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If an electron gains mass as it moves towards the speed of light where does this mass-energy come from? Does this not violate conservation of energy?
HallsofIvy
Jan4-04, 10:33 AM
Exactly! With relativity there is no "conservation of energy", there is a "conservation of mass-energy" because mass and energy are different aspects of the same thing.
Originally posted by HallsofIvy
Exactly! With relativity there is no "conservation of energy", there is a "conservation of mass-energy" because mass and energy are different aspects of the same thing.
Where does the gain in mass come from.
Originally posted by tenzin
Where does the gain in mass come from.
you have to do work to accelerate the object. all the energy stored in its motion which we call kinetic energy, comes from the work you did to accelerate it.
actually, the situation is the same as in the nonrelativistic case, only, in the nonrelativistic case, we don t call kinetic energy mass (sensible people don t call it mass in the relativistic case either, but that s a different story)
Given the equivalence of mass and energy why is it that massive objects can not go the speed of light but massless objects can go the speed of light. It seems to have a relation with mass as a material manifestation of energy.
Originally posted by tenzin
Given the equivalence of mass and energy why is it that massive objects can not go the speed of light but massless objects can go the speed of light. It seems to have a relation with mass as a material manifestation of energy.
i am going to strongly discourage you from using relativistic mass. it confuses the issues more than it helps.
when i say mass, i mean the lorentz invariant length of the momentum of the particle. energy and mass are not equivalent, using these definitions.
anyway, massive objects cannot go the speed of light because it is dynamically ruled out: it would require an infinite force to accelerate to that speed, or a constant force for an infinite amount of time. in either case, an infinite amount of energy would be required.
Originally posted by lethe
i am going to strongly discourage you from using relativistic mass. it confuses the issues more than it helps.
when i say mass, i mean the lorentz invariant length of the momentum of the particle. energy and mass are not equivalent, using these definitions.
anyway, massive objects cannot go the speed of light because it is dynamically ruled out: it would require an infinite force to accelerate to that speed, or a constant force for an infinite amount of time. in either case, an infinite amount of energy would be required.
So then E = mc^2 is not correct according to you.
You seem to have a good grasp of the mathematics and on this basis can rule out a massive object going the speed of light. There are many intelligent people who do not really think though. You can regurgitate what you learned but you still have not answered my question. It is a why question.
Why is it that massive objects can not travel the speed of light but massless objects can.
Originally posted by tenzin
So then E = mc^2 is not correct according to you.
correct. this equation is not true in general, according to this definition. it does happen to be true in the rest frame of a particle though.
Why is it that massive objects can not travel the speed of light but massless objects can.
well i already told you why massive objects cannot travel at the speed of light.
as for massless particles, it is not so much why they can go the speed of light (which is the only natural speed that the universe has other than 0), but rather why they cannot go slower than light. they cannot go slower than light because this is kinematically forbidden: if a massless particle is going slower than light in some frame, then there is a frame in which it is at rest. in this frame, we see that there is no particle at all.
Originally posted by lethe
correct. this equation is not true in general, according to this definition. it does happen to be true in the rest frame of a particle though.
So in the rest frame of a photon the it is true?
well i already told you why massive objects cannot travel at the speed of light.
as for massless particles, it is not so much why they can go the speed of light (which is the only natural speed that the universe has other than 0), but rather why they cannot go slower than light. they cannot go slower than light because this is kinematically forbidden: if a massless particle is going slower than light in some frame, then there is a frame in which it is at rest. in this frame, we see that there is no particle at all.
No all you told me is what the equations allow and do not allow. Secondly, it is a question as to why massless particles can go the speed of light. Either way you answer you are only regurgitating results from formulas. You need to interpret what the equations are saying.
Why is it that no one has even tackled the question as to why light is measured the same speed by all intertial reference frames? Without answering this question there is no way to progress with anything resembling real understanding.
UltanByrne
Jan5-04, 12:01 AM
Why is it that no one has even tackled the question as to why light is measured the same speed by all intertial reference frames?
You should and on that!(and thank lethe for his help in the mean time [6)])
Ultan!
Originally posted by UltanByrne
You should and on that!(and thank lethe for his help in the mean time [6)])
Ultan!
Lethe had nothing to do with my thinking. I have been considering this for over 10 years.
Originally posted by tenzin
So in the rest frame of a photon the it is true?
photons do not have a rest frame. they are massless, remember? this was the whole point of my above post. did you read it?
