1935: Einstein, Podolsky and Rosen show that quantum mechanics doesn't make sense.
1982: Aspect shows that nature doesn't make sense either.
Thanks to that i understand what "Aspect shows that nature doesn't make sense either" means. I can recommend the article (and the three others) but it takes a few hours to get through.
However, the article also explains it without quantum mechanics. Polarized photons are enough to understand why our universe is not "locally realistic". Read part 2.
> Since that time, there has been ample evidence that wavefunction collapse is not driven by conscious observers alone. In fact, every interaction a quantum particle makes can collapse its state. Careful analysis reveals that the Schrodinger Cat "experiment" would play out in the real world as follows: as soon as the radioactive atom interacts with the Geiger counter, it collapses from its non-decayed/decayed state into one definite state. The Geiger counter gets definitely triggered and the Cat gets definitely killed. Or the Geiger counter gets definitely not triggered and the cat is definitely alive. But both don't happen.
In QM you have the observer, in relativity you have the reference frame, I think physics is exploring fundamental properies of the reality we experience,that it is a subset of something else.
Edit: I'll rephrase (I'm serious) - isn't the idea of the multiverse based on the schrodinger's cat in a box idea, and the need for an observer? Or is the whole multiverse idea just sci fi? Or is there another physical basis for the idea of a multiverse?
You are the cat inside the box. You exist as a person, live in a planet and the entire setup could and couldn't be real. The experiment prooves that something is uncertain and all these are nonsense.
Doesn't the paradox arise precisely because the time at which the atom will interact is probabilistic?
I think you are misinterpreting what "observe" means in this context. Conciousness has nothing to do with it.
Any sort of visiting paralell universes stuff is pure sf.
[1] https://www.preposterousuniverse.com/blog/2015/02/19/the-wro...
Thing is, multiverse ideas are not testable and therefore not physics. Theorists like to entertain ourselves with them to a certain degree, but they are just that, a kind of Science Fiction. For that reason, theorists never bother to distinguish between the different kinds of multiverses, that is a tedious and ultimately not important task.
Now science writers love to write about the multiverse, because they are good entertainment, however they lack the technical sophistication to actually distinguish between the different kinds of multiverse.
Having said that, I think you're actually correct to point this out! The cat will obviously have a look around inside the box and likely cause wavefunction collapse. I believe the cat is meant to be fundamentally unable to effect things though.
After all, it's mostly an interesting problem because it posits that anything that could be "alive" inside the box would be in a superposition of alive and dead which is something that's never been observed and probably can't happen due to the unstable nature of wavefunction collapse in the real world.
But its been a very long time and my physics is pretty rusty
When the observer's state gets entangled with the cat's state (whether gradually or suddenly) it's still perfectly valid to say that the cat is in a superposition of being dead and alive, and so is the observer in the superposition of observing the cat dead and observing the cat alive. That doesn't mean that the observer ever can nor should observe the cat being both dead and alive.
That much is not true though. Of course an ordinary cardboard box does not thoroughly isolate its inside from its outside, but complete isolation is possible in other situations (e.g. two spatially separated labs making measurements at the exact same time, which has been done in tests of the Bell inequalities).
That seems like a very anthropocentric view of the universe. Why would it matter whether a particle is “being observed”, UNLESS the act of observation has a side-effect. If “observation” is purely passive then it can’t affect anything, by definition.
A MUCH simpler explanation is that the way that we observe things (by looking at them) is by bouncing photos off of them. Quantum particles are small enough that bouncing a photon off of it can change its course.
Here’s an analogy : you’re blind, but you’re super good at throwing and catching basketballs. The way that you observe the world is by throwing a basketball and then timing how long it takes to come back to you and catch it, and by observing if it comes back at an angle or with some spin on it. Imagine you come across a pigeon. You throw the basketball at the pigeon. You observe strange behavior of the pigeon when you “observe” it vs when you don’t. You formulate the pigeon uncertainty principle. You describe pigeons as spooky. You just accept that pigeons follow different physics than school buses.
To me, it sort of sounds like how time dilation works in relativity except for a different dimension.
