A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.
Rules
This is a science community. We use the Dawkins definition of meme.
"Well... You see... When its a particle it spins. When its a wave its still doing that. How does a waveform spin you ask? Listen. Shut the fuck up. The math is really weird and some of this stuff just happens and you can't visualize it in your head. We didn't believe it at first either but after 50 years of experiments we have to just accept that reality is consistent with the math even if we don't fully conceptualize what that means even"
We are all just folds in this wonderfully weird thing we call spacetime!
The prions of spacetime.
Out here folding along.
Nice reference to PBS Space Time. The YouTube channel where I just get bullied with science, and for some weird twisted reason I like it.
pbs space time is awesome, and this description is even more so.
Hah! Time. Like that's a real thing.
You wrote a comment so good that I screenshotted it.
Awww thanks
Also please don't look at it
I mean, you can but it won’t be there.
Actually, it can be there, but then you won't know how fast it's moving.
think of it as a camera.
if you set it up with a high speed to take a picure of a bouncing ping pong ball you will know its precise location at the moment of the shot.
if you set it up with a low speed you will see a blur of the path it took, but not a precise location.
That's not a good analogy because typically cameras don't change the things they're observing. But, a camera with a flash...
Imagine a guy driving down a dark road at night. Take a picture of him without a flash and you'll get a blurry picture.
Take a picture of him with a powerful flash and you'll get an idea of exactly where he was when the picture was taken, but the powerful flash will affect his driving and he'll veer off the road.
You can't measure something without interacting with it. This is true even in the non-quantum world, but often the interactions are small enough to ignore. Like, if you stick a meat thermometer into a leg of lamb, you'll measure its temperature. But, the relatively cool thermometer is going to slightly reduce the temperature of the lamb.
At a quantum level, you can no longer ignore the effect that measuring has on observing. The twin-slit experiment is the ultimate proof of this weirdness.
"All models are wrong, but some are useful." -George Box
My advanced E&M professor said "Imagine a sphere of radius zero. Trust me, it works."
"...Imagine a sphere of radius zero."
and a spherical cow. imagining lots of spherical cows helps quite a bit.
You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.
It's a point but it doesn't actually exist at any point. It exists in a cloud where it could exist anywhere in there.
You can observe it but doing so changes its behavior. Why? Well... Um... Maybe it's just the simulation breaking down?
It's because to observe something you have to interact with it. Dealing with particles is like playing pool in the dark and the only way you can tell where the balls are is by rolling other balls into them and listening for the sound it makes. Thing is, you now only know where the ball was, not what happened next.
In the quantum world, even a single photon can influence what another particle is doing. This is fundamentally why observation changes things.
holy shit the pool explanation is so good, I'm gonna recycle it for sure
Good metaphor
I think a lot of the confusion people have is around the word “observation” which in everyday language implies the presence of an intelligent observer. It seems totally nonsensical that the outcome of a physics experiment should depend on whether the physicist is in the lab or out for a coffee! That’s because it is!
I have this beef with a lot of words used in physics. Taking an everyday word and reusing it as a technical term whose meaning may be subtly and/or profoundly different from the original. It’s a source of constant confusion.
think of it as a camera.
if you set it up with a high speed to take a picure of a bouncing ping pong ball you will know its precise location at the moment of the shot.
if you set it up with a low speed you will see a blur of the path it took, but not a precise location.
Google "Electron Orbitals". All the spaces there are all the ~~possible~~ highest likely locations for the electrons. Good Introduction to some Quantum Mechanics 👍
No! I will not relive the horrors of that chemistry class again... you can't make me. I am happily an aerospace engineer now where I don't need this chemistry nonsense, or quantum mechanics.
Ah let's see, of the top of my head...
~~1s² 2s² 2d⁶ 3s² 2p¹⁰ ...~~
Edited (iirc now, the d block is in the middle with the transition metals, p block with metallics, Halogens, Noble Gases...):
1s² 2s² 2p⁶ 3s² 2d¹⁰ ...
+1/2 h and -1/2 h
Fucking hate the people that insist on using only half of the number as if it was a real value. At least say you are working with natural unities or something.
" - How far is your house? - Oh, it's just 5!"
Except in this context the question is "how many blocks away is your house?" Where "5" is a completely valid response
It's h-bar, not h. And it really does make sense if you look deeper I to the math.
Using "+1/2" and "-1/2" as vector labels is fine. Using it on the context of "the spin can have those 2 values here" for laypeople without further explanation is just making the subject less accessible.
Also, yeah, I was too lazy to search for the unicode ħ.
If we theorize that the universe is like a computer program, then maybe the Universe has several layers of abstraction and we only can access our current layer, therefore forever having an incomplete model. If something external to our layer is affecting it, it would probably be impossible to know.
Quantum mechanics (and spin) isn't really mysterious or inaccessible, it's just not intuitive.
Ahh... hmm. In some ways it is literally inaccessible, because we can't observe it directly. All of our experimental (e.g. real) subatomic knowledge comes from smashing particles into each other at near-light speed and observing the bits that come out, which is somewhat like dropping a smartphone off the Empire State building and trying to figure out how it works by picking up the broken pieces off the sidewalk. We can probe the structure of molecules with electron microscopes, but there are no tools for directly observing anything smaller than that. We draw conclusions for how smaller things behave through inference.
And frankly, the entire concept of spinors and the relationship to observed properties like electron charge is pretty mysterious, and nobody really understands wave-particle duality, that's just the best explanation we have for what we observe.
This is basically "hidden variables hypothesis".
Now everything is clear. Thanks!
they don't actually spin but they're little bar magnets as if they do. if you charge a sphere and spin it, you'll generate exactly the same kind of bar magnet, but they don't actually spin. and just like bar magnets, like repels like. but they're neither bar magnets nor spinning. why don't they spin? because they're point masses, which don't have any extent. but actually, you can't really observe them as point masses because they're waves.
^^ this was the exact point at which I said quantum mechanics wasn't for me and I'm done with physics, after completing most of a degree. it sort of all makes sense but at the same time it completely doesn't. it all makes sense as pure math but the second you try to make sense of the math, sense goes out the window.
It is a good demonstration of the limitations of our own thought. We understand new concepts in terms of familiar concepts. If there is no direct analogy to something familiar, the human mind is utterly lost and has to trust in rigorous analysis while only half believing what it proves.
It all makes sense and the more you dig deeper the more it makes sense, but then you zoom out a little and then realize it actually doesn't make any sense in any sort of palatable way.
yeah, I was lucky to have already taken Classical Mechanics prior to Quantum Mechanics (it wasn't a prereq so most of my classmates jumped straight into QM), so the math was all perfectly sensible. but the second any prof started trying to use English to interpret the math, I started having these moments where I'd have to sit back and think about the words coming out of their mouths, and sitting with how it was all actually gibberish. Feynman's "shut up and calculate" started to feel incredibly valid really fast, whereas prior to QM, I was under the impression that physics was natural philosophy. it's not and QM was the breaking point, at least for me, personally.
