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April 17, 2014

CATEGORY: Blog [back]
TOPIC: The Convexity Club [refresh]
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Blogger Matthew Saul Leifer wrote on Aug. 15, 2007 @ 17:31 GMT
Plenty of people have been writing about the recent fqxi conference, which was excellent by the way, so I'll write instead about another fqxi-funded event that happened at the beginning of July in St. Catherine's college, Cambridge.

The two-week workshop was entitled Operational Probabilistic Theories as Foils for Quantum Theory and organized by Rob Spekkens, Jonathan Barrett and...

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this post has been edited by the author since its original submission

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paul valletta wrote on Aug. 16, 2007 @ 03:02 GMT
"How can we understand why the world obeys quantum theory rather than any of the other theories?"

One can start with the H.U.P?..can one really locate (measure) a particle..anywhere?

If you know a particle's position, you may not know it's momentum. Relative to the process of measure is what one is asking about the process of measure and measurer. The history of a particle WRT time, is "fixed". You can know a particles path in a past history, it is "fixed", without knowing it's path in a future trajectory, "random" and uncertain.

Now WRT the H.U.P, one can make assumptions based on position and momentum, thus:If one knows a particles future path, then it's location history is unknown. (this is my intepretation).

Seems straight forward for observers, time dictates an observer to be the measurer in a "now" context, if the measurer tries to observe a particles future, then the observation will fail to make sense?

Thinking about the "contact" needed for measurement, how does one locate something that has not yet reached there?..I mean I am trying to pinpoint an objects position of where it is "not" ( it's future location ), by determining where it is ( where it HAS been ), the possible way I can determine a full observation measurment, is to perform the measuments at a very fast rate,(signaling the results performed, to confirm measures taken) faster than the devise is capable of?

The is a limit of observation, random variables operate differently for every measure needed, if say one random variable becomes known (random variable of particles future location), then the corrsponding momentum (which is really nothing more than the particles history), will become unknown, or in the context of particle interactions, become a changed (as opposed to fixed, perminant) factor.

This can be translated to the appearance of "unmeasured" particles, and dissapearance of "measured" particles, as QM shows.

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Blogger Matthew Saul Leifer wrote on Aug. 16, 2007 @ 16:48 GMT
I think this is a fairly conventional view, but I don't think the HUP can really be used as a founding principle for quantum theory, at least not in its usual form. In particular, it is not strong enough to entail the canonical commutation relations. In fact, having something like a HUP is another thing that's going to be generic in the framework I described.

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Bee wrote on Aug. 20, 2007 @ 13:33 GMT
off topic: there's something wrong with the picture placement using Internet Explorer (pics are on top of each other and cover the text).

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Ian Durham wrote on Aug. 27, 2007 @ 01:18 GMT
Actually, the commutation relations *lead* to HUP (well, to Schrödinger's generalization of HUP) so, in a sense, you'd almost be better off building everything on that (the commutation relations). In essence, what I think Matt is describing is a generalization that contains sets of inequalities, one class of which are Schrödinger's generalized HUP, and so forth. Reminds me a bit of something I tried to do once with set theory ( I don't think I was terribly successful, but I'm sure these insanely smart folks will succeed.

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paul valletta wrote on Aug. 28, 2007 @ 19:40 GMT
Ian, are you the same I T Durham, as cited in this co-incedetally topic relevant recent paper? :

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