Ankit Gupta Posted August 15, 2014 Share Posted August 15, 2014 which thing oscillates in a matter wave like electric field and magnetic field in a light wave ? my brother told me that its a topic of quantum mechanics so it will be hard to under stand so would any of u please explain it in a simple way ? 1 Link to comment Share on other sites More sharing options...
Nicholas Kang Posted August 15, 2014 Share Posted August 15, 2014 It is electron. When electron accelerates (in physics, acceleration can either be change in direction or change in magnitude since it is a vector quantity), its magnetic field will collapse and creates an electric field. This cycle continues. The quantum particles involved is known as photon, which carries no charge and no mass. According to quantum mecanics, force is formed when 2 particles exchange quanta-a descrete and tiny but incontinuous packet. Electrons exchange photons and they oscillate in the EM field. This is light wave. You must remember that light does not mean visible light, it also means gamma rays, X-rays, Infared rays, Ultraviolet rays and Radio wave. They aren`t visible but are parts of the electromagnetic spectrum. For your extra knowledge, quantum mechanics emerge in 1900s after Max Planck. It was based on Heisenberg`s Uncertainty Principle which states that you cannot know the position and the momentum of a particle exactly. If you know the position 100%, you won`t know the momentum, but this is practically impossible, since a drawing of an atom of the size of the universe would only be possible to determine the postition of the electron in an atom 100% precisely. Normally, the probability is 95% in most chemistry and physics. Enjoy quantum mechanics. You will love it. The common advice is "shut up and calculate". Here is why. Quantum mechanics is a bizarre theory. An electron placed in a box will disappear and exist outside the box because its probability wave may travel through the obstruction, known as quantum diode. This is quantum leap/jump. Quantum entanglement tells you a particle would "remember" its co-exist partner or an antiparticle or just ordinary particle and won`t forget it no matter how far they are and even independent of their speed,thus violating Einstein`s Theory of Relativity, which states that the speed limit of universe is light speed c=299792458 m/s. Enjoy. Regards Nicholas Kang Link to comment Share on other sites More sharing options...
swansont Posted August 15, 2014 Share Posted August 15, 2014 which thing oscillates in a matter wave like electric field and magnetic field in a light wave ? my brother told me that its a topic of quantum mechanics so it will be hard to under stand so would any of u please explain it in a simple way ? That's an excellent question. Here's the problem: when you say a light wave oscillates and refer to the electric and magnetic field, you have to realize that the electric and magnetic fields aren't real things. They are concepts we use to model behaviors/effects. So asking "what is waving?" points to a fundamental issue that physics describes behaviors, rather than explain the nature of the existence of things, i.e. what something is. This is physics, not metaphysics. The waves in quantum mechanics are a description of where the entity in question can be found and what properties it has. It's tied in with probabilities. Nothing physical is actually waving. One could say that what is waving is the electron field, but that just moves the goalposts; the electron field is just another tool used for calculation of behavior and just as unreal as other fields are. "What is waving" is a philosophy question, not a physics question (though some may disagree. We'll see how that goes) "What is waving" is one of a class of concepts that doesn't translate well from the macroscopic scale to the quantum scale. 1 Link to comment Share on other sites More sharing options...
Nicholas Kang Posted August 15, 2014 Share Posted August 15, 2014 Am I wrong? Link to comment Share on other sites More sharing options...
swansont Posted August 15, 2014 Share Posted August 15, 2014 "The electron is a wave" is not quite the same answer as "the electron is what is waving", which is kind of a circular argument. I don;t think anything you said was wrong, I just don't think it answers the question. But I don't think the question can be satisfactorily answered. Link to comment Share on other sites More sharing options...
Nicholas Kang Posted August 15, 2014 Share Posted August 15, 2014 Sorry for talking irrelevant topics. By the way what is the difference between wave and waving? Link to comment Share on other sites More sharing options...
swansont Posted August 15, 2014 Share Posted August 15, 2014 Sorry for talking irrelevant topics. By the way what is the difference between wave and waving? Saying something is a wave recognizes that it has wave properties, e.g. a wavelength. A question about what is waving is asking what is actually oscillating (and tacitly assumes it's not a standing wave, i.e. that there is something undergoing an oscillation) Link to comment Share on other sites More sharing options...
