QED meets General Relativity
by Eric Drexler on 8 November 2010
“Quantum gravitational contributions to quantum electrodynamics” (D. Toms, Nature, 4 Nov.) is the most exciting paper I’ve seen on quantum field theory and gravitation in a long time. It offers no speculations about strings, extra dimensions, new symmetries, or the like, and no loop quantum gravity or causal dynamical triangulations, just a carefully cross-checked mathematical analysis that reveals how general relativity transforms quantum electrodynamics at very edge of the breakdown of GR itself.
The question is the strength of electric interactions — the effective magnitude of a single charge — and how it changes (as it does) at high energies and small distances.
In brief, QED predicts that the strength approaches infinity;
QED + GR predicts that the strength approaches zero.
Many of the (meager) news reports to date describe Toms’ paper as if it merely smoothed out some difficulties with calculations in QED — those pesky infinities! — but that misses the point: This result extracts new physics from old physics, sharply revising our understanding of current physical theory as it approaches the Planck scale, the very edge of the unknown.
QED meets GR
There is an overview on PhysicsWorld.com:
http://physicsworld.com/cws/article/news/44235
And the article on Arxiv:
http://arxiv.org/abs/1010.0793
http://physicsworld.com/cws/article/news/44235
And the article on Arxiv:
http://arxiv.org/abs/1010.0793
Thanks Henning!Henning wrote:There is an overview on PhysicsWorld.com:
http://physicsworld.com/cws/article/news/44235
And the article on Arxiv:
http://arxiv.org/abs/1010.0793
I wonder how I missed it from my search in Arxiv......
On a first quick read I noticed quite a lot of logic jumps to get to the final result.
Needless to say that the more assumption and hypothesys you make in writing a theory the more the possibility that nature didn't follow your logic.
I'll read it again more carefully tonight.
If you like Supersimmetry theory you should give a check to his paper.
Needless to say that the more assumption and hypothesys you make in writing a theory the more the possibility that nature didn't follow your logic.
I'll read it again more carefully tonight.
If you like Supersimmetry theory you should give a check to his paper.
This is supposed to be a parallel replication of Toms' work.Giorgio wrote:On a first quick read I noticed quite a lot of logic jumps to get to the final result.
Needless to say that the more assumption and hypothesys you make in writing a theory the more the possibility that nature didn't follow your logic. I'll read it again more carefully tonight.
Vae Victis
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johanfprins
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Giorgio asked me on the thread
viewtopic.php?p=51097#51097 to comment on Tom's article being discussed on this thread: I am going to try and keep it as short as possible but since it touches on the most fundamental aspects in physics, I hope that you will forgive the length:
Firstly the title: Maybe I am pedantic, but as far as I know there is not an accepted theory for quantum gravity. Thus how can Tom combine quantum gravity with QED if he cannot even model quantum gravity; or know whether it really exists? Has the graviton been discovered while I have been asleep? I do not think so, and anticipate that the LIGO experiments will also not find one; except if they announce finding it just like CERN announced finding the vector bosons which, most probably, also do not exist; and will probably announce the Higgs’ boson which, most probably, also does not exist.
Nonetheless I have read the article a few times without checking the mathematics in depth, and already have a lot with which I just cannot agree. I found, however, that the more I wanted to formulate my criticisms, the further back I had to go into the foundations of quantum field theory (QFT). This would require an encyclopaedic response. I thus came to the conclusion that within the paradigm of QFT, Tom’s paper can be considered as an interesting speculation; but like most, if not all; manuscripts within the field of QFT, my conclusion is that, quoting Pauli, It is not even wrong . I realise that I am now setting myself against thousands and thousands of theoretical physicists, many of whom received Nobel Prizes. Judging in terms of the latter consensus this probably defines me as a “crank”. It is like a person shouting in an Irish pub: “Down with the Pope!’
This, however, reminds me of the book that was published by the Nazi’s entitled: One hundred authorities against Einstein: When shown to Einstein, he responded by saying: Why 100 authorities when one small fact would have been sufficient? Now, according to my logic, there are many facts which torpedo QFT; not all of which I can go into on this thread without making it far longer than it already is.
