The Universe
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Infiltrator
Member # 4256
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written Monday, March 21 2005 10:12
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The other two are the nuclear Weak force and the nuclear strong force. Since the writing of that book the Electro-Magnetic force has been combined with the Nuclear Weak force and is now called the Electro-Weak force. Here is a brief wiki explaining this a little without the mathmatics. quote:I like this analogy, especially as it suggest some things. The mass of the balls is not the only thing that affects the steepness of the "well" produced. The "stretchability" of the rubber also affects it. With gravity(or E&M) the "stretchability" perhaps seems comparable to permittivity. Though no known variations in the permittivity of gravity exist(i.e. you can't block gravity) it is difficult to say that the it was the same at a singularity. -on a minor side note, here is a parody of this subject that I found mildly amuzing. Posts: 564 | Registered: Wednesday, April 14 2004 07:00 |
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Shock Trooper
Member # 3980
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written Monday, March 21 2005 12:40
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With all the beauty of electroweak unification and the standard model we should not forget that in all of cosmology we are dealing with extrapolations in time and space - being very happy whenever we have found some other new observation that fits in and which allows to narrow down the limits on previously assumed "confidence" intervals for physical constants. Close to the big bang singularity there were energy densities that we cannot reproduce in present supercolliders and there may have been additional interactions or forms of matter. Our concepts of space and time are not garanteed to hold there at all. We have to live with these horizons in time and space. They allow a lot of entertaining speculations and provide jobs for scientists. Explanations of observable astronomical features would be slightly more to my taste, however, e.g. what is the mechanism that gives rise to spiral arms of galaxies? What is the effect of the delay in the gravity interaction due to the large distances? How come the sky is dark at night and what can we conclude from this? Posts: 311 | Registered: Friday, February 13 2004 08:00 |
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Electric Sheep One
Member # 3431
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written Wednesday, March 23 2005 18:46
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Usually the only reason anyone asks why the night sky is dark is that they know the answer; most people don't even realize it's at all hard to understand why the night sky is dark. The sky is dark at night because the universe is not eternal, but began a finite time ago. The portion of the universe from which light has had time to reach us is thus finite. If this were not so, then in every direction in the night sky there would surely be a star shining on us, however far away, and so there would be no dark spaces visible between stars. But in any finite volume of space, the stars just have to be scattered thinly enough for the sky to look mainly black. And in fact they sure are scattered thinly. The ongoing expansion of the universe enhances this basic effect by stretching light waves from distant stars so that their wavelength grows beyond the visible range. One trouble with the 'rubber sheet' image for gravity is that in Einstein's theory it is spacetime that bends and stretches, not just 3D space. In fact, in most cases the bending of space is negligible, and it is the varying rate at which time flows in different places that produces the effect we usually think of as gravity. If anyone still cares I can also try to answer questions about the Hawking effect. I'm supposed to know this stuff. [ Wednesday, March 23, 2005 18:51: Message edited by: Student of Trinity ] -------------------- It is not enough to discover how things seem to seem. We must discover how things really seem. Posts: 3335 | Registered: Thursday, September 4 2003 07:00 |
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Warrior
Member # 5619
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written Wednesday, March 23 2005 20:18
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When Stephen Hawkin Say "multiple universe" did he mean different dimension? -------------------- If you fail to plan, you plan to fail. Posts: 90 | Registered: Wednesday, March 23 2005 08:00 |
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Shock Trooper
Member # 4214
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written Wednesday, March 23 2005 23:05
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He meant, if I am correct, that he believed that there were multiple four-dimensional places in the multiverse. I most-probably misinterpreted his theory. If not, it is, in my insight, nonsensical. [ Thursday, March 24, 2005 03:57: Message edited by: Mind ] Posts: 356 | Registered: Tuesday, April 6 2004 07:00 |
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Electric Sheep One
Member # 3431
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written Thursday, March 24 2005 05:43
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The word 'dimension' is sometimes used in popular speech to mean something like 'alternate universe', but the term 'dimension' is never used for that concept in physics. Physics theories about having more than three dimensions in space really do mean that there are extra directions to go in, not that there are alternative 'planes of existence' or whatever. But there are respectable physics theories about multiple or alternate universes. This can be in two senses. The first is the sense of the so-called 'many worlds' interpretation of quantum mechanics, in which one supposes that the incompatible alternatives which may be 'superposed' in quantum mechanics all actually exist, in separate versions of reality. Rival interpretations, such as the so-called 'Copenhagen' school of thought, say instead that there is only one reality, but that quantum mechanics doesn't always predict which alternative will actually happen. The second is the sense Mind mentions, of one reality that includes