Is the Quantum-Classical Boundary correlated to Quantum Wavelength?

[pittsburghjoe]

 

 

You can in principle entangle arbitrarily large systems, but to do so requires you to cool down these systems. And cooling down means... increasing their quantum wavelengths.

 

 

 

I originally assumed gravity had something to do with the cutoff ..but now this seams like a good answer?

[swansont]

Gravity has very little to do with the cutoff. We aren't anywhere close to a realm where quantum gravity would be important.

 

Yes, a reasonable estimation of the quantum/classical divide in many cases would be looking at the deBroglie wavelength and comparing that to some scale in the system. You see diffraction, for example, when the wavelength is of order the slit or hole size.

[pittsburghjoe]

Isn't this a rather big revelation to QM? Or is this something you already knew about for years?

[swansont]

Isn't this a rather big revelation to QM? Or is this something you already knew about for years?

 

 

It's something that you should come to understand when you take quantum mechanics in school. So yes, I've known about this for years.

[pittsburghjoe]

Why isn't knowledge of the Quantum-Classical Boundary good enough for unification?

[Mordred]

Why isn't knowledge of the Quantum-Classical Boundary good enough for unification?

Why would it be unification?

[pittsburghjoe]

All the craziness from QM is significantly narrowed down to basically just free individual particles (anything with a long enough quantum wavelength ). General Relativity takes over for everything else.

Edited December 20, 2016 by pittsburghjoe

[Mordred]

I'm afraid your missing too many key details on what can constitute a GUT. Far too many.

 

As far as quantum weirdness a good understanding of QM and relativity certainty helps remove those weird seeming aspects. However is there truly quantum weirdness or simply not fully understanding the phenomena.

[pittsburghjoe]

QM isn't needed unless an object can go in to superposition. GUT = kicking QM to the curb and asking it for help on a per needed basis.

[Mordred]

Sorry you need QM to formulate a GUT. For example just in the kinematic motion in terms of action. A fairly encompassing GUT style metric can be presented as follows

 

[latex]\stackrel{Action}{\overbrace{\mathcal{L}}} \sim \stackrel{relativity}{\overbrace{\mathbb{R}}}- \stackrel{Maxwell}{\overbrace{1/4F_{\mu\nu}F^{\mu\nu}}}+\stackrel{Dirac}{\overbrace{i \overline{\psi}\gamma_\mu\psi}}+\stackrel{Higg's}{\overbrace{\mid D_\mu h\mid-V\mid h\mid}} +\stackrel{Yugawa-coupling}{\overbrace{h\overline{\psi}\psi}}[/latex]

 

However this doesn't necessarily include all the needed details. Yet its close to a GUT I wouldn't count it as such except in terms of action. Yet one can use this equation to plot all field interactions and multiparticle motion.

Edited December 20, 2016 by Mordred

[pittsburghjoe]

Because you would be out of a job if not?

 

edit: gah, you wrote more stuff, so now I look like a big jerk

Edited December 20, 2016 by pittsburghjoe

[Mordred]

GUT involves every field, force, thermodynamics, kinematic motion and interaction, interferance and also details which particles decay into which particles.

 

A full blown GUT (or closest we have) is

 

[latex]SO(10)\otimes SO(5)\otimes SO (3)\otimes SO(2) \otimes U(1)[/latex]

 

these gauge groups describe every particle interaction/interferance/decay etc. However it is most certainly not a single master equation.

Because you would be out of a job if not?

No danger of that if you understood what a GUT theory entails.

 

Just as quantum weirdness isn't weird if you understand QM and relativity.

 

There is nothing weird about superposition, cutoffs or even entanglement. Not if you fully understand how the probability functions of a waveform works.

 

Maybe a bit of study into GUT theories will help.

 

http://arxiv.org/pdf/0904.1556.pdf The Algebra of Grand Unified Theories John Baez and John Huerta

 

http://pdg.lbl.gov/2011/reviews/rpp2011-rev-guts.pdf GRAND UNIFIED THEORIES

Edited December 20, 2016 by Mordred

[pittsburghjoe]

ok, ok, I thought unifying the theories only involved the the studies of very large and the very small

[Mordred]

It does but includes every possible dynamic at every size scale. The one were still having trouble with is quantum gravity. Ie being able to properly quantize gravity. Otherwise we would probably have a full blown GUT. Well we still need to explain DM and DE and determine if supersymmetry is valid.

 

Then we still need a good theory on baryogenesis.

 

There is hope for the above under SO (10) but not for quantum gravity just the other mentioned items. Needless to say physics has numerous unresolved problems yet to solve.

 

In essence GUT unifies all four forces but also describes their interactions/interferance/decays etc.

Edited December 20, 2016 by Mordred

[swansont]

All the craziness from QM is significantly narrowed down to basically just free individual particles (anything with a long enough quantum wavelength ). General Relativity takes over for everything else.

 

 

No. This is grossly wrong.

