tag:blogger.com,1999:blog-2180213878983238960.post2905597490792551366..comments2022-04-25T07:52:56.341-04:00Comments on a filosofer's thots: Bohr's reply to EPR (Part III)WayneMyrvoldhttp://www.blogger.com/profile/17862508459057431817noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-2180213878983238960.post-20025013472343684872015-10-17T10:09:53.353-04:002015-10-17T10:09:53.353-04:00Serendipity: this just showed up on my fb feed. V...Serendipity: this just showed up on my fb feed. Video from New Scientist about discord as the mark of quantumness.<br /><br />https://www.youtube.com/watch?v=CDorBWsRd6w&feature=youtu.be&utm_source=NSNS&utm_medium=SOC&utm_campaign=hoot&cmpid=SOC%257CNSNS%257C2015-GLOBAL-hootWayneMyrvoldhttps://www.blogger.com/profile/17862508459057431817noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-69866993572226131142015-10-17T00:26:06.420-04:002015-10-17T00:26:06.420-04:00Oh yes, they are clear that certain conditions (no...Oh yes, they are clear that certain conditions (no longer interacting, in the ordinary physical understanding) imply no disturbance. And that is in the spirit of the rest of their paper --- they only need a sufficient condition, so they only give a sufficient condition. That's why I agree that (2) is not what they could mean by no-disturbance. They don't actually define what "disturbance" is, but Bohr is surely knowingly rejecting their notion.Howard Wisemanhttps://www.blogger.com/profile/17376582034313295394noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-29009238409743156102015-10-16T22:21:52.349-04:002015-10-16T22:21:52.349-04:00Do they really not specify? They say that after a...Do they really not specify? They say that after a time, the systems no longer interact. We know how to model interactions in QM: via interaction terms in the Hamiltonian. I think it's clear that what they mean is absence of interaction in this ordinary sense.WayneMyrvoldhttps://www.blogger.com/profile/17862508459057431817noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-361164996192379132015-10-16T21:38:11.005-04:002015-10-16T21:38:11.005-04:00Sure. And I agree that (2) is not a plausible read...Sure. And I agree that (2) is not a plausible reading of what EPR meant. So by "ambiguity" Bohr seems to mean "You have not really specified what you mean by disturbance, so this is my opportunity to attack your argument at a technical level by interposing my own definition".Howard Wisemanhttps://www.blogger.com/profile/17376582034313295394noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-62883113760600603872015-10-16T21:08:54.512-04:002015-10-16T21:08:54.512-04:00Ok, "whole point" is overstatement.
But...Ok, "whole point" is overstatement.<br /><br />But, while it's true that Bohr emphasized the exclusivity of the measurements more than EPR do, EPR do make the point that one has to make a choice, and that one choice excludes the other. If the experiments weren't exclusive, then there'd be no need for the argument; one could ascertain both position and momentum at the same time, and it would be evident that QM description is incomplete.WayneMyrvoldhttps://www.blogger.com/profile/17862508459057431817noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-22910918488062369632015-10-16T21:04:53.233-04:002015-10-16T21:04:53.233-04:00From Howard Wiseman, via facebook:
One could inde...From Howard Wiseman, via facebook:<br /><br />One could indeed wonder why Bohr didn't just give a coherent defence of operationalism. I suspect that he didn't want to do that because he saw complementarity as more than that --- he saw it as offering insights into all manner of things outside quantum physics.<br /><br />But I don't quite agree on your analysis of the two meanings you offer to reflect Bohr's "ambiguity". You say "the choice of experiment done on one particle has an effect on the sorts of predictions that can be made about the other; that’s the whole point of the [EPR] argument!" I don't think that's true. The ability to make different predictions by different measurements is the whole point of EPR. The inability to make other predictions (by making further measurements), having made a certain type of measurement, is what Bohr meant by non-mechanical disturbance.<br /><br />Interestingly (to me at least), Bohr's non-mechanical disturbance at a distance does not require entanglement to manifest:<br />http://arxiv.org/abs/1208.4964<br />WayneMyrvoldhttps://www.blogger.com/profile/17862508459057431817noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-6558882087150799262015-10-16T21:04:08.388-04:002015-10-16T21:04:08.388-04:00Thanks, Don. I'll look at that.Thanks, Don. I'll look at that.WayneMyrvoldhttps://www.blogger.com/profile/17862508459057431817noreply@blogger.comtag:blogger.com,1999:blog-2180213878983238960.post-58274232466713483122015-10-16T15:41:14.079-04:002015-10-16T15:41:14.079-04:00No, that was not Bohr's meaning wrt to context...No, that was not Bohr's meaning wrt to context - the possible types of predictions - being an inherent element of the description. All he meant was what kind of measurement was being performed. In the spin case, it would be the orientation of the Stern-Gerlach apparatus and the analyzers. For a fuller account of all of this, look at this paper of mine:<br /><br />https://www.academia.edu/1294403/What_makes_a_classical_concept_classical_Toward_a_reconstruction_of_Niels_Bohrs_philosophy_of_physicsAnonymoushttps://www.blogger.com/profile/17746697972962655101noreply@blogger.com