The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know

This is the video that finally made it click for me[1]. Despite the somewhat click-baity title ("What Popularizers of QM Don't Want You to Know") it actually goes into quite a bit of detail of what is and isn't a measurement, in the sense of interactions in a quantum mechanical system that strongly resemble classical behavior (it can be said that the quantum mechanical world is a simulator that can run classical mechanics). [1]: ▶ this video

If I may recommend a lecture given at Google Tech Talks-- "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know", It really clarified some things for me. ▶ this video

This Google Talk ▶ this video uses entanglement and quantum information theory in a clear and understandable way to explain 'spooky' quantum phenomena, like the quantum eraser, de-coherence, the aspect experiment, and the measurement problem. Even if you don't know any QM, just basic algebra and calculus, it's really approachable. I used to be a fan of the Many Worlds interpretation, but after seeing this, I'm now a big fan of the Quantum Information Theory explanation. Starting about 43 minutes in, he goes into the QM Information Theory explanation, but I'd recommend watching the entire prezo. Link to my original post on the subject: link

Before you invest three hours to watch these lectures you should know that the title is terribly misleading. These lectures are not about QM at all, they are about the history of QM, albeit told by someone who was actually part of it. But the coolness of hearing the history of QM firsthand is undermined by the fact that Bethe is clearly well past his prime, and he's not particularly good at telling stories. If you want a video that is true to this title I'd recommend this: link EDIT: And if you want to really understand QM, there's this: ▶ this video :-)

Ages ago I talked about this with Ron Garret here on HN and he pointed me to his Google Talk: ▶ this video He makes a tremendous case that, yes, we're in a simulation, and the more I learn the more that conviction grows.

There is a very important and often forgotten caveat to the Bell's inequalities: it covers local hidden states. If we are to assume that measurement and particle creation apparatuses are entangled with each other (after all, they had plenty of opportunities since the big bang), then we have a global hidden state and the quantum measurment randomness becomes a simple artifact of removing global state from the picture. This interpretation of QM is usually called "superdeterminism" and, personally, I like it much more than the black vodoo measurement magic with collapsing wave functions or creation of whole new worlds on each tiny measurement. This video can be a good introduction to this topic: ▶ this video (don't mind the clickbaity title, the video itself is good)

Personally, I am firmly in the "superdeterminism" camp. To me it's the most elegant interpretation of QM without any mystical measurements magically dependent on "consciousness" and whole universes created on each interaction. If you want to learn basics about it, I recommend watching this video: ▶ this video Do not mind the (joking) clickbait title, the talk itself is quite good even if you only vaguely remember QM.

Ron Garrett gave a presentation at Google years ago on Quantum Information Theory that kind of demystified a lot of spooky stuff (like quantum eraser), and I'm wondering how much of this is merely an artifact of the way we're interpreting the math. ▶ this video

No, it's a little more subtle than that. If you really want to know, the answer is in this paper: link Or if you prefer, this video: ▶ this video

One explanation[1] i heard is observation is a actually equivalent to entanglement. Now we know that two elements entangled will have to maintain the state corresponding to its entangled peer. Now if you observing (or taking measurement) the whole system gets entangled to the particle. you are observing and hence the wave function collapses. You can look at a better explanation here [1] ▶ this video

Nothing changes at the time of "wave function collapse". When you measure one particle of an entangled pair, nothing actually happens to the other one. But you don't need to listen to me, check this out: ▶ this video

> Isn't the entire universe one quantum system? Yes. > If so, how can we talk about discrete systems. That is an excellent question! And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system. If you want the details, see this paper: link Or this video ▶ this video which covers the same material.