other things, and can be thought of as a single  point. Think of it this way, an atom is made up of protons, neutrons and electrons. However they account for a tiny tiny fraction of the volume of an atom. Therefore theoretically you could condense many billions of atom parts into the space occupied by a single atom. When you have enough mass to cause such a collapse (such as in a black hole) the mass of the star is squished down into a tiny tiny fraction of its original  size.\nAlso remember that neutrons and protons are themselves made up of quarks which are very much smaller again.\n\nNow because of the extreme bending of space around this mass a distortion of what we think of as size occurs, and when you start talking about distorted space time all sorts of weird things happen as a consequence. One being that the mass is concentrated in what we call a singularity, and we define it as having no dimentions. (although different theories pedict a one dimentional line or a two dimentional sheet)\n\nhttp://www.universaltheory.org/where_is_singularity.htm\n\nhttp://timetravelportal.com/viewtopic.php?t=554\n\nIn the same way in electro statics we make calculations using "point charges" where we assume that a charge is a perfect point. We know it actually has a tiny volume but it makes the calculations easier and for all intents and purposes the answers come out the same.\n\nAnother example is gravity, when calculating the  mass of the sun and planets we assumer the mass is all concentrated in one spot (a sort of point mass) but once again this is just for ease of calculations. The answers come out the same either way,\n\nso a bigger black hole will have a singularity which is the same "size" and just more "powerfull" if you will.\n\nif it is hard to grasp dont worry, you are talking about something that is very foreign to our everyday experiences.
414520
That is a very theoretical question that mathmaticians don't like to hear.\nZero was just recently added to math. Before it wasnt even a number. It was only an idea.\nThink about it this way,\n What happenes when you zoom in to the size of a proton? Now a needle point seems like infinity to you. \nWhat about the size of a string( if you believe in string theory)? Now an electron seems infinitely big.\nInfinity and zero are so relative to the observer that they must be related.  \nThe problem with this relationship is that it breaks down mathematics to only an observation and not an absolute truth. Every mathmetician thinks that math is the universal language, and no mathematician or physicist for that matter wants to even ponder the possibility that everything they have dedicated their life for could have flaws. \nSo as an everyday person 1/0 is just undefined. \nBut to anyone who wants to think past our rules of math and see ideas zero is just as indefinite as infinity.
320529
Any line you can make in this physical Universe is 3-dimensional.  A drawing has a 3rd dimension - no surface is ideal, and there has to be something beyond this surface.\nIf you draw a line, it is also 3-dimensional (otherwise, you would not see it - it would be infinitely thin, and if it is not, it is a rectangle on an uneven surface).\n\nIf you ask whether truly 1-D or 2-D objects can exist in our Universe, there is an answer: no and yes.\n\nNO for macroscopic objects: the reason is that there is a minimum unit of space: Planck length. Therefore, you may think of all non-elementary objects in this Universe as being at least 1 Planck length thick in all 3 dimensions.  \nhttp://en.wikipedia.org/wiki/Planck_length\n\nYES for elementary particles. They are viewed either as zero-dimension (points) or one-dimension (strings, with the size of - I think you guessed it - Planck length).\nhttp://en.wikipedia.org/wiki/String_theory
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zero to infinity.\n\nYou see hadrons (a kind of tiny particle smaller than an atom) have properties of both a solid particle, and a wave.\n\nA single quark can't really exist in nature (as far as scientists think for now), but anyway all particles have a wavefunction. Even your body has a wavefunction which is the sum of all the particles in your body.\n\nA probability wavefunction gives you an idea of how much time a thing is likely to be hanging around in a particular area.\n\nImagine a map of the word and you stick a red pin for every month you have been in a particular place. What would your wavefunction look like?\n\nA quark will have a wavefunction which is thickest (most red pins) near its locations inside a proton -- but it will also have some theoretically mathematically small probability of being on the other side of the moon for instance.\n\nThe wavefunction depends on mass, so we could just compare the electron mass to the quark mass -- but there is a fly in  the ointment. Quarks don't really have a real mass. They have various types of theoretical masses, but really they are measured by kooky-sounding properties like flavor, charm and color! Wacko huh? So there is no direct way to compare wavefunction/size to an electron.\n\nSo the answer is, it depends! zero to infinity.
