yguy

No, I'd say it is determined by a cause or causes.

That, at least, would be more honest in my view.

While both are epistemological claims, there is no implicit ignorance in those based on a claim of causality, without regard to whether such claims are veridical.

I suppose it does in the sense that probability theory can help describe reality to some useful degree. Like the theory of gravitation, however, it is a construct of the human mind rather than a law which the universe is constrained to obey.

There are no claims whatsoever which are outside the domain of epistemology.

Yes.

I haven't the knowledge base to be able to argue that intelligently, but I must point out that weirdness is hardly antithetical to QM.

Look, man - I'm way out of my depth here. We may as well drop this part of it.

To be sure. I am suggesting the degree of subjectivity inherent in probalistic theories hampers discovery to an unacceptable degree.

Lobstrosity

It doesn't seem to me that you actually understand what Feynman is saying here--he's giving a warning not to do exactly what you happen to be guilty of in this thread. His statement is a colloquial hyperbole founded on the basic premise that quantum mechanics is completely counterintuitive. Anyone who goes into it using "logic" derived from classical thinking will be completely lost. You have to enter QM ready to discard notions you previously considered as immutable laws of the natural world. These preconceptions are mere delusions, macroscopic averages of something fundamentally different and unfamiliar. Because nearly all quantum-type events never occur on a macroscopic level, they are completely foreign to us. The naive and uninitiated (e.g. you) take this strangeness (absurdness, I believe, is what you called it) to be equivalent to "logically impossible" or "false understanding." It is this that Feynman is warning against--you will not understand QM at an intuitive, "ah, I see, that makes sense" level. You will hurt your brain attempting to inject the classical physics you observe around you (i.e. the laws you have come to know simply by experiencing them over the course of your life) into the microscopic world. You will fail. That is the understanding he was talking about in that passage. This has nothing to do with our empirical understanding of quantum mechanics or with our ability to mathematically express how the universe behaves.


But we have considered those problems before, and the answer is rather obvious. Unfortunatly, the obvious answer is completely wrong. If, before Einstein, I told you that a person walking 4 mph on a train moving 70 mph would not be moving 74 mph, you would have said such a thing was absurd, illogical, even impossible. We all have more than enough intuition to tell that velocities add. Hell, ask any child that question about walking on a train and see what answer you get. This isn't because they've been taught classical physics, it's because the answer is intuitively obvious. Same thing for massive particles being particles, not waves. If I told you that you had a wavelength, you would tell me to go fuck myself (or maybe just say I was nuts). It is obvious that particles are particles. They have no wave-like properties. How could a particle also be a wave? The two are completely contradictory. Intuition gives you all the answers (unfortunately in this case, however, the answers are wrong).


Einstein makes me think Einstein was using intuition. He has said that the only reason he added the cosmological constant to his theory was because he felt that the universe should be static. He believed that nature had a certain intrinsic elegance and he viewed a static universe as the most elegant solution. An expanding universe, to him, was unelegant. As such, he modified his theories to enforce his preconceptions based on nothing more than intuition (i.e. they were not based on any empirical data at all). It actually seems like Einstein was correct in postulating a cosmological constant, however he was incorrect in its value. What he should have done was left it as a parameter to be empirically determined, not put it in as a fudge-factor in order to force a static (and unstable) universe.


Yes, why does this sound strange to you? Why do you think Einstein called the cosmological constant the biggest mistake of his life. The Big Bang model was adopted after Edwin Hubble made the startling observation that all distant galaxies are redshifted and the farther the galaxy, the higher the redshift. The relationship between distance and redshift is linear. Now, a redshift implies that the galaxy is moving away from us--the higher the shift, the faster it's moving radially away. So, after determining that every galaxy in the universe seems to be moving away from us, the natural conclusion is that at some point in the past all galaxies were located at some common point. An expanding universe implies a Big Bang. Empirical data supported what Einstein's theories naturally predicted prior to making the ad hoc alteration to force a static universe. Had Einstein left out the cosmological constant and seriously considered the implications of his work, he could have predicted an expanding universe and hence a "big bang." Instead, Friedmann came up with the Big Bang theory using Einstein's own equations, beating him to a conclusion Einstein by all rights should have made himself, if only he could have ignored his intuition and freed his mind from the prevailing notions the universe was static.

From http://map.gsfc.nasa.gov/m_uni/uni_101accel.html

• Einstein first proposed the cosmological constant (not to be confused with the Hubble Constant) usually symbolized by the greek letter "lambda" (&#923), as a mathematical fix to the theory of general relativity. In its simplest form, general relativity predicted that the universe must either expand or contract. Einstein thought the universe was static, so he added this new term to stop the expansion. Friedmann, a Russian mathematician, realized that this was an unstable fix, like balancing a pencil on its point, and proposed an expanding universe model, now called the Big Bang theory. When Hubble's study of nearby galaxies showed that the universe was in fact expanding, Einstein regretted modifying his elegant theory and viewed the cosmological constant term as his "greatest mistake".

No, it's not. You cannot use intuition where intuition is not valid. When you attempt to do so, you fail miserably and deem things as illogical or unphysical that in fact are not.


