Why monopoles are not found ?
88042
Actually, according to my text book (I'm a physics major at the University of Rochester), there is one reported observation of a magnetic monopole in the literature - that of B. Cabrera in 1982.\n\nApparently, magnetic monopoles were first suggested by Dirac in 1929, and are also proposed by a number of GUTs. Dirac showed that relativistic quantum mechanics leads to the quantization of both the electric charge e and the magnetic charge qm. The magnetic charge of a magnetic monopole would be given by:\n\nqm = n(h-bar)c/(2e) where h-bar = (plank's constant)/(2pi), e=the charge on the electron, n=an integer, and c=the speed of light. \n\nThe mass of a magnetic monopole is predicted to be on the order of 10^6 MeV/c^2, and, therefore, far beyond the range of what we can produce in any accellerator. Numerous cosmic ray searches have concluded that the flux is about 10^-15 cm^-2 s^-1 per unit solid angle (in other words, if magnetic monopoles do exist in cosmic rays, they are extroardinarily rare.) As I said before, there is a single reference in my text book to the only purported observation of a magnetic monopole - that of B. Cabrera in 1982.
542625
It's either just one charge: The electrical, which appears in positive and negative characteristics, or if you see "charge" in a more general way it's more then one charge: magnetism has also a source, but that appears always in dipoles, mass is the "charge" of gravity, but that appears just with a positive sign, and the strong interaction has three kind of charges, called "colour charges": red green and blue.\n\nTwo see an underlaying principle for this "chaos" we need the "Grand Unified Theory" which still is "work in progress" ;)
590743
The most interesting fact I know?  That they don't exist and that they're some stupid idea somebody came up with to help explain a few things we don't currently understand.  Singularities have infinitely dense mass?  Riiiight.\n\nYou'd better start reading up on the Electric Universe, buddy.  There are powerful magnetic fields all over the Universe, and the stupid idiot "scientists" running the show right now don't like to acknowledge that maybe there are electric currents shaping our galaxies.
694010
If the laws of physics have the same forms in all frames of reference than the cause of interaction is confirmed.\nIn the case of this question there must have  been someone who caused  this fine question.\nOther wise it would have never existed.
62175
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.
1170767
Magnetism arises from the movement of electric charge. It is a manifestation of the electrosatic force (there is per se no magentic force). \n\nA moving charge always creates and polarised magnetic field - ie it has a north and south. Monopoles do not exist.\n\nHowever, it would be equally possible to describe the situation with magnetic monpoles leading to polarised electric charge. \n\nNo magenticm monopoles have been found to exist.
845910
I think nobody....because the gravitatory force is very weak.\n\nThe nuclear and strong forces hold together particles
1104368
Hi Aaron\n\nThe W+, W- and Z particles are actually intermediate vector bosons - they're the exchange bosons for the weak force, not the strong force.  The unification of weak force with electromagnetism requires these bosons to be massive (so that the strengths reconcile at the unification energy).  A consequence of the boson mass is that the weak force is short ranged.\n\nBoth W and Z bosons have been detected at CERN.  The detected masses match those predicted by electroweak theory. The mass of these bosons is posited to occur via the Higgs mechanism, the interaction of the bosons with the Higgs scalar mass field.  The charged W bosons take part in quark decays (eg beta decay) whereas the Z boson shows influence through weaker neutral currents.\n\nStrong nuclear interactions are mediated by gluons.  There are 8 different gluon types (compare to four electroweak bosons) and all gluons are massless (like the photon).\n\nHope this helps!\nThe Chicken
177391
No\n\nThe reason this has\nnever happened is due to the source of magnetic fields:  moving electric\ncharges.  When electric charges (e.g. electrons) move in circles, they\nproduce a magnetic field.  In a piece of iron, it is very easy to line up\nthese circles, getting all the little magnets to work together as one big\nmagnet.\n\nFor each of these circles, one side is the north pole and one side is the\nsouth pole.  Since each circle has two sides, each circle has a north and a\nsouth pole.  Even the smallest possible magnets (spinning electrons) have a\nnorth and a south pole.
717863
If we consider that neutrinos are present in the emptiness of the atoms, the wave theory is negated. What you call free space does have countless of neutrinos zipping past but electrons have a dual character thus it is incorrect to think of them as strictly particles whirling around nuclei. Think of them as a cloud or even better as a distribution of charge.\n\nAlso, the question as to whether neutrinos have mass is still open. Answering it will solve some of the last unanswered questions. There is a massive experiment going on I think in the US where a lot of Heavy Water has been stored in an abandoned mine and scientists are patiently waiting for neutrinos to make impact.
