Understanding Quantum Theory: A Beginner's Guide to Particle Physics

[yoda jedi]

Thrilling Update:

It looks like my question in https://www.physicsforums.com/showpost.php?p=2555746&postcount=21" about macroscopic EPR is just on the edge of being realized:


A 60µm resonator isn’t directly a "human observer", but it is definitely macroscopic!

http://www.sciencenews.org/view/download/id/57383/name/Quantum_object.jpg
Amazing!

posted time ago:
Mar18-10
Micron sized object observed in quantum state

https://www.physicsforums.com/showthread.php?t=387688

Thanks again.
Maybe it’s luck that I don’t work with these things (as it probably would drive me crazy ).

This is so extremely weird... almost as if there are two separate worlds, the macroscopic and the microscopic...

Hasn’t anyone tried to build a 'bridge' between the two, to see what happens? Like extremely large fullerenes, or something else? How about running the EPR paradox with objects on the 'border' to the QM world...

Or is it just impossible...

there is no border, is continous...
the microscopic and the macroscopic

 

[DevilsAvocado]

posted time ago:

Thanks for the info yoda jedi. Well, there seems to be 'some' discussion whether:
https://www.physicsforums.com/showpost.php?p=2630488&postcount=4"

As long as no one has showed me a cat that is simultaneously dead and alive, I regard this as an "open question"...

But macroscopic EPR, if possible, would be thrilling.

"If a Boeing 747 is filled with petite ballet dancers, it doesn’t automatically mean the Boeing 747 also can dance." -- DevilsAvocado

 

[Chalnoth]

The fundamental problem is that to get something in a coherent superposition, you have to ensure that it's not doing much of any interacting with anything else. The larger an object is, however, the more likely you'll end up with that coherence destroyed by interactions with surrounding photons (which are always present to some degree at temperatures above absolute zero). So to get a coherent superposition for a macroscopic object, you it to be both very cold and very isolated. And that's for stuff in the micrometer size range.

 

[DevilsAvocado]

Hi Chalnoth, interesting info. I guessed it would imply some 'restrictions' on large macroscopic objects.

(I’ll continue my 'processing' of post #59)

P.S. Is there any such thing as a "decoherent superposition"...?

 

[Chalnoth]

P.S. Is there any such thing as a "decoherent superposition"...?

Well, if it's decohered, then we can only measure one of the decohered components of the superposition.

 

[DevilsAvocado]

Thanks!

 

[yoda jedi]

Thanks for the info yoda jedi. Well, there seems to be 'some' discussion whether:
https://www.physicsforums.com/showpost.php?p=2630488&postcount=4"

As long as no one has showed me a cat that is simultaneously dead and alive, I regard this as an "open question"...

But macroscopic EPR, if possible, would be thrilling.

"If a Boeing 747 is filled with petite ballet dancers, it doesn’t automatically mean the Boeing 747 also can dance." -- DevilsAvocado

I regard this as an "open question"...

of course, soon it will be known...
but the superposition it will last some time...



for a
"to observe the oscillations of a 2.7 kg pendulum mode at a level close to its quantum ground state"
http://www.sciencedaily.com/releases/2009/07/090716093526.htm

"Observation of a kilogram-scale oscillator near its quantum ground state"
http://iopscience.iop.org/1367-2630/11/7/073032/

..."cool the mirror oscillator to about 1 millionth of a degree above absolute zero"...





i think nonlinearity it will broke the superposition at some level (and/or some time) and NONLINEAR QUANTUM MECHANICS (NLQM) it will supersedes STANDARD QUANTUM MECHANICS (SQM) in the realm of physics..



..."If the nonlinearity idea is correct, this superposition will not last forever".....Singh.



nonlinearity collapses the superposition.

 

[DevilsAvocado]

... i think nonlinearity it will broke the superposition at some level (and/or some time) and NONLINEAR QUANTUM MECHANICS (NLQM) it will supersedes STANDARD QUANTUM MECHANICS (SQM) in the realm of physics..

..."If the nonlinearity idea is correct, this superposition will not last forever".....Singh.

nonlinearity collapses the superposition.

Wow! This is interesting!

Tejinder Singh
There is perhaps a more promising experimental test of the nonlinearity. The experiment being planned by the group of Aspelmeyer at Vienna (jointly with Kieth Schwab of Cornell) will attempt to create a superposed quantum state of micromirrors having a billion atoms.

If the nonlinearity idea is correct, this superposition will not last forever. It will have a finite lifetime, which decreases with the increasing number of atoms in the micro mirror. According to the calculations based on my paper

http://arxiv.org/abs/0711.3773

http://arxiv.org/abs/0711.3773"
...
Standard linear quantum mechanics is an approximation to this non-linear theory, valid at energy scales much smaller than the Planck scale. Using ideas based on noncommutative differential geometry, we develop such a reformulation and derive a non-linear Schrödinger equation, which can explain collapse of the wave-function. We also obtain an expression for the lifetime of a quantum superposition.

I shall definitely read this paper (as well as the one by Maximilian Schlosshauer).

This is so amazingly weird... logically one would think that we and the world is built by tiny little 'bricks', behaving 'unreal', and therefore we should also behave 'unreal'. But 'mostly' we don’t...

And at the same time: If we look at very large objects like galaxies they, behave in way that doesn’t work in a scale model on Earth (they rotate too fast to keep the outer stars, but DM 'fixes' the problem).

Maybe, just maybe, there are 'transitions', between different 'scales', that makes the nature work differently at different 'scales', that we are not fully aware of yet...?? 1+1=3...!?

Just a philosophical thought...

 

[yoda jedi]

and:


Singh
Quantum Theory, Gravity, and the Standard Model of Particle Physics.
http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.3391v1.pdf

Nonlinear Quantum Mechanics, the Superposition
Principle, and the Quantum Measurement Problem.
http://arxiv.org/PS_cache/arxiv/pdf/0912/0912.2845v2.pdf