Presumably they didn't want to pile the Slashdot Effect on top of their server woes. But a quick google search turns up: http://www.ocearch.org/profile/katharine/

is my go-to source for internet shorthand. Any reason the FBI's too good to just use that?

oblig. FoxTrot

This is wrong. Before one "collapses" a particle's state, it actually *does* exist in all states simultaneously. See the double-slit experiment.

his initials, Paul Ingrisano

See, that's the danger, and why I made my original comment in the first place: Schrodinger's cat (and Quantum Mechanics as a whole) has absolutely nothing to do with consciousness. Here's a great piece explaining in more detail.

Indeed. Parent was talking about Special (simultaneity).

Re: Mercury's precession, I'm still a believer in Vulcan.

Surprised you didn't link to the oblig.

There's no fixed limit--the double-slit experiment has been run on gold particles, I know, I think I heard of it even being performed on DNA molecules. It's not about the size, it's about the act of measurement. However, I've gotten responses in the other place I posted this comment that are basically along the lines of, "there's a certain class of detectors that will entangle with the system rather than collapse it." If that's the case, then the Schrodinger's Cat problem becomes a practical one (it's impossible to truly isolate the cat from the outside world) than the fundamental one I've described.

Everything is made out of quantum particles, so this is rather a moronic reply. That being said, I'm quite satisfied with the "entanglement" arguments made by others (the photon detector needn't decohere/collapse the waveform--it could simply entangle with it, in which case, if you really did have a box with a cat completely isolated from the outside universe, then the paradox would still hold). I probably won't be making this response in the future, or at least not without the caveat of "from a practical perspective" or "I prefer Bohr's resolution to the paradox wherein..."

Right. Okay. So where I went wrong here was the "absorb" and "re-emitted" part, but the interpretation that stuck with me from undergrad was the question of, when interactions of this type occur, does it make sense to think of the photon as the same photon pre- and post- interaction? Or can we think about this as the photon destroyed and replaced with a new one that is travelling in roughly the same direction? If I recall correctly (it's been four years, so pardon me if I'm wrong), since [a,a^+]=0 for bosons, then the answer is, "sure, if you want," because you can create+annihilate a boson as many times as you want with no difference. So it's just an interpretation. But yeah, it doesn't sound like it's a good answer to why light travels slower in a medium.

Yep. Sorry about that. I meant to link to the Niels Bohr answer above it (which I copy-pasted into a separate response below).

It's true, I might have glossed over some of the subtleties, but my point with that line is that people think of observation and detection as a passive event when it's anything but, and not for any sort of mysterious "the mind makes it so" bullshit but because when you're looking at the wall in front of you what's actually happening is that photons are hitting the wall, bouncing off (or being absorbed and re-emitted--though I got chided for saying something similar about this earlier) and being collected in your eye. Without the stream of photons hitting the wall, you'd have no way of knowing it was there (extend photons to other force-mediating particles).

You're presenting this response as if the Copenhagen Interpretation were not still the standard interpretation of QMech nearly a century after its formulation. In all the academic circles in which I've run (I have a Ph.D in physics, although my field was pretty far from quantum mechanics), Many World is considered an interesting idea with little practical consequence, and almost everything Einstein said regarding Quantum Mechanics has turned out to be disproved (though I'm not familiar with this specific interpretation).

Except that the math there works out completely differently.

See: double-slit experiment. If photons didn't exist in a superposition of states, then the distribution of light you'd get with the double slit would be the distribution you get from having one slit covered plus the one you'd get from covering the other one. But you don't--the distribution is completely different, which means that a single photon somehow travel though *both* slits and "interferes with itself."