What is the definition of QFT? Julian Schwinger in his Nobel Prize speech defined it as follows: Indeed, relativistic quantum mechanics- the union of the complementarity principle of Bohr with the relativity principle of Einstein - is quantum field theory. Thus if Bohr’s principle of complementarity is not valid, QFT falls flat on its face. When, as a young student, I first heard of this principle I was extremely impressed with Bohr’s scientific acumen. Here we have a situation where for twenty years some experiments with electrons could be modelled as “particles” and some experiments as “waves”; and since physics is “experimental philosophy” one must accept the experimental result; no matter how counter-intuitive it is. Bohr grabbed the nettle!
It only later struck me that there is no, and never has been a physicist in the world who could or can define what a “particle” is. A wave can in general be defined as an energy-field in space. But what is a “particle”? If you cannot give a separate definition what a “particle” is, then it is absolutely nonsensical to state that it cannot behave like a wave and therefore, since it does behave like a wave under certain circumstances, we must accept the principle of complementarity as an inherent property of our universe which we just have to accept.
When a planet moves around the sun it can be interpreted as a “particle” with the same mass moving around the sun. Obviously a planet is not a particle so there is no reason to postulate that a planet and a particle are “complimentary”. Why can an “electron-particle” then not be a wave-field with a centre-of-mass? After all, the intensities of all harmonic wave-fields ever discovered are equal to the wave’s energy; but suddenly in the case of an electron-wave this intensity distribution is a “probability distribution” of where an “electron-particle” will be found when a measurement is made. The worst aspect is that for most of the electron-wave intensities deduced from the electron’s differential wave equation, the “expectation value”, or “most probable position to find the electron”, is where this intensity distribution is zero: i.e. where it is impossible to find the electron. And then according to Heisenberg there exist an uncertainty in position around this position where an “electron-particle” can never be present.
But a position at zero-intensity can be the centre-of-mass of the intensity distribution, if the intensity of the electron-wave is equal to its mass-energy as it must be. It is at this point where wave mechanics went wrong. Schroedinger’s, as well as Dirac’s equation, use the rest mass of the electron as an input, where-as the rest mass of an electron must be the solution of a more general differential wave equation (not using the electron’s mass as input) which for a solitary electron will give a wave-solution with energy equal to the rest-mass of the electron. Using the mass as input had a detrimental effect, since it gave Schroedinger’s equation in a format that can be associated with the non-relativistic expression (in the sense of Einstein’s relativity) for the energy conservation for a particle with mass; and this in turn led to the belief that mass waves must be modelled in terms of Hamilton operators, which must be changed when incorporating Einstein’s relativity. And this was the beginning of the great delusion in physics called QFT.
Why these religious beliefs in the existence of “particles” when nobody can even define what a “particle” is? The first red herring was the Bohr model of the atom which requires that electrons around a nucleus to have momentums. Such electrons cannot have momentums since their mass-energies are all below their rest-mass energies. Furthermore such a circling electron cannot cause a magnetic moment as Bohr has assumed and everybody since then believed. The reason for this is simple: Both the electron and the proton rotates around their mutual centre of mass. During each revolution a negative and a positive charge circles around the centre-of-mass. The total circular current is thus zero, and according to Ampere’s law there can thus not be a magnetic moment.
I can now proceed further to discuss other “pillars” on which QFT is based which are also nonsense, like Fock’s gauge symmetry of the wave function, Feynman’s path integrals, renormalization, spontaneous symmetry breaking. etc., etc., etc. But not to make this posting too long, I will end by commenting that the Bohr atom should not be taught in elementary text books except to illustrate how easy it is to generate a model that is not physically viable; and secondly that QFT should be relegated to the trash can.
viewtopic.php?p=51097#51097 to comment on Tom's article being discussed on this thread: I am going to try and keep it as short as possible but since it touches on the most fundamental aspects in physics, I hope that you will forgive the length:
Firstly the title: Maybe I am pedantic, but as far as I know there is not an accepted theory for quantum gravity. Thus how can Tom combine quantum gravity with QED if he cannot even model quantum gravity; or know whether it really exists? Has the graviton been discovered while I have been asleep? I do not think so, and anticipate that the LIGO experiments will also not find one; except if they announce finding it just like CERN announced finding the vector bosons which, most probably, also do not exist; and will probably announce the Higgs’ boson which, most probably, also does not exist.
