this post was submitted on 27 May 2024
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Electrons (mander.xyz)
submitted 5 months ago by [email protected] to c/[email protected]
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[–] [email protected] 42 points 5 months ago (4 children)

Up and down in what direction, electron?!?

Up and down on what direction?!?

[–] [email protected] 18 points 5 months ago (1 children)

Relative to A'Tuin

[–] [email protected] 2 points 5 months ago

My favourite quark is the hubwise quark, closely followed by the widdershins quark

[–] [email protected] 12 points 5 months ago (2 children)

Actually a good point, tho. And also a good thought: If there is no special direction, what would be up? And that's where quantum mechanics gets even weirder: It's either up or down in the direction you measure.

[–] [email protected] 8 points 5 months ago* (last edited 5 months ago) (1 children)

It's either up or down whatever the direction.

If you measure 100%up-0%down then you rotate your frame of reference by 90°, you automatically get 50%up-50%down... (iirc)

It's weirdly teasing us like that!

[–] [email protected] 8 points 5 months ago* (last edited 5 months ago) (1 children)

Just in case it wasn't clear you can't measure anything other than "100%" up or down spin. The quantum state of it being 50/50 is described by 1/sqrt{2} times the up and down vector, when you measure it you have a probability of getting either result calculated by the square of the absolute (||psi||^2) that way you avoid getting a complex probability.

btw I was too scared to try in case it doesn't but can I use LaTeX in Lemmy comments? $\psi$ Edit: No LaTeX doesn't seem to work and btw I didn't study this so it might be taught differently at uni. This was explained to me in/for the context of quantum computing.

[–] [email protected] 3 points 5 months ago (1 children)

True! Thanks for the clarification, it's been a while since i played with the maths of quantum physics!

After you measure a spin as 100% up, the state will be close to that for a while, si the next measurement has higher chance of being up, with this probability slowly decreasing with time.

[–] [email protected] 1 points 5 months ago (1 children)

I think that assuming the particle has no (extra?) energy it's state does stay the same. That is of course not possible in real life though but the <20 millikelvin in some quantum computers get pretty close.

Also I think nobody says they measure it as 0/100% up, They just say up or down in my limited experience.

Does anyone have any good resources on quantum mechanics? (Most of my information comes from a few professors) There's some useful stuff on chem libretexts (I think that's what it's called) for simple wave functions, but it doesn't seem perfect.

[–] [email protected] 1 points 5 months ago

I have old college textbooks in my library, Cohen-Tannoudji. I'm not sure about online resources though...

[–] [email protected] 3 points 5 months ago (1 children)

At least in the Stern-Gerlach experiment it's relative to the magnetic field.

[–] [email protected] 4 points 5 months ago

Yeah, quantum mechanics lingo: measurement = interaction

[–] [email protected] 7 points 5 months ago

Yes and no