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I recently became interested in entangled photons. But after a brief introduction to the problem, I had a question: what exactly is the problem? What happened to the law of conservation of spin? It seems obvious that if one photon has a certain spin, the other will have the opposite spin, and that's it. Why all the fuss? Where did this idea of non-locality come from, and why is it needed?
And then I came across this article: http://habrahabr.ru/post/225583/. It really struck a chord with me! Since I don't have an invitation, I can't comment, but I really want to. Because, frankly, the article is strange. The commenter Disertbo is right about it... But, what's noteworthy. Okay, let them look at spin along three directions. Okay, instead of spin, they talk about some magical "hidden parameters" (what are they, and why are they needed? Why aren't they satisfied with spin, which is a perfectly open parameter, a projection of spin, and has been known for a long time?). But they can't even use theoretical calculations properly. Let me show you. In the article, they obtained a magical number of 55.55%, supposedly when calculating options for HIDDEN PARAMETERS. And in the experiment, it's 50% (I won't explain in detail, it's easier to read, the article is short). And now, my calculation. I won't denote spin with colors; it's easier to work with + and - (positive and negative spin, respectively).
So. They measured one photon. The projection of its spin onto one of the directions turned out to be positive (+). What are the possible options for all its projections?
+++
++-
+-+
+--
The second photon, entangled with the first. What options exist for it? Also four:
-++
-+-
--+
---
Important! +++ and the like cannot exist; this contradicts the law of conservation of spin! Because for the first photon, we already know that the spin is + in the first direction. Now let's look at the second column and what do we see? Two pluses and two minuses! The probability that the spin in the first direction of the first photon is equal to the spin in the second direction of the second photon, what do you think, is 50%! Exactly like in the experiment! So, why are they confusing us? What are these 55.55%?! Where did that come from? Did Doctor Doom mess with their heads? Is that why they don't know the basics of theoretical calculations?! This is crazy, guys.
And then I came across this article: http://habrahabr.ru/post/225583/. It really struck a chord with me! Since I don't have an invitation, I can't comment, but I really want to. Because, frankly, the article is strange. The commenter Disertbo is right about it... But, what's noteworthy. Okay, let them look at spin along three directions. Okay, instead of spin, they talk about some magical "hidden parameters" (what are they, and why are they needed? Why aren't they satisfied with spin, which is a perfectly open parameter, a projection of spin, and has been known for a long time?). But they can't even use theoretical calculations properly. Let me show you. In the article, they obtained a magical number of 55.55%, supposedly when calculating options for HIDDEN PARAMETERS. And in the experiment, it's 50% (I won't explain in detail, it's easier to read, the article is short). And now, my calculation. I won't denote spin with colors; it's easier to work with + and - (positive and negative spin, respectively).
So. They measured one photon. The projection of its spin onto one of the directions turned out to be positive (+). What are the possible options for all its projections?
+++
++-
+-+
+--
The second photon, entangled with the first. What options exist for it? Also four:
-++
-+-
--+
---
Important! +++ and the like cannot exist; this contradicts the law of conservation of spin! Because for the first photon, we already know that the spin is + in the first direction. Now let's look at the second column and what do we see? Two pluses and two minuses! The probability that the spin in the first direction of the first photon is equal to the spin in the second direction of the second photon, what do you think, is 50%! Exactly like in the experiment! So, why are they confusing us? What are these 55.55%?! Where did that come from? Did Doctor Doom mess with their heads? Is that why they don't know the basics of theoretical calculations?! This is crazy, guys.