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When researchers say “observe” they actually mean “measure”. And when you’re working with sub-atomic particles, “measure” isn’t some passive activity. It’s an active thing. When you measure small particles you are applying some force upon them, changing them in some way from how they would otherwise act.
Imagine if you were tasked with measuring traffic on the other side of the planet, but you had no cameras. The only tool you had was a gigantic 30 ton, satellite-networked pendulum swinging across the highway. The only way you know if there are cars on the highway is if the pendulum thwacks into one of them. That’s quantum particle physics… I think.
Not exactly. Quantum physics applies no matter how you measure it. The double-slit experiment is an example of this: Photons moving through two slits will form a wave interference pattern on a detector plate, even though the detector doesn’t affect the position of the photons beforehand.
It’s more like: when you become aware of the results of a quantum measurement, you yourself become a part of the quantum system, and being a part of the system requires measurements to have real values. Whether you should interpret this as a wave-function collapse or branching into multiple parallel universes is up for debate though.
When you perform the measurement on which slit the particle passes through, then the measuring device is also part of the system and it affects it. The measurement reduces the degrees of freedom in the system so there are no longer two equivalent ways for the particle to pass through the slits (either A or B), but rather you now have a measured slit and an unmeasured slit. Since there are no longer multiple ways to achieve the same result, the is no longer interference due to equivalent probabilities.
Matt Stassler has a nice series of blog posts on this.
Yes, but that’s semantics. Clearly the observation has some effect, but it’s not from any force we recognize.
It gets even more interesting: to interfere in the double slit experiment, the light has to take a longer path for some points and light is really good at finding the shortest path. And, since you can extend the double slit experiment to infinite slits with infinitely thin blockers between the slits, you can leave away the slits entirely and still have a valid version of that experiment and get interference. It’s just, that most interference is destructive.
Veritasium had a very interesting video about that recently and my extrapolation of this is that there is neither a collapse of wave functions nor multiple parallel universes.
My intuition says that the wave function is there after being “observed”. There is no multiple possible outcomes, just very visible ones and a lot of destructive interfered ones.
However what i just wrote is not science but me extrapolating from science so don’t take it for anything more than that. It somehow causes quantum physics to make intuitive sense for me so i like it. Nothing more than that.
Honest question: what happens afterwards? When we’ve stopped observing, does it reassemble into it’s superpositive form? Are we depleting quantum states somehow?
Sorta! According to the Heisenberg Uncertainty Principle, there’s an upper limit to how much we can “know” about the given state of a quantum system. This isn’t an issue with our measurements, but a fundamental property of the universe itself. By measuring one aspect of a quantum system (for example, the momentum of a particle), we become less certain about other aspects of the system, even if we had already measured them before (such as the position of the same particle).
Though (as far as we know), we aren’t going to run out of quantum states or anything like that.
Thank you for your answer!
Maybe I’m too dense, but what happens with other quantum states that aren’t position/velocity based? I’m thinking things like when we collapse spin, e.g. in entangled particles.
I’ve heard that entangled particles are “one use”, I’d assume they can be restored and possibly re-entangled, but how?
Good question! You are certainly not dense!
The position-momentum uncertainty relationship is just a specific case of a more general relationship. There are other uncertainty relationships, such as between time and energy or between two (separate/orthogonal) components of angular velocity. The relationships basically state that whenever you measure one of the two values, you are required to add uncertainty to the other.
Unfortunately, this is kinda where my knowledge on the subject starts to hit its limits. As for spin, it has a lot of effects on the energy of the system it’s involved with, so I believe the energy-time or angular momentum exclusion principles would apply there.
You might also be thinking “why not have two entagled cloned particles, and measure the momentum of one and the position on the other?”. While you can duplicate particles, there are reasons why that doesn’t work that I don’t really remember tbh. I’m sure PBS Spacetime on Youtube has an episode on it somewhere though if you’re interested
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My example is more in regards to wave/particle duality as it shows up in variations of the double slit experiment. Putting a detector at one of the slits is an active interaction, giving you the particle-like behavior rather than the interference pattern.
What I mean to say is that the detector is not what’s changing the particle; It’s the process of learning about an aspect of the quantum system that forces it into one state or another (at least from our own personal perspectives).
uh, I’m a total quantum layman, but I’m pretty sure its the detector.
Nerds!
Put my head where pendulum is for super powers, got it.
