throw another bear in the canoe

What science fiction writers talk about in their spare time (with free Buckaroo Banzai quote):

[20:11] matociquala: The concept of a quantum eraser hurts my head.
[20:12] matociquala: http://en.wikipedia.org/wiki/Quantum_eraser
[20:13] stillnotbored: yeah....
[20:13] stillnotbored: I don't understand any of that
[20:14] matociquala: I kind of understand it.
[20:14] matociquala: but it hurts my head that it works.
[20:14] stillnotbored: I think I used all my brain power at work today
[20:14] matociquala: Okay.
[20:15] matociquala: first, you turn one photon into twins
[20:15] katallen: is pretty
[20:15] matociquala: an entangled pair
[20:15] stillnotbored: OH
[20:16] stillnotbored: got it now
[20:16] matociquala: then you send one to a detector and the other through the classic double slit experiment
[20:16] matociquala: where it generates an interference pattern.
[20:17] matociquala: because according to qunatum mechanics, your one photon went through both slits.
[20:17] matociquala: right?
[20:17] matociquala: right.
[20:17] stillnotbored: right
[20:17] matociquala: Okay, so. Now you take a polarizing plate and put it between the slits and the target
[20:17] matociquala: so you can tell which slit the photon went through
[20:17] matociquala: and the interference pattern vanishes
[20:18] matociquala: because now it only went through one slit.
[20:18] matociquala: In other words, you retroactively erased its path through the other slit.
[20:18] matociquala: THAT is the part that hurts my head.
[20:18] stillnotbored: yeah
[20:18] matociquala: And if you put the polarizing plate BEFORE the slit?
[20:18] stillnotbored: wow
[20:18] matociquala: interference pattern remains.
[20:19] matociquala: because now it went through both slits after you detected it.
[20:19] stillnotbored: wow
[20:19] matociquala: Thus the non-bogus part of the quantum mechanics in Undertow.
[20:19] matociquala: *g*
[20:19] stillnotbored: is this part of the observer effect or what ever its called?
[20:19] matociquala: You really can change the universe by looking at it.
[20:19] matociquala: This is the observer effect
[20:20] stillnotbored: then I did get it *g*
[20:20] matociquala: *g*
[20:20] matociquala: You can change what USED to happen in the universe by looking at it NOW.
[20:20] stillnotbored: and it does twist my head around backwards, but how friggin cool
[20:21] matociquala: It's so damned neat
[20:21] stillnotbored: it really is
[20:22] katallen: I am all about the QM
[20:23] matociquala: You know, I swear I can handle everything except the retroactivity part.
[20:24] stillnotbored: it makes me think time travel
[20:24] matociquala: Yeah
[20:24] stillnotbored: changing the past by looking at the present
[20:24] katallen: well if it helps... you can always work with a different time paradigm
[20:24] matociquala: Actually, I think they have gotten particles to travel back in time
[20:25] matociquala: Well, yeah, it's just a direction.
[20:25] katallen: (and I do not want Kickback and Taya muttering at me)
[20:25] matociquala: But I am a flatlander trying to grok up.
[20:25] matociquala: yanno?
[20:25] katallen: well you can always consider that everything is actually happening simultaneously
[20:26] katallen: and linear time is just the way that a flatlander can reduce the information to a comprehensible level
[20:26] matociquala: *g* Which is why the snide thing about "time is what keeps everything from happening at once" is really a profound bit of wisdom.
[20:26] matociquala: Much like "wherever you go, there you are."
[20:26] katallen: ::grins::
[20:28] katallen: you know... physics just isn't as hard a science as it used to be
[20:28] katallen: it's gone all wishy-washy and feminine ::grins::