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A Step Closer to Quantum Theory of Gravity
ruszka writes "PhysicsWeb has an article on two condensed matter theorists that have come up with a new way of looking at the Quantum Hall effect.. It says this could go to be "a small step towards one of the ultimate goals in theoretical physics - a quantum theory of gravity""
I wonder what this discovery means for the arguments of Roger Penrose ? Some of his stuff in the 'Emperor's new Mind' seems to hint that quantum effects may hold the key to consciousness, and could explain why strong AI is so difficult to achieve.
Will someone please explain what a quantum hall effect is, and how it relates to superconductivity and/or electron spin?
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
that at a website where virtually EVERYONE is a geek, that so few of us know enough about quatum physics to make relevent remarks. You guys apparently never had courses in quantum chemistry or physics. Hmm pictures of lots of so called computer geeks scratching their heads. We're smiling.
It's really hard to tell what's going on from this article directly - it mostly just points out that some research is going on in this field. (And I haven't read the original article)
What I can read into it is that by working out the equations for a condensed matter system with where the interactions between individual particles are strong enough to influence the larger properties of the material - the authors have recognized that the equations look very similar to standard equations found in the classical fields of physics (E&M, Relativity, etc.)
If this is the case, then assuming that the basic assumptions are portable (that these types of quantum interactions are important on a macroscopic scale) then you have basically derived classical physics from Quantum mechanics.
This would hint (at least) that Quantum theory is scientifically more fundamental than classical physics. It gives a motivation for the observation that Quantum equations tend to reduce to classical equations when the systems get large.
Pretty cool if it all pans out. Lovely philosphical shift in thinking...
In illa quae ultra sunt
If it's true that classical physics can be derived from QM, then the question turns to the teaching of science in schools. How early should QM be taught in science classes?
Shifting from CM to QM results in significant cognitive dissonance, both because QM is such a counter-intuitive subject and because QM is so different from the science that students are used to. Would introducing QM at a younger age lessen this problem?
The trouble with teaching quantum mechanics before classical physics (assuming that this is what the article implications lead to...) is that the math is more advanced to do real Quantum Mechanics.
With Quantum you at least need Fourier Series and partial Diff. Eq. to solve basic problems. In classical physics you can often get by with just Algebra.
Perhaps someone particulary bright will come along and restate QM so that it's easier to express, but until then - I expect it will always be Classical first then Quantum.
Besides, Classical physics is probably more intuitive simply because our consciousness seems to function in the classical regime primarily.
In illa quae ultra sunt
How nice it will be to have an explanation of QM that was readily accessible. It's something that even Feynman couldn't pull off.
With Quantum you at least need Fourier Series and partial Diff. Eq. to solve basic problems. In classical physics you can often get by with just Algebra.
I really think you have that backwards. The only kind of classical physics you can do without calculus is the sort where you plug numbers into equations. $x=(1/2)at^2$. You can do that just as well with QM: the energy states of the hydrogen atom are given by $E=-\frac{\mu Z^2 e^4}{2 \hbar^2 n^2$, what are the first three when Z=2?
On the other hand, the fundamental mathematics of QM is linear algebra, and in its discrete version (matricies) you can go a long long way. Matrix Algebra is commonly taught as part of second-year calculus, but really has little to with the rest of that subject and you could easily teach it first.
I do agree that the cognitive dissonance many students get from the historical progression we use in physics education is unnecessary. I'm not even sure qm is especially counter-intuitive if you haven't just spent a couple years learning to think classically; from a practical point of view they're equally abstract.
Actually a wonderful Quantum Gravitational Theory has been put forward by Superstring theory.
1 1/ qid=1004615200/sr=2-1/ref=sr_2_11_1/103-5726037-41 19066
In the mid 90's, the 5 seemingly disparate String theories were united by a common, unifying theoretical structure that included 11 Dimensional Quantum Gravity.
The problems that have beset String theory since are the limitations of perturbative methods of mathematical solutions in providing exact answers in the extreme arena of string theory.
If you've not already read it, the book "The Elegant Universe" by Brian Greene gives a great explanation of this area of theoretical physics, even if it is 5 years out of date now.
http://www.amazon.com/exec/obidos/ASIN/03757081
if you're interested, priced 9 of your US Dollars.
Chris.
Come on, the man is still a genius! ;)
Fractional quantum hall effect
By the way, another candidate for a theory of quantum gravity besides superstring theory is the so-called canonical formulation of general relativity, which can be used as a basis for quantization. Much information on this line of research can be found for example at John Baez' web page.
Try Feynman's book QED.
It explains how quantum mechanics works, without using any equations. Of course, it will not teach you how to calculate anything.
what are the first three when Z=2?
Well, that's easy to do when there is only one electron involved. When there are two electrons, it is a three body problem. (Of course there are analogous problems just as easy to state and difficult to carry out in classical physics.)
I think QM really is counter intuitive in that many of the ideas are totally unfamiliar and have no real analogue in the everyday world -- but I also think acceleration and classical electrodynamics are about as non intuitive to the average person.
The best justification for teaching classical physics first is that it is more useful to the average person today... Of course, it looks like this may well be changing.
What trully puzzels me isn't the article in question it is the fact that modern Physics has yet to accurately define what we know as gravity. First of all modern computations with regard to vectoring in say space explorations have yeilded some strange annomallies. Such as space pobes not being exactlly where they are supposed to be, this I believe is attributed to miscalculation of the force of gravity. Newton and many of me past teachers swear that gravity is only the result of mass, that thought works theoretically but not in reality. If this planet was spinning approximately 24 times faster there would be an equilibrium reached between gravity and centrifugal motion. Thus if the planet was spinning at less of an RPM we would sense more gravity and less spin however minute. Think about the difference in your calculations if gravity is no longer just the result of mass but mass devided by rotational speed. Think I am nuts work it as a logic problem and due some real out of box thinking , just remember that there is a very fine line between insanity and genius.