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The magical creation of the photon.


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#1 Little Bang

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Posted 11 December 2007 - 01:32 PM

I'm going to describe what I know of the process that produces the infrared photon and let someone fill in the gaps that I have or correct anything I have wrong.

I have two hydrogen atoms on a collision course at some low velocity. When the fields of each atom get to some point in their approach each electron jumps to a higher energy level and then as they began to separate each electron falls back to the lower energy level and creates a complete infrared waveform with a crest and trough. Could someone please elaborate on this to give us a good description of each step in this event?

#2 Little Bang

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Posted 11 December 2007 - 07:10 PM

Great thread, I couldn't even spell creation.

#3 Buffy

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Posted 11 December 2007 - 09:46 PM

Great thread, I couldn't even spell creation.

Just to remind everyone, while proper spelling and grammar might help, no one here--well no one with any *manners* (and those that lack them don't last very long in most cases!)--cares if you can spell. Most folks around here have English as their second or third language, so its really unimportant...

Now I know absolutely nothing about this topic, so I'll yield the floor to someone (with good manners!) who does... :)

At the Derek Zoolander Center For Children Who Can't Read Good And Wanna Learn To Do Other Stuff Good Too, we teach you that there's more to life than being really, really good looking, :hihi:
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#4 billby

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Posted 12 December 2007 - 11:55 AM

and then as they began to separate each electron falls back to the lower energy level and creates a complete infrared waveform with a crest and trough. Could someone please elaborate on this to give us a good description of each step in this event?


the only thing i can think to add is that the electron will drop specifically into the third energy level of a hydrogen atom when photons in the infra-red spectrum are emitted. A small point but apparently it was significant enough for me to have to learn it for my physics exam that i put behind me about a month ago.

P.S. i have a dictionary sitting next to me and i still make plenty of spelling mistakes, making me a prime example of laziness. :(

#5 Little Bang

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Posted 12 December 2007 - 02:51 PM

Come on guy's and gal's, this should be a piece of cake for such an elegant theory as the standard model.

#6 snoopy

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Posted 13 December 2007 - 06:43 AM

To describe this properly you need to have
the dirac equation

Dirac equation - Wikipedia, the free encyclopedia

and the free maxwell equations

Maxwell's equations - Wikipedia, the free encyclopedia

sorry I dont know how to write equations in this editor havent figured it out yet

In 1928 when dirac put his equation forward the only particles known to science were the electron proton and photon.

The free maxwell equations describe the photon which in 1927 Jordan and Pauli provided an overall scheme for describing free photons according to a quantized free field maxwell theory.

Dirac's equation seemed to describe both electron and photon.

The EM interaction describing how electrons and protons are influenced by photons was handled by diracs gauge idea

Quantum field theory - Wikipedia, the free encyclopedia

If dirac style protons and electrons interacting merely electromagnetically were the only constiuents of atoms then atoms would immediately disintegrate.

In 1932 Chadwick discoverd the neutron and it was realised there must be a strong force binding neutrons and protons together
Radioactivity was desribed in another interaction the weak force.

Many other particles have been added since then

positron neutrino muons pions kaons lambda and sigma particles
omega minus particle antiparticles quarks gluons and W and Z bosons.

The modern theory also demands transient entities called virtual pair particles to exist..


So the Standard Model is as you can see far from elegant.

As for your question on desribing the production of infrared waves from the electron this comes under QED and would involve feynmann diagrams , I have no idea how to display feynmann diagrams on this thing so I will pass it over to someone who does.

Adios
True Beleivers

#7 Little Bang

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Posted 13 December 2007 - 08:48 AM

Snoopy I appreciate your efforts and admire your obvious knowledge of the situation. I guess my point is that all the equations and diagrams make excellent predictions about this process, they do not describe the actual event. An example would be an automobile collision, we can visualize what actually transpires during this event, metal gets bent and mashed, passengers get hurt and things that we can use words to explain happen. I would like someone to give a verbal description like they were in front of a high school first year physics class.

#8 Qfwfq

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Posted 14 December 2007 - 05:45 AM

Actually the Dirac equation isn't so necessary for the case under discussion. The non-relativistic Schrödinger equation with a time dependent potential term ought to be fine enough.

they do not describe the actual event.

True, it would be very complicated to discuss the exact details of this type of thing, although not inconceivable. It would require a lot of numerical calculation. It isn't difficult to qualitatively describe transitions between energy eigenstates, for the fixed Coulomb potential, as discussed in, for example, the Eisberg Resnick textbook. This is simple compared with actually integrating the differential equation.