661343
- They are the basics for all electrodynamical phenomenas (well, unless you go to high energy physics or go to the next "higher" level of abstraction, which would be electroweak interaction and quantum field theory).\n\n- They describe in an elegant way the physics over a HUGE amount of magnitudes. \n\n- They show the symmetry and also the assymmetry (no magnetic monopoles) between electric and magnetic fields.\n\n- They are Lorentz-invariant, which means that they hint to the special theory of relativity.\n\n- They explain why electromagnetic waves need no medium to propagate, which was a real puzzle at that time.\n\n- As they are partial differential equations they inspired phisicists and mathematicians to develop methods to develop more and more methods to solve these type of equations, which are now usefull in all kind of modern physics even in fields like many body quantum physics or high energy physics, that Maxwell never thought of, which closes the circle to what I mentioned first.\n\nIn short: They are a brilliant part of physics. (Although students hate them since the mathematics of partial differential equations is hard to learn ;) )
612178
When I think of "polarized", I interpret that to mean a system with a fixed, unchanging electric moment.  Electric  containment with static fields is generally not possible within any hollow space.  That's because those particular static fields can always be written as the gradient of a scalar field, the voltage field.  If the space is hollow, with no internal contributing sources, then the forces have zero divergence.  The Laplacian of the scalar field is zero.\n\nA fundamental result of the calculus of multiple variables is that if you have a volume completely enclosed by a surface, and the Laplacian of a scalar field is zero everywhere inside the volume, then the field takes its minimum and maximum values on the surface.\n\nThe energy state of a charged particle in such a field is the produce of the charge and the field value, which we've said is at its minimum and maximum on the surface.  So, either the field is constant everywhere within the container, in which case the container has no influence at all, so there is no containment, or the field is non-constant, and the minimum energy state is obtained when the particle collides with the containment somewhere.\n\nOK, so unchanging electric fields are not going to constrain a charged particle in a hollow space.  How about magnetic fields?  Well, apply a large magnetic field through the space, and inject charged particles into it such that they have no velocity in the direction parallel to the magnetic field, and those particles will orbit in the magnetic field.  If the radius of the orbit is smaller than the distance to the side walls, we can say that the particles have partial containment in the system.  A uniform magnetic field can hold moving charged particles in two dimensions, but provides no containment in the direction parallel to the magnetic field.\n\nIf we start modifying the electric and magnetic fields in more detailed ways, it becomes possible to contain a plasma.  That is, after all, what happens in a Tokamak.
463641
see\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/surten2.html#c1\n\n here you can find the answer for your question with MATHEMATICAL EXPLANATIONS.
394958
Sorry, but we've ruled out the majority of dark matter being massive concentrations of mass (small black holes etc).  Things like that can be detected in gravitational lens searches, and the numbers of lensing events that we have detected pretty much rules out any type of "massive compact" dark matter being the bulk of what is out there.  This leaves us looking for even more exotic stuff - there is likely a nobel out there for someone who figures it out.\n\nAs for directly answering the question... I'm really at a loss to even begin to understand what is being said there.
1179398
That is a very good question. We currently do not know definitively the answer to this question. Thousands of years ago, the Greeks believed that all matter were composed of some indivisble units called "atoms". This was irrefutably proven by Einstein at the turn of the 20th century (and he received a Nobel Prize for it). However, as we probe further, we discovered that even atoms has internal structure: protons, neutrons and electrons. For awhile we thought that was it, but then later we found that protons and neutrons were also made of more fundamental particles called quarks (now confirmed by experiements).\n\nSo is this it? Quarks is the final indivisible unit? It turns out that it is most likely not the case. The reason is not that we have discovered anything smaller than quarks. The reason is because our 2 current theories of the physical world, quantum mechanics and theory of general relativity, are not compatible with each other. What this means is that these 2 theories are not completely correct. They are good for most situations, but they can not explain objects like black holes or explain the big bang (the beginning of the universe). There are other things that these 2 theories can't explain, but I won't go into that right now.\n\nThese serious flaws has been the mother of all physics problems for the most of the 20th century. The Holy Grail of modern physics is to find a single theory that can combine the 2 theories together and explain all physical phenonmenons. So far we have one candidate: Superstring Theory.\n\nSo in our effort to solve this problem, we created String Theory, which tells us that quarks are not the fundamental building blocks of matter, but tiny filaments of vibrating energy called Strings. They are much much smaller than quarks. Quarks are estimated to be about to 10^-16 centimeters, but strings are around 10^-33 centimeters. So is this it? We really don't know for sure, but all the signs points to a yes (I won't explain why here because it's too long and it wasn't your question.).\n\nSo does this imply that matter/energy always existed? The answer is NO. because the universe is about 14 billion years old. That's how long anything has existed, including all the matter and energy.
194000
It's just like "positive and negative" for magnetism, isn't it?  People say them as though they mean something.  All they really mean is that there are two types of magnetic things--like ones repel, opposite ones attract.  We don't know why it's so, but we feel much better when we can attach a word to it.\n\nWe understand many things about gravity (as we do about magnetism), but we can't explain why it exists in the first place.  That question is not even in the scope of physics, really, because it can't possibly be confirmed or denied by any experiment.  But like many things, we want to believe that we understand it.
311168
I haven't been able to find one. \nI guess you just gotta keep searching....REALLY hard. \nThey are realy rare these days.