Thursday, May 07, 2009
The WSJ on Hardy's paradox.
In 1990, the English physicist Lucien Hardy devised a thought experiment. The common view was that when a particle met its antiparticle, the pair destroyed each other in an explosion. But Mr. Hardy noted that in some cases when the particles' interaction wasn't observed, they wouldn't annihilate each other. The paradox: Because the interaction had to remain unseen, it couldn't be confirmed.I thought as much: if a tree falls in the woods and no one hears it, it didn't make a noise. ¶ 8:54 AM
In a striking achievement, scientists from Osaka University have resolved the paradox. They used extremely weak measurements -- the equivalent of a sidelong glance, as it were -- that didn't disturb the photons' state. By doing the experiment multiple times and pooling those weak measurements, they got enough good data to show that the particles didn't annihilate. The conclusion: When the particles weren't observed, they behaved differently.
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It actually probably doesn't establish quite as much as the WSJ suggests. This was talked a lot about back in March when the paper came out. The problem is that the "glance" that they metaphorically talk about may count as a measurement. This is called weak measurements and how to interpret it all is a bit unclear.
Unfortunately the way this paper (link) was publicized wasn't that great. So it led to a lot of confusion, especially in the press. Useful for reading are the original papers by Hardy. (here and here)
I do think most take this as a subtle jab at the Copenhagen interpretation. (Which roughly takes odd quantum effects as an epistemological matter rather than an ontological one) I've not done a lot of reading on it, but I believe that "standard" interpretation of QM was highly influenced by the neo-Kantians which of course was an interesting context for Heidegger. Heidegger was pretty interested in the topic, frequently praising Heisenberg's little book on philosophy as I recall. I don't believe the feeling was mutual though.
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Unfortunately the way this paper (link) was publicized wasn't that great. So it led to a lot of confusion, especially in the press. Useful for reading are the original papers by Hardy. (here and here)
I do think most take this as a subtle jab at the Copenhagen interpretation. (Which roughly takes odd quantum effects as an epistemological matter rather than an ontological one) I've not done a lot of reading on it, but I believe that "standard" interpretation of QM was highly influenced by the neo-Kantians which of course was an interesting context for Heidegger. Heidegger was pretty interested in the topic, frequently praising Heisenberg's little book on philosophy as I recall. I don't believe the feeling was mutual though.
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