Then why don’t we see other universes, and why do we make only classical observations?
What do you mean by this. What are you expecting to be able to do here?
Shrodingers cat. Cat is in a superposition of alive and dead. Scientist opens box. Scientist is in superposition of feeding live cat and burying dead cat.
The only way to detect a superposition is through interference. This requires the 2 superimposed states to overlap their wavefunction. In other words, it requires every last particle to go into the same position in both worlds. So it’s undetectable unless you can rearrange a whole cat to atomic precision.
Coherent states continue to interact, so you need decoherence for causally separate, non interacting worlds.
In practice, if two states are wildly different, the interaction term is small. With precise physics equipment, you can make this larger, making 2 states where a bacteria is in different positions and then getting those to interact. Basically, blobs of amplitude need to run into each other to interact. Quantum space is very spacious indeed, so the blobs usually go their own separate way once they are separated. It’s very unlikely they run into each other at random, but a deliberate collision can be arranged.
No, rather the reverse. It’s when off diagonal elements are zero or negligible.
That is what the matrix looks like, yes.
But thats also the evidence for collapse.
Interaction with the environment is a straightforward application of schrodingers equation. Collapse is a new unneeded hypothesis that also happens to break things like invarence of reference frame.
Show that coherence is simple but inadequate, and decoherence is adequate but not simple
.
Shrodingers cat. Cat is in a superposition of alive and dead. Scientist opens box. Scientist is in superposition of feeding live cat and burying dead cat.
The two problems with this account are 1) “alive” and “dead” are classical states—a classical basis is assumed. and 2) the two states of the observer are assumed to be non-interacting and unaware of each other. But quantum mechanics itself gives no reason to suppose that will be the case. In both cases, it needs to be shown, and not just assumed that normality—perceptions “as if” of a single classical world by all observers—is restored.
So it’s undetectable unless you can rearrange a whole cat to atomic precision.
So you can’t have coherent superpositions of macroscopic objects. So you need decoherence. And you need it to be simple, so that it is still a “slam dunk”.
Basically, blobs of amplitude need to run into each other to interact.
How narrow a quantum state is depends, like everything, on the choice of basis. What is sharply peaked in position space is spread out in frequency/momentum space.
Interaction with the environment is a straightforward application of schrodingers equation.
No it isn’t. That’s why people are still publishing papers on it.
What do you mean by this. What are you expecting to be able to do here?
Shrodingers cat. Cat is in a superposition of alive and dead. Scientist opens box. Scientist is in superposition of feeding live cat and burying dead cat.
The only way to detect a superposition is through interference. This requires the 2 superimposed states to overlap their wavefunction. In other words, it requires every last particle to go into the same position in both worlds. So it’s undetectable unless you can rearrange a whole cat to atomic precision.
In practice, if two states are wildly different, the interaction term is small. With precise physics equipment, you can make this larger, making 2 states where a bacteria is in different positions and then getting those to interact. Basically, blobs of amplitude need to run into each other to interact. Quantum space is very spacious indeed, so the blobs usually go their own separate way once they are separated. It’s very unlikely they run into each other at random, but a deliberate collision can be arranged.
That is what the matrix looks like, yes.
Interaction with the environment is a straightforward application of schrodingers equation. Collapse is a new unneeded hypothesis that also happens to break things like invarence of reference frame.
Show that coherence is simple but inadequate, and decoherence is adequate but not simple .
The two problems with this account are 1) “alive” and “dead” are classical states—a classical basis is assumed. and 2) the two states of the observer are assumed to be non-interacting and unaware of each other. But quantum mechanics itself gives no reason to suppose that will be the case. In both cases, it needs to be shown, and not just assumed that normality—perceptions “as if” of a single classical world by all observers—is restored.
So you can’t have coherent superpositions of macroscopic objects. So you need decoherence. And you need it to be simple, so that it is still a “slam dunk”.
How narrow a quantum state is depends, like everything, on the choice of basis. What is sharply peaked in position space is spread out in frequency/momentum space.
No it isn’t. That’s why people are still publishing papers on it.