Well, for starters, this:

It strikes me as funny that someone who admits to having almost no knowledge of physics will rail against a theory's "unacknowledged assumptions" and argue that "absurd" consequences make it impossible. Please tell me what those assumptions would be and how exactly you're in a position to judge their validity. How do you have the foundation to assess their logic? You are supposed to be impressed that this theory is internally self-consistent given that it is also externally consistent. It makes testable predictions that are then confirmed via experiments. As such, your uneducated notions that it is illogical are rather unfounded. They are, as Feynman warns against, based on nothing more faulty intuition you have mistaken for logic (and how can they be based on anything else given that you know almost nothing about the theory to which you are objecting and also probably know next to nothing about about the empirically-observed nature of the microscopic world).

Hawkingfan

We don't know whether any coin flip will be heads or tells, but we can tell you how likely each outcome is. And that is all QM claims to do. It does not claim anything more. It does not claim to make a single PREDICTION. It tells you how likely any outcome is using PROBABILITIES. Your second statement is completely false, but it was made because you misunderstand what QM claims to do. ALL events in QM are based on probability. To say otherwise, is very ignorant. BUT, I think what you mean to say is that QM events are not based on PREDICTIONS.

NialScorva

yguy,

Have you looked into the reasons that quantum mechanics is a necessary part of describing the univers? The first half of the 20th century was spent by physicists trying to resolve the apparent contradictions, only to prove in many ways that the apparent contradictions are not real contradictions and are required to discribe the universe.

Take the two slit expirement. It shows that electrons will act as waves, generateing an interference pattern that cannot be generated by particles. Not only that, but a *single* electron will go through both slits of the two-slit experiment.

Quantum tunneling happens because the particle's position is a probability region rather than an actual point.

The Casimir effect shows another absurd sounding but empirically existant phenomenon: particles spontaneously pop in and out of existences if given enough space to do so.

The Bose-Einstein Condensate is another example of something that cannot exist according to classical physics (and our intuition), but makes sense in the light of a quantum physics interpretation.


There are many other examples, but all of these are phenomenon that require the probabilities of quantum physics. Not just an "expression of ignorance" probability, but a fundamental aspect of reality.

yguy

I'm perfectly aware of that. The question is whether the reality QM attempts to describe is counter-intuitive.

You missed the point. Obviously, someone had to have considered it first. The intuitive approach would not be to jump to the conclusion that the velocities can be summed arithmetically, but to realize one didn't know whether they did or not. You might start with the assumption that they did and then test it, but you would do so knowing all the while that you didn't know.

Such thought processes have nothing to do with intuition. They have to do with thought. Intuition is what tells you that the results of your thought processes are correct, are incorrect, or that you don't know.

You project your own proclivity to jump to conclusions onto others. Bad move.

My intuition doesn't tell me that a particle cannot be a wave. It tells me that given the evidence, we have insufficient understanding of the thing we call a particle/wave to describe it in a way that is comprehensible.

What is intuitive about that? Sounds to me like something didn't make sense and he fabricated an intellectual band-aid to fix it. I'd call that counter-intuitive.

You can't argue against the validity of intuition when you don't know what it is.

The only one I have a problem with is at the moment is the one I initially responded to in this thread.

That's up to you to decide. If you think I don't, you are wasting your time.

This statement is redolent with implicit arrogance, since we haven't experienced enough of reality for external consistency to be of any moment beyond the infinitesimally puny little slice of spacetime we happen to occupy.

ex-xian

No you're not, or else you wouldn't have made this ignorant statement:
Check out this thread, Sagan on Quantum Mechanics
I assume that you're referring to this exchange.
The problem is that my statement is a basic tenent of quantum physics. Once again, your own ignorance about this topic is causing you to make wrong statements. Learn some math, take some physics classes, then you'll understand better. Not totally, but better.

The problem is that english is terribly insufficient to describe QM. You need the math.

Lobstrosity

You've admitted you don't and as such we are all wasting our time. On top of this you seem to have a somewhat poor grasp on the English language and use that weakness as a red herring to avoid addressing the issues at hand. Couple this with the hypocrisy of your responses in light of other posts I have seen you make and most certainly this is a discussion I don't think you can productively contribute to in any way, although that never seems to have stopped you before so I shouldn't be surprised. I shall now return to ignoring your posts.

And, before I go, just to help you out, one valid definition of "intuition" is "a perceptive insight." Another is "the act or faculty of knowing or sensing without the use of rational processes." Specifically, intuitive knowledge is that which we form through subconscious perceptions as opposed to conscious deductions.

yguy

I'm aware of that. If QM was known to comprise the set of operating principles by which particles behave as they do, you would have a point. As it is, QM no more determines how particles behave than the laws of gravitation determine how the earth orbits around the sun. Both are mental constructs which describe how physical realities behave, not what makes anything happen. An "event in QM" as an abstraction of reality may be based on probability, but the actual event is not.

Abacus

How do you know that the actual event is not based on probability?

ex-xian

What the hell? So basically you're conceding that you're wrong and now your trying to turn this into a debate about the philosophy of science? Are you aware that the mathematical methods of doing QM were developed years and decades before QM was found?

Of course all we have are approximations. But the reality of what we believe, Einsteins's theories of relativity, QM, and everything else, have been proved to such an extent that to question their validity is moronic. Probably new theory will come along eventually that will incorporate these theories, but it won't make them wrong at the level that we understand them. Just as Einstien doesn't prove Newton wrong at the levels that Newton was working.

Here are a few quotes from Einstein:
-No amount of experimentation can ever prove me right; a single experiment can prove me wrong....
-All our science, measured against reality, is primitive and childlike-- and
yet it is the most precious thing we have
and finally,
-Two things are infinite: the universe and human stupidity; and I'm not sure about the universe....