Comment on Electrons are easy

• peto@lemm.ee ⁨5⁩ ⁨months⁩ ago

  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.

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  • isolatedscotch@discuss.tchncs.de ⁨5⁩ ⁨months⁩ ago

    holy shit the pool explanation is so good, I’m gonna recycle it for sure

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  • Notyou@sopuli.xyz ⁨5⁩ ⁨months⁩ ago

    Image

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  • Fedizen@lemmy.world ⁨5⁩ ⁨months⁩ ago

    Good metaphor

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  • Swedneck@discuss.tchncs.de ⁨5⁩ ⁨months⁩ ago

    like trying to measure a soft noodle lengthwise with a caliper

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  • tryitout@infosec.pub ⁨5⁩ ⁨months⁩ ago

    So, if we had a machine that could “see” without photons, we could observe an electron directly?

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    • peto@lemm.ee ⁨5⁩ ⁨months⁩ ago

      We have such devices, unfortunately they tend to use electrons instead (electron microscopes). We also have devices that just work by measuring the electromagnetic field (atomic force microscopes). Again though, to measure the field you have to interact with it, so you can’t do it immaculately.

      When talking about particles, the interaction very rarely involves actual contact, as that tends result in some manner of combination. Two electrons for instance don’t really bounce off each other, they just get close, interact and then diverge. If a photon ‘hits’ an electron it gets absorbed and a new one is emitted. Look up Feynman Diagrams if you want to see some detail to this. I don’t think you need any deep knowledge to benefit from looking at them, they are really quite an elegant way to visually show the mathematics.

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  • bunchberry@lemmy.world ⁨5⁩ ⁨months⁩ ago

    If you suggest every observation is an interaction then you inherently are getting into the relational interpretation. Which I am not saying you’re wrong to do so, I think it is the most intuitive way to think about things, but it is not a very popular viewpoint.

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    • peto@lemm.ee ⁨5⁩ ⁨months⁩ ago

      Do expand, please. It has been a while since I have studied this seriously. Do you have any examples of observations that don’t involve interacting with the system?

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      • bunchberry@lemmy.world ⁨5⁩ ⁨months⁩ ago

        That’s not what I’m saying. My point is just that observation = interaction has a lot of implications. Particles are always interacting, so if the wave function represented some absolute state of all systems, then the statement would just be incorrect because the wave function would be incapable of ever “spreading out” as it is constantly interacting with a lot of things.

        The only way it can be made consistent is to then say that wave functions are not absolute things but instead describe something relative to a particular system, sort of like how in Galilean relativity you need to specify a coordinate system to describe certain properties like velocity of systems. You pick a referent object as the “center” of the coordinate system which you describe other systems from that reference frame.

        You would have to treat the wave function in a similar way, as something more coordinate than an actual entity. That would explain why it can differ between context frames (i.e. Wigner’s friend), and would explain why you have to “collapse” it when you interact with something, as the context would’ve changed so you would need to “zero” it again kinda like tarring a scale.

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• chonglibloodsport@lemmy.world ⁨5⁩ ⁨months⁩ ago

  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.

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  • bunchberry@lemmy.world ⁨5⁩ ⁨months⁩ ago

    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? They just inventing confusing terms then getting frustrated people are confused about them.

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    • chonglibloodsport@lemmy.world ⁨5⁩ ⁨months⁩ ago

      Yep! Same thing with black holes which are not holes at all!

      Even very basic physics terms such as positive and negative electric charges lead to a lot of confusion for ordinary people. There’s nothing positive or negative about them, they’re just names for the fundamental property of protons and electrons that leads them to attract one another.

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  • uis@lemm.ee ⁨5⁩ ⁨months⁩ ago

    At least physicists don’t call particles “Sonic Hedgehog” like biologists do with proteins

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• Fedizen@lemmy.world ⁨5⁩ ⁨months⁩ ago

  Its that an observation is always an energetic interaction. You can’t measure a system without interacting with it and at the particle scale every interaction has enough energy to affect the particle in some way.

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