Reason for wave-particle duality?

[Fast77]

Recently been thinking about the double slit experiment, and Schrodinger's cat thought experiment. And realized that quantum mechanics only applies to the atomic, and subatomic level of the universe as far as we know. And what's more that I realized that gravity does not play any significant role in the subatomic level.

What I questioned out of curiosity, was could it not just be the fact that since subatomic particle's do not have much mass/energy that they do not affect spacetime its self, being the reason that they can behave as a wave, and spontaneously be in different places until actually measured at a certain time?

I'm no physicist yet btw, so if I missed something big that could make that question seem childish, I apologize only in high school.

Thanks for reading,and contributing ideas and knowledge to this thread.

 

[huelsnitz]

Hi Fast77,

You are basically on the right track. Because the mass of subatomic particles is so small, their gravitational effects are negligible compared to nuclear forces (strong and weak) and the electromagnetic force. So physicists can make accurate predictions while ignoring gravity. Also, as de Broglie initially showed, a particle's wavelength is inversely proportional to it's mass. So for everyday objects, the wavelength is so small that it has no measureable effect.

You also mentioned how something can behave as if it were in different places at once (or simultaneous paths, as Feynman would describe it). How the wave function collapses upon a measurement is still an eerie mystery.

Warren

 

[StarsRuler]

Also, as de Broglie initially showed, a particle's wavelength is inversely proportional to it's mass. So for everyday objects, the wavelength is so small that it has no measureable effect.

It is inversely proportional to its canonical moment, no his mass, where canonical moment is the magnitude that is conserved because QM postulates, and its value from a composite system is the sum from the moments for the

 

[ZapperZ]

Recently been thinking about the double slit experiment, and Schrodinger's cat thought experiment. And realized that quantum mechanics only applies to the atomic, and subatomic level of the universe as far as we know. And what's more that I realized that gravity does not play any significant role in the subatomic level.

What I questioned out of curiosity, was could it not just be the fact that since subatomic particle's do not have much mass/energy that they do not affect spacetime its self, being the reason that they can behave as a wave, and spontaneously be in different places until actually measured at a certain time?

I'm no physicist yet btw, so if I missed something big that could make that question seem childish, I apologize only in high school.

Thanks for reading,and contributing ideas and knowledge to this thread.

This actually is not correct. For example, in the neutron drop experiment, the MASS of the neutron is definitely a factor where the gravitational potential energy comes into play.

http://physicsworld.com/cws/article/news/2002/jan/17/neutrons-reveal-quantum-effects-of-gravity

So while the mass of elementary particle often is not a factor in the quantum properties, this experiment by itself negates the idea what you proposed.

Zz.

 

[huelsnitz]

Hi ZapperZ,

Interesting point. I also recently read an article about a proposal to do the double slit experiment with the slits horizontal. The idea is to use particles heavy enough, and moving slowly enough, so that the gravitational potential (different for the two paths) causes each path to see a different time interval. The experiment will be a test of quantum and gravitational effects simultaneously. The experiment is a ways off, though, due to the technical challenges.

But, I think Fast77 asks interesting questions and he/she recognizes that the turnover between quantum and classical behavior is a continuum.

Warren

 

[huelsnitz]

It is inversely proportional to its canonical moment, no his mass, where canonical moment is the magnitude that is conserved because QM postulates, and its value from a composite system is the sum from the moments for the

I was trying to avoid the use of "canonical momentum" since Fast77 mentioned he/she is in high school and has not had much physics yet. But I agree with you - a more accurate description would have been to state that the wavelength is inversely proportional to momentum. And for the purposes of this question, no need to refer to or define "canonical".

 

[ZapperZ]

Hi ZapperZ,

But, I think Fast77 asks interesting questions and he/she recognizes that the turnover between quantum and classical behavior is a continuum.

Warren

No, we don't know that. We have seen "large" conglomerate that exhibits quantum effects, including a super current consisting of 10^11 particles. The transition between quantum and classical is still being studied and still not known. So I don't know where you got the idea that it is a continuum.

Zz.

 

[vanhees71]

First of all one should emphasize that according to "modern quantum theory" (discovered in 1925/26) there is no such thing as wave-particle duality but only the probablistic description of the behavior of matter in quantum theory. So, it's best not to worry about "old quantum theory" and to try to understand an inconsistent picture about quantum phenomena like "wave-particle duality" of "old quantum theory".

Further one should say that, according to our present knowledge, quantum theory applies to everything, not only subatomic particles. The challenge is more to understand, why classical physics works so well in everyday life for macroscopic objects. The answer is that it is very difficult to isolate macroscopic objects from their interaction with the environment and that we are not able to describe their behavior in all tiny little details of the motion of each of their microscopic constituents. Instead, we use a few macroscopic observables like the center of mass of a solid body to define it's location and velocity when moving. Such macroscopic observables are averages over very many microscopic degrees of freedom which are interacting all the time with the environment and among themselves. Averaging out all the microscopic details leads, using the concepts of quantum-statistical mechanics, leads to the classical behavior of macroscopic objects.