Originally posted by lethe
well i already told you why massive objects cannot travel at the speed of light.
No all you told me is what the equations allow and do not allow.
well, listen man, this is how physics works:
1. start with some physical assumptions.
2. derive the mathematical consequences of those assumptions.
you asked about why some physical phenomenon happens, and i explained to you how it follows from the principles of physics.
to recap: massive particles cannot travel at the speed of light because the basic laws of physics do not allow it.
what more do you want? if you want to see a mathematical derivation, i can surely provide it, but now i am thinking it would be a waste of my time and of yours.
if you want to know why the basic laws of physics are what they are, then i have nothing more to say. i have neither the inclination, nor the expertise, to give history lessons.
Secondly, it is a question as to why massless particles can go the speed of light. Either way you answer you are only regurgitating results from formulas. You need to interpret what the equations are saying.
i don t know if this is supposed to be insulting, but i do find it so.
Why is it that no one has even tackled the question as to why light is measured the same speed by all intertial reference frames? Without answering this question there is no way to progress with anything resembling real understanding.
this question has been tackled, and the answer is understood. if you are implying that i lack understanding, then i guess i have nothing more to say to you that wouldn t be a waste of your time.
to recap: massive particles cannot travel at the speed of light because the basic laws of physics do not allow it.
How do you know the so called basic laws of physics are always correct?
what more do you want? if you want to see a mathematical derivation, i can surely provide it, but now i am thinking it would be a waste of my time and of yours.
Don't worry your level of math does not impress me. I know more than I have let on. I learned QED renormalization in about 15 minutes of reading a book I just picked up off the shelf.
if you want to know why the basic laws of physics are what they are, then i have nothing more to say. i have neither the inclination, nor the expertise, to give history lessons.
So you don't know.
Originally posted by tenzin
Originally posted by lethe
what more do you want? if you want to see a mathematical derivation, i can surely provide it, but now i am thinking it would be a waste of my time and of yours.
Don't worry your level of math does not impress me. I know more than I have let on. I learned QED renormalization in about 15 minutes of reading a book I just picked up off the shelf.
well, i guess i just don t have as high a math level as you. i feel so humiliated, you know it is my only source of self worth, to know that i can impress people on message boards with my math knowledge.
but truth be told, you are right, the proof that massive objects cannot go the speed of light is mathematically well beyond my level. renormalization too.
arrogant prick. your medal for learning renormalization in 15 minutes is forthcoming.
Originally posted by tenzin
So you don't know.
i ll tell you what: if you want to ask questions about physics, go ahead and do that. i don t think i will be answering any more of your questions, as i think you are an ***-hole, but perhaps someone else will.
if you want to make conjectures about what i know instead of talking about physics, i will respond as before: mind your own fvcking business.
well, i guess i just don t have as high a math level as you. i feel so humiliated, you know it is my only source of self worth, to know that i can impress people on message boards with my math knowledge.
but truth be told, you are right, the proof that massive objects cannot go the speed of light is mathematically well beyond my level. renormalization too.
arrogant prick. your medal for learning renormalization in 15 minutes is forthcoming.
It didn't take 15 mintues because of me. It took 15 mintues to learn because it is easy. Any person who inderstands the probablity of coin flips can understand QED. The stange thing is how easy these things are once the shroud of imaginged difficulty is lifted. The so called intellectuals purposely make things harder than they are in order to promote themselves as smart.
i don t think i will be answering any more of your questions
Why start now.
Originally posted by tenzin
It didn't take 15 mintues because of me. It took 15 mintues to learn because it is easy. Any person who inderstands the probablity of coin flips can understand QED. The stange thing is how easy these things are once the shroud of imaginged difficulty is lifted. The so called intellectuals purposely make things harder than they are in order to promote themselves as smart.
oh yes, the international conspiracy of physicists trying to make themselves look smart and exclude the common man.
you hit the nail right on the head.
Originally posted by lethe
oh yes, the international conspiracy of physicists trying to make themselves look smart and exclude the common man.
you hit the nail right on the head.
I don't know where I implied conspiracy.
BigRedDot
Jan5-04, 01:14 PM
If I were as gifted and smart as you truly are tenzin, I think I'd find a more useful or at least profitable out let for my gifts than trolling internet messages boards. That would just be me, though. I mean, whatever floats your tub toys.
