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Comment by d_sem | Hacker News Reader

because there is no information transmitted once you've measured one of the entangled particles.

The other particle never knows the first one was measured.

Consider the analogy that in a box there are two apples. A Red delicious and a green apple. You and a friend close your eyes and take one and go home. You know look at your apple -- its red. Now you know your friend as a Green one without asking them. Was information magically transmitted? No. Was that faster than light communication? No. Could you keep taking apples out of boxes to transmit data? no

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Your analogy with the apples is an oversimplification of what is going on that misses an important aspect of the system: the measurements aren't independent. The type of measurement you do effect the result of the measurement your friend does.

Yes but all analogies of physics are oversimplifications; d_sem's analogy still conveys "why it's not FTL communication", even though it suggests a hidden variable that doesn't actually exist — that the colour genuinely isn't determined until one of you measures it, is only something you can verify by talking about it with each other afterwards (and even then as a statistical artefact of many such measurements not just one).

No, not all analogies of physics are oversimplifications, only those that leave out parts that are essential to the discussion.

If you leave out the properties that are special about entangled systems from the analogy, it can't shed any light on entangled systems.

> only those that leave out parts that are essential to the discussion.

I have yet to see a single physics analogy that covers every single aspect of the physics without being misleading. If the maths is easy enough to follow without needing an analogy, you just get the maths.

They don’t have to cover every single aspect, only those that are relevant to the discussion. The analogy with water in tubes for electricity is not an oversimplification when you explain relationships between voltage and current in a resistance. It only becomes an oversimplification when you try to explain, say, electromagnets.

Water tubes thus cannot explain AC skin effect, inductance.

Which isn’t relevant to the discussion in the example.

The only way to not leave out critical details is to just learn the math behind it.

The problem with doing this is that getting an extra graduate degree is a lot of work.

You certainly don't need a grad degree to understand the math behind entanglement or basic QM!

"Just" partial differential equations of complex fields for Schrodinger; the fourier transform to shift between, what was it, momentum and position?; matricies and/or quaternions for the Bloch sphere; bra-ket notation; and the Hermitian, Hamiltonian, and Laplacian operators.

Of these, the only one I did in my double maths A-level was matricies and partial differential equations of single dimensional real functions, and the absolute basics of what complex numbers are.

Seems like it needs a degree to me, having tried to teach myself using brilliant.org

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