My favorite thing about quantum physics is that Schrodinger’s Cat was presented as a criticism. It was the most ridiculous extension of quantum superposition that Schrodinger could come up with. But then all the quantum physicists went, “YES! That’s a perfect way to explain it. Let’s teach that to middle schoolers!”
Specifically a criticism of the Copenhagen interpretation of quantum mechanics. Schrödinger’s thought experiment is intended to make a person consider where/when the wave function is supposed to collapse.
Pilot-wave theory is another interesting interpretation. I feel like it’s a much more “intuitive” interpretation.
I’m actually very fond of elements of the pilot wave concept.
I think there is a pilot wave, and I think it’s in an inaccessible dimension, and I also think whatever drives it also obeys quantum weirdnesses.
Pilot wave isn’t another dimension. It exists in configuration space which is a concept of quantum mechanics in general. What pilot wave provides is a deterministic narrative for quantum mechanics.
Well it is in another dimension. We analyze spatial dimensions in a 3D framework, but it’s very obvious there are additive forces that we don’t understand and are forever inaccessible to us, outside of inferring properties based on outcomes we observe.
We don’t live in a 3+1 dimensional universe, at minimum we live in a 4+1 universe.
Quantum physics doesn’t make sense until you just let the math take you to the results and stop worrying about your intuition. You have to absolutely trust the math and work through the results as many times as you need to for them to make mathematical sense in spite of your intuition. Further, have some grace with yourself. It took us 7,000 years from the dawn of civilization to get to Aristotle, 2000 years to get from Aristotle to Newton, and 218 years to get from Newton to Einstein. In that time a lot of progress has been made to our understanding of physics, and a lot of the confusion about quantum physics is due to flawed understandings of the people who created it. Spin was literally thought to be rotational motion of the particle in the of
I think you fell asleep or something, your last sentence may have disappeared.
That is exactly what happened lol
I love Lemmy lol
I remember explaining something regarding special relativity to my colleagues once, and they replied that I must be wrong because “That doesn’t make sense at all”. Of course it doesn’t make sense, that’s how you know I’m right!
Quantum Scientists: Hey, man, you just don’t get it.
Hipster Artists: Hey, man, you just don’t get it.
superdeterminism gang represent ✌️
The thing is I agree with nearly every premise of superdeterminism. But the conclusions seem stretched.
I love the idea of not abiding to the strict assumptions set forth by Bell’s theorem. The idea that determinism doesn’t have to hide within the simple hidden variable model bell’s theorem disproves to be true. The idea that we are essentially always part of the experimental system. The questioning of the objective rational experimenter with free will ideal.
Yet I haven’t seen any serious mechanism explaining how the required correlations between experimenter choices and particle states could have been embedded in the universe’s initial conditions in such a finely tuned manner, given that experimentally, the outcomes are indistinguishable from standard quantum mechanics… I just can’t imagine how this could likely be the case without adding quasi-conspiratorial assumption.
I mean, effectively superdeterminism’s natural conclusion is that time is an illusion. Everything that will be was already fixed at the start of the universe.
But turning this back on itself, what’s the proposed mechanism for quantum wave collapse at superluminal speeds?
Our understanding is fundamentally flawed, but thankfully the math works!
Hidden-variable cult skulking in the background 🫥
I was into quantum books until I read the book with word “quantum” in description that had a story about guy who imagines diamonds in his head and they appear in real world. After that I stopped reading quantum books.
It’s “The Holographic Universe: The Revolutionary Theory of Reality” - it have very good reviews.
suspension of disbelief is a requirement
It’s called “shut up and calculate”
The most important thing I’ve ever been told about quantum is “shut up and calculate.” Results don’t seem physical? That’s quantum. Results don’t make sense? That’s quantum. Shut up and calculate
How much research is being done on the parts of quantum physics that would allow me to be in two places at once?
Chainsaws have existed for quite a while already.
Those were invented to separate two people.
What’s so hard to understand about subatomic particles doing anything, everything, and nothing simultaneously everywhere at all times for no reason? It all cancels out in time for Newtonian Physics to take over anyway.
I cannot intuitively grasp that I’m holding a ball in my hand that is 10 to the umpteenth power particles, each of which is made of smaller particles, each of which is everywhere in the universe at the same time all at once.
Maybe you just need to watch more Rick & Morty lol
