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Quantum Physics / Quantum Mechanics

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*** Mod's note: merged with earlier topic. sN ***

Objectivism holds that reality exists independent of consciousness; that individual persons are in contact with this reality through sensory perception; that human beings can gain objective knowledge from perception through the process of concept formation and inductive and deductive logic; that the proper moral purpose of one's life is the pursuit of one's own happiness or rational self-interest; that the only social system consistent with this morality is full respect for individual rights, embodied in pure laissez faire capitalism; and that the role of art in human life is to transform man's widest metaphysical ideas, by selective reproduction of reality, into a physical form—a work of art—that he can comprehend and to which he can respond emotionally.

source:wikipedia

Quantum version of the Young's double slit experiment has shown the exact opposite to be true. There are two slits and electrons are bombarded through the slits. If there is no observer, then interference pattern emerges. But if you place a measuring device/detector, interference pattern disappears and two solid lines appear.

The mere act of observing the experiment changes the outcome of the experiment!

Edited by softwareNerd
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Objectivism holds that reality exists independent of consciousness; that individual persons are in contact with this reality through sensory perception; that human beings can gain objective knowledge from perception through the process of concept formation and inductive and deductive logic; that the proper moral purpose of one's life is the pursuit of one's own happiness or rational self-interest; that the only social system consistent with this morality is full respect for individual rights, embodied in pure laissez faire capitalism; and that the role of art in human life is to transform man's widest metaphysical ideas, by selective reproduction of reality, into a physical form—a work of art—that he can comprehend and to which he can respond emotionally.

source:wikipedia

Quantum version of the Young's double slit experiment has shown the exact opposite to be true. There are two slits and electrons are bombarded through the slits. If there is no observer, then interference pattern emerges. But if you place a measuring device/detector, interference pattern disappears and two solid lines appear.

The mere act of observing the experiment changes the outcome of the experiment!

This is simply a feature of quantum mechanics (wave-particle duality) that has been know since Einsteins day, and it involves sub-atomic particles not our physical reality. Additionally, you state that the difference in the experiment is the presence of a measuring device, not an observer. So the reality of the wave-particle duality of sub-atomic particles exists independent of a human consciousness observing it.

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This is simply a feature of quantum mechanics (wave-particle duality) that has been know since Einsteins day, and it involves sub-atomic particles not our physical reality. Additionally, you state that the difference in the experiment is the presence of a measuring device, not an observer. So the reality of the wave-particle duality of sub-atomic particles exists independent of a human consciousness observing it.

nope, the act of measuring changes the outcome of the experiment. Not simply the presence of a object.

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This may be valid sub-atomic research, but does this really affect interpersonal relationships, human nature, or the rights of man?

If not, I say it doesn't come close to removing a single brick in the wall that's objectivist reasoning..

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I was not clear. Observing the path the electron takes through the slit is optional. Not the wall where the pattern emerges.

So if I set up the experiment and walked home without bothering to see the conclusion of the experiment, that's going to have a different outcome than if I do the same exact thing but didn't walk home?

Damn, I shouldn't have skipped work that day...

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So if I set up the experiment and walked home without bothering to see the conclusion of the experiment, that's going to have a different outcome than if I do the same exact thing but didn't walk home?

Damn, I shouldn't have skipped work that day...

hmmm......the experiment is a fact!

This may be valid sub-atomic research, but does this really affect interpersonal relationships, human nature, or the rights of man?

If not, I say it doesn't come close to removing a single brick in the wall that's objectivist reasoning..

but the thing is that reasoning cannot lead you everywhere....

reasoning told us that the earth was flat a few hundred years ago......now better reasoning tells us that the earth is not flat

in other words.....we had one view of reality in the past and another view of reality today....and a few hundred years from now reasoning will lead us

into another version of reality of the earth and the universe which is a modification of our present perceptions.....

but we know that the reality is one and the same..it cannot be two or more different things....therefore saying "Man's reason is fully competent to know the facts of reality" is fundamentally flawed...

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but we know that the reality is one and the same..it cannot be two or more different things....therefore saying "Man's reason is fully competent to know the facts of reality" is fundamentally flawed...

So, we're just going to take your word that human reason is incompetent?

This would mean that what you said is not really based on human reason at all. Amazingly, I agree with you on that.

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So, we're just going to take your word that human reason is incompetent?

This would mean that what you said is not really based on human reason at all. Amazingly, I agree with you on that.

I would say that the human reason has limits.

Like Kant, I would say this world consists of a phenomenal part and a Noumenon part. Or like Arthur Schopenhauer, the world is a combination of Will and representation.

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You know nothing of physics or even simple reasoning. You are attempting to use a contradiction to refute the principle of non-contradiction. You didn't even bother to read the Wikipedia entry for the double-slit experiment, how could you possibly expect to be taken seriously?

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but the thing is that reasoning cannot lead you everywhere....
And yet you make a statement like this and hope we see your reasoning!

Aren't you simply putting together a word soup that has no "real" meaning?

BTW: Use search in "title only" mode, to find more threads on the topic.

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nope, the act of measuring changes the outcome of the experiment. Not simply the presence of a object.

