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Author Topic: Electrons emitting radiation  (Read 13939 times)

Offline lightarrow

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Re: Electrons emitting radiation
« Reply #25 on: 20/10/2014 11:47:45 »
Quote from: lightarrow
Wrong, the system is not only proton+free electron.
Beautiful response. I bet he didn't realize this since he's ignoring the mass due to potential energy.
For future reference when I, myself, speak of particles such as electrons and protons then since an electric field is part of those particles they don't need to be mentioned explicitly.
But since not all people knows it, maybe it would be better if you give at least a little mention of it.
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I recently came across a good explanation of this from an authority on the subject, i.e. Sheldon Glashow. I found it in his text From Alchemy to Quarks. On pages 581-582 the author discusses this subject in terms of quantum electrodynamics
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...
     Energy and momentum conservation imply that none of these acts can take place as real physical processes. An electron cannot simply emit a photon: The invariant mass of the electron and photon necessarily exceeds that of the initial electron, and the invariant mass of an isolated system cannot change. Similarly, an electron or positron cannot simply absorb a photon. Nor can electron-positron annihilate into or be created by a single photon. The fundamental acts of QED are forbidden!
Of course! I knew but I didn't remember it...
My meomory is bad recently  :(

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Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #26 on: 20/10/2014 12:28:55 »
Wrong, the system is not only proton+free electron. Probably you didn't know, but fields in a fixed region of space have mass too (and I mean proper = invariant, mass). A simple static electric field HAS mass.
It's quantum field theory. The electron isn't some billiard-ball thing that has a field, it is field. We made it out of a light wave in pair production, and we can diffract it. See this in the Wikipedia atomic orbitals article: "The electrons do not orbit the nucleus in the sense of a planet orbiting the sun, but instead exist as standing waves." Think standing wave, standing field. Don't think there's some massive little point-particle in the middle.

About gravitation, I cannot answer: according to GR, there is no field, just space-time curvature, so I cannot say that bodies proper masses don't vary when they interact gravitationally.
Read up on gravitational binding energy. In the simple case, imagine two 1kg bricks in space, they fall together and coalesce, and their kinetic energy is radiated away. Conservation of energy means what you're left with weighs less than 2kg. 
 

Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #27 on: 20/10/2014 12:32:19 »
Beautiful response. I bet he didn't realize this since he's ignoring the mass due to potential energy.
When you lift a brick you do work on it, and you give it potential energy. This is not in some mystical place, it's in the brick. Its mass-energy is increased. When you drop the brick this potential energy is converted into kinetic energy and dissipated, and the mass of the brick is reduced. 
 

Offline lightarrow

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Re: Electrons emitting radiation
« Reply #28 on: 20/10/2014 14:01:30 »
Wrong, the system is not only proton+free electron. Probably you didn't know, but fields in a fixed region of space have mass too (and I mean proper = invariant, mass). A simple static electric field HAS mass.
It's quantum field theory. The electron isn't some billiard-ball thing that has a field, it is field.
It doesn't matter, what I wrote is still valid in classical theory (special relativity included).
Have you ever tried to compute the difference of energy of the classical electrostatic field after two charges have approached from, e.g., infinite distance? I have done it. Guess what i found...

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Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #29 on: 20/10/2014 16:26:41 »
It doesn't matter, what I wrote is still valid in classical theory (special relativity included).
There's no problem with classical theory or special relativity. Or general relativity for that matter. IMHO the question you have to ask yourself is where does the kinetic energy of a falling body come from? The answer is: the body itself. Hence the mass deficit. Flip it around, and if you were to launch a brick upwards at 11.2km/s it slows down, and as it does its kinetic energy is converted into potential energy. But 11.2km/s is escape velocity, so the brick departs the system, taking that potential energy with it. It isn't in the Earth's gravitational field or "in the system". It's in the brick. And that brick is gone forever.   

