More quantum mind-bending

[ciphergoth]

I thought I knew that quantum mechanics was mindbending, but I never anticipated this:

[[Elitzur-Vaidman bomb-testing problem]]

which is now proposed as a new way to build quantum computers!

Comments

[drdoug.livejournal.com]

Quantum effects like this are a great example of the universe being "not only queerer than we suppose, but queerer than we *can* suppose", to use Haldane's phrase.

People Just Don't Get It - understandably so since it's bonkers.

For example, I recently came across the publisher's reading group guide for Saturday by Ian McEwan, which includes this question:

3. When Henry hears about the cargo plane's safe landing, McEwan observes, "Schrödinger's cat was alive after all." How does Schrödinger's thought-experiment, allowing two outcomes to co-exist during a period of uncertainty, apply to Henry's daily life? How does it express the nature of human thought during times of anxiety?

Quantum superpositions and Schrödinger's cat is nothing to do with that sort of mundane, every-day uncertainty, where there is a definite answer but you just don't know what it is. It's way, way weirder than that. It's not that you don't know whether the cat's alive or dead: the cat is literally, actually, both alive and dead simultaneously. Which is obviously impossible.