Uhhh, that's what I said. Since an observer is not required to change the result of the experiment, rather a measuring device's presence or absence changes the outcome of the experiment, then that objective reality exists outside of human consciousness. The experiment seems to prove the Objectivist principle that you first stated - 'objective reality exists outside of human consciousness'.

As I understand it, quantum physicists today still do not understand the mechanism of the wave-duality nature of sub-atomic particles, there is a lot of debate about just how it works. But the fact that we can observe it working each way does nothing to disprove that Objectivist principle.

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Redmaverick, you seem to be discussing the Copenhagen interpretation of quantum mechanics, which is largely ignored by physicists (since it is centered around a measurement and a consciousness, etc. and so is, well, dumb). Physicists largely subscribe to the decoherence interpretation, which basically says that the quantum uncertainty about the position or path of a particle leaks into the environment through interaction. For example, in the double slit experiment, you either end up with an interference pattern (the reason of which is interference in the particle's wave function) or you end up with two bars. Now, most say "oh well its a wave and a particle." Well, no, its not. What actually happens is when you measure which path it takes, the interaction massively reduces (to basically zero) the uncertainty in the wave function of the particle, but that uncertainty is carried over into the wave function of the experimental apparatus. Since the apparatus is trillions of times bigger, the uncertainty is so small as to be unnoticeable on a macroscopic scale. That's how macroscopic objects all behave "normally", and subatomic particles behave all weird. Its not a duality, its just the nature of the interactions.

And this still allows for an objective reality which my consciousness becomes aware of. No one ever said it can be aware of it without interacting with it though. That's why I can't know the exact position and momentum of a particle, knowing one forces me to interact with it in such a way as to lose all information about what the other may be. That's a natural and obvious limitation on knowledge, but isn't at all an attack on the idea of a reality which exists outside of my mind.

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  • 1 month later...

I think the entire issue stems from an irrational, but nearly unanimously accepted, explanation of the Uncertainty Principle. The common view is that the inability to know simultaneously both the momentum and position of a particle is a feature of the nature of the universe, and not simply a limitation of present scientific or human capability. Perhaps it is a problem that we will never be able to solve, but that does not mean it is a feature of the physical universe. It is because of man's nature that we must use light to observe these particles, and in doing so we cause the effects on them. It is only by ignoring this fact that scientists can accept such things as "the cat is both dead and alive".

The Uncertainty Principle, and the science done in its name, is only proof that we suck at observing particles.

Edited by Alexandros
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Retract my previous statement. Local hidden variable theories are out. Bohmian mechanics are a nonlocal hidden variable theory.

Still, the inability to know simultaneously both the momentum and position of a particle is a permanent limitation of scientific or human capability, so what is the objection to ascribing it to the nature of the universe?

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so what is the objection to ascribing it to the nature of the universe?

The nature of the universe would be that to observe something is to necessarily bounce light off it. The nature of the universe would not be - as QM states - that the particle therefore has no definite position or momentum. That is primacy of consciousness - our uncertainty becomes a physical uncertainty - the particle exists in multiple places at the same time, or exists as a wave with no location, etc. The usual contradictory nonsense.

The speed with which you discounted Bohmian mechanics reveals your unfamiliarity with the subject. I suggest checking out Oist professor Travis Norsen's writings, and Understanding Bohmian mechanics: A dialogue freely available from the American Journal of Physics at arxiv.org. For the more rigorous philosophical implications, check out the article in the Stanford Encyclopedia of Philosophy.

Bohmian mechanics makes the same predictions as QM - the difference is that the former is possible, while the latter is not.

Edited by brian0918
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Retract my previous statement. Local hidden variable theories are out. Bohmian mechanics are a nonlocal hidden variable theory.

Still, the inability to know simultaneously both the momentum and position of a particle is a permanent limitation of scientific or human capability, so what is the objection to ascribing it to the nature of the universe?

You made the objection yourself: Man is incapable of knowing simultaneously the momentum and position of a particle. That man's ability to conceptualize goes unsurpassed by all other organisms does not mean that there necessarily can not be aspects of the universe that we are incapable of understanding for lack of empirical evidence. Homosapien is the most recent step in a long line of evolution that is based on the ability to survive on Earth. One of the results of our evolutionary tract is the human eye, a sensory mechanism, whose effectiveness is tied directly to how much light is available for it to receive. Insofar as particle physics is concerned, the only way that we have been able to research is through the use of light. To put it another way: of all the senses humans have, only one of them has proven suitable for research in particle physics. That sense is based on light, and that is exactly the issue. Because we have found no other sense that can be used to study particles without interfering with the particles themselves, we have to turn to reason to tell us the rest: A is A; things can not be while not being, or exist here while existing there; things must be discrete. It is for this reason that the Uncertainty Principle and the science behind it is only proof that we are, at our present level of sophistication, incapable of studying particle physics any further than we already have.

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The nature of the universe would be that to observe something is to necessarily bounce light off it. The nature of the universe would not be - as QM states - that the particle therefore has no definite position or momentum. That is primacy of consciousness - our uncertainty becomes a physical uncertainty - the particle exists in multiple places at the same time, or exists as a wave with no location, etc. The usual contradictory nonsense.