Nowadays pretty large objects could in fact be isolated well enough from the environment to establish also quantum-mechanical behavior for them. The double-slit experiment could be performed successfully with Buckyball molecules (a molecule shaped like a soccer ball consisting of 60 carbon atoms). To that end you had to make sure that the Buckyballs are cooled down to very low temperatures so that their intrinsic vibrations were reduced to a minimum. One could also show that the Buckyballs behaved classical, i.e., they were showing no "wave-like interference effects" anymore when heated up slightly, so that the emitted a few soft photons throught ("heat radiation") when flying throuth the slits. This is precisely the "decoherence effect" leading from quantum-mechanical behavior to classical behavior through "coupling to the environment", in this case exciting the electromagnetic field through the intrinsic motion of the atoms in the molecule (excitation and deexcitation of higher-energy states due to the finite temperature of the molecules).

The quantum behavior is even not restricted to single molecules. Even macroscopic objects like diamonds can be brought to show quantum behavior, even so very unusual behavior as described by quantum-theoretical entanglement (leading to non-local correlations, unknown to classical stochastic systems):

http://physicsworld.com/cws/article/news/2011/dec/02/diamonds-entangled-at-room-temperature

 

[Fast77]

This actually is not correct. For example, in the neutron drop experiment, the MASS of the neutron is definitely a factor where the gravitational potential energy comes into play.

http://physicsworld.com/cws/article/news/2002/jan/17/neutrons-reveal-quantum-effects-of-gravity

So while the mass of elementary particle often is not a factor in the quantum properties, this experiment by itself negates the idea what you proposed.

Zz.

I was merely saying that physicists don't take account gravity when working with quantum mechanics. Correct me if I'm wrong there.

 

[Fast77]

First of all one should emphasize that according to "modern quantum theory" (discovered in 1925/26) there is no such thing as wave-particle duality but only the probablistic description of the behavior of matter in quantum theory. So, it's best not to worry about "old quantum theory" and to try to understand an inconsistent picture about quantum phenomena like "wave-particle duality" of "old quantum theory".

Further one should say that, according to our present knowledge, quantum theory applies to everything, not only subatomic particles. The challenge is more to understand, why classical physics works so well in everyday life for macroscopic objects. The answer is that it is very difficult to isolate macroscopic objects from their interaction with the environment and that we are not able to describe their behavior in all tiny little details of the motion of each of their microscopic constituents. Instead, we use a few macroscopic observables like the center of mass of a solid body to define it's location and velocity when moving. Such macroscopic observables are averages over very many microscopic degrees of freedom which are interacting all the time with the environment and among themselves. Averaging out all the microscopic details leads, using the concepts of quantum-statistical mechanics, leads to the classical behavior of macroscopic objects.

Nowadays pretty large objects could in fact be isolated well enough from the environment to establish also quantum-mechanical behavior for them. The double-slit experiment could be performed successfully with Buckyball molecules (a molecule shaped like a soccer ball consisting of 60 carbon atoms). To that end you had to make sure that the Buckyballs are cooled down to very low temperatures so that their intrinsic vibrations were reduced to a minimum. One could also show that the Buckyballs behaved classical, i.e., they were showing no "wave-like interference effects" anymore when heated up slightly, so that the emitted a few soft photons throught ("heat radiation") when flying throuth the slits. This is precisely the "decoherence effect" leading from quantum-mechanical behavior to classical behavior through "coupling to the environment", in this case exciting the electromagnetic field through the intrinsic motion of the atoms in the molecule (excitation and deexcitation of higher-energy states due to the finite temperature of the molecules).

The quantum behavior is even not restricted to single molecules. Even macroscopic objects like diamonds can be brought to show quantum behavior, even so very unusual behavior as described by quantum-theoretical entanglement (leading to non-local correlations, unknown to classical stochastic systems):

http://physicsworld.com/cws/article/news/2011/dec/02/diamonds-entangled-at-room-temperature

Yes I've also heard of this disturbance theory if you will, where it's suggested that since everyday objects are consistently being measured(gravity, light etc.) that it's the reason they do not behave so strangely as they should according to QM. Which is why we use classical physics for macroscopic. That's great and it even goes with what I'm suggesting.

I think many of you misunderstood what I'm trying to say. I'm just suggesting that perhaps the reason for wave-particle duality is gravity its self. I'm suggesting that since subatomic particles don't have as much energy/mass as a neutron or proton that they are not affected by SPACETIME, so they can behave as a wave, and this wave function collapses because we measure it at a CERTAIN TIME. We are presenting time in the measurement of the particle. In the end its about measurement.

 

[Fast77]

Is there actually any research being done on what I'm suggesting?

Thanks for the replies

 

[ZapperZ]

I was merely saying that physicists don't take account gravity when working with quantum mechanics. Correct me if I'm wrong there.

I did correct you! I cited an experiment that took into account the quantized drop due to gravity!

Zz.

 

[bohm2]

Is there actually any research being done on what I'm suggesting?

