Why do we need a photon to mediate the electromagnetic force?

[Anonym]

You got my pun. It's another way of looking upon ontological questions.

So in as much as "photons" are helpful concepts in explaining lab experiments, they are "real" (possibly in a similar way as natural numbers are, when dealing with accountants ).

No. The natural numbers are not real. It is their internal inconsistency with the real, objectively observed outside world led to the major developments in the mathematics. It is their internal inconsistency with the real, objectively observed outside world led to the real numbers (field). And Julius Wilhelm Richard Dedekind, Stetigkeit und irrationale Zahlen, vierde editie, Braunschweig: Friedr. Vieweg & Sohn (1912) completed the story originally started by your philosophical friends which called them “irrational”.

The philosophy is not a science. The science understands the empirical facts through the adequate mathematical formulation and solution of the problems posted by the observations.

You statement is not so innocent. The people that investigate now the problems of information do not distinguish between the information and the information rate. Then the numbers have mass.

Regards, Dany.

 

[lightarrow]

If person A observes person B, he can see it's actions, but not his thoughts.

To make this statement you should have a definition of "thought"; otherwise we could as well say that measuring a specific chemical/electrical brain's activity we can have a reading of thoughts; it would be just a technological problem then, that is, you couldn't prove that reading thoughts is theoretically impossible (as instead in the case of detecting a flying low-energy photon).

 

[Anonym]

I still maintain that the word "exists" is the wrong word to use before the wave function collapses.In fact, most people call it a 'wave packet' instead of a 'photon' during this phase of its evolution. You could try and say that 'it exists as a wave packet' which gives a probability distribution that it'll be detected at certain points in time and space; but note that you won't get a probability of 1 for any finite region.

My logic is like this: a 'photon' is a particle. However, before the wave function collapses, light is a wave, so the photon particles do not exist yet.

You have no idea what you are talking about since you don’t know math.
exp(i*phi)=cos(phi)+i*sin(phi). It is two component wave packet and it is QM all about. If “wave packet” don’t exist “during this phase of its evolution”, collapse of what you have in mind?

Regards, Dany.

 

[vanesch]

No. The natural numbers are not real. It is their internal inconsistency with the real, objectively observed outside world led to the major developments in the mathematics. It is their internal inconsistency with the real, objectively observed outside world led to the real numbers (field). And Julius Wilhelm Richard Dedekind, Stetigkeit und irrationale Zahlen, vierde editie, Braunschweig: Friedr. Vieweg & Sohn (1912) completed the story originally started by your philosophical friends which called them “irrational”.

We could go on a long discussion here about the "reality" of the real number system, and the "reality" of the natural numbers, or the reality of algebraic fields, rings and groups. The only thing I wanted to indicate is that "it exists" for a mathematical concept is also a matter of convention, up to internal consistency. If a mathematician says that a specific mathematical structure "exists", then that is up to a part "conventional" - the only thing that wouldn't be accepted is a mathematician who comes up with an inconsistent structure, and insists upon its existence. I see "photons", "electrons", "atoms", "the moon", "my mother", "my body"... on almost the same level, with one single difference: those concepts are related to observations, while an algebraic structure isn't. That's why those last concepts are "physical concepts", and in as much as they seem to be very useful concepts, we can call them "real". In as much as "reality" for a mathematician only requires internal consistency (or at least not a clear indication of inconsistency, by lack of proof of consistency), physical concepts also demand agreement with perception/observation.

The philosophy is not a science. The science understands the empirical facts through the adequate mathematical formulation and solution of the problems posted by the observations.

Indeed, and ontological questions are of a fundamentally philosophical nature, which can hence not be addressed by a purely scientific approach - or better, the philosophical meta-science that underlies a specific scientific approach will determine entirely the ontological questions.

You statement is not so innocent. The people that investigate now the problems of information do not distinguish between the information and the information rate. Then the numbers have mass.

then most of the real numbers are black holes

 

[Fra]

I see "photons", "electrons", "atoms", "the moon", "my mother", "my body"... on almost the same level, with one single difference: those concepts are related to observations, while an algebraic structure isn't. That's why those last concepts are "physical concepts", and in as much as they seem to be very useful concepts, we can call them "real". In as much as "reality" for a mathematician only requires internal consistency (or at least not a clear indication of inconsistency, by lack of proof of consistency), physical concepts also demand agreement with perception/observation.

It seems to me that since these algebraic structures should also somehow be related to "observations" in a general sense, possibly self-observation - if you can consider thinking "self-observation".

What might have started as fairly philosophical questions, have probably evolved in mysterious ways into an definite and clear structure to satisfy even the most extreme demands of anality. I'd conjecture that this is even part of the problem here, no matter how contradictory it may seem

Sometimes real lifte questons does seem unclear and fuzzy. Yet, there is something that does keep bringing you back to the issue, until it gets clear enough to make more sense. Part of the problem seem to be inherently fuzzy.

Indeed, and ontological questions are of a fundamentally philosophical nature, which can hence not be addressed by a purely scientific approach - or better, the philosophical meta-science that underlies a specific scientific approach will determine entirely the ontological questions.

