Recent content by jbergman

I mean at ##t_1##, we have only measured the z-spin, so I would consider the x spin not known. But if we choose the projectors I described in framework 2 we are forced to conclude that the electron had spin ##x^+## at ##t_1##.

Yeah. What really bothers me is in the second framework where we say that the particle has spin ##x+## with 100% probability. If we had a rule to the effect that at time steps where measurements have been made, frameworks are preferred that commute with the measurement result so you don't get...

Suppose you have a 2 step Stern Gerlach where you measure spin in the z-direction and then in the the x-direction. I can have two incompatible frameworks for the two time steps. Not sure on the correct notation here. For Framework 1 we have the projectors at ##t_1## ##[z^+]##, ##[z^-]## and...

I would look at Folland's book or Talagrand's "What is a quantum field theory".

A bit of a misnomer to measure position at one point. Detectors measure a position interval therefore they don't collapse the state to a position eigen-vector but instead just narrow the resulting state vector.

Just to be clear the Cauchy Stress tensor is actually a ##(1,1)## tensor so ## T: V\times V^* \to \mathbb R##. So no isomorphism is needed at all. I don't believe this is quite true. If you scale your normal vector instead of getting the Traction vector for a plane of unit area you get it for a...

I want to elaborate on my previous post. Imagine the game is changed. You have three doors, one, with a car behind it. Now you can either choose to look behind 2 doors or just 1. Obviously everyone will look behind 2. This is identical to the Month Hall problem! For example, if you would pick...

It's really simple. Would you rather get to pick 2 doors or 1. By switching you are essentially getting to look behind the two doors you originally didn't pick. So the strategy should be pick the one door you don't think the car is behind and switch to the other 2 doors.

There are critiques of this argument similar to this, see https://arxiv.org/abs/quant-ph/0312058?hl=en-US . Not sure how accepted Zurek's arguments are.

This Zurek paper explains in more detail how you get multiple different decoherent branches, https://arxiv.org/abs/quant-ph/0405161 . The argument is too complicated for me to reproduce it here without spending more time. But I think the essence is that whenever you do an experiment say measure...

Yes, I guess that's true. Now, I think you need some preferred basis of some kind.

Two branches are considered distinct if they are decohered. Do you understand that concept? Not sure I can explain it in a few words but essentially branches are distinct when they become entangled with a system with a large number of particles that it is essentially irreversible, i.e., the...

I haven't had a chance to reread this in detail but I believe this paper by Zurek discusses it, https://doi.org/10.1103/PhysRevA.71.052105

This paper by Zurek may be a better reference. He discusses orthogonal microstates, https://doi.org/10.1103/PhysRevA.71.052105

I will try to reply when I have more time later today.