Originally posted by BigRedDot
If I were as gifted and smart as you truly are tenzin, I think I'd find a more useful or at least profitable out let for my gifts than trolling internet messages boards. That would just be me, though. I mean, whatever floats your tub toys.
A. I am not trolling.
B. I don't know where you get the idea that I am gifted and smart.
C. who cares what you think.
BigRedDot
Jan5-04, 01:28 PM
A. I am not trolling.
A matter of opinion, surely. It looks to me like you posted your question, with your answer already in mind ("I know more than I have let on.") just so that you could pounce on a well-meaning respondent. I call that a troll.
B. I don't know where you get the idea that I am gifted and smart.
In fact I don't; I was being facetious.
C. who cares what you think.
A few people come to mind.
Originally posted by tenzin
A. I am not trolling.
B. I don't know where you get the idea that I am gifted and smart.
i can assure you, not everyone here shares that opinion.
C. who cares what you think.
actually, i liked BigRedDot s response.
Originally posted by BigRedDot
A matter of opinion, surely. It looks to me like you posted your question, with your answer already in mind ("I know more than I have let on.") just so that you could pounce on a well-meaning respondent. I call that a troll.
So now you can read my mind.
Originally posted by lethe
i can assure you, not everyone here shares that opinion.
actually, i liked BigRedDot s response.
A. I never said anything about my smarts but if you feel upset that (in your mind) there is someone smarter than you this is really not my problem.
B. Who cares what you like.
BigRedDot
Jan5-04, 01:36 PM
Does anyone have any physics they want to talk about here?
Edit: I mean really, the questions you ask -- the ultimate "why" sort of questions -- belong to the realm of philosophy. Why is a photon evidently massless? Who knows, that's just the way our universe operates. No experiment will tell you "why." Ultimately, at some level, science only offers descriptions and models, not explanations.
Originally posted by BigRedDot
Does anyone have any physics they want to talk about here?
Yes see my thread under general physics -> theory developmment -> Questions on Light
Originally posted by tenzin
B. Who cares what you like.
you asked who cares about what BigRedDot said, and i was simply answering your question: i do.
Originally posted by lethe
you asked who cares about what BigRedDot said, and i was simply answering your question: i do.
Why don't you simply say something that actually makes sence.
odiedog
Jan11-04, 12:01 AM
If an electron gains mass as it moves towards the speed of light where does this mass-energy come from? Does this not violate conservation of energy?
Why is it that massive objects can not travel the speed of light but massless objects can.
No all you told me is what the equations allow and do not allow. Secondly, it is a question as to why massless particles can go the speed of light. Either way you answer you are only regurgitating results from formulas. You need to interpret what the equations are saying.
Okay. So this is a "why" question, is it?
1. What is "electron"?
2. What is "mass" and "energy"?
3. What is "speed"?
Nothing but ideas, really. Mental constructs, mathematical crutches. What you need here is not an answer to your question but a good read on philosophical aspects of physics (or science in general). Try some Karl Popper (http://plato.stanford.edu/entries/popper/) for starters.
Since you are good at math - you question the axioms here. And ask for someone to prove them to you. Silly - don't you think?
You see, there is no need for an electron to gain mass as it approaches the speed of light - 'tis but a theory. What "really" happens is that some guys at CERN speed up some electrons (or so they think), and watch the results (whatever they think they are watching), then they use some formulae (perhaps tweak some constants for better fitting), rarely come up with a new formula (which doesn't break the other) and then go and get something to eat.
You are free to make a theory of your own. It will be quite hard to make it as consistent as the current one though (and even the current one has cracks all over).
BTW: You've used the term "conservation of energy". What it this, if not a regurgitation of a formula. A really old and simple one at that.
PS: Really... Go read some Popper. It'll do you good.
ranyart
Jan11-04, 03:40 AM
Originally posted by odiedog
Okay. So this is a "why" question, is it?
1. What is "electron"?
2. What is "mass" and "energy"?
3. What is "speed"?
Nothing but ideas, really. Mental constructs, mathematical crutches. What you need here is not an answer to your question but a good read on philosophical aspects of physics (or science in general). Try some Karl Popper (http://plato.stanford.edu/entries/popper/) for starters.
Since you are good at math - you question the axioms here. And ask for someone to prove them to you. Silly - don't you think?