Nicholas Kang Posted August 16, 2014 Share Posted August 16, 2014 This means that we don't know what is oscillating/waving? Link to comment Share on other sites More sharing options...
Enthalpy Posted August 16, 2014 Share Posted August 16, 2014 If you say "the particle is the wave" it makes many things easier. Though, this wave is not a 19th century styled one, because some properties like an electron's charge don't split - hence the usefulness of the particle idea. Beware most people only say "the wave defines particle's probability density" but I've seen no advantage to this more common expression up to now. Link to comment Share on other sites More sharing options...
Ankit Gupta Posted August 16, 2014 Author Share Posted August 16, 2014 ok , i think electron cannot oscillate itself because as we know to cause any change in momentum we need an external force and (i think) there is nothing around an electron (in wave) which provide force to it . atleast in newtonian mechanics it happens but in quantum mechanics , i dont know Link to comment Share on other sites More sharing options...
Enthalpy Posted August 17, 2014 Share Posted August 17, 2014 (edited) The atom's nucleus provides this force. The electron oscillates when it is not an orbital (=a stationary bound wave), for instance when it's a combination of several orbitals of different energies. The energy difference defines the frequency of oscillation and of the radiated photon. Edited August 17, 2014 by Enthalpy Link to comment Share on other sites More sharing options...
swansont Posted August 17, 2014 Share Posted August 17, 2014 The atom's nucleus provides this force. The electron oscillates when it is not an orbital (=a stationary bound wave), for instance when it's a combination of several orbitals of different energies. The energy difference defines the frequency of oscillation and of the radiated photon. Free electrons are waves, too. Link to comment Share on other sites More sharing options...
Ankit Gupta Posted August 18, 2014 Author Share Posted August 18, 2014 The atom's nucleus provides this force. The electron oscillates when it is not an orbital (=a stationary bound wave), for instance when it's a combination of several orbitals of different energies. The energy difference defines the frequency of oscillation and of the radiated photon. ya i know that but i was asking about the electron wave of a single(or many or i dont know how much) electron in empty space or just simply space as swansont told Link to comment Share on other sites More sharing options...
Enthalpy Posted August 18, 2014 Share Posted August 18, 2014 OK, I hope to understand the question better now. In empty space, hence without an external force, the electron's position doesn't oscillate. The electron just propagates smoothly, with its phase rotating. Take for instance a plane wave psi(x, y, z, t) = exp[i(w*t-k*x)] where w is the angular frequency related with the electron's energy, and k the wave vector. The distribution |psi|2 is uniform over time and space. It doesn't oscillate. The electron needs no external force for that. The electron does move, and has a momentum, because the locations of constant phase do. k*x just increases as much as w*t does, so the speed is w/k, exactly like any wave. Link to comment Share on other sites More sharing options...
swansont Posted August 18, 2014 Share Posted August 18, 2014 In empty space, hence without an external force, the electron's position doesn't oscillate. The electron just propagates smoothly, with its phase rotating. A changing phase implies an oscillation. Link to comment Share on other sites More sharing options...
Enthalpy Posted August 19, 2014 Share Posted August 19, 2014 A changing phase implies an oscillation. No. At least the position does not oscillate, which is consistent with the original question, the lack of external force. Link to comment Share on other sites More sharing options...
swansont Posted August 19, 2014 Share Posted August 19, 2014 No. At least the position does not oscillate, which is consistent with the original question, the lack of external force. The OP asks what is oscillating, and uses EM radiation as an example. Nothing about position. Link to comment Share on other sites More sharing options...
Enthalpy Posted August 20, 2014 Share Posted August 20, 2014 It boils down to a matter of wording... In post #10 the thread opener tells "change of momentum, external force" and to this my example is an answer, with "the position does not oscillate". An exp(i*w*t) oscillating, I have nothing against. Link to comment Share on other sites More sharing options...
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