Re: [math-fun] If We Have Free Will, Then So Do Electrons
What is the definition of a measurement at A being "influenced" by what happened at B ? --Dan Gene wrote: << [A] source S produces a pair of particles that are detected at A and B at space-like separation, so that A and B cannot influence each other (if you believe causality and relativity). It can happen that the measurements at A and B are correlated, e.g. if the z components of spins are measured, A has spin up if and only if B has spin up. These correlations become evident only when the recorded measurements are brought together and compared. The cause and effect relation responsible for such correlations is the common origin of the particles at S. There is no possible measurement at A that can be influenced by what happened at B.
_____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele
From: Dan Asimov <dasimov@earthlink.net> To: math-fun <math-fun@mailman.xmission.com> Sent: Saturday, March 21, 2009 11:32:18 AM Subject: Re: [math-fun] If We Have Free Will, Then So Do Electrons What is the definition of a measurement at A being "influenced" by what happened at B ? --Dan Gene wrote: << [A] source S produces a pair of particles that are detected at A and B at space-like separation, so that A and B cannot influence each other (if you believe causality and relativity). It can happen that the measurements at A and B are correlated, e.g. if the z components of spins are measured, A has spin up if and only if B has spin up. These correlations become evident only when the recorded measurements are brought together and compared. The cause and effect relation responsible for such correlations is the common origin of the particles at S. There is no possible measurement at A that can be influenced by what happened at B.
This means that measurements made at space-time location A produce outcomes that depend on what measurements were (or will be) performed at location B, or depend on whether or not measurements occur at B. -- Gene
Well, I'm a particle physicist, and I know a lot about relativistic quantum mechanics, which is *not* the same thing as knowing a lot about the mathematical foundations of quantum mechanics (though I have read Eyvind Wichman's lecture notes), *nor* is it the same thing as knowing a lot about the philosophy of quantum mechanics (I'm not sure who is an expert there). But it does seem to me that tossing out the old Copenhagen interpretation of the collapse of the wave function (which is what I was taught in college), and accepting the Everett interpretation (which I know a bit about) *does* seem to imply, at least in my naive perspective, the requirement of a self-aware observer. (Is there any other kind of observer?) I am not comfortable with this conclusion, and I would welcome people to correct me. I do know that some very smart physicists that I respect a great deal seem to accept Everett. Also, some superficial web research shows at least one other interpretation that looks compelling, namely the Penrose interpretation. I don't know very much about the latter, but the descriptions that I have read show that it at least covers some the core issues in relativistic QM that bothered me when I was a young grad student. (Namely the relation of distribution theory to the quantum field theory, and how this relation leads to the requirement of renomormalization of physical quantities.) Like I say, I am not an expert on these issues, but they are things that occasionally cause me to lose sleep at night. And I am interested in them. Is John Baez in this list? He could certainly correct me in many ways. Rowan.
participants (3)
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Dan Asimov -
Eugene Salamin -
Rowan Hamilton