You see, there is no need for an electron to gain mass as it approaches the speed of light - 'tis but a theory. What "really" happens is that some guys at CERN speed up some electrons (or so they think), and watch the results (whatever they think they are watching), then they use some formulae (perhaps tweak some constants for better fitting), rarely come up with a new formula (which doesn't break the other) and then go and get something to eat.
You are free to make a theory of your own. It will be quite hard to make it as consistent as the current one though (and even the current one has cracks all over).
BTW: You've used the term "conservation of energy". What it this, if not a regurgitation of a formula. A really old and simple one at that.
PS: Really... Go read some Popper. It'll do you good.
Now we have someone who actually "reads-between-the-lines" of the threads on this boards![a)]
So let's re-evaluate where the thread disintegrates?..
Tenzin ask's:If an electron gains mass as it moves towards the speed of light where does this mass-energy come from? Does this not violate conservation of energy?
And now we find the answer to this question lies in the very first word> If..
Should not tenzin be explaining to the rest of us what his/her meaning of this word (If) is?, in relation to the rest of the sentence?
Some 'if's' are well worth exploring more than others! before moving on to the full question, I ask tenzin to give everyone here viewing the thread his/her a physical explanation of his/her (tenzin's) relation to this word 'If'..where it originated?...whats it relationship in meaning to the user?.. and why this word was used in the context of the full sentence...
Then tenzin may get some insights to his/her's own ability to formulate questions, and not be so dis-respectful to other people's response's?
I would be quite happy if (
[*(] ) tenzin provides the mathematical proof of the word if!..or if thats asking just a tad to much.. if 'If' (word) exists , then where? and how?..and what this if can be?[:))]
The only thing I personally do not understand from tenzins original post are the words [If] and the word [Does]? and their relationaship to the rest of the question, I freely admit this may be due to my own deep understanding of Einstien..Feynman..Born..Bohr..and others..but its definatly..(well..definate maybe!) not due to my understanding of tenzin.
Originally posted by odiedog
Okay. So this is a "why" question, is it?
1. What is "electron"?
2. What is "mass" and "energy"?
3. What is "speed"?
Nothing but ideas, really. Mental constructs, mathematical crutches. What you need here is not an answer to your question but a good read on philosophical aspects of physics (or science in general). Try some Karl Popper (http://plato.stanford.edu/entries/popper/) for starters.
I didn't ask for your advice, I asked you a question. Keep you advice to yourself.
Second if velocity is a construct maybe you should step in front of a car in trafic.
You see, there is no need for an electron to gain mass as it approaches the speed of light - 'tis but a theory. What "really" happens is that some guys at CERN speed up some electrons (or so they think), and watch the results (whatever they think they are watching), then they use some formulae (perhaps tweak some constants for better fitting), rarely come up with a new formula (which doesn't break the other) and then go and get something to eat.
If both mass and speed are constructs why is one not important but the other happens?
BTW: You've used the term "conservation of energy". What it this, if not a regurgitation of a formula. A really old and simple one at that.
Where did I give the formula for COE?
PS: Really... Go read some Popper. It'll do you good.
I am glad you have finally reached the level of a the Christians. Why don't you just tell me to read the bible.
Should not tenzin be explaining to the rest of us what his/her meaning of this word (If) is?, in relation to the rest of the sentence?
What do you mean by 'is'?
I would be quite happy if (
) tenzin provides the mathematical proof of the word if!..or if thats asking just a tad to much.. if 'If' (word) exists , then where? and how?..and what this if can be?
Please explain what you mean by the work 'if' as in 'if thats asking just a tad to much.'
[b]
The only thing I personally do not understand from tenzins original post are the words [If] and the word [Does]? and their relationaship to the rest of the question, I freely admit this may be due to my own deep understanding of Einstien..Feynman..Born..Bohr..and others..but its definatly..(well..definate maybe!) not due to my understanding of tenzin.
[/b/
I am not surprised you don't understand me. If you keep working hard someday you will be as smart as me.
ranyart
Jan11-04, 01:39 PM
[/b]
Please explain what you mean by the work 'if' as in 'if thats asking just a tad to much.'
I am not surprised you don't understand me. If you keep working hard someday you will be as smart as me. [/B][/QUOTE]
The only thing I personally do not understand from tenzins original post are the words [If] and the word [Does]? and their relationaship to the rest of the question, I freely admit this may be due to my own deep understanding of Einstien..Feynman..Born..Bohr..and others..but its definatly..(well..definate maybe!) not due to my understanding of tenzin.
