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“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”
- When it’s* a particle
- When it’s* a wave
- it’s* still doing that
We are all just folds in this wonderfully weird thing we call spacetime!
The prions of spacetime.
Out here folding along.
Hah! Time. Like that’s a real thing.
A channel I subscribe to just posted an explainer on spin, for anyone interested
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 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.
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.
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.
Physicists seem to love their confusing language. Why do they associate Bell’s theorem with “local realism”? I get “local,” that maps to Lorentz invariance. But what does “realism” even mean? That’s a philosophical term, not a physical one, and I’ve seen at least 4 different ways it has been defined in the literature. Some papers use the philosophical meaning, belief in an observer-independent reality, some associate it with the outcome of experiments being predictable/predetermined, some associate it with particles having definite values at all times, and others argue that realism has to be broken up into different “kinds” of realism like “strong” realism and “weak” realism with different meanings.
I saw a physicist recently who made a video complaining about how frustrated they are that everyone associates the term “dark matter” with matter that doesn’t interact with the electromagnetic field (hence “dark”), when in reality dark matter just refers to a list of observations which particle theories are currently the leading explanation for but technically the term doesn’t imply a particular class of theories and thus is not a claim that the observations are explained by matter that is “dark.” They were like genuinely upset and had an hour long video about people keep misunderstanding the term “dark matter” is just a list of observation, but like, why call it dark matter then if that’s not what it is?
There really needs to be some sort of like organization that sets official names for terminology, kinda like how the French government has an official organization that defines what is considered real French so if there is any confusion in the language you at least have something to refer to. That way there can be some thought put into terminology used.
At least physicists don’t call particles “Sonic Hedgehog” like biologists do with proteins
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.
Sorry I didn’t just Google, but could you give me a rundown of the twin slit experiment?
Sure. So, imagine a rectangular pool of water. You have a little weight on one end of the pool bobbing up and down producing waves. Then you put a wall halfway down the pool with two gaps in the wall. The waves from the wave-generator hit the gaps and go through. At the back wall of the pool you can measure the wave height. What you see is that at some points there are big waves, and at other point no waves at all. What’s happening is that the waves coming through each gap travel different distances. If the wave from one gap is at a trough when the wave from the other gap is at a peak, they interfere with each-other and the water doesn’t move much. If, instead, the distance is right so that both waves are at a trough or both waves are at a peak, the wave height is doubled at that point.
If the weight bobbing up and down is very regular, the pattern stays very regular. The places on the back wall with no waves are always in the same spot, and the places with big waves are in the same spot.
Now, do a similar experiment but instead of using water, you use light. To keep the waves all the same wavelength / frequency, you need a laser. So that laser shines forward and hits a barrier with two small slits in it. When the laser hits a wall after that you get the same pattern of bright spots and dark spots. Light is acting like a wave and the light waves are interfering with each-other in the way you’d expect.
But, what if you turn the laser way down. You can reach a point where instead of getting a continuous pattern on the back wall of the experiment, you only get an occasional “blip”. What’s happening there is that the intensity of the laser is so low that you get a single photon being emitted, passing through the slits and hitting the back wall.
So, this basically shows that light is acting like a particle. It is emitted from the laser, passes the slits, and hits at one single, specific point on the back wall. So, this shows that light is both a particle in some ways (individual light “packets” can be emitted and strike one specific spot on the back wall), and it’s a wave, because the light passing through the two slits interferes and produces a strong/weak pattern on the back wall.
But, the truly mind-blowing part of the experiment is what happens if you record the positions of each hit on the back wall when the laser is tuned way down and only emitting one photon at a time. If you record the location of the hits (or say, use something like photographic film that you expose over multiple days while you run the experiment), what you see is that there are points where you get many single-photon hits on the back wall, and points where you don’t get any single-photon hits on the back wall. And, the points where you don’t get any hits are exactly the points where you get dead zones from the wave interference when you run the laser at full intensity. Even though you’re only allowing one photon to go through at once, it’s still acting as if it’s going through both slits in some way.
The obvious question at that point is “Which slit is it actually going through?” So they measured that, and as soon as they could determine which slit the photon went through, the interference pattern disappeared. Instead it looked exactly how it would look if you blocked the other slit. But, when they stopped measuring which slit the photon went through, the interference pattern comes back.
This revealed a few fundamental things in quantum mechanics:
- Everything is both a particle and a wave. That applies to things we mostly think of as particles like protons and electrons, but also to things that mostly act like waves like electromagnetic radiation (light, gamma-rays, x-rays, radio waves, etc.)
- Measuring fundamentally changes the result. It’s not possible to observe passively. This isn’t just a vague statement though. There’s an equation that says that the uncertainty in position multiplied by the uncertainty in momentum is always bigger than a certain value which is related to the Planck Constant. It’s a tiny, tiny value so it doesn’t much affect human-scale things, but massively influences things at a sub-atomic scale.
- For many quantum phenomena, something can be in an indeterminate state and interact with the world in some ways until something forces the quantum state to collapse. Instead of going through either of the two slits, there’s a probability distribution about its position, which doesn’t collapse until it interacts with the back wall of the system, which forces the wave function to collapse and results in a single spot being produced on the back wall.