multiple separate universes. There are theories that allow this, that have nothing to do with quantum mechanics. Imagine a bunch of beachballs drifting separately through the air, with ants living on their 2D surfaces. Now if your imagination could replace each of these 2D surfaces with a 3D world, you would have a picture of multiple universes. In both quantum and non-quantum versions of multiple worlds, it is possible for single worlds to divide and for separate worlds to recombine. In the quantum version, it would be a big, all-or-nothing melding of everything in the universe at once (though you might never notice it because the initial difference between the merging worlds might be very tiny and localized). In the non-quantum version, a wormhole would appear somewhere in each universe, connecting to the other one. I believe that the quantum cosmology theories that Hawking has formulated incorporate both kinds of multiplicity of universes -- though for the quantum multiplicity it is still just a matter of personal taste whether one believes or not that the quantum alternatives all actually exist. Of course, the whole thing is just a very speculative theory, and in that sense it's up to you whether or not to believe any of it. Hawking's quantum cosmology has not been accepted, or even considered plausible, by many of his colleagues. I'm just pointing out that even in itself his cosmological theory does not imply any particular commitment for or against the many worlds interpretation of quantum mechanics. That's a separate issue, bigger than cosmology, but even further from physics and closer to metaphysics. -------------------- It is not enough to discover how things seem to seem. We must discover how things really seem. Posts: 3335 | Registered: Thursday, September 4 2003 07:00 |
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Shock Trooper
Member # 4214
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written Thursday, March 24 2005 06:27
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I still haven't heard of any indication that Stephen Hawkings theory is correct. Posts: 356 | Registered: Tuesday, April 6 2004 07:00 |
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...b10010b...
Member # 869
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written Thursday, March 24 2005 12:32
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The only sort of evidence for models in theoretical physics is that the mathematical predictions generally fit our observations slightly better. I repeat: that is the *only* justification for *any* of the various variations of theoretical physics over any of the others. If you want to look at most of the theoretical constructs directly, you're going to be disappointed -- the best they've managed is a handful of trails in particle accelerators that they believe correspond to new kinds of particle. -------------------- My BoE Page Bandwagons are fun! Roots Hunted! Posts: 9973 | Registered: Saturday, March 30 2002 08:00 |
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Electric Sheep One
Member # 3431
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written Thursday, March 24 2005 12:53
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Which of Hawking's theories do you ask about? Quantum radiance from black holes -- the 'Hawking effect' -- is of course his main claim to fame; though he was already famous before that for his singularity theorems in general relativity. There is no shred of evidence for the Hawking effect. This is not evidence against it, but still, Hawking isn't going to get a Nobel prize for it, because it's too far removed from observation or experiment. Why people rave about the Hawking effect, though, is that it implies a deep connection between gravity, quantum mechanics, and thermodynamics, which are the pillars of creation, but which have always seemed completely independent apart from Hawking's calculation. So it's the kind of thing that people think should be true, if the universe is at least as cool was we can imagine it to be. On the other hand, Hawking's calculation includes one step that has always seemed rather doubtful, so even as pure theory it remains a bit up in the air. I believe it's fair to say the consensus is that he is probably right, but that his case is not yet proven even given the assumption that our current theories are on the right track. About Thuryl's contention that theoretical physics is rarely directly verifiable, I'd agree except for the adjective 'slightly'. Accepted theories simply fit the observations better, but I don't know of any cases where the accepted theory works only slightly better. It's generally night-and-day, bang-on versus way off. Or else the theory is not considered a serious contender. There are theories for which there is no relevant data available, and theories which currently offer only predictions that are badly wrong, but which seem to have potential for eventual improvement. String theory remains in both of these latter categories, as it has for about forty years, despite regular waves of hype to the effect that a breakthrough will soon be at hand. -------------------- It is not enough to discover how things seem to seem. We must discover how things really seem. Posts: 3335 | Registered: Thursday, September 4 2003 07:00 |
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Warrior
Member # 5619
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written Friday, March 25 2005 16:09
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I think I found the answer you guy. Try to find and read the book call "Timeline" by Michael Crichton. -------------------- If you fail to plan, you plan to fail. Posts: 90 | Registered: Wednesday, March 23 2005 08:00 |
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The Establishment
Member # 6
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written Friday, March 25 2005 16:26
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Timeline is an okay book, but it will not answer any of the deeper questions here. It is merely fiction based upon conjectural things. I say, read it if you have a few spare evenings, but for entertainment purposes only. -------------------- Your flower power is no match for my glower power!! Posts: 3726 | Registered: Tuesday, September 18 2001 07:00 |
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...b10010b...