I only say this with the LEAST!, Definate of the Most Probable Certainty according to the Understanding Principle, based on nothing but good intentions!
You may want to read the posts again, as some of them have an inbuilt Time-delay-Mechanisim, based on Sarcasm?
You are an idiot. Why don't you waste someone else'e time. The people I want here are intelligent.
ranyart
Jan11-04, 03:43 PM
Originally posted by tenzin
You are an idiot. Why don't you waste someone else'e time. The people I want here are intelligent.
Tenzin, you are one of those people who THINK you know everything, and are really starting to Annoy those of who do!
Coming to an office near you soon :Eagles may soar high, but weasels dont get sucked into Jet engines! David Brent 'THE' office Philosopher.
America look out![:D]
http://www.bbc.co.uk/comedy/theoffice/characters/profile_david.shtml
And here is the Ultimate Mr Spock Question:http://www.bbc.co.uk/comedy/theoffice/clips/series1/clip6.shtml
As defined by the One and Only DB.
odiedog
Jan12-04, 04:51 AM
I didn't ask for your advice, I asked you a question. Keep you advice to yourself.
I am very sorry. I only tried to be helpful.
Second if velocity is a construct maybe you should step in front of a car in trafic.
Speed in Newtonian physics seems quite simple - being a subject our mind is well adjusted to. The concept of speed on the quantum level, especially when you start mixing it up with relativity, is not. Along with concepts like causality, spatial determination (but you know all this).
If both mass and speed are constructs why is one not important but the other happens?
Not important? Very much important even really trully! You don't understand.
We were talking about the concepts, which are far removed from what one could consider everyday experience. Electron is a particle, as well as wave-function. This is weird. This is modelling to fit what we can observe.
So going back to CERN - when one accelerates (adds kinetic energy to) the electron, its kinetic energy continues to mount, but its speed starts to lag behind. This is what happens. Did its mass increase? According to the law of maximum conservation of physical formulae - it does.[:))]
Where did I give the formula for COE?
My dear, COE is a formula, saying Energy(System,time1)+Energy(Universe/System,time1)= Energy(System,time2)+Energy(Universe/System,time2)
I am glad you have finally reached the level of a the Christians. Why don't you just tell me to read the bible.
LOL. What are we but Newton-Einstein- Bohr-...-ians. We have our faith in science, in scientific method. We belive in statistics and Gaussian (Poisson, beta,...) distrubution. This is just what you need to see for yourself. This is what mr. Popper was talking about (plus introduced some pretty fresh concepts like falsifiability).
Originally posted by odiedog
Speed in Newtonian physics seems quite simple - being a subject our mind is well adjusted to. The concept of speed on the quantum level, especially when you start mixing it up with relativity, is not. Along with concepts like causality, spatial determination (but you know all this).
Regardless of what science 'says' they must be a relation between the everyday world and the quantum world. The same laws must apply. Reason is more powerful than observation. If science's picture of reality contradictions valid logic and reasoning it is wrong. Since perception can be fradulent it is not a valid basis to establish something as true.
Not important? Very much important even really trully! You don't understand.
We were talking about the concepts, which are far removed from what one could consider everyday experience. Electron is a particle, as well as wave-function. This is weird. This is modelling to fit what we can observe.
So going back to CERN - when one accelerates (adds kinetic energy to) the electron, its kinetic energy continues to mount, but its speed starts to lag behind. This is what happens. Did its mass increase? According to the law of maximum conservation of physical formulae - it does.[:))]
The electron is a particle. It is not a wave because something can not be both.
My dear, COE is a formula, saying Energy(System,time1)+Energy(Universe/System,time1)= Energy(System,time2)+Energy(Universe/System,time2)
No, COE is an principle that can be shown to hold mathematically. The COE itself is not an equation. If you can even separate the two you are really stupid.
LOL. What are we but Newton-Einstein- Bohr-...-ians. We have our faith in science, in scientific method. We belive in statistics and Gaussian (Poisson, beta,...) distrubution. This is just what you need to see for yourself. This is what mr. Popper was talking about (plus introduced some pretty fresh concepts like falsifiability).
Don't include me in your 'we' above. I am not a hero worshiper. I believe in myself and my abilities to understand through reason. I think you should spend more time with the christians. They are more into the preaching that you seem to like.
