You're viewing a single thread.
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.
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.