It's not feasible yet but some have suggested that it may be testable one day. Note the 4-year period has passed and I haven't read/heard anything:

The team at Santa Barbara is running the experiment right now, but with a significantly smaller mirror than needed to test Penrose’s theory. If the current tests succeed, Bouwmeester will gradually increase the size of the mirror up to the necessary tenth-of-a-human-hair diameter. He and his colleagues are also working out ways to shield the experiment from the vibrations, stray photons, or temperature changes that would ruin the results.“It is not something that will happen overnight,” he says. “We need to isolate the quantum world from our world and see what happens. If everything works well, I expect some results four years from now.”

If an Electron Can Be in Two Places at Once, Why Can't You?
http://timfolger.net/penrose.pdf

Another approach:
Testing Gravity-Driven Collapse of the Wavefunction via Cosmogenic Neutrinos
http://arxiv.org/pdf/quant-ph/0503001v3.pdf

According to Penrose, the fundamental conflict between the superposition principle of quantum mechanics and the principle of general covariance of general relativity entails the existence of wavefunction collapse, e.g. a quantum superposition of two different space-time geometries will collapse to one of them due to the ill-definedness of the time-translation operator for the superposition. In this paper, we argue that Penrose's conjecture on gravity's role in wavefunction collapse is debatable. First of all, it is still a controversial issue what the exact nature of the conflict is and how to resolve it. Secondly, Penrose's argument by analogy is too weak to establish a necessary connection between wavefunction collapse and the conflict as understood by him. Thirdly, the conflict does not necessarily lead to wavefunction collapse. For the conflict or the problem of ill-definedness for a superposition of different space-time geometries also needs to be solved before the collapse of the superposition finishes, and once the conflict has been resolved, the wavefunction collapse will lose its physical basis relating to the conflict. In addition, we argue that Penrose's suggestions for the collapse time formula and the preferred basis are also problematic.

Does gravity induce wavefunction collapse? An examination of Penrose's conjecture
http://philsci-archive.pitt.edu/9606/4/penrose_collapse_v9.pdf

 

[Naty1]

Never apologize for asking questions. You CAN be embarrassed for NOT asking questions if you like! Great insights, by the way, for someone in high school.

Instead of direct answers, I'll first provide you some general insights for perspective. I have found those are tough to find..so when I do, I make notes:

mostly from prior discussions in these forums:
[My explanatory comments thus {}.

Simon Bridge: All classical physics is a consequence of quantum physics - but not all quantum physics can be described classically. Classical physics is what QM does on average ... so the math is different.

...the quantum mechanics viewpoint would be to note that Max Planck discovered physical action at small scales takes place in discrete steps, not continuous ones. Action at the sub atomic scale is quantized. For example, the wave function of an electron in [ideal] free space can take on continuous values, but when in an orbital {around a nucleus} is constrained to discrete values...quantized energy

...Planck's constant doesn't appear in the Einstein field equations. Therefore it's not possible to derive anything quantum-mechanical from them…
the key difference between classical mechanics and QM is that in QM you can have observables that don't commute. This gives rise to the uncertainty principle…..So QM is a statistical rather than a deterministic formulation.

The telltale difference between quantum and classical notions of probability is that
the former is subject to interference and the latter is not. Brian Greene.

{Interference is a result of superposition. Have you had any trigonometry??...if so you will probably recognize things like
Sin2X =2SinXCosX... So a wave function describing a system has all sorts of underlying wave functions...and they can come together [superimpose] in constructive ways [where you find a particle] and destcructive ways [where the wave functions cancel] ..} Note that in this view 'discretness' of quantum theory is not so prominent.

Using these ideas, here is what a prominent physicist has to say:
Unfinished revolution

A broader, more comprehensive description:

Roughly speaking, we learn from GR that spacetime is a dynamical field and we learn from QM that all dynamical fields are quantized. A quantum field has a granular structure, and a probabilistic dynamics, that allows quantum superposition of different states. Therefore at small scales we might expect a “quantum spacetime” formed by “quanta of space” evolving probabilistically, and allowing “quantum superposition of spaces”. The problem of quantum gravity is to give a precise mathematical and physical meaning to this vague notion of “quantum spacetime”...

Fast77

And realized that quantum mechanics only applies to the atomic, and subatomic level of the universe as far as we know.

I'd say ok as a start, but note that quantum theory also apply to large...as Vanhees71 posted. Here is an example: The Horizons of black holes. Have you heard of black holes??
If you have or are interested, there are LOTS of discussions about them in these forums.

The idea that there is an absolute limit to information on the other side of such a horizon is known as Bekenstein’s bound. The information of the volume [everything inside the horizon] resides on the enclosed horizon surface!; as if that were not crazy enough, the information is quantized...in discrete morsels...planck sized pixels...that's why it is FINITE...if it were continuous as prescribed by General Relativity the information content would be infinite!

So we discovered black holes via a continuous theory [general relativity] but discovered it has quantum mechanical characteristics! Reconciling such views is what quantum gravity is all about...melding the discrete with the continuous...and the deterministic [exact] with the probabilistic [somewhat random].