Nonetheless I have read the article a few times without checking the mathematics in depth, and already have a lot with which I just cannot agree. I found, however, that the more I wanted to formulate my criticisms, the further back I had to go into the foundations of quantum field theory (QFT). This would require an encyclopaedic response. I thus came to the conclusion that within the paradigm of QFT, Tom’s paper can be considered as an interesting speculation; but like most, if not all; manuscripts within the field of QFT, my conclusion is that, quoting Pauli, It is not even wrong . I realise that I am now setting myself against thousands and thousands of theoretical physicists, many of whom received Nobel Prizes. Judging in terms of the latter consensus this probably defines me as a “crank”. It is like a person shouting in an Irish pub: “Down with the Pope!’
This, however, reminds me of the book that was published by the Nazi’s entitled: One hundred authorities against Einstein: When shown to Einstein, he responded by saying: Why 100 authorities when one small fact would have been sufficient? Now, according to my logic, there are many facts which torpedo QFT; not all of which I can go into on this thread without making it far longer than it already is.
What is the definition of QFT? Julian Schwinger in his Nobel Prize speech defined it as follows: Indeed, relativistic quantum mechanics- the union of the complementarity principle of Bohr with the relativity principle of Einstein - is quantum field theory. Thus if Bohr’s principle of complementarity is not valid, QFT falls flat on its face. When, as a young student, I first heard of this principle I was extremely impressed with Bohr’s scientific acumen. Here we have a situation where for twenty years some experiments with electrons could be modelled as “particles” and some experiments as “waves”; and since physics is “experimental philosophy” one must accept the experimental result; no matter how counter-intuitive it is. Bohr grabbed the nettle!
It only later struck me that there is no, and never has been a physicist in the world who could or can define what a “particle” is. A wave can in general be defined as an energy-field in space. But what is a “particle”? If you cannot give a separate definition what a “particle” is, then it is absolutely nonsensical to state that it cannot behave like a wave and therefore, since it does behave like a wave under certain circumstances, we must accept the principle of complementarity as an inherent property of our universe which we just have to accept.
When a planet moves around the sun it can be interpreted as a “particle” with the same mass moving around the sun. Obviously a planet is not a particle so there is no reason to postulate that a planet and a particle are “complimentary”. Why can an “electron-particle” then not be a wave-field with a centre-of-mass? After all, the intensities of all harmonic wave-fields ever discovered are equal to the wave’s energy; but suddenly in the case of an electron-wave this intensity distribution is a “probability distribution” of where an “electron-particle” will be found when a measurement is made. The worst aspect is that for most of the electron-wave intensities deduced from the electron’s differential wave equation, the “expectation value”, or “most probable position to find the electron”, is where this intensity distribution is zero: i.e. where it is impossible to find the electron. And then according to Heisenberg there exist an uncertainty in position around this position where an “electron-particle” can never be present.
But a position at zero-intensity can be the centre-of-mass of the intensity distribution, if the intensity of the electron-wave is equal to its mass-energy as it must be. It is at this point where wave mechanics went wrong. Schroedinger’s, as well as Dirac’s equation, use the rest mass of the electron as an input, where-as the rest mass of an electron must be the solution of a more general differential wave equation (not using the electron’s mass as input) which for a solitary electron will give a wave-solution with energy equal to the rest-mass of the electron. Using the mass as input had a detrimental effect, since it gave Schroedinger’s equation in a format that can be associated with the non-relativistic expression (in the sense of Einstein’s relativity) for the energy conservation for a particle with mass; and this in turn led to the belief that mass waves must be modelled in terms of Hamilton operators, which must be changed when incorporating Einstein’s relativity. And this was the beginning of the great delusion in physics called QFT.
Why these religious beliefs in the existence of “particles” when nobody can even define what a “particle” is? The first red herring was the Bohr model of the atom which requires that electrons around a nucleus to have momentums. Such electrons cannot have momentums since their mass-energies are all below their rest-mass energies. Furthermore such a circling electron cannot cause a magnetic moment as Bohr has assumed and everybody since then believed. The reason for this is simple: Both the electron and the proton rotates around their mutual centre of mass. During each revolution a negative and a positive charge circles around the centre-of-mass. The total circular current is thus zero, and according to Ampere’s law there can thus not be a magnetic moment.
