I think I have a decent grasp on the dual-slit experiment, but I don’t know how the waveforms know when to collapse into a particle. Also, what counts as an observation and what doesn’t?
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Simple answer is you interact with things when observing them, an apple needs to have light hit it, energize its electrons, those electrons become unstable drop energy levels and give off visible light which we perceive, we can say the apple is red in this case. Adding a light source to see what color the apple is, effects the apple to some degree. What we can also do is observe what the apple has done to other things in its surroundings. For this example let’s say the apple was rolled down a snowy hill, we know what a snowy hill looks like without an apple rolling down it, we notice a small path and we see a round indent. We can kinda infer that the apple is small and that it’s also kinda round, but less accurate information is gained this way. I hope this helps.
I’ve always felt like observation is poor wording for what’s actually going on. In reality, it’s the action of interacting with something else that which collapses the wave form. This happens whether or not “observes” it. It’s just that for us to make an observation, we need it to interact with something else. It’s that interaction that collapses the wave function. No observer necessary.
Imagine trying to determine the position and velocity of a small pebble. The problem is that the only means by which you have to measure these quantities is by using other pebbles, either by shooting them at the subject pebble and noting where they end up, or by scattering them about and waiting for the subject pebble to collide with them.
For measurement to occur, one of your “observation” pebbles must collide with the “subject” pebble. This collision perturbs the “subject” pebble’s motion. The result is that the “subject” pebble now behaves differently that it would have had it been left unobserved.
So it is with light. We cannot measure the passage of a photon without interacting with it in some way. This interaction disturbs its motion, leaving us with an incomplete sense of what is happening.
when thinking about observation in quantum mechanics, just think of it as extracting information through special tools, in some cases these tools may be photo detectors or cameras, anything that can aid in gaining insight to where the photons are going. as for why the observation of photons collapses the wave function, it’s simply the act of observing or measuring that is doing so, as of to how and why the photons “decide” to act like particles and collapse the wave-function when being observed is a great question, unsolved, up for debate and no consensus has been reached.
is waveform made of something? I have many doubts.
You would know when a blind, deaf person is detecting you because they are touching you with their arms. It’s basically the same way for really tiny things. We can’t detect them without hitting them with something and watching the bounce.
As near as I can tell, this is one of the mysteries physicists are still working to solve. In other words, no one knows for sure.
OK, imagine you’ve heard about a phenomenon about invisible dodgeballs. You can’t see them, but you have evidence they’ve been around by leaving wet trails on the floor as they’ve passed by. This is how you can tell it’s direction and likely properties of the balls but not any other information. They haven’t been directly observed.
So now you want to get more information about these invisible dodgeballs. One way to do it is to roll a bag of baseballs to a likely spot where the balls are known to go by. Eventually you get a bunch of baseballs rolling back towards you and you measure the speed, direction they were going, etc. to gather more about the invisible dodgeballs. So you can calculate where it *was*, but not where it currently *is*. Now that the invisible dodgeballs have been observed, their conditions have been changed.
You can’t observe something without interacting with it. Think about what it takes to “see” something. For something large, in order to see something you need light to bounce off of it, or in the case of echolocation you have sound bounce off of it. Well, that light or sound wave will exchange momentum and energy with the thing you are observing but that energy isn’t enough to actually change that thing. Similarly if you are observing light, the photon will come in and interact with your eyeball. The act of interacting with your eye will change that photon and it will either reflect in a different direction or be absorbed. You might think you are observing the light source but you are really just interacting with the photons it emits.
Quantum mechanically we are talking about things that are very small like a single particle or photon. If you shine a light on it then it will change it. If you direct it toward a particle director that also interacts with it and changes it. There is no way to observe a waveform without disturbing it and causing it to collapse.
When you see a car, the photons bouncing off of it don’t move the car. But when you look at quantum particles, like individual atoms, they DO get impacted by bouncing photons off them.
They don’t “know”. We just can “see” without poking them, which changes them, their direction or spin.
So it becomes a study of how much we can know something before we “touch” it. This, turns out, to be fascinating and exploitable – that these particles carry types of information in them that we can save, extract, and send along, and until they’re poked by something again, they keep that information.
And this ends up being useful in some ways, like quantum computing.
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