BigRedDot
Jan12-04, 09:44 AM
Stop feeding the troll! Just ignore it and it will go away.
odiedog
Jan12-04, 11:11 AM
Mmm. Right. [;)]
Is that all you do when someone asks questions you can't answer. This seems like a very totalitarian way of doing things.
It is not something to be ashamed of that you don't understand my posts. What is shameful is that you really don't want to learn.
The reason you don't understand what I write is because you have this attitude.
tenzin,
I am curious. I see from your profile that you are a physics teacher. May I ask what grade? Surly it isn't college is it?
Originally posted by dlgoff
tenzin,
I am curious. I see from your profile that you are a physics teacher. May I ask what grade? Surly it isn't college is it?
What the hell does this mean? It is clear you have no understanding of teaching. What I am doing is exactly what a good teacher does.
Originally posted by tenzin
What the hell does this mean? It is clear you have no understanding of teaching. What I am doing is exactly what a good teacher does.
well i really hope he s not a high school teacher....
typical. Statement with no reason.
Originally posted by tenzin
What the hell does this mean? It is clear you have no understanding of teaching. What I am doing is exactly what a good teacher does.
Never had a good teacher I guess. At least on that talks so much without teaching me anything.
Originally posted by tenzin
If you can even separate the two you are really stupid.
Originally posted by tenzin
What the hell does this mean? It is clear you have no understanding of teaching. What I am doing is exactly what a good teacher does.
Originally posted by dlgoff
Never had a good teacher I guess. At least on that talks so much without teaching me anything.
I can't teach if you don't listen.
Sammywu
Jan13-04, 09:56 AM
Hi, Tenzin, I am a layman.
Your question interests me a lot. Two electrons, one at rest and one at moving at constant speed. From a relative point of view, both are at rest to their own observations. I can't see why their energy shall be different. But some told me the moving one shall be radiating the photon in order to lower its energy dow to the lower state.
Well, I can see an accelerated electron will need to radiate photons to lower its energy down to a stabler state. I have problem seeing an electron in constant speed movement will have additional energy need to be released.
Now going a step back, an electron is usually caught in the molecular EM force or field. Its energy could be increased when a photon hits it and if the photon has the right frequency. Now when the photon has high enough frequency taht can shake photon out of the trap, we can see a free electron. I can't imagine a free electron truely at rest except those static electrons collected at the surface of metal.
Any way, back a bit, when a electron was knocked out of its trap, it now possesed more energy than its lowest state; with the energy state usually want to go lower, the electron with a moving speed will tend to release photons in order to shake out the additional energy. Does this click?
Originally posted by tenzin
If an electron gains mass as it moves towards the speed of light where does this mass-energy come from? Does this not violate conservation of energy?
Consider an electron in a static electric field E in an inertial frame of reference. As the electron accelerates work is being done by the field (the following does not address the energy of the radiation from the accelerating charge). As such the kinetic energy increases while the potential energy decreases. The total energy, W, remains constant. I.e.
W = T + E0 + V = constant
where
T = Kinetic Energy
E0 = Rest Energy
V = Potential energy
For a derivation of the above relation please see the gory details at
http://www.geocities.com/physics_world/em/relativistic_charge.htm
The inertial energy, E, of a particle is defined as energy sum of the kinetic energy and rest energy, i.e.
E = T + E0
where
m = \frac {m_{0}}{\sqrt {1 - \beta^{2}}}
For derivation please see
http://www.geocities.com/physics_world/sr/inertial_mass.htm
E = mc^{2} = \frac {m_{0}c^{2}}{\sqrt {1 - \beta^{2}}}
The mass-energy relation is with respect to inertial energy, not total energy. Therefore inertial energy is not conserved just as kinetic energy is not conserved. Only the total energy of a paritlce in a conservative field is conserved.
Long story short - An increase in mass-energy is compensated for in a decrease in potential energy.
Sammywu
Jan13-04, 07:00 PM
Arcon, Thank you for your lesson. I just have some questions.
Does this mean we always assume that there is a certain background electric field E in space?
Or, are we assuming electromagnetic force is the only way to accelerate an electron? Is it possible we can accelerate an electron by gravity?
Tenzin, Is this your question?
Back a small step, I would just say somethings I know of an electron. First radio wave is basically generated by moving a free electron back and forth or around a circle, in that way, it's under an acceleration and return to the original state usually. Is this right?