I can now proceed further to discuss other “pillars” on which QFT is based which are also nonsense, like Fock’s gauge symmetry of the wave function, Feynman’s path integrals, renormalization, spontaneous symmetry breaking. etc., etc., etc. But not to make this posting too long, I will end by commenting that the Bohr atom should not be taught in elementary text books except to illustrate how easy it is to generate a model that is not physically viable; and secondly that QFT should be relegated to the trash can.
Huh ?
"Both the electron and the proton rotates around their mutual centre of mass. During each revolution a negative and a positive charge circles around the centre-of-mass."
As I see it, due to the proton being significantly more massive than the electron, the latter moves further from centre of mass, causing an non-zero product: A current circulates...
As I see it, due to the proton being significantly more massive than the electron, the latter moves further from centre of mass, causing an non-zero product: A current circulates...
Nik:
Interesting point, so the Bohr magneton could be related to a rotational velocity (via non-zero current) of the pair about the center of mass in such a model ...As I see it, due to the proton being significantly more massive than the electron, the latter moves further from centre of mass, causing an non-zero product: A current circulates...
Just wanted to point out an obvious correction. at least in the classical sense that you have presented.Furthermore such a circling electron cannot cause a magnetic moment as Bohr has assumed and everybody since then believed. The reason for this is simple: Both the electron and the proton rotates around their mutual centre of mass. During each revolution a negative and a positive charge circles around the centre-of-mass. The total circular current is thus zero, and according to Ampere’s law there can thus not be a magnetic moment.
magnetic moment: m = I*A
The angular frequency of both bodies have to be the same: w = v_i/r_i = v_e/r_e.
I = (+/-)e*v/(2*pi*r) = (+/-)e*w/(2*pi)
(the currents are indeed equal and opposite)
A = pi*r^2
but the areas are not.
and so the net moment
m = w*e*(r_i^2 - r_e^2)/2
Clearly, if the electron radius is different then the ion radius then you have a net magnetic moment. And m_i*r_i = m_e*r_e, m_i >> m_e, which means r_e >> r_i. thus m = w*e*((m_e/m_i)^2 - 1)r_e^2/2 ~ -w*e*r_e^2/2.
Also notice that angular momentum is L = mass*w*r^2. which means the moment can be written m = -e*L/(2*m_e). Add in the quantization of angular momentum in terms of h_bar and I just recovered the bohr magnetron. QED.
Carter
kcdodd:
I agree, thnx for that.
So a center of mass calc. has net zero current but gives rise to non-zero magnetic moment (and equates to the Bohr magneton as required from experiments). Ampere's law doesn't come into it, as Prins is saying.
Sum of the moments NOT a naive moment of the sum of currents. Even more interesting.
I agree, thnx for that.
So a center of mass calc. has net zero current but gives rise to non-zero magnetic moment (and equates to the Bohr magneton as required from experiments). Ampere's law doesn't come into it, as Prins is saying.
Sum of the moments NOT a naive moment of the sum of currents. Even more interesting.
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johanfprins
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Re: Huh ?
Wrong!! Go back to Ampere's law and you will find that it is the TOTAL current which causes a magnetic moment: Within a wire it requires positive charge-carriers to move relative to negative charge-carriers (or vice versa). A single charge following a circular path cannot constitute a current as demanded by Maxwell's equations and thus also Ampere's law. It is required that charges must move RELATIVE to each other and for this reason Maxwell's equations are commensurate with Einstein's special theory of relativity: In fact they define it.Nik wrote: As I see it, due to the proton being significantly more massive than the electron, the latter moves further from centre of mass, causing an non-zero product: A current circulates...
Consider the Bohr hydrogen atom also in another manner: When you "sit" on the proton, the electron is circling the proton. Assuming that you can say that the electron constitutes a current one will have a magnetic moment through the circular path of the electron. Now "sit" on the electron: The proton is now following a circular path with the same radius around the electron, and if it now constitutes a current, it generates a magnetic moment in the opposite direction than the electron generates and through a different area marked out by the path of the proton. Which magnetic moment must be used? It is clearly a paradox which can only be removed by accepting that there is no magnetic moment at all
Another way is to realize that it is really the joint center-of-charge of the of the proton and the electron that revolves around the center-of-mass; and this joint center-of-charge is zero. No current; no magnetic moment!