Comment on Electrons are easy
peto@lemm.ee 5 months agoIt’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.
Notyou@sopuli.xyz 5 months ago
Fedizen@lemmy.world 5 months ago
Good metaphor
Swedneck@discuss.tchncs.de 5 months ago
like trying to measure a soft noodle lengthwise with a caliper
tryitout@infosec.pub 5 months ago
So, if we had a machine that could “see” without photons, we could observe an electron directly?
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.
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.
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?
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.
peto@lemm.ee 5 months ago
AHH, I think I see what you have misunderstood. I am not saying all interactions are observations, rather that observations are a subset of interactions, hence uncertainty.
Furthermore I think it would be more useful to say that the wave function only collapses when it is actually necessary to the interaction rather than when it interacts with ‘us’. Unless you can provide a counterexample. Privileging observations made by humans reeks of mysticism in my opinion and is the cause of a lot of the misunderstandings about quantum physics among laypeople.
isolatedscotch@discuss.tchncs.de 5 months ago
holy shit the pool explanation is so good, I’m gonna recycle it for sure