unansweredquestions
Rising Star
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Only 4% of the Universe is known
- Thread starter Ice
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gibran2 said:
It works both ways: electric fields produce magnetic fields and magnetic fields produce electric fields – that’s how generators create electricity.Saidin said:
And as you said, wherever there are electric currents, including in the body, there are magnetic fields.
gibran2 said:
also... every nucleus has this intrinsic magnetic moment, an intrinsic magnetic field to it. Physicists usually work with what they call the Spin, which is a vector that among other things gives the direction of this magnetic field. These vectors add up, so that if you have a heap of matter and the spins in it are not quite random the sum of all these little magnetic fields will give you a macroscopic magnetic field, like in ferromagnets for example.
How this could relate to the sun I don't know, unless it has perhaps, similar to the earth, a solid core with magnetic properties that are more ordered than the plasma we see. either way, magnetism is intrinsic to matter, just as electric charge is intrinsic. At the moment we use the model of charge and spin to explain this, but of course these are only models and perhaps in the future better ones will come along that can better our understanding of what the hell matter is, with all its bizarre properties (like inertia/mass, gravity, charge, spin, wave/particle duality...)
..statistics is manipulation..
hey Ice, hi, love your everinquiring mind, did you do an intro. essay i can read?
hey Ice, hi, love your everinquiring mind, did you do an intro. essay i can read?
Citta
Skepdick
As for the whole deal with dark matter, let's talk abit about it;
As far as "ordinary" matter goes, the stuff of life, the stuff of stars and the stuff of the computer in front of you - it was thought until very recently that the universe consisted only of these types of particles; that is protons, neutrons and electrons, also just refered to as baryonic matter by astronomers and physicists (protons and neutrons are composite particles made up of three quarks, and we put them under the term baryons. These are the particles within the nucleus of the atom, thus making up most of the visible matter in the universe). What happened within astronomy that opened up the possibility for unseen matter?
It was the swiss astrophycisist Fritz Zwicky that first theorized about dark matter. In 1933 at the California Institute of Technology he observed that there had to be about 400 times the mass in the Coma cluster (large cluster of galaxies, over 1000 of them, approximately 321 million light years away from us) than he expected it to be or that it "should" have been. He reached this conclusion quite easy, observing that the relative speeds of the galaxies to eachother were far too great to be held together by the gravitational attraction by the observable matter alone. Thus he understood that there had to be more matter there, matter that couldn't be seen and that accounted for the missing gravitational attraction. Since he couldn't see this matter, he called it "invisible matter" or simply "dark matter" as it didn't emit light. Other (similar) discoveries sprang forth to further support this idea in the time following Zwicky's discovery.
For example, a woman named Vera Robin made another extraordinarly observation in 1950 that totally contradicted Newtons famous gravitational law. Newtons law of gravitation predicts that bodies orbiting far away from a center moves more slowly than bodies orbiting closer to that same center. This has to do with the fact that gravitational attraction between bodies varies inversely as the square of the distance between them. Just look at Pluto's orbit around the sun compared to that of, say, Mars. Anyway, by examining galactic light signatures Vera found that bodies orbiting at the outskirts of galaxies actually traveled at approximately the same speed as bodies orbiting closer to the center of a galaxy. For this to be possible, there had to be more matter in these galaxies than that which could be seen. The idea of dark matter become more and more clear.
Let's not dwell more into observational evidence (there is certainly more), but take a look at dark matter candidates. We talked earlier about the baryonic matter, the ordinary matter which we ourselves are made of. We have these dark matter candidates we call MACHOs (Massive compact halo objects) that might account for some of the dark matter we know to exist in the universe. It is a general name for any astronomical object that are composed of usual baryonic matter, but that emits very little to no radiation, making them extremely hard to detect through direct observational methods. These objects drift through interstellar space in the halos of galaxies, or in other words the outskirts of galaxies. These may sometimes be black holes, brown dwarfs, neutron stars or unassociated planets. The observations talked about earlier supports the existence of these MACHOs in the halos of galaxies. Other observations, just to mention one, is the fact that we observe what we call gravitational lensing (the bending of light by gravity) in front of stars or galaxies. MACHOs can account for this gravitational lensing that we observe, as they will bend light because of their gravity if they pass in front a radiating body.
And then we have the non-baryonic candidates for dark matter. We call these WIMPs (weakly interacting massive particles). We're not quite certain what these exotic types of particles are, and they are extremely hard to detect. They are hard to detect because 1), they do not interact through electromagnetism, making them invisible, and 2) they do not interact through the strong force and thus they do not interact strongly with atomic nuclei. They only interact through gravity and the weak force (for more about these fundamental forces, please ask or just google it). These are hypothetical particles, and as said we do not know much about what they really are, but we have some ideas; they might be electron-neutrinos, muons, taus, neutralinos and other light supersymmetic particles as we call them (LSPs).
