I am not a boy because my parents observed my penis at the 12 week echo. I am a boy because the sperm cell that made me, carried the right chromosome. It was decided at fertilization. Even if my parents never observed me, I would still be a boy.
The experiment described in the Veritasium video splits a particle in an electron and a proton. They must have opposite spin and that is measured at the time of observation. Than there’s a whole discussion about faster than light communication, but if the spin is given at the moment of creation, both will have the opposite spin from the start. It can still be random and measurements will still have a 25% failure rate.
What am I missing? Can the spin change between creation and measurement?
What happens if a particle doesn’t get observed, does it not have spin?
One of the best things I’ve read recently (wish I could find it again) said that quantum mechanics isn’t about reality, it’s a model of what we can measure and study. We simply can’t know what reality is like at atomic and subatomic scales, we can only model what the measurements say. It turns out we can do a lot of really impressive science with those models (nuclear power, semiconductors, lots of other stuff), but acting as if we know what’s actually going on at those levels is fooling ourselves. Even the people who laid the foundation for modern quantum theory knew this:
- A Short History of Nearly Everything
So what does this have to do with your question? Well, I’m not saying that fundamental reality does not exist at subatomic scales. But I am saying that we can’t really know anything about that reality until we measure it.
Did the electron have its spin at creation, or at measurement? We can’t really say, and it’s not especially important.
A bit of a tangent: we don’t fully understand quantum entanglement over distances (e.g., the fact that we can know the spin of one particle from another entangled particle’s spin even over great distances), but the explanation I like is that both particles’ states are just the propagation of their combined wave equation since they were first entangled. So were their spins assigned at entanglement or at measurement? Well, we don’t know and it’s not a meaningful question because we can’t determine the answer without measurement.
Your chromosome analogy doesn’t really work because your chromosomes are a classical system. They have been entangled with countless other molecules for as long as they have existed, so we can use our human intuition to reason about their past and future in ways that we can’t reason about things at quantum scales.
Ah yes, the classic mistake I made was trying to understand something about quantum physics XD
Your quotes explain it well.
I once knew I shouldn’t do that, that’s why we have these seemingly ridiculous theories. But it’s been a while since I’ve occupied my mind with the subject.
I’m now reminded of this old joke by Dutch commedian Herman Finkers