Member # 869
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written Friday, March 25 2005 16:31
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quote:Okay, I should probably rephrase myself. Different theoretical physical models fit our observations much better than each other in some ways and much worse in others. In general, any given model will explain a few things really conveniently and stumble badly on a few others. -------------------- My BoE Page Bandwagons are fun! Roots Hunted! Posts: 9973 | Registered: Saturday, March 30 2002 08:00 |
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BoE Posse
Member # 112
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written Friday, March 25 2005 18:59
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Just an interesting thought here. Matter can be converted into energy and vice versa (at least in theory). Now consider a ball that has been thrown. It has kinetic energy. Therefore the ball and its movement through the air are in fact the same kind of thing in different forms. -------------------- Rate my scenarios! Areni Revenge To Live in Fear Deadly Goblins Ugantan Nightmare Isle of Boredom Posts: 1423 | Registered: Sunday, October 7 2001 07:00 |
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...b10010b...
Member # 869
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written Friday, March 25 2005 20:15
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What I find even more interesting is that no matter how fast the ball is thrown, the mass-energy locked up inside it will be many, many orders of magnitude higher than its kinetic energy, even though the latter is the only thing we normally observe. -------------------- My BoE Page Bandwagons are fun! Roots Hunted! Posts: 9973 | Registered: Saturday, March 30 2002 08:00 |
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Triad Mage
Member # 7
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written Saturday, March 26 2005 01:41
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It's not converting matter into energy - it's converting the ball's energy into a different form of energy, from potential to kinetic. -------------------- "At times discretion should be thrown aside, and with the foolish we should play the fool." - Menander ==== Drakefyre's Demesne - Happy Happy Joy Joy desperance.net - We're Everywhere ==== You can take my Mac when you pry my cold, dead fingers off the mouse! Posts: 9436 | Registered: Wednesday, September 19 2001 07:00 |
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...b10010b...
Member # 869
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written Saturday, March 26 2005 01:48
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Actually, the energy you give to a ball by throwing it comes from the chemical potential energy in the muscles of your arm. -------------------- My BoE Page Bandwagons are fun! Roots Hunted! Posts: 9973 | Registered: Saturday, March 30 2002 08:00 |
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Triad Mage
Member # 7
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written Saturday, March 26 2005 02:00
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That's true. I just wasn't thinking. -------------------- "At times discretion should be thrown aside, and with the foolish we should play the fool." - Menander ==== Drakefyre's Demesne - Happy Happy Joy Joy desperance.net - We're Everywhere ==== You can take my Mac when you pry my cold, dead fingers off the mouse! Posts: 9436 | Registered: Wednesday, September 19 2001 07:00 |
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Electric Sheep One
Member # 3431
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written Saturday, March 26 2005 05:24
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Actually the whole point of physics is that it isn't good enough for a theory to work only for some things and not for others. The standard is to just work, period. How far this standard is actually met depends on what you recognize as a 'theory', as opposed on the one hand to 'speculative hypothesis', and on the other hand to 'approximation to the full theory'. In the strictest sense there are only two theories in physics today: Quantum Field Theory with the so-called 'Standard Model' of particles and interactions, and General Relativity. And it is sad to confess that for these theories, Thuryl is quite right. General Relativity is great for gravity, but says nothing much about anything else. Quantum Field Theory works wonderfully well for everything else, but says nothing intelligible about gravity. What I don't think is right is to take from Thuryl's remarks the impression that theoretical physics is a disparate collection of ad hoc theories, each of which is only good for its specific problem. That is totally not so, and moreover it is the very foundation of physics, and thus the cornerstone of natural science, that it not be so. The one true faith of physics is that nature is one, and that one theory must govern all. And although this dream is not yet perfectly realized, it is already realized to an amazing extent. There are no rival schools of thought in physics. Disagreements among physicists are almost always, ultimately, disagreements about arithmetic. As such, they are eventually resolved by one or both sides confessing error -- and the time scale for 'eventually' is a matter of years at most, not decades or centuries. The only other disagreements are those that prove to be independent of quantitative equations -- like the interpretation of quantum mechanics. This independence also becomes clear within a matter of years, and the whole issue then gets reclassified as personal philosophy, and ceases to be recognized as physics. Finally, specialization among physicists is actually much less extreme than one might think. Any trained theoretical physicist can explain to any other what they are doing, within at most a few hours, because we all share the same common theoretical base. -------------------- It is not enough to discover how things seem to seem. We must discover how things really seem. Posts: 3335 | Registered: Thursday, September 4 2003 07:00 |
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...b10010b...
