heisenbourgs   uncertainty  principle....why?
103137
To detect something, you have to observe that something has interacted with it.  In Heisenberg's Uncertainty Principle, that "something" is a photon.  As a spinoff of the quantized nature of reality at that small level, you can measure THIS with precision, only by losing precision on THAT: the commonest pairing is change in energy times duration, dE and dt.  In this case, dt*dE has to be on the order of Planck's Constant--this being the classical statement of Heisenberg's Uncertainty Principle.\n\nIf I may offer a simplistic example...  With a photograph, you can only record things on the image that are at least the size of the "grain" of the dye on the film.  Smaller things will disappear, or their color will be blurred in with things near by.  (In CT/MRI technology, we say that the volume element averages anything in it with all else in it)  The grain size limits your ability to see the small stuff, and if you can detect it (by a bit of fancy guesswork in color distortions of nearby 'grains') you're going to be left with increased doubt about its actual color.\n\nThe Heisenberg's Uncertainty Principle is a lot more complex than that--it's a very sloppy analogy!--but I hope that it helps.
64985
Quantum Theory, also quantum mechanics, in physics, a theory based on using the concept of the quantum unit to describe the dynamic properties of subatomic particles and the interactions of matter and radiation. The foundation was laid by the German physicist Max Planck, who postulated in 1900 that energy can be emitted or absorbed by matter only in small, discrete units called quanta. Also fundamental to the development of quantum mechanics was the uncertainty principle, formulated by the German physicist Werner Heisenberg in 1927, which states that the position and momentum of a subatomic particle cannot be specified simultaneously.
189103
im not sure if i know what youre asking. but from what i understand from my QM class, for question 1 youre right. as in the double slit experiment. when they shot electrons at it, there was a wave pattern on the screen but when they watched the slitz there wasnt. the whole thing behind this is tht by watching it, they changed somethin in the situation and cause it to be just a particle pattern. so in theory if there was an infinitely efficient watcher, then thye could see that the elctron goes through both slits and makes a wave.\nthe 2nd question, the whole theory about quantum mechanics is that nothing is definite. its a probability distribution for everything. but just some items   have a 100% probability of being in 1 spot. as in say you have a pen in your hand   then the pen has a 100% probability of being in your hand and 0% everywhere else. but for an electron, you cant see it and since it wont stop moving  there is a different probability for it. theres a probability of say 40% of the electron being over there and 60% of it being here. or somethin. and i dont know what the earthquake thing meant. but i guess the probability distribution they calculated did a really bad job and the QM probability theory could also have done a really really bad job but nobody would know since electrons cant be measured yet (i think)
277032
I assume you are talking about any wave equation, not just a QM probability density function.\n\nIn any case, what do you mean that you have a "different x for every instant t"?  That is not the case.  I suspect you are thinking of travelling along with the crest or trough of a wave.  As t changes, the location of the crest and trough changes, but that is not the only location on the wave.\n\nWhat the wave equation specifies is the magnitude of the wave at *any* location x, at any time t.  So, if you are at a constant location x', the magnitude of the wave will vary periodically in time at that location. If you were a cork on the water, you would bob up and down at your location as the waves passed you. But similarly, if we were to somehow freeze time, and travel up and down our x axis, the magnitude of the wave would vary periodically in space as well.  So now, rather than a cork bobbing on the water, imagine you're on a jet ski that is going across the water so fast, compared to the speed of the waves, that it's almost like the waves aren't moving.  Yet you bob up and down as you cross the waves that lie in your path in space.\n\nHence, the wave varies both in x and t, independently.
847615
Heisenbergs uncertainty principle states we cannot tell where any electron is at any given moment.
68214
zero-point energy is one of the most widely misunderstood concepts of quantum mechanics.  all it says is that space has fluctuations of non-zero energy at a temperature of absolute zero.  the casimir force, which is a measurable effect, can be modeled as a consequence of zero-point energy, but it's essentially the same thing as the van der waals interaction - also a consequence of quantum fluctuations.  \n\nthese fluctuations do physically exist but are not 'harnessable' any more than the random thermal fluctuations of matter at non-zero temperature.  at least, the 2nd law of thermodynamics says it is so - any technology that did such a thing would overturn hundreds of years of evidence for the validity of the 2nd law.  i for one am not holding my breath.\n\ndon't let the crackpots confuse you with their nonsense.
656145
Originally, it was a "fudge factor" that Planck used to explain certain phenomena in physics.\n\nAs we have matured in our understanding, it turns out to be a fundamental concept in quantum physics--don't recall its exact value, but it relates the energy of a quantum to its frequency.\n\nBelieve me, this is one TOTALLY horrible oversimplification of things, but it has a good deal of the basics...  OK, a little of the basics...
15904
Probably not.  There are several problems\n\n1) because of the Heizenberg(sp?) uncertainty principle to learn of the exact direction of an atom one would change it's original direction.\n\n2) even if we could know a priori all that information it would require a simulation machine the size of the universe to calculate everything exactly.\n\n3)  I think there are still events of randomness at the atomic level that cannot be predicted.
903526
I dont know what dead time is. If you took multiple data points the uncertainty can be related to the statisitcal variance or standard deviation of your data. Maybe you are refering to Heisenberg uncertainty principle where:\ndelta E * delta t greater than or equal to hbar/2
820204
under quantum mechanics...\nit's a thought experiment, called the EPR paradox...\nthis paradox is more severe or seious than schroedinger's cat paradox...\n\nquantum mechanics says that a motion of a particle can be deermined by its wave function, thus the results of an experiment or probabilities or predictions...\n\nbut E, P and R thought that this is true only with statistical distributions of the particles tested by the experiment (the properties of particles)...
