“Observation” or “measurement” actually means interaction. We literally can’t measure anything without interacting with it. If you place something at the slits which is able to detect a photon going through, it can only do so by interacting with it.
The common way seems to be that the passing particle induces a tiny electric current in a wire loop. Obviously, that takes energy away from the particle (that energy is now in the movement of one or more electrons in the wire). And that means, its wave function in that very moment is one locational probability of 1 - it is collapsed.
EVIL_MAN@lemmy.zip 3 days ago
It doesn’t work like this, popular misconception. It is cool in sci-fi though.
pcalau12i@lemmygrad.ml 3 days ago
The easiest way to understand this is in terms of mutual information.
If we both flip a coin independently of one another, then both coins have a 50%/50% chance of being heads/tails and the distributions are independent of one another and thus uncorrelated, but imagine the two coins are initially attached to one another, flipped, and then we separate them. Now they’re both still 50%/50% for heads/tails but are perfectly correlated, so they are guaranteed to have the same value, and so if you know one, you know the other. In this case, the coins are said to have mutual information on one another.
It turns out in the physical world that mutual information, or more specifically quantum mutual information (QMI) plays a very important role. The marginal statistics on the behavior of a system can depend upon whether or not it shares mutual information with something else. You see this in the double-slit experiment because if you record the which-way information of a particle, then necessarily it must have interacted with something to record its state, and thus whatever measured it must possess QMI between itself and the particle, and thus the particle’s behavior will change.
This is in no way unique to human observers or human measurement devices. You can introduce just a single other particle into the experiment that interacts with the particle such that they become statistically correlated and it will have the same effect.
QMI is rather counterintuitive because you can establish QMI in ways that you would intuitively think would not impact the system being measured. For example, you can have an entirely passive interaction whereby only the measuring device’s state is altered and not the particle in order to establish QMI between them.
You can also establish QMI without an interaction at all, such as, imagine that the measuring device is only placed on 1 of the 2 slits and you only fire a single photon and that photon is not detected. If it’s not detected, you still know where it is, because it must have traversed the slit the measuring device was not on. Hence, the non-detection of something can still be a detection and thus can still establish QMI.
Intuitively, you would think a passive measurement, or a measurement that does not even involve an interaction at all, should not alter the system’s behavior. But the mathematical structure of quantum mechanics is such that the system’s marginal stochastic behavior is genuinely statistically dependent upon the quantity of QMI, and so things you would intuitively believe should not affect the system do, in fact, affect the system.
You can even use this effect to ]detect the presence or absence of something without ever (locally) interacting with it](arxiv.org/abs/hep-th/9305002).
ivanafterall@lemmy.world 3 days ago
Agree to disagree!
Beacon@fedia.io 3 days ago
Nothing to agree or disagree with, you're factually incorrect. The observer effect has nothing to do with whether someone's eyes are looking toward it or not. It basically just means when a process is happening and anything external occurs to it then that will change the way the process is happening.
EVIL_MAN@lemmy.zip 3 days ago
You are wrong though.
Xavienth@lemmygrad.ml 3 days ago
Observation in quantum mechanics isn’t like everyday observation. There is no passive observation, you have to interact with a particle to observe it. It’s like putting your hand in front of the hose to see if it’s on. You can see from the spray pattern that when the hose is “observed” the pattern changes.
Quibblekrust@thelemmy.club 3 days ago
Nah, man, it’s literally how it works (for all we know). The wave function doesn’t collapse until the data is read. You can’t prove otherwise, so people are free to believe it.
CovfefeKills@lemmy.world 3 days ago
PotatoesFall@discuss.tchncs.de 3 days ago
Your joke was funny you just forgot the /s
Buddahriffic@lemmy.world 3 days ago
Does the result of the experiment change if there’s a sensor active that records data to a hard drive that no one ever looks at and it just gets deleted? Does the result change again if someone decides that if they get a wave pattern, they will interrupt the deletion process and look at the data?
Bluescluestoothpaste@sh.itjust.works 3 days ago
But the way it works is only the top one if im not mistaken