Have you ever tried to compute the difference of energy of the classical electrostatic field after two charges have approached from, e.g., infinite distance? I have done it. Guess what i found...
I don't know. But the binding energy of ground-level hydrogen is -13.6eV. The mass of the hydrogen atom is less than the mass of the free proton plus the free electron. And there is no component of the system that is made of negative energy. The binding energy is negative by convention, but the only things there, the proton and the electron, are comprised of positive energy.
 

Offline lightarrow

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Re: Electrons emitting radiation
« Reply #30 on: 20/10/2014 17:50:28 »
It doesn't matter, what I wrote is still valid in classical theory (special relativity included).
There's no problem with classical theory or special relativity. Or general relativity for that matter. IMHO the question you have to ask yourself is where does the kinetic energy of a falling body come from?
?
I was talking of the electromagnetic field when a proton and an electron interact, here, not of gravitational potential energy.
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Have you ever tried to compute the difference of energy of the classical electrostatic field after two charges have approached from, e.g., infinite distance? I have done it. Guess what i found...
I don't know. But the binding energy of ground-level hydrogen is -13.6eV. The mass of the hydrogen atom is less than the mass of the free proton plus the free electron.
...because the "missing mass" is of the electromagnetic field. Actually mass doesn't "miss" at all, if you make the correct computation, that is, if you comprises the field in the system of which you can compute the energy.
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(1) And there is no component of the system that is made of negative energy.
(2) The binding energy is negative ...
(1) is in contradiction with (2)  :)

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Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #31 on: 20/10/2014 18:12:44 »
I was talking of the electromagnetic field when a proton and an electron interact, here, not of gravitational potential energy.
OK.

...because the "missing mass" is of the electromagnetic field. Actually mass doesn't "miss" at all, if you make the correct computation, that is, if you comprises the field in the system of which you can compute the energy.
You missed the important point: the electron IS field.

(1) is in contradiction with (2)
There's no contradiction. There's nothing there that consists of negative energy. Field energy is positive. Even if you think of the electron as something separate to its field, you know that its mass-energy is positive. Ditto for the proton. Everything there is comprised of positive energy. There's just less of it.
 

Offline lightarrow

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Re: Electrons emitting radiation
« Reply #32 on: 21/10/2014 19:49:30 »
...because the "missing mass" is of the electromagnetic field. Actually mass doesn't "miss" at all, if you make the correct computation, that is, if you comprises the field in the system of which you can compute the energy.
You missed the important point: the electron IS field.
And which is the fundamental invariant energy of that field? Hint: electron's proper mass.
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(1) is in contradiction with (2)
There's no contradiction. There's nothing there that consists of negative energy.
Let's make a simple example: an hydrogen atom.
As you know you can define as zero the energy of the H atom, and so an ionized hydrogen atom has energy +13.6 eV.

Question: which is the system's energy if the electron approaches the proton more than when the atom is in its fundamental state? And don't tell me this is impossible, because it wouldn't be true: when a neutron decays, it "breaks" in a proton and an electron (plus an antineutrinos) which are initially very close together, much closer than in the H atom. The system of proton+electron would have negative energy, then.

You miss the important fact that you cannot know the absolute value of a physical system's energy, because it's not measurable, for example. Actually, in physics, that concept is meaningless: only energy differences are meaningful.

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« Last Edit: 21/10/2014 19:51:13 by lightarrow »
 

Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #33 on: 21/10/2014 20:58:37 »
And which is the fundamental invariant energy of that field? Hint: electron's proper mass.
We say the electron mass is 511keV/c, but it isn't invariant. If it was, there would be no such thing as a mass deficit. 

Let's make a simple example: an hydrogen atom. As you know you can define as zero the energy of the H atom, and so an ionized hydrogen atom has energy +13.6 eV.
No you can't define the energy to be zero. The hydrogen atom has a non-zero mass, and mass is a measure of energy-content. You can't define it away.

Question: which is the system's energy if the electron approaches the proton more than when the atom is in its fundamental state? And don't tell me this is impossible, because it wouldn't be true: when a neutron decays, it "breaks" in a proton and an electron (plus an antineutrinos) which are initially very close together, much closer than in the H atom. The system of proton+electron would have negative energy, then.
I'm sorry lightarrow, I don't know what you mean. Whatever the electron's approach, the hydrogen-atom system doesn't consist of negative energy. Nor does it have negative mass. It doesn't fall up.