475479
here's my guess --\nthat these particles are somehow "connected" . that they do not violate casuality (this one is proveable) or locality....somehow.
1093639
What meant Indeed ?\n\nIt is not a easy question. This question was originally highlighted by Niels Bohr in the Copenhagen interpretation, where a system stops being a superposition of states and becomes either one or the other when an observation takes place. This makes apparent the fact that the nature of measurement, or observation, is not well defined. In other words we can measure position, but not the velocity or we can measure velocity, but not the position. \n\nI did mention Schrödinger's cat did not I? The Schrödinger's cat paradox suggests that by the act of quantum measurement we are destroying the object of measurement and hopefully not before we obtain one particular property. \nhttp://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat  \n\nSo by ‘measurement’ in QM we mean “In classical physics the mathematical model talks about the things we observe. In QM the mathematical model by itself never produces observations. We must interpret the wave function in order to relate it to experimental observations.” http://www.mtnmath.com/faq/meas-qm-2.html   \n\nI hope that tickles you, but I suspect you knew the answer.
664927
First, can a subatomic particle appear to be in two places at once?\n\nAccording to Quantum Theory, the answer is yes, because in order to know where a particle is, we have to measure its position, but the very act of measuring its position will alter the particle's behavior. So in effect we can never be sure where it is exactly. So in this sense, we may get measurements that give results that says the particle is here and there (this is the Uncertainty Principle).\n\nOf course, this is NOT new to quantum theory. So what's new? Someone mentioned "quantum entanglement" and "quantum teleportation". These are some of the new topics in quantum theory.\n\nPS - there is no such thing as Aether quantum dynamics or\n Auto dynamics, and Bohr's quantum mechanics is alive and well. The only addition we've added to Bohr's theory is the concept of electron cloud (i.e. a probability cloud) around the nucleus of an atom rather than electron orbits.
634237
Ok here is my best explanation of the problem. The Schroedinger's Cat paradox is meant to try and disprove the Uncertainty Principle. This principle stats that particles do not actually have one set state, that they hover in limbo until you observe them. Therefore Schroedinger stated that since you cannot know if the particle decayed until you look does that mean that the cat is in a state or being both alive and dead since the particles decay directly affects the cats life. \n\nThe way I interpret this, being that I believe completely in the quantum theory is that a human need not be the observer once the particle is measured in any way it decides on a state and occupies it. Since the whole cotnraption is dependent on the state of the particle the particle is being measured. During this measurement the particle will "decide" whether it is going to decay or not, and the cat will be affected justly. It doesnt matter that no human has observed it the act of measuring its decay is enough to cause it to shake out of the murky non state and assume a definate state. I hope that helped
967856
They're both right. To the limits of our ability to measure relativistic effects, they confirm the theory. Of course we can't measure anything with absolute precision, and that's where Heisenberg's Uncertainty Principle comes in. \n\nThe uncertainty principle states that either a body's position or momentum (state of motion) can be measured to an arbitrary degree of accuracy, but not both at the same time. In fact, the more accurate one measurement becomes the less accurate will be the other. \n\nThis is rather obvious, since if you have an exact position for something it's like one frame in a movie, so you have no idea how fast it's moving or in what direction at that instant. Conversely, the longer you observe an object in motion the better idea you have of its momentum, but to acquire this information the position of the object has to change.\n\nUncertainty usually applies to quantum mechanics but the principle applies everywhere. The biggest problem physics faces today is the fact that quantum theory and relativity theory work fantastically well with the very small and the very large, respectively, but they don't overlap or imply each other. We have two entirely separate theories to describe different aspects of reality - but they *must* be related in some subtle way that we haven't figured out yet, the so-called Theory Of Everything, or TOE.
350188
The proper way to do this would be to calculate the quantum mechanical energy levels for an electron in a spherical well with potential = 0 for r < 10^-15 m, and infinite potential for r >= 10^-15m (ignoring relativistsic effects for now).  Because, by definition, the potential energy of the electron is zero everywhere within this spherical "box", all the energy is kinetic energy.  You can then calculate what the classical velocity would have to be in order for the electron to have such a kinetic energy.  You should find that the answer is an appreciable fraction of c (if not in excess of c).  This tells you that you need to consider relativistic effects.\n\nA back-of the envelope calculation to show the same thing invokes the uncertainty relationship, delta-x * delta-p > h/4*pi, where delta-x is the uncertainty in position, delta-p is the uncertainty in momentum, and h is Planck's constant.\n\nIn this case, by definition, the uncertainty in position is +/- 10^-15*m.  Plugging this into the uncertainty relationship and solving for delta-p yields:\n\ndelta-p = 5.3 * 10^-15 gm*cm/s\n\nClassically, the momentum is equal to m * v, so dividing the momentum uncertainty by the rest mass of an electron (9.1 * 10^-31 kg) yields:\n\ndelta-v = 5.8 * 10^10 m/s,\n\nwhich exceeds c, telling us that we need to go back and take relativistic effects into account.
328
An equally valid question would be "what is the mechanism that causes WF_A to collapse when it is measured?"  The schroedinger equation does not predict collapse as a result of any interaction, so it is outside the theory taught in undergraduate classes.  There is no accepted theory (or in my opinion, any reasonable theory at all) as to why measurement causes a selection of a single eigenvalue out some non-eigenstate.  The idea that measurement on one object has ramifications on another object seems more mysterious, but it's not fundamentally different than the idea that measurement causes collapse in the first place.  You won't find a satisfying answer.