It has been proven that non-concious observers can trigger a wavefunction collapse through variations of the dual slit experiment. What we don't necessarily know is exactly how the chain of wavefunction collapse occurs from e.g. the "opening of the box" to e.g. the human eye. This is known as "the measurement problem".
Also, fwiw, in both the Copenhagen interpretation (1) and the Many Worlds Interpretation (2), the observer is simply any particle which measures the event. It may be more intuitive to say that as soon as particle/s depend on knowing the answer to the wavefunction collapse, it will collapse.
This may be "fuzzy" as well meaning that if the particles don't need a precise answer only the amount of wavefunction collapse needed to give that level of precision will occur.
>Now in (2) isn't this the same as the problem with (1)? the collapse happens near instantaneously and so these other worlds are fleeting possibilities that never really existed, its the same fallacy as the cat in the box never really being dead
Many Worlds Interpretation posits that the _all_ other worlds absolutely exist before and after the collapse. After wavefunction collapse, each possible outcome occurs in a separate world. The one that "we see" is merely one outcome being experienced. Indeed, the reason this may be confusing is that you have to realize that other versions of yourself will see the different outcomes, each one convinced that they're the only version.
It can sound kind of crazy and we have no way of proving the existence of these other worlds but the interpretation is still taken seriously by many in part due to it being the most literal interpretation of the Schrodinger Equations.
>the wave form collapses in a small delta of time, and provides the continuity we see in the macroscopic world
You refer to this as a "problem" i.e. that these collapses are vanishingly small and so we never encounter them. But we can in fact encounter them!
Imagine shooting thousands of bullets through two slits with some degree of known error in aiming. The wall on the other side of the two slits will likely have holes in two vertical lines.
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Now imagine you push liquid water through the slits instead. The water forms waves as it passes through the slits. The peaks of the waves when they hit the wall on the other side form something different that looks like this instead.
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This is what happens (after shooting multiple photons) when we make no such measurement of the photons.
Now, to us, each photon comes out in different spots instead of all at once like with the wave. The first might be
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This means that either:
Copenhagen:
A pretty literal wave of possibilities travels through the slits. When it hits the wall, this so-called wavefunction collapses into a single point. That point will be statistically likely to land somewhere on the many-lined diffraction pattern.
Many Worlds:
Multiple worlds exist in which each of the single points follow the different trajectories we see. They still form a diffraction pattern because these worlds are defined by the same Schrodinger Equations that may also define the wavefunction collapse.
There's a lot more that I'm skipping over such as Pilot Wave Theory which posits that each particle was in fact always a particle that instead is guided by a "pilot wave" that can sort of see the future, or travel faster than light in order to determine where it should land. Ultimately what I'm trying to say though is that there is no way around quantum mechanics. Yes, the timeframes are tiny and the cat probably isn't alive and dead at the same time due to decoherence occuring well before you open the box; but reality is still very much quantum and there are ways to observe that.
It's weird af, but it's absolutely happening.
Edit: is a collapse a measurement? Before the measurement all the possible states are there, then a measurement occurs, and we then know the result (within uncertainty).
The collapse is a measurement. It is also the instantaneous moment that a particle such as a photon goes from being a wave-like to being particle-like. In many ways it is just a name given to the phenomenon that we know occurs - that particles act as waves until we need them to be more "real" so to speak.
In Copenhagen, the "wavefunction collapse" is when the particle "picks a spot to land" inside of its wave. The spots it is likely to land are defined by the peaks and valleys of the wave.
Imagine liquid waves in the ocean again. They go up and down with fairly predictable heights of waves. Wavefunction collapse is when those waves decide to collapse into a small rock instead. But where should the small rock wind up? Well the highest wave of course. The wavefunction collapse is when the decision occurs to _place_ the rock; when the universe says "throw a dart somewhere along this path of likely positions".
That's a bit more metaphorical and philosophical but maybe it puts it into perspective a bit better? To be honest, I don't understand it very well and certainly couldn't tell you why it happens from more basic principles. This is part of the reason there are competing interpretations which is that even Copenhagen style wavefunction collapse _feels_ weird.