No computer is capable of producing random numbers -- that's why they're called "pseudorandom." Particles are imbued with real randomness. It isn't that physical events are hard to predict; it's that they are impossible to predict. I can't tell if you're waxing philosophic, or asking a question, sorry. Again, I don't really know exactly what you're trying to ask. You yourself balk at the concept of personifying the universe; I balk equally at personifying particles. Make sure you call the Universe's complaint department and file a strong complaint. I'm going to say this again, exactly as I said it before: It is rather impossible to obtain, from the mathematics of quantum mechanics, an interpretation that "it is us humans that have the probability." Sorry. The particles DO have probability and indeterminism. Are you just going to keep asking the same questions over and over again, or what? It's a moot point, because you can't have perfect measurement; but even if you did, the uncertainty principle would still hold. The uncertainty principle is deeply ingrained in the mathematics of a particle's motion. By "wave graph" I assume you mean "interference pattern." Please at least attempt to use the scientific terms, so I'll know what you're talking about. It turns out that even if you only fire one photon at a time -- guess what? The interference pattern is still built up, exactly as if you fired a bunch of photons at once (except of course the pattern takes longer to become visible). Think about that for a minute. Please Register or Log in to view the hidden image! No, as I've said, the amplitude of a signal is the number of photons per unit time reaching your detector, regardless of their frequency. The only advantage to having a higher frequency station is that your photons act more like bullets, typically don't suffer as much from various forms of distortion, and therefore provide a cleaner signal to the receiver. - Warren
"It isn't that physical events are hard to predict; it's that they are impossible to predict." I think you mean that events are hard to predict with exact precision. As I see it, the impossibility of this comes solely from our inability to measure things exactly. Remember, impossible just means infinely hard, thus holding to my sentence. "You yourself balk at the concept of personifying the universe; I balk equally at personifying particles." I "balk" at personifying the universe in someones explanation of how it works. I don't have your expertise in either definitions or terms of how to explain it in my question. So Ill try again: Is there a finite number of possibilities that can happen to a particle? If there is, then what are they? I said: "So what randomness EXACTLY are we talking about?" Randomness of what? Movement? position? Force? What exactly are we saying is random? "It's a moot point, because you can't have perfect measurement; but even if you did, the uncertainty principle would still hold. " YES, you claim that even if you have perfect measurement, the uncertainty principle would still hold. WHEN WOULD this happen? Give me an example, as you so far have NOT done. "By "wave graph" I assume you mean "interference pattern." " No actually, I do NOT mean interference pattern. I was not talking about the double slit experiment or I would have used the scientific term. I am talking about the actual Visual representation of an electromagnetic wave. "The interference pattern is still built up, exactly as if you fired a bunch of photons at once " I know that. That is not what I was talking about. Have you ever seen a sinusoid? That is the type of graph usualy used to represent a wave. According to most people, waves have amplitude and wavelength. When I asked this question I was directly reffering to this sinusoidal graphical representation. If you have four peaks in the sinusoid, how many photons would have hit the detector?
Crisp: "Well, yes that's what a branch of modern theoretical physics is all about, and guess what, it works " Well, what I meant was that you cannot say the following and call it a scientific theory: "A human has a 70% probability of dying before age 60 -A molocule of plutonium has a 20% probability of decomposing after 1 year. -A photon has a 30% probabilty of hitting here rather than there." Note: those are not correct data, if anyone was wondering No, a theory has to be more fundemental than that. It has to explain WHY, at the molecular level, plutonium will decay and how that probability is determined by its subatomic structure. A statistics book is not a theory.