While I complete my reading assignment, would you care to comment on manifestation of macroscopic scale uncertainty in Bose-Einstein condensates? A BEC seems to refute the contention that the uncertainty is merely one of technique, or is merely epistemological. In this case, a measurement of position and momentum is not attempted directly by illuminating a particle with a sufficiently energetic photon but instead the reduction of momentum to zero by cooling causes a reduction in the uncertainty in the momentum, and then for some reason the BEC state of matter springs into being. Taking the U.P. seriously as a physical phenomena is a good reason.

edit: added link

Edited by Grames
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In this case, a measurement of position and momentum is not attempted directly by illuminating a particle with a sufficiently energetic photon

Indeed that is how it's done. Here's a pretty straightforward explanation of how the velocity measurement is made (from Scientific American). The author then goes on to describe it as an example of the reality of uncertainty, as you assert.

How do we know that we have in fact produced a Bose-Einstein condensate? To observe the cloud of cooled atoms, we take a so-called shadow snapshot with a flash of laser light. Because the atoms sink to the bottom of the magnetic bowl as they cool, the cold cloud is too small to see easily. To make it large, we turn off the confining magnetic fields, allowing the atoms to fly out freely in all directions. After about 0.1 second, we illumiminate the now expanded cloud with a flash of laser light. The atoms scatter this light out of the beam, casting a shadow that we observe with a video camera. From this shadow, we can determine the distribution of velocities of the atoms in the original trapped cloud. The velocity measurement also gives us the temperature of the sample.

In the plot of the velocity distribution, the condensate appears as a dorsal-fin- shaped peak. The condensate atoms have the smallest possible velocity and thus remain in a dense cluster in the centre of the cloud after it has expanded. This photograph of a condensate is further proof that there is something wrong with classical mechanics. The condensate forms with the lowest possible energy. In classical mechanics, "lowest energy" means that the atoms should be at the centre of the trap and motionless, which would appear as an infinitely narrow and tall peak in our image. The peak differs from this classical conception because of quantum effects that can be summed up in three words: Heisenberg's uncertainty principle.

The uncertainty principle puts limits on what is knowable about anything, including atoms. The more precisely you know an atom's location, the less well you can know its velocity, and vice versa. That is why the condensate peak is not infinitely narrow. If it were, we would know that the atoms were in the exact centre of the trap and had exactly zero energy. According to the uncertainty principle, we cannot know both these things simultaneously.

Einstein's theory requires that the atoms in a condensate have energy that is as low as possible, whereas Heisenberg's uncertainty principle forbids them from being at the very bottom of the trap. Quantum mechanics resolves this conflict by postulating that the energy of an atom in any container, including our trap, can only be one of a set of discrete, allowed values-and the lowest of these values is not quite zero. This lowest allowed energy is called the zero - point energy, because even atoms whose temperature is exactly zero have this minimum energy. Atoms with this energy move around slowly near-but not quite at-the centre of the trap. The uncertainty principle and the other laws of quantum mechanics are normally seen only in the behaviour of submicroscopic objects such as a single atom or smaller. The Bose-Einstein condensate therefore is a rare example of the uncertainty principle in action in the macroscopic world.

So basically, they are letting the particles expand out a bit, then zapping them with light to measure their motion, and because they are not able to zap it quickly enough, nor with high enough energy, they see a spread-out spike. They conclude from this that the atoms actually are somehow "spread out" - which makes no sense.

If you go back and re-read what you have said - that an issue regarding the capabilities of knowledge is not an epistemological issue, but an existential one - does that make any sense?

Another good article I've found: Bohmian Mechanics as the Foundation of Quantum Mechanics.

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Indeed that is how it's done.

That is indirect. The U.P. as an observer effect is explained as the photon perturbing the observed entity, but the U.P. is not an observer effect and has other manifestations. The backward plotting used in the experimental measurement of the BEC separates in time the momentum observation and the position observation, making the observer effect interpretation of the U.P. not applicable. And yet the predicted broadening was still observed. Wikipedia has a decent explanation of how it is misleading to consider the U.P. as an observer effect only.

If you go back and re-read what you have said - that an issue regarding the capabilities of knowledge is not an epistemological issue, but an existential one - does that make any sense?

Straightforwardly, it is a causal generalization that what is known is caused by what exists.

Now, Bohmian Mechanics. I think QM is obsolete in all of its interpretations. The dichotomy between waves versus particles is false, the ontology I accept is that 'everything is fields'. Quantum field theory is an improvement over QM in that it is also compatible with relativity. QFT avoids the "particles and void" ontology and is compatible with a full-plenum metaphysics.

Plato has an article on QFT . Most philosophical speculation is based on QM and its paradoxes mainly because its older and has famous people like Einstein and Bohr opining on it.

Edited by Grames
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  • 1 year later...

*** Mod's note: Merged with an earlier topic - sn ***

 

A new experiment has been done in which "The trajectories of the photons within the experiment - forbidden in a sense by the laws of physics - have been laid bare." - http://www.bbc.co.uk/news/science-environment-13626587

What is a reasonable interpretation of these results?

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