Member # 869
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written Saturday, March 26 2005 13:43
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I don't think we're actually disagreeing; I'm sorry if I'm giving the wrong impression. All I'm saying is that theoretical physics is still pretty rough around the edges, and the fact that we can't find a consistent theory to explain every phenomenon is a serious problem. (For example, as far as I know, there's no single physical model or consistent set of physical models to satisfyingly explain every observed gamma-ray burst). -------------------- My BoE Page Bandwagons are fun! Roots Hunted! Posts: 9973 | Registered: Saturday, March 30 2002 08:00 |
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Electric Sheep One
Member # 3431
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written Saturday, March 26 2005 18:31
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Yeah, them darned GRBs. All the bets are that they'll turn out not to be anything fundamentally revolutionary. But the jury is indeed still out. The main thing I learned from teaching astronomy for the first time this past fall was that we still have no idea how any astronomical magnetic fields are generated -- not even Earth's. Oh, the basic ingredients are there -- conductors and rotation and some general swirling around -- but all the models anyone has thought of for exactly how it works out have glaring problems. So there remains a certain role for the Seuss effect: Funny things are everywhere. -------------------- It is not enough to discover how things seem to seem. We must discover how things really seem. Posts: 3335 | Registered: Thursday, September 4 2003 07:00 |
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Shock Trooper
Member # 4214
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written Monday, March 28 2005 23:58
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I mistrust the trustworthiness of the bizarre quantum mechanics. A book I am reading says that subatomic particles which have the absolute speed have no mass. Thus, they actually do not exist. Can someone help this confused fool? [ Tuesday, March 29, 2005 01:23: Message edited by: Mind ] Posts: 356 | Registered: Tuesday, April 6 2004 07:00 |
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Triad Mage
Member # 7
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written Tuesday, March 29 2005 01:00
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Fire and heat have no mass. Do they exist? Light has no mass. Does light exist? -------------------- "At times discretion should be thrown aside, and with the foolish we should play the fool." - Menander ==== Drakefyre's Demesne - Happy Happy Joy Joy desperance.net - We're Everywhere ==== You can take my Mac when you pry my cold, dead fingers off the mouse! Posts: 9436 | Registered: Wednesday, September 19 2001 07:00 |
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Shock Trooper
Member # 4214
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written Tuesday, March 29 2005 01:22
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Heat doesn't consist of particles. It is, as I said, the vibration of molecules. Light consists of subatomic particles. More specifically, photons. This theory has been considered scientifically proven. [ Tuesday, March 29, 2005 02:06: Message edited by: Mind ] Posts: 356 | Registered: Tuesday, April 6 2004 07:00 |
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Triad Mage
Member # 7
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written Tuesday, March 29 2005 02:02
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Heat is more than the vibration of molecules. That is an overly simplistic viewpoint. Making bonds releases energy, usually in the form of heat or light. Heat can also be in the form of radiation (like from sunlight). It's much more than vibrating molecules. Light has both wave and particle form. Photons can also be perceived as both waves and particles. -------------------- "At times discretion should be thrown aside, and with the foolish we should play the fool." - Menander ==== Drakefyre's Demesne - Happy Happy Joy Joy desperance.net - We're Everywhere ==== You can take my Mac when you pry my cold, dead fingers off the mouse! Posts: 9436 | Registered: Wednesday, September 19 2001 07:00 |
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Shock Trooper
Member # 4214
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written Tuesday, March 29 2005 03:11
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The fact that warmth has many forms does not disprove that it is the vibration of molecules. Explain yourself, instead of constantly and laconically claiming that I'm wrong. I, who am, should you have forgotten, still a puny child, can not learn from my mistakes if they are not even corrected. If warmth isn't the vibration of molecules, then how do you explain the absolute zero-point, being -273,15 degrees Celsius? If warmth was not the vibration of molecules, there would be no absolute zero-point. Light behaves as a wave, because photons can be reflected by other particles. [ Tuesday, March 29, 2005 03:53: Message edited by: Mind ] Posts: 356 | Registered: Tuesday, April 6 2004 07:00 |