The manmade acceleration to a free electron usually has a low frequency and lon wavelength. Visible lights are produced in different ways. From the Sun or the heated bulb. Why? Xray came out from radiation and Gamnma ray came from an even higher radiation. Actually, a gamma ray can split into an electron and positron. Why?
Time for my diner. Continue when I have free time.
Sammywu
Jan13-04, 07:14 PM
Tenzin, Any way, what is your question exactly? Are we just llok at an accelerated free electron?
Or if Arcon already answer your question, I will stop here and not waste my time any more.
Originally posted by Sammywu
Arcon, Thank you for your lesson. I just have some questions.
Does this mean we always assume that there is a certain background electric field E in space?
No. This was just one way to explain it and it was the simplest way. The whole notion is the same as it is in Newtonian physics - When a body is accelerated it's kinetic energy increases. For energy to be conserved that energy must come from somewhere else and as such there is a decrease in some other form of energy. Kinetic energy is not conserved. Potential energy is not conserved. Only total energy is conserved. You can push a charged ball by hand and the work you do on the ball is at the expense of the energy which came from your muscle's which comes from [ATP = "Adenosine triphosphate"
For info on ATP see
http://entertainment.howstuffworks.com/sports-physiology2.htm
The magnitude of the eletric field is relative so in some situations there can be an electric field in one inertial frame of referance and no electric field in another frame of referance.
Is it possible we can accelerate an electron by gravity?
Yes.
The magnitude of the eletric field is relative so in some situations there can be an electric field in one inertial frame of referance and no electric field in another frame of referance.
How can this be?
Sammywu
Jan14-04, 07:27 AM
Tenzin,
I am not sure where you want to lead to. Before I do something, I have a dumb question.
My friend, an EE master, told me that there will be photon ( EM wave ) radiation from a constantly moving free electron.
I thought only acceleration of a free electron can do that.
What do you think? Any answer about that?
Back to your question, are you trying to refer to the effect of magnectic force generated when an electron is in relative movmement which triggered Einstein's SR theory and the main part of ite SR electrodynmamic theory?
Originally posted by tenzin
How can this be?
Think of it like this: Consider an inertial frame, S, in which there is only a uniform magnetic field given by B = B0 ex where B0 = constant. If there is a charge at rest in S then there the force on the charge is zero in that frame. If a test charge, q, is at rest in this frame then the value of the electric field in that frame is E = F/q = 0. Now consider the same test particle moving in S. There is now a force on that charge due to the magnetic field of B = qvxB as measued in S. If there is a force on a particle in one inertial frame then there is a force on the particle in all inertial frames.
Now change your frame of referance to the rest frame, S'. Note that the particle is moving in S and at rest in S'. In S' the force is b]F[/b] and this is non-zero. The electric field in S' is E' = F'/q != 0
Therefore in S there is no electric field where there is an electric field in S'.
Arcon
Sammywu
Jan14-04, 10:12 AM
Arcon,
Thank you for your lesson.
Apparently, you are very knowlegeable about SR and ED ( Electrodynamitcs).
In another thread titled 'SR and the earth, sun and galaxy' in subsection 'Special & General Relativity' of the section 'Astronomy & Cosmology', Edwin raised a question related to Lorentz force, ED and SR. Would you mind helping me and him there. Thanks
Originally posted by Sammywu
Arcon,
Thank you for your lesson.
Apparently, you are very knowlegeable about SR and ED ( Electrodynamitcs).
In another thread titled 'SR and the earth, sun and galaxy' in subsection 'Special & General Relativity' of the section 'Astronomy & Cosmology', Edwin raised a question related to Lorentz force, ED and SR. Would you mind helping me and him there. Thanks
Sure. I'll give it a try. Glad to help. Can you boil it down to one question since that thread is getting pretty long? I'd rather not have to read that whole thread if I don't have to, especially if you can simplify to a single simple question.
Thanks
Conceptually these are some answers to your questions that do not even require math. (Although a thorough understanding of the algebra in special relativity will formally show you)
Think of 3 things:
1. Definition of mass.
2. What happens when a photon hits a massive object.
3. What will never happen when massive object is trailing a photon.
1. Mass is anything with resistance to acceleration, accleration is change in velocity... You can not accelerate something with a constant velocity like light can you?
2. Light is absorbed or reflected by mass, but that does not mean it has changed velocity. Either it gets taken in or spit out. So there is no real way to "