#9 Little Bang

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Posted 15 December 2007 - 10:07 AM

I think everyone made a good effort at helping me out and I appreciate it. Those efforts have I think, illustrated my point. We do not have an understanding of the steps that produce a photon. The equations work beautifully but they do not paint (the picture is worth a thousand words). In my opinion we are missing an important piece of information about the relationship between the electron and proton. What that might be I don't know. I hope that someone somewhere will answer that question before I die.

#10 snoopy

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Posted 15 December 2007 - 02:11 PM

I think everyone made a good effort at helping me out and I appreciate it. Those efforts have I think, illustrated my point. We do not have an understanding of the steps that produce a photon. The equations work beautifully but they do not paint (the picture is worth a thousand words). In my opinion we are missing an important piece of information about the relationship between the electron and proton. What that might be I don't know. I hope that someone somewhere will answer that question before I die.



Ok I will try a different tack,

The atom consists of the nucleus and electrtons
these electrons around the atomic nucleus can only exist at certain energy levels.

For simplicity we can call these energy levels 'Shells'

When an electron 'jumps' between 'Shells' it releases an electromagnetic wave in other words a 'photon' given by the relationship E=hv.

The link between electrons and protons is they are both fermions with half integer spin.

I hope this helps

Peace :rotfl:

#11 CraigD

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Posted 15 December 2007 - 03:46 PM

I’ll take a shot at the question. I’m not capable of the formal math of it, but think I can outline photon-atom interaction without it.

Let me begin by filling in some of what I think are key details needed for understanding in Little Bang’s original description

I have two hydrogen atoms on a collision course at some low velocity. When the fields of each atom …

Here, we need to consider what we mean by “the fields of each atom”.

In particle physics, force fields (except for gravity) are the result of exchanges of particles in the boson family by particles in the fermion family. In this example, the bosons are photons of magnetic force, exchanged mostly between the two electrons of the hydrogen atoms, but also, to a smaller net effect, between the two protons. Protons, or more properly, their constituent quarks, are also exchanging photons of magnetic force with electrons. Because we can’t measure these photons any way but by their effect on the protons and electrons, they’re called virtual. Precisely how many and when they’re exchanged is a matter of probability, not certainty – “quantum weirdness”, but very physically real.

The major thing all this virtual photon exchanging accomplishes is changing the momentum of the most massive parts of the atoms, their protons – or more properly, their most massive constituents, which are not their quarks, but the boson exchanged by the quarks, gluons.

… get to some point in their approach each electron jumps to a higher energy level …

In the process of this, the electrons will be placed in a “higher”, which is to say, less statistically likely, ”orbit”. These orbits are due to the exchange of magnetic force photons with the quarks of their protons, and are further constrained by the quantum wave functions of the electrons. These wave functions essentially require that the circumference of the electrons’ orbits be an even multiple of their de Broglie wavelength, causing these orbits to be discrete, or “quantatized”. The electrons then return to their lower, “ground” orbits. In so doing, they emit real photons of radiation. A hydrogen atom, or a system of two hydrogen atoms, can emit only photons of various discrete frequencies. Since this example states that the atoms were colliding at a low speed, we can assume that the electrons will have been raised to orbits not much greater than their ground states, and all these photons will be fairly low energy, in the infrared range.

… and then as they began to separate each electron falls back to the lower energy level …

There’s no requirement that the hydrogen atoms separate. They can remain close together, with nearly all of the kinetic energy of their former relative motion converted to photons of infrared radiation. This is the process by which a warm hydrogen gas, and eventually, a liquid and solid, cools, and can continue until the atoms near absolute zero temperature, and their relative motion is too low to raise many electrons above their ground orbits.

… and creates a complete infrared waveform with a crest and trough. …

The electrons just emit discrete photons of an energy exactly equal to the difference in potential energy between their higher, “excited” orbit, and their ground orbit. The wave nature of this photon is inherent in it, requiring no special timing on the part of the electron or the other particles interacting with it.

If you research the details of the above, the degree of my simplification of my explanation will become apperant. In particular, you’ll see I fudged considerably with the idea of the ground state orbit of an electron, because hydrogen emits infrared photons only for transitions to it’s second-from lowest orbital and above (for example, for Paschen series transitions to its 3rd orbital).

