h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Superposition, Entanglement and other Strange Things - A1053776
Author: Atlantic_Cable - U196159

This is the remains of an entry that was originally tagged on to one about Schröedinger's cat, but proved to be irrelevant, so I put it in it's own entry. It's still a little rough, so be gentle.

Apart from saying that it still looks like another two entries, and thus may benefit from either being split, or more tightly integrated together, I don't have any ignificant comments.

I have split the entry.

I don't know how relevent it is, but recently they have been having some sucess with looking at hardy's paradox, using something called "weak measurement", which lets them look at quantum states without disrupting them.

while not being young's slit experiment, it is peripherally related, as is shroedinger's cat.

this "weak measurement" using some very strange effects on the quantum level, and while you would think it would colapse the superposition, it doesn't seem to do that.

here is a link, and you can use it to figure out which of your entries it is relevent to, and if you want to do another one covering it. http://www.umsl.edu/~altmanc/measurement.html

Thanks. I've added it.

"Neutrons do now act like waves, and so the interference pattern is not observed."

Should be:

"Neutrons do noT act like waves, and so the interference pattern is not observed."

I think.... Tell me if i'm wrong.

another problem recently spotted (with reality) is that entanglement has been observed to act across time as well as space.

in particular, you measure the same particle stream, sometimes once, sometimes twice, in a time frame such that the second measurement affects particles which have already been measured.

they you look only at the first result for each particle, and you can spot those that were measued twice from the data.

this no more fits the theories than the instant action at a distance that you get with ordinary entanglement, but has the extra problem that it seems to defy causality.

really strange.

Thanks, I've incorporated you points into the entry.