No, friend, I believe I say what I mean. It is impossible to predict exactly when a nucleus will decay, or an electron will emit a photon. Your question is not very direct, but I think you're asking about the different kinds of interactions. Each specific particle interacts through at least one of the four interactions. These interactions can lead to a lot of behaviors: attractions repulsions transmutations (i.e. that of gluons) decays emission of gauge bosons absorption of gauge bosons (and probably some more than I have forgotten) In QM, all observable are effectively random -- momentum, position, energy, time, etc. These quantities each follow a particular distribution, but measurements are random. For example, you can specify that a particle will have a momentum within a given range. However, there is no way to determine exactly which precise momentum you'll measure. The particle simply randomly chooses one possible momentum when observed. A particle can exist in several states at once -- this is QM's superposition principle -- but a measurement will show the particle to be in exactly one state, or exactly in the other. There is no experiment capable of showing the particle to be in both states simultaneously. QM provides a means to evaluate how frequently you'll find the particle in one state, versus the other. Do you want an example of the math itself? As I've said, understanding such an example will require you to obtain a fairly high degree of mathematical sophistication. While I'd love to teach you, both our time may be better spent if you go purchase a texbook and learn the mathematics there. I can make several suggestions, if you'd like, and will be glad to help you with any problems you encounter in your reading. My apologies for misunderstaning you. There is no "visual representation of an electromagnetic wave." They do. There is unfortunately no such representation for photons. It's just not valid. There is no experiment which will show a photon as "four peaks" of a sinusoid, on any kind of detector. - Warren
Who says such a theory is not acceptable? You? The scary, unfortunate truth is that there is no more fundamental level. There is no way to predict when a free electron will emit a photon, except statistically. It just happens when it happens. We can see experimentally, and prove mathematically, that the electron cannot have any deeper structure. It is truly fundamental. It has no internal watchworks that make it emit a photon at a particular time. You continue to strive for a classical picture of the subatomic world, with precise, deterministic behavior and precise visual concepts and so on. Everyone, when learning QM, seeks those kinds of pictures. Unfortunately, such pictures just don't exist. The nature of very small things troubles many people. Einstein himself never fully believed in QM, and said "God does not play dice." As I've said before, he didn't have the benefit of the last 100 years of particle experiments. You're welcome to come to your own conclusions about the subatomic world -- but the only conclusion currently known that agrees with all experimental evidence is that which I've been explaining to you for weeks. - Warren
In principle I must agree that Frencheneesz is correct. A theory tells us why we get results (statistics). And the results can then support the theory.
i cant believe this thread is still going on. chroot: how about the advantage of higher bandwidth for digital data on higher frequncy stations? i would see that as an advantage.
There is no relationship between bandwidth and frequency. Bandwidth is bandwidth. However, it's easier to design large-bandwidth radio devices at high frequencies, because a constant percentage of the frequency (i.e what filters will give you) equates to a larger bandwidth at higher frequencies. - Warren
okay, my bad. i know bandwidth was the wrong term here, i know what bandwidth is. what i meant was, "isn't there more information carrying ability for digital at a higher frequncy?" but this is probably going to end up as some complex discussion about how much bandwidth is required ect...
The length of football field is measured in units of length -- so is the wavelength of visible light. Is there a relationship between football fields and photons? - Warren
No. First, you pick a center frequency, say, 105.3 MHz (my favorite FM station here in the bay area). The bandwidth of an FM transmission lies symmetrically around the center frequency. In the case of American standard commerical radio, the bandwidth is specified to be 200kHz. The bandwidth is selected based on how much information you need to transmit. It is selected independently of the center frequency. - Warren
Chroot: Since I have not read all of the posts to this thread, I cannot be sure, but from what I have read, you seem to be the only one here who knows anything about Quantum Theory. It seems to me that many do not even know much about classical physics. You have been incredibly patient with Frencheneesz. Due to you as a role model, I will not be as nasty and critical as I might have been. Being slightly drunk after an excellent dinner, fine wine, and some Irish Cream liquor in my coffee might also be responsible for my mellow mood. Some drunks are sad & depressed, some are nasty & looking for a fight. I am a pleasant, happy drunk. Frencheneesz: You are lacking any understanding of Quantum theory and the Uncertainty Principle, and you do not seem to pay attention to what is posted. Let me start explaining some concepts you seem to be unaware of. First and foremost, Physics answers questions like It never answers questions like BTW: Radioactive decay is a nuclear phenomenon, not a molecular one. Furthermore, there is no explanation for why it decays. There is no way to determine the time of decay of a particular nucleus based on the nuclear structure. The probability has been measured and we know which nuclei decay and which are stable. Beyond that, we know little and do not expect to learn more. Decay obeys the laws of probability, and is not deterministic. See below for a more thorough description of