Just Some Guy Posted June 24, 2012 Share Posted June 24, 2012 (edited) So I'm trying to clarify in my head a better idea of the observer, and how it fits into relativity and quantum mechanics, but I'm not finding the info I need scattered about. Anyone mind just giving me whatever rundown you think fits the question, and/or if there's any equations that directly relate? Edited June 24, 2012 by Just Some Guy Link to comment Share on other sites More sharing options...
ydoaPs Posted June 24, 2012 Share Posted June 24, 2012 So I'm trying to clarify in my head a better idea of the observer, and how it fits into relativity and quantum mechanics, but I'm not finding the info I need scattered about. Anyone mind just giving me whatever rundown you think fits the question, and/or if there's any equations that directly relate? Do you have a specific question? Link to comment Share on other sites More sharing options...
Just Some Guy Posted June 24, 2012 Author Share Posted June 24, 2012 Not a specific one, no. I just can't wrap my mind around how it fits into already established theories like quantum mechanics and relativity. Something like just saying "this is how it's defined in relation to ______." And yes, I do realize this is a strange question. Link to comment Share on other sites More sharing options...
elfmotat Posted June 24, 2012 Share Posted June 24, 2012 In relativity an observer is just a coordinate system. It's sort of a lattice of rulers and clocks. In quantum mechanics, it's something that collapses the wave function. It could be, for example, a detector that uses EM radiation. 1 Link to comment Share on other sites More sharing options...
Delta1212 Posted July 2, 2012 Share Posted July 2, 2012 (edited) For QM, just think of an observer as something that interacts with the system. If a particle hits a brick wall, the wall has "observed" the particle. It's not a perfect analogy, but it's closer than the image most people bring up in their minds when they hear the word 'observer' used in quantum mechanics. Edited July 2, 2012 by Delta1212 Link to comment Share on other sites More sharing options...
pmb Posted July 4, 2012 Share Posted July 4, 2012 So I'm trying to clarify in my head a better idea of the observer, and how it fits into relativity and quantum mechanics, but I'm not finding the info I need scattered about. Anyone mind just giving me whatever rundown you think fits the question, and/or if there's any equations that directly relate? The following definition of observer is from A first course in general relativity by Bernard F. Schutz, page 4 It is important to realize that an 'observer' is in fact a huge information-gathering system, not simply one man with binoculars. In fact we shall remove the human element entirely from our definition, and say that an inertial observer is simply a coordinate system for spacetime, which makes an observation simply by recording the location (x, y, z) and time (t) of an event. This coordinate system must satisfy the following three properties to be called inertial: (1) The distance between point P1 (coordinates x1, y1, z1) and point P2coordinates x2, y2, z2) is independant of time. (2) The clocks that sit at every point ticking off the time coordinate t are all synchronized and all run at the same rate (3) The geometry of the space at any constant time t is Euclidean. I don't see that there needs to be an observer in quantum mechanics, just something that can make measurements. But if it is required then the above should work fine. Link to comment Share on other sites More sharing options...
IM Egdall Posted July 5, 2012 Share Posted July 5, 2012 For QM, just think of an observer as something that interacts with the system. If a particle hits a brick wall, the wall has "observed" the particle. It's not a perfect analogy, but it's closer than the image most people bring up in their minds when they hear the word 'observer' used in quantum mechanics. I think your explanation is really good. Some writers talk about this so-called quantum consciousness, as though you need a conscious observer to collapse the wave function to get a localized particle like an electron. But its really an interaction which results in the wavefunction collapse, and that, as you say, can be with a brick wall -- so human or other consciousness is not needed. At least that's my take on the subject. Link to comment Share on other sites More sharing options...
_heretic Posted August 27, 2012 Share Posted August 27, 2012 I don't see that there needs to be an observer in quantum mechanics, just something that can make measurements. But if it is required then the above should work fine. Interesting thread here! So what's a "Measurement"? Link to comment Share on other sites More sharing options...
Ronald Hyde Posted August 27, 2012 Share Posted August 27, 2012 (edited) Interesting thread here! So what's a "Measurement"? A process that returns the value of an 'observable' quantity, a number related to energy, momentum, field intensity, etc..It usually involves some special instrument. Edited August 27, 2012 by Ronald Hyde Link to comment Share on other sites More sharing options...
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