As Qfwfq notes, actually working out the details of what I’ve outlined would be a very complicated calculation. You’d have to statistically account for a literally infinite number of discrete exchanges of virtual photons, and many other difficult details. As many physics wags have noted over since Dirac and others first described this stuff, the only simulator really adequate for these sorts of calculations is the universe itself :rotfl: I hope, though, I’ve left Little Bang with a different opinion than

We do not have an understanding of the steps that produce a photon. The equations work beautifully but they do not paint (the picture is worth a thousand words). In my opinion we are missing an important piece of information about the relationship between the electron and proton. What that might be I don't know. I hope that someone somewhere will answer that question before I die.

The understand he seeks exists, I think, even if the exact mathematical mechanics of it are complex beyond practical calculation, and even approachable only by a small number of superbly educated and practiced physicists.

#12 Little Bang

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Posted 19 December 2007 - 09:28 AM

Craig, your post was excellent. It was well written and showed good knowledge of the standard model. Is it guaranteed that all forces are carried by a particle or is there some small possibility that we are totally wrong and that they might in fact be magnetic in nature? I realize that 99% of the community thinks the standard model is the only way to go so it is very hard to get anyone to entertain anything outside of it. We all know that SM has many gaps or gray areas that need improvement. I suspect this to be one.

#13 Qfwfq

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Posted 19 December 2007 - 10:28 AM

First, the Standard Model isn't necessary, what Craig was talking about was quantum field theory. I wasn't talking about that, even. I said one could, at least conceptually, integrate the differential equation starting from initial state. It would only be a matter of gross number crunching and not nearly as complicated as working it out in terms of virtual particles, which however would have to (if there be justice) give the same result as using a potential; actually this would be, strictly, neglecting effects which are very slight in the case you are discussing.

Regardless of this being feasible or not, I agree that an understanding isn't impossible. What we don't understand is certain aspects of quantum reality itself.

#14 Little Bang

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Posted 19 December 2007 - 12:35 PM

Q, quantum field theory is not part of the standard model, if not then I was incorrect, but my question is still valid.

#15 Erasmus00

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Posted 19 December 2007 - 04:12 PM

I will give the original post a bit of an attempt, based on my understanding of field theory/standard model. HOWEVER, keep in mind there is sort of a heisenberg uncertainty between clarity and actual truth.

Anyway, we don't NEED two hydrogen atoms to make a photon. Simply punching (accelerating) an electron will create a photon. In this case, I believe that narrative description would be as follows:

The electron is sitting in space, surrounded by a cloud of virtual particles, constantly absorbing and emitting them in accordance with the uncertainty principle ([imath] \Delta E\Delta t \approx \hbar [/imath]). When the electron is accelerated away, it will leave behind (one or more) virtual particles, which become real, and travel away as photons. Descriptions for hydrogen atoms work similarly- only is a bit more complicated due to the fact that there are more particles involved.

Is it guaranteed that all forces are carried by a particle or is there some small possibility that we are totally wrong and that they might in fact be magnetic in nature?


It might be possible that certain forces (well, at least gravity) might NOT be carried by a particle. It is,though, considered very unlikely. However, gravity can't be magnetic in nature as magnetic forces have no (observed) monopoles, while gravitational monopoles are everywhere. (anything with mass).

We have observed the particle that carries the electromagnetic force (photons), we have also observed W and Z bosons (carrying the weak force). We have not yet observed gluons, but have lots of circumstantial evidence. This suggests that if not all, most of the fundamental forces are carried by particles.

I realize that 99% of the community thinks the standard model is the only way to go so it is very hard to get anyone to entertain anything outside of it. We all know that SM has many gaps or gray areas that need improvement.


I don't think this is necessarily true- the problem with the standard model is that a. we know it isn't perfect, and b. there are absolutely no experimental faults in it. The problem isn't that it has many gaps or gray areas, but rather that it has too few!

I admit that the lack of a good "gut-level" interpretation of everything quantum (not just the standard model) is very unsettling. However, given that our intellects evolved to deal with a certain scale (not too fast, not too small), I don't think it should be a deal breaker that our intuition fails at the quantum level.
-Will

#16 Little Bang

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Posted 19 December 2007 - 09:04 PM

Excellent post Will, I could not put up any argument against anything in your response. I just have difficulty buying that all the forces are carried by particles and I still think there is a relationship between charge and gravity. One more question and I'll drop it. What particle carries the force that holds the electron to the proton?

#17 Erasmus00

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Posted 19 December 2007 - 10:32 PM

What particle carries the force that holds the electron to the proton?


More photons. A proton is surrounded by virtual photons that it is emitting and absorbing (just like an electron). When we put an electron down in this cloud of virtual photons it interacts with them (and it has its own cloud of virtual photons which interact with the proton).

It is this mutual exchange of photons that holds the electron to the proton.
-Will