radioactive decay, an understanding of which gives a lot of insight into Quantum physics. Next: As hard as it is to live with, all the experimental evidence indicates that the universe is not deterministic, not even in principle. At a fundamental level, it obeys laws of probability and statistics. Our modern theories are statistical and probabilistic. Radioactive decay and other Quantum based phenomena are random processes. Since the classical physics world of our senses is fundamentally based on Quantum World phenomena, it too is based on probability and statistics, not on deterministic laws. It only seems deterministic due to the incredible number of Quantum entities involved in macroscopic processes. If every gambler who went to a casino could roll the dice 10<sup>23</sup> times in a few seconds, every gambler would lose at the same very precise rate. No gambler would ever win. It would look like a fundamental law because nobody would be able to analyze the individual dice throws, but the results of a second or more of play would be precisely predictable. There is every reason to believe that even simple classical world events like dice throws are truly random processes, since they are based on Quantum events governed by probability. The questions you ask indicate that you do not really understand what the Uncertainty Principle is claiming. It is stating that Quantum particles (even atoms) do not have a precise position, and that they do not have a precise momentum (or velocity). It is not claiming that there is some practical problem preventing precise measurements. If you read and think about Bose-Einstein condensates, you might get some understanding of the Uncertainty Principle. You also seem to misunderstand the wave/particle duality of light and various other Quantum processes. If you set up an experiment to measure wave properties, light seems to act like a wave phenomenon. If you set up to measure particle properties, it seems to behave like a particle phenomenon. When dealing with the wave experiments, you have wavelength and amplitude, with the wavelength inversely related to the frequency. When dealing with particle experiments you have energy per photon and number of photons. The energy per photon is related to the frequency, and the number of photons is related to the amplitude. For visible light, energy per photon (particle view) and frequency (wave view) are related to the observed color. Number of photons (particle view) and amplitude (wave view) are related to brightness (or strength of signal for radio transmission). When Niels Bohr was asked what light was, instead of answering directly, he described a well know optical illusion. The illusion can be seen as a black vase or two white profiles facing each other. It cannot be seen as both simultaneously. It is directly analogous to wave/particle experiments with light & other Quantum entities. You can measure wave properties or particles properties, but never both in the same experiment. If asked what was really there, Bohr would answer “Black ink on white paper.” In a profound manner, he was answering the question about light. It is neither a wave nor a particle. Those are human interpretations of what is measured by our experiments. Our views and interpretations are biased by our familiarity with the classical world of our senses. We can neither visualize nor comprehend what goes on at the Quantum level. The most we can do is a good job of predicting what measurements and classical world effects will result from certain activities. The Quantum World behaves in a manner contrary to our intuition and common sense. Until you realize that & stop trying to make it conform to your intuition, you will forever misunderstand. Niles Bohr once said something like the following. BTW: he was not making a joke. Consideration of radioactive decay provides an insight into some aspects of the Quantum World. Have you ever wondered why the half life of a radioactive material is specified, but never the whole life? It would make sense to specify the quarter life or 90% life, but never the whole life. To understand this, Consider an incredible number of radioactive nuclei like 32*10<sup>23</sup>, which is about one kilogram of material. If the material has a half life of 10 minutes, it means that after 10 minutes 16*10<sup>23</sup> nuclei have decayed, and the same number remain. After 20 minutes, 8*10<sup>23</sup> remain, and so on. Half the nuclei decay every 10 minutes. Now suppose you had one atom of this material. In 10 minutes, there is a 50-50 chance that it would have decayed, and a 50-50 chance that it would not. In 20 minutes, the odds are 3 to 1 that it would have decayed. In 30 minutes there is once chance in 8 that it has not decayed. In several hours, there is a very small probability that it has not yet decayed. This is exactly the mathematics one would expect if you were flipping true coins with a 50-50 chance of heads (decay) or tails (no decay). This is compelling evidence that radioactive decay is a random phenomenon. Similarly, other Quantum processes obey the laws of probability and statistics, rather than obeying deterministic laws. While it is hard to comprehend, physics obeys probabilistic or statistical laws rather than deterministic ones. When I first learned this, it bothered me. I have since consoled myself with the thought that free will cannot exist in a deterministic universe, but it might be possible in a more capricious universe governed by probability & statistics. BTW: Prior to about 1900, physicists believed in a universe which was in principle deterministic. Quantum theory refutes that notion. Oddly enough, Relativity & chaos theories indicate that it is impossible (even in principle) to predict the future accurately. Relativity states that we cannot know what is now happening on Alphas Centauri for another 4 years. Yet due to chaos theory, events there could have an effect on our future. Hence, even if the universe obeyed deterministic laws and we had the computer power (silly assumption, anyway) to apply them, we could not collect the necessary input data.