You miss the important fact that you cannot know the absolute value of a physical system's energy, because it's not measurable, for example. Actually, in physics, that concept is meaningless: only energy differences are meaningful.
It isn't true. Nor is it true that you can declare that the hydrogen atom has zero energy. You can annihilate it, you get gamma photons etc. It does not consist of zero energy, or negative energy. It consists of positive energy. Only it consists of less positive energy than the free electron and the free proton added together. Because their masses  are not invariant. Think it through for yourself.
 

Offline lightarrow

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Re: Electrons emitting radiation
« Reply #34 on: 21/10/2014 22:24:59 »
The electron's mass is not invariant?
And it's not because otherwise it couldn't vary its mass, according to your personal toy theory? Boy, you are really funny! You have a career in theatre!
Sorry, I'm not interested to discuss the subject any longer, so I won't reply you.
Regards.

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Offline JohnDuffield

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Re: Electrons emitting radiation
« Reply #35 on: 21/10/2014 23:04:35 »
The electron's mass is not invariant?
That's right. The electron's mass varies. So does the mass of the falling brick. Its kinetic energy doesn't come from nowhere. It comes from the brick. Gravity converts internal kinetic energy into external kinetic energy.

And it's not because otherwise it couldn't vary its mass, according to your personal toy theory? Boy, you are really funny! You have a career in theatre! Sorry, I'm not interested to discuss the subject any longer, so I won't reply you. Regards.
The mass deficit is not my personal toy theory. See Andrew Duffy's Nuclear Binding Energy and the Mass Defect:

"Something should strike you as strange about the table above. The carbon-12 atom has a mass of 12.000 u, and yet it contains 12 objects (6 protons and 6 neutrons) that each have a mass greater than 1.000 u, not to mention a small contribution from the 6 electrons.

This is true for all nuclei, that the mass of the nucleus is a little less than the mass of the individual neutrons, protons, and electrons. This missing mass is known as the mass defect, and represents the binding energy of the nucleus."


There is nothing within that carbon atom that is made of negative energy. All that's there is positive energy, only there's less of it. But suit yourself. If you want to stick with what you think you know and persuade yourself that I'm just making this stuff up, that's your choice. 
 

Offline PmbPhy

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Re: Electrons emitting radiation
« Reply #36 on: 22/10/2014 02:16:05 »
The electron's mass is not invariant?
And it's not because otherwise it couldn't vary its mass, according to your personal toy theory? Boy, you are really funny! You have a career in theatre!
Sorry, I'm not interested to discuss the subject any longer, so I won't reply you.
Regards.

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As I said, he's a crackpot and not to be taken seriously. He makes outrageous statements and believes that by merely repeating his claims constitutes proof. Utter nonsense.
 

Offline alancalverd

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Re: Electrons emitting radiation
« Reply #37 on: 22/10/2014 07:42:01 »
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This is true for all nuclei, that the mass of the nucleus is a little less than the mass of the individual neutrons, protons, and electrons. This missing mass is known as the mass defect, and represents the binding energy of the nucleus.


Probably not a good idea to quote a source that thinks there are electrons in the nucleus. Always check your compass against the sun before setting off into the unknown, JD!
« Last Edit: 22/10/2014 07:45:26 by alancalverd »
 

Offline PmbPhy

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Re: Electrons emitting radiation
« Reply #38 on: 22/10/2014 09:01:13 »
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This is true for all nuclei, that the mass of the nucleus is a little less than the mass of the individual neutrons, protons, and electrons. This missing mass is known as the mass defect, and represents the binding energy of the nucleus.


Probably not a good idea to quote a source that thinks there are electrons in the nucleus. Always check your compass against the sun before setting off into the unknown, JD!
This is the same nut who in another forum claimed that there's no such thing as negative energy. Lol!!
 

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Re: Electrons emitting radiation
« Reply #38 on: 22/10/2014 09:01:13 »

 

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