Dark matter is believed to be partly these hypothetical WIMPs and the more easy-to-grasp MACHOs. Dark matter is all around us in the universe, and if neutrinos really are some of the dark matter in this universe, you have, every second, more than 60 billion of these things travel through every square centimeter of your body - in other words pretty damn much dark matter flowing through you all the time! Dark matter is the stuff that doesn't emit light, but that we know to be there, making up most of the known universe.
Hope this cleared up a little bit =)
As far as "ordinary" matter goes, the stuff of life, the stuff of stars and the stuff of the computer in front of you - it was thought until very recently that the universe consisted only of these types of particles; that is protons, neutrons and electrons, also just refered to as baryonic matter by astronomers and physicists (protons and neutrons are composite particles made up of three quarks, and we put them under the term baryons. These are the particles within the nucleus of the atom, thus making up most of the visible matter in the universe). What happened within astronomy that opened up the possibility for unseen matter?
It was the swiss astrophycisist Fritz Zwicky that first theorized about dark matter. In 1933 at the California Institute of Technology he observed that there had to be about 400 times the mass in the Coma cluster (large cluster of galaxies, over 1000 of them, approximately 321 million light years away from us) than he expected it to be or that it "should" have been. He reached this conclusion quite easy, observing that the relative speeds of the galaxies to eachother were far too great to be held together by the gravitational attraction by the observable matter alone. Thus he understood that there had to be more matter there, matter that couldn't be seen and that accounted for the missing gravitational attraction. Since he couldn't see this matter, he called it "invisible matter" or simply "dark matter" as it didn't emit light. Other (similar) discoveries sprang forth to further support this idea in the time following Zwicky's discovery.
For example, a woman named Vera Robin made another extraordinarly observation in 1950 that totally contradicted Newtons famous gravitational law. Newtons law of gravitation predicts that bodies orbiting far away from a center moves more slowly than bodies orbiting closer to that same center. This has to do with the fact that gravitational attraction between bodies varies inversely as the square of the distance between them. Just look at Pluto's orbit around the sun compared to that of, say, Mars. Anyway, by examining galactic light signatures Vera found that bodies orbiting at the outskirts of galaxies actually traveled at approximately the same speed as bodies orbiting closer to the center of a galaxy. For this to be possible, there had to be more matter in these galaxies than that which could be seen. The idea of dark matter become more and more clear.
Let's not dwell more into observational evidence (there is certainly more), but take a look at dark matter candidates. We talked earlier about the baryonic matter, the ordinary matter which we ourselves are made of. We have these dark matter candidates we call MACHOs (Massive compact halo objects) that might account for some of the dark matter we know to exist in the universe. It is a general name for any astronomical object that are composed of usual baryonic matter, but that emits very little to no radiation, making them extremely hard to detect through direct observational methods. These objects drift through interstellar space in the halos of galaxies, or in other words the outskirts of galaxies. These may sometimes be black holes, brown dwarfs, neutron stars or unassociated planets. The observations talked about earlier supports the existence of these MACHOs in the halos of galaxies. Other observations, just to mention one, is the fact that we observe what we call gravitational lensing (the bending of light by gravity) in front of stars or galaxies. MACHOs can account for this gravitational lensing that we observe, as they will bend light because of their gravity if they pass in front a radiating body.
And then we have the non-baryonic candidates for dark matter. We call these WIMPs (weakly interacting massive particles). We're not quite certain what these exotic types of particles are, and they are extremely hard to detect. They are hard to detect because 1), they do not interact through electromagnetism, making them invisible, and 2) they do not interact through the strong force and thus they do not interact strongly with atomic nuclei. They only interact through gravity and the weak force (for more about these fundamental forces, please ask or just google it). These are hypothetical particles, and as said we do not know much about what they really are, but we have some ideas; they might be electron-neutrinos, muons, taus, neutralinos and other light supersymmetic particles as we call them (LSPs).
Dark matter is believed to be partly these hypothetical WIMPs and the more easy-to-grasp MACHOs. Dark matter is all around us in the universe, and if neutrinos really are some of the dark matter in this universe, you have, every second, more than 60 billion of these things travel through every square centimeter of your body - in other words pretty damn much dark matter flowing through you all the time! Dark matter is the stuff that doesn't emit light, but that we know to be there, making up most of the known universe.
Hope this cleared up a little bit =)