Dinosour: Thank you for your essay. It has actually helped me understand the light thing clearly, yet the entire essay assumes that I am some kind of idiot. "It [science] never answers questions like: "Why does it work that way? Why is gravity attractive instead of repulsive? Why does Plutonium decay?"" Actually it does. You may not realize it, but we do not know everything. We do not know why gravity is attractive, yet this does not meant that it is the end of the story. We may yet find out later why. Science is all about why. "Radioactive decay is a nuclear phenomenon, not a molecular one. " Excellent, write a dictionary. "Furthermore, there is no explanation for why it decays. There is no way to determine the time of decay of a particular nucleus based on the nuclear structure." How do you know this? Why MUST there be no way to predict it. Isn't it plausible that we just do not have the capability to probe inside the nucleus without destroying the atom? "Beyond that, we know little and do not expect to learn more. " So you are saying we know everything..... "Decay obeys the laws of probability, and is not deterministic." Everything obeys the laws of probability, because probability is determined by everything. Its circular logic. 'Our modern theories are statistical and probabilistic. " Statistsics are extremely practical when it come to predicting things that we cannot fully anylize, such as the working of an atomic nucleus. Yet I think it is a little much to say that just because we cannot observe the reasons under the probability, there is no reasons at all. "If every gambler who went to a casino could roll the dice 10^23 times in a few seconds, every gambler would lose at the same very precise rate. " If an infinite number of gamblers rolled 10^23 times, one of them (or more mathmatically, an infinite number) would win 10^23 times, thus defying your example. "It is stating that Quantum particles (even atoms) do not have a precise position, and that they do not have a precise momentum (or velocity). " You obviously have a strong lacking of reading comprehension skills. I am arguing against this statement, therefore I have to have understood that that is what it WAS stating. "It is not claiming that there is some practical problem preventing precise measurements." I realize that, that is what I am claiming.... You cannot have a perfect measurement, just like in math you cannot find the number that is closest to zero and you can't find infinity. "The illusion can be seen as a black vase or two white profiles facing each other. It cannot be seen as both simultaneously. It is directly analogous to wave/particle experiments with light & other Quantum entities. " They have little to zero relation to eachother. One has to do with the pattern recognization and outline distinguishment of the human mind. A "wave" and a "particle" is not a property of matter. You cannot measure how much of a wave something is or how much of a particle. Matter is matter, waves and particles are asthetic labels for our human brain that always likes to categorize things. "We can neither visualize nor comprehend what goes on at the Quantum level. " Bullshit, where is your proof. Never say never.... "Similarly, other Quantum processes obey the laws of probability and statistics, rather than obeying deterministic laws. " Thank you for the riveting explanation of half-life: a middle school concept. This sound very much to me like a "life-force" discussion. Sure, all you religious people can say there is a life force, but we athiests know that the deterministic laws give us reasons why life works. In my VERY strong opinion, statistics are NOT laws. Laws are meant to describe the statistics. The deterministic laws of the universe would be able to explain the probabilities if we had them. "I have since consoled myself with the thought that free will cannot exist in a deterministic universe, but it might be possible in a more capricious universe governed by probability & statistics. " I don't believe in free will.