I think often philosophical elaborations tend to get very fuzzy and often merely just reduce the useful processing power, but OTOH I do not like when it's claimed that philosophical ponderings is completely irrelevant to science. I can not prove this, but this somehow seems to be a simplification uncalled for in the general case. I suspect that even seemingly unambigous things, may have started out ambigously. It seems to be one of the mysteries of life and reality. I like to defend both sides :) There are times where the fuzzy and poorly defined questions are the important ones

I think we need to have faith in stringent formalism, but we should not overestimate it's universality, because maybe it was orignally born out of what seem as plain baloney?

/Fredrik

 

[Anonym]

It seems to me that since these algebraic structures should also somehow be related to "observations" in a general sense...

It is discussed in quant-ph/0606121.

What might have started as fairly philosophical questions, have probably evolved in mysterious ways into an definite and clear structure to satisfy even the most extreme demands of anality… It seems to be one of the mysteries of life and reality.

I don’t see here any mystery. As you talk English and probably don’t understand and use Chinese, God talk mathematics and probably don’t understand and use English or Chinese. I am not telling God what to do, I quote Yuval Ne’eman:” God choose to be mathematician”.

Regards, Dany.

 

[Anonym]

We could go on a long discussion here

We already did that in “Particle-Wave duality and Hamilton-Jacobi equation”. You should take what I said literally. I am talking math only.

If a mathematician says that a specific mathematical structure "exists"…

I don’t use word mathematicians in that case, the people that I have in mind are usually called mathematical physicists, for example I. Newton, W.R. Hamilton, J.C. Maxwell, D.Hilbert, A.Einstein, E.Schrödinger, W. Heisenberg, P.A.M. Dirac, J. von Neumann, H.Weyl, E.P.Wigner, C.N. Yang , R.P.Feynman etc.

I see "photons", "electrons", "atoms", "the moon", "my mother", "my body"... on almost the same level, with one single difference: those concepts are related to observations, while an algebraic structure isn't. That's why those last concepts are "physical concepts", and in as much as they seem to be very useful concepts, we can call them "real". In as much as "reality" for a mathematician only requires internal consistency (or at least not a clear indication of inconsistency, by lack of proof of consistency), physical concepts also demand agreement with perception/observation.

I call them the perfectly defined mathematically and physically Real Hilbert Spaces.They are called the classical physics (dispersion free physical theories) and the measurement instruments are the physical objects described by the laws of the classical physics.

The underlined algebraic structure is easily observed in the tons of the observations (measurements), for example in SR: 4-dim space-time with the signature {+,-,-,-}; 2-dim complex wave function in non-relativistic QM: double slit interference pattern; 4-dim C2 algebra of Pauli spin in SG, etc.

You try to defend your position which is impossible. That led you to absurd statements.

then most of the real numbers are black holes

It is silly to ask explain joke but I dead to understand yours.

Regards, Dany.

 

[bruce2g]

Probably it's possible to detect an atom's recoil after the emission.

This is interesting. Sorry to take so long replying, but I needed to do a little research.

In order to measure the recoil, you need to measure the change in the atom's momentum. So you need to measure the momentum twice. Heisenberg then steps in and says that after the first measurement, the position of the atom becomes uncertain.

Here are some numbers, courtesy UI Urbana (http://online.physics.uiuc.edu/courses/phys214/Spring07/discussions/html/wk4/sol4_5.pdf):
Assume a rubidium atom at rest (mass 87 amu; 1 amu = 1.6 ´ 10-27kg ) emits a photon of wavelength 780 nm. Energy = hc/lambda, and momentum = E/c = h/lambda = 8.47E-28 kgM/sec (End of stuff from UIU).

Our measurement error needs to be less than this. Since deltaP*deltaX<h, an easy approximation to the resulting position uncertainty deltaX is just h/p, which is easy since it's h/(h/lambda) = lambda. So our position error for the atom is at least lambda, which is 750 nm. This looks small, but it's actually a pretty big area compared to the size of an atom (750 nm = 7500 Å vs atomic radius = a few Å). So I don't see how you could find the atom again in order to measure the change in momentum.

This is no proof, but in this case it looks like it would be impossible to detect the atom's recoil, due to the uncertainty principle.

 

[Anonym]

This is interesting. Sorry to take so long replying, but I needed to do a little research.

Our measurement error needs to be less than this. Since deltaP*deltaX<h, an easy approximation to the resulting position uncertainty deltaX is just h/p, which is easy since it's h/(h/lambda) = lambda. So our position error for the atom is at least lambda, which is 750 nm. This looks small, but it's actually a pretty big area compared to the size of an atom (750 nm = 7500 Å vs atomic radius = a few Å). So I don't see how you could find the atom again in order to measure the change in momentum.

Reinvent wheel from the scratch is O.K. There is nothing wrong with the wheel. But why to do that? It will take time to reinvent all of QM by yourself and you will succeed nothing since it is already done. It is natural to travel forward in time. Believe me, you will enjoy yourself reading J.A.Wheeler and W.H. Zurek, “Quantum Theory and Measurement”, Prinston Univ. Press (1983). Then the results of your research will be interesting to everybody.

Regards, Dany.

P.S. However I consider your post beautiful and completely wrong indeed.

 

[bruce2g]

Thanks, I'll check out the Wheeler & Zurek book, which I expect to be authoritative on this subject. (BTW, the California library system now has a Link+ service that permits you to request just about any book in the state with a couple of clicks).