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Actually, the wiki on this one is unusually good (and right, for once):\nhttp://en.wikipedia.org/wiki/Cosmic_string\n\nCosmic strings are sometimes confused with the strings of string theory.  There's considerably more observational evidence for the former than the latter. \n\n(I say they're different things, but every time someone like me says something like that, some party-pooper like Bohr comes along and makes a liar out of us.  There's a chance, in my mind at least, that they could be closely related somehow since, supposing either of the things even exist, they're both topological defects in space.  But, that's pure conjecture on my part).\n\nMichio Kaku of the City College of New York has written on both.  If you're looking for something on string theory, and not cosmic string theory, Barton Zwiebach has written the only introductory book worth reading.  If you really did mean cosmic strings, there are several recent journal publications listed in that wikipedia article (and they're all, for once, actually referreed journals).\n\nAs an aside, I see a lot of people posting on both of these around here as though they were somehow proven fact.  There is almost no observational evidence for cosmic strings, and there is none at all for string theory.  There isn't anything wrong with thinking about things like this -- that's where new answers come from.  It's just that I'd like to see the certainty levels turned down a bit.  In the case of string theory, the theory is in much better shape than it was a few decades ago, but it still has no real central theme, it has no real sharp predictions (like the Higgs-Boson, for example, of the standard model of particle physics), and absolutely no experimental verification or support of any kind.\n\nIt just kind of torques me a little that so many people run around on these boards decrying the theory of evolution as unproven, wild-ass conjecture (when, in fact, the evidence supporting the theory of evolution has been more exhaustively catalogued than it has been for probably any other theory in history), while still others are lauding string theory as something as sure as Maxwell's equations.  String theory is a fun idea, and probably a necessary one, but it isn't a sound idea just yet.
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The existence of gravitons has not been proven.   \n\nThe existence of gravitons is postulated by quantum theory.  For them to exist, they must be massless.  Assuming that they massless, they are unaffected by gravity.  Thus, they can escape from a blackhole.
31971
They are real particles.  They really exist.  The two types are mesons and baryons.  Mesons are made of one quark and an anti-quark.  Solid matter we touch in every day life is made up of atoms made of protons, neutrons, and electrons.  Protons and neutrons are two kinds of hadrons called baryons, made up from the same particles (quarks) that make up mesons, except protons and neutrons are made up of 3 quarks.  Unlike protons and neutrons, mesons are unstable, so they quickly decay.  But they can be produced and studied in particle colliders, such as the Tevatron at Fermilab, and other big colliders at the Stanford Linear Accelerator Collider (SLAC), and at Cornell.  Have a look at the following websites for more info:\n\nhttp://www2.slac.stanford.edu/vvc/theory/hadrons.html\nhttp://www.fnal.gov\nhttp://www.slac.stanford.edu
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i have to agree with absynthian.  if they are in fact "physicists" then that means they have doctoral degrees in physics and telling them about quantum entanglement or string theory is going to be like giving a bunch of senators a talk about legislative procedure.  \n\nchaos theory, quantum entanglement/teleportation, and string theory are all huge and hot topics these days in physics, and they'll all have read plenty about them in physics today, nature and science, even if they aren't active researchers in that area.  you are going to bore their socks off if you get up there and start telling them about how strings are 11-dimensional objects, unless you have some really seriously deep and intuitive observations on the subject that you can share.\n\nhere is some good advice:  physicists are always interested in the historical development of their field.  the work of the big-name scientists - newton, galileo, maxwell - is well-known.  but there are a lot of physicists from the annals of history who led interesting lives and who often worked on subjects ahead of their time.  if you can find a research topic and show how someone from the 18th century studied a related phenomenon, and give it a historical twist, i think THAT would be a hit talk.\n\nanother thing might be to discuss some weird little topic from the back waters of physics.  people do research on all kinds of crazy stuff that's fun and interesting, but doesn't get much press.  for instance, nasa does a buttload of research into weird little problems - an example is that nobody understood why ketchup flows so slow at first, and then comes pouring out, until nasa figured it out.  that's one of many examples from this great page that might help you get started:\nhttp://exploration.nasa.gov/articles/index.html#fris\n\nanother way to get into this stuff is to just start searching around the web and looking at the research pages of faculty at various universities.  many of them will be working on hot topics - high-temperature superconductors or quantum information theory or photonics or something.  but you'll probably find one or two old guys at every place who are working on some totally off-the-wall thing.  THAT kind of stuff will be much better than the talk that ends with "..but we still have no idea whether string theory is really correct or not."\n\ncheers
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One should not group antimatter particles all into the word element. It is possible to make any of the elements in the form of antimatter, and for any element the antimatter equivalent would be incredibly rare here on earth. Now to say the rarest is very hard because there could be at any given point in time a number of antimatter hydrogen atoms that might seem like a large number, to the human mind, here on earth. Anti hydrogen would be the most abundant anti element, although still inconcievably rare. However, some of the heaviest non-antimatter elements that have been created in the lab probably ocasionally briefly come into existence in nature here on earth. Some of these metals might be rarer than antihydrogen, the most abundent antielement here on earth. \nNote: positrons, anti electrons, are the most abundent easily observable antiparticle, but I have left them out because they are not an element.\n\nNow, as for the universe in general: It is a real curiousity that there does not seem to be an equal amount of antimatter as matter. We humans do not now how to create matter without also creating an equal amount of antimatter. Yet, it seems as though our universe is made up almost entirely of matter... What happened to all of the antimatter during the creation of the Universe??? I don't know, and as far as I am aware of there is not a solid leading theory to explain this enigma, but many ideas have been suggested with associated mathematics. Some of them propose that the antimatter went into another dimension. Others propose that there was a very slight inequality in the quantity of matter and antimatter with the difference being the matter that is currently in existence. Still others contend that the some total of matter and antimater within the Universe are still of equal quantities, but the areas where this antimatter is hiding is too far for light to have reached us from those locations. Although I have a preference between these ideas, I will not say what it is. So, lets just say that that might be a good topic for someone interested in the subject to do some real research.
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You have gotten some great answers up to this point.  I'd like to add yet another one...the pre big bang scenario re string/M theory.\n\nOne spin off of string/M theory is that parallel null universes are feasible.  Brian Greene pictures them as slices of bread in a cosmic, N-dimensional loaf of bread. [See source.]\n\nThese are "null" universes because, as far as we are concerned, from our myopic four dimensional world (the metric, observable universe one answerer talked about), these universes exist only in higher dimensions and cannot be observed in 4D.\n\nAccording to one hypothesis, based on string/M theory, two of these slices of bread collided.  That collision point is called the singularity where the big bang originated.  The energy such a collision could generate is one way to account for all the mass-energy postulated for our own known universe.\n\nOf course, as pointed out by other answerers, time and other physics phenomena in null universes may not exist as we know them in metric space.  Null universes are beyond our ken to understand and explain...now.  But who knows, with people like Hawkings, Witten, and others attacking the cosmos and its mysteries, we might just yet unlock the nature and existence of null universes and our own.\n\nPS:  Not all explosions are chemical explosions requiring air (oxygen) to work.  The atomic bomb, for example, does a really nice explosion by simply splitting atoms.   The sun makes spectacular explosions by fusing (putting them together) atoms.  Bottom line, the big bang is not a chemical explosion requiring oxygen.
661018
Don't know who told you that "atoms only consist of energy", but in general, that's nonsense. Atoms consist of electrons and the nucleus (protons and neutrons, which again are made up from quarks), and these particles have a well defined rest mass. Einsteins theory of relativity is well proved and gives us the famous equation E=mc^2 for the energy equivalence of a rest mass, *which does not mean that energy and mass are the same*. It just means that you can transform energy and mass into each other and are equivalent in a certain (relativistic) way.\n\nSo if you want to make a fool out of yourself: Go ahead and try to disproof Einstein, like thousands of fools have tried before. If you're really interested in physics, go and get some good books about the basics, and you're welcome to come back with some more serious questions.
177357
Basically no. The idea behind subatomic physics is that when things get stuck together, you have to put energy into them to split them apart. (just like "real" physics). The tighter they are stuck together, they more energy it takes to split them apart. And the smaller they are, the tighter they are stuck together.\n\nQuarks are stuck together into subatomic particles so tightly that we need to build even bigger more powerful "atom smashers" to bust them loose; big "racetracks" miles across where the electrons can wind up faster and faster until they get released at the target. Costs a LOT to build. Until then, they're just a theoretical toy.\n\nAs for 'colors', that's just a name they made up to classify them by, doesn't apply to anything real. Same as the properties they call 'strangeness' or 'charm'.
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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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I know of no reputable astrophyscists who claim space is empty.  In fact, Brian Greene's "Fabric of the Cosmos" spends a lot of time talking about the stringy stuff that fills space.  The Higgs Field is also a something that fills space according to some theories.  Further, mass bends space, bent space has been observed; so it seems logical that space is a something (not a nothing) that can be bent.  So your premise that space is not empty is widely accepted.\n\nAlthough there are some short-lived massless quanta that can penetrate great distances, most cannot.  And the great distances have limits.  Even neutrinos have a limit on how deep they can penetrate a mass.  Gravity, on the other hand, is not diminished by interceding mass.  We are affected by measurable gravity in the deepest, darkest caves, for example.  So none of the known and theoretical quanta, save one, exhibit the characteristics of gravity.  \n\nThat one exception is the graviton, which is predicted by string/M theory.  The graviton has never been observed; so its existence has never been proved.\n\nSo your supposition that the effects of gravity are due to bombardments of quanta of some sort does not generally stand up to the evidence.  The one exception is the graviton, which is strictly theoretical and may not exist.