Why physics has become fantasy fiction

[Philip Thrift]

Sean Carroll

@seanmcarroll

·

What really happens to Schrödinger’s cat is that it becomes entangled with its environment, so that the wave function comes to describe multiple almost-classical worlds! Happens to all of us, and nicely explained in this @veritasium video.

https://twitter.com/seanmcarroll/status/1235999175428333568

@philipthrift

[Alan Grayson]

I've  asked this before and might have gotten some replies, but I can't recall what they were. Many of the quantum paradoxes arise due to a particular interpretation of superposition, namely, that all alternatives happen simultaneously (before measurement). Why can't superposition be interpreted to mean that each alternative has a probability of occurrence and nothing more? TIA, AG 

[Bruce Kellett]

In a collapse or an epistemic interpretation, that is exactly what it means.

Bruce

[Alan Grayson]

So why not leave it at that? What's the reason some go beyond this which creates unresolvable issues? Presumably, if it's just epistemic, no need to worry about collapse and how it happens. AG 

[Brent Meeker]

The problem is saying exactly when the Schroedinger equation stops describing the evolution and the alternative happens, i.e. the wf collapses.  In QBism it's when you learn the result and you update your knowledge.  In the Transactional interpretation it's when an interaction is realized.  I think Zurek's quantum Darwinism could be given this interpretation: when the cross terms in the pointer basis become sufficiently small.

Brent

[Alan Grayson]

I think the Transactional Interpretation has additional problems, such as forward (or backward?) in time signaling. Does a comparable problem arise when using Heisenberg's formulation of QM? AG 

[Brent Meeker]

Ruth Kastner has tried to fix that by postulating a possibility space where the offer wave elicits the answer wave; so it's not in spacetime.

Does a comparable problem arise when using Heisenberg's formulation of QM? AG

Matrix mechanics is equivalent to Schoedinger's equation, so I think it has the same problem of having an evolution phase and a measurement phase.

Brent

[Bruce Kellett]

On Sun, Mar 8, 2020 at 3:10 PM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 3/7/2020 7:38 PM, Alan Grayson wrote:

I think the Transactional Interpretation has additional problems, such as forward (or backward?) in time signaling.

Ruth Kastner has tried to fix that by postulating a possibility space where the offer wave elicits the answer wave; so it's not in spacetime.

Possibility space sounds very much like magical space, where anything you want to happen can happen......

Bruce

[Brent Meeker]

No, it's like the wave function where possibilities are encoded with amplitudes.  The essential idea isn't the possibility space, it's the idea that "events" which are interactions that transfer energy really happen.  This takes the place of decoherence and collapse of the wave function.

Brent

[Philip Thrift]

The nature of the probability space is that it is based on complex numbers q from the unit circle group |q| = 1 rather real numbers p in [0,1].

Rather than an event weighted by a real number, an event is a set of counterevents - each c.e. weighted by a complex number (which are then summed and the norm is taken) to get the real number weight of the event.

@philipthrift

[Philip Thrift]

Actually there's a list of references that's been collected:

http://physics.bu.edu/~youssef/quantum/quantum_refs.html

@philipthrift 

[John Clark]

On Sat, Mar 7, 2020 at 7:25 PM Alan Grayson <agrays...@gmail.com> wrote:

 > Why can't superposition be interpreted to mean that each alternative has a probability of occurrence and nothing more? 

Because if a particle undergoes a reaction but I DON'T look at it and then let the particle undergo another reaction and then look at it I get one outcome, but if a particle undergoes a reaction but I DO look at it and then let the particle undergo another reaction and look at it I get a completely different reaction. If I start at the very beginning and want to calculate the outcome at the very end it matters if I looked at anything in the middle or not. This is the measurement problem, and Many Worlds is the only quantum interpretation that even tries to give an explanation for this bizarre behavior, Copenhagen basically says just shut up and calculate. And that works fine if you're a engineer and have no interest in the philosophical implications, but for others not so much.

John K Clark

[Alan Grayson]

How is this related to superposition? AG