 

QM does not just apply to free individual particles; there is a lot going on in composite systems, starting with the simplest one on the atomic scale, the hydrogen atom. It is still present in many-atom systems as well.

 

And there's a gap between that and the applicability of GR that you could drive all of pre-GR classical physics through.

QM isn't needed unless an object can go in to superposition. GUT = kicking QM to the curb and asking it for help on a per needed basis.

 

Again, no. Absolutely not, and this was covered in another discussion (where you claimed all QM "weirdness" comes from superposition). It was wrong then, and is wrong now.

[Strange]

There is a new thread asking about the frequency (wavelength) of matter.

 

This got me thinking about the relationship between the de Broglie wavelength of a composite object and the de Broglie wavelength of its constituent parts; and then how/if this is related to the quantum-classical divide ...

[swansont]

There is a new thread asking about the frequency (wavelength) of matter.

 

This got me thinking about the relationship between the de Broglie wavelength of a composite object and the de Broglie wavelength of its constituent parts; and then how/if this is related to the quantum-classical divide ...

 

 

A hydrogen atom, for example, has a deBroglie wavelength that depends on its center-of-mass motion, and the wavelength of its electron is completely unaffected by this, as it has to be, since the atom can consider itself to be at rest. So I don't see how this relates to the divide at all.

[pittsburghjoe]

 

No. This is grossly wrong.

 

QM does not just apply to free individual particles; there is a lot going on in composite systems, starting with the simplest one on the atomic scale, the hydrogen atom. It is still present in many-atom systems as well.

 

 

I know QM can apply up to a full molecule in the double slit. But bigger than that, you are saying composite systems can have free particles within them?

 

 

And there's a gap between that and the applicability of GR that you could drive all of pre-GR classical physics through.

 

Is pre-GR newton? I don't get your point here. A large solid object will have lots of connected atoms and yes the individual atoms will have a electrons floating around doing the bonds ..but that's negligible.

Again, no. Absolutely not, and this was covered in another discussion (where you claimed all QM "weirdness" comes from superposition). It was wrong then, and is wrong now.

 

 

If you solve superposition, you solve wave phenomena.

[Mordred]

There is nothing to solve in superposition. It is simply a statistical average of all possible states/positions/spin etc. The minute you measure you no longer have a statistical average as you have determined the state/particle position/spin etc.

 

Take a macro example.

 

A shopper buys 5 pounds of apples each day. Someone else can only guess how many apples it takes to make 5 pounds worth.

 

So to someone else that bag of apples is in a superposition of probabilities he can only average the number of apples based on an average weight per apple.. Once he counts the apples he knows how many apples. Superposition is no longer applicable as he has determined the number of apples.

 

 

Now apply this to the two slit experiment. You cannot determine the particles spin. Which determines its polarity you can only average the probabilities (superposition) Once you measure the particle you know its spin (decoherence).

 

Now for waveforms. You cannot determine a particles position and momentum simultaneous (Heisenburg uncertainty) you can only average the particles probable location. (waveform) once you measure its true position you decohere its position but at the cost of a decrease in accuracy of its momentum.

Edited December 20, 2016 by Mordred

[pittsburghjoe]

I'm pretty sure "superposition" translates to "we don't know" in Greek. You love stating the incomplete math side. Yes it can give us good enough results ..BUT that's not good enough for me! There is magic going on an I want in on it!

 

"there are hidden variables" will be engraved on my tombstone.

[Mordred]

Your choice doesn't matter to the meaning of superposition.

[pittsburghjoe]

let's see your math explaining spooky action at a distance

[Mordred]

Why bother you won't accept one of the key equations namely Schrodinger nor Dirac. However fundamentally when you entangle two particles you also encode a wavefunction that encoding occurs at the time the entanglement first takes place.

 

They are quantum correlated.

 

https://en.m.wikipedia.org/wiki/Quantum_correlation

 

However you don't know how the two are correlated until you measure one or the other.

 

That coorelation has everything to do with conservation laws. For example conservation of spin. If one particle is spin up the other must be spin down. The total spin is zero.

 

So prior to moving either particle a or b it already has a set spin value. You just don't know what it is till you measure it.

 

There is no spooky action at a distance. Its simply indeterminate until one or the other is determined. In essence it is predetermined but you don't know which particle you have while in superposition.

 

A macro example take two colored balls one red one yellow. Place them in two seperate boxes. Give one to Alice and one to Bob. When Bob opens his box he knows his ball is red. Alice ball must be yellow. However before either opens their box they each have an equal probability of their ball being either color.

 

No communication between the two is needed. No FTL communication no action.

Edited December 21, 2016 by Mordred

[swansont]

"there are hidden variables" will be engraved on my tombstone.

Pretty sure that's Greek for "I can't be bothered to learn physics"

[Mordred]

And here I thought it meant " I'd rather have the weird " instead of the tools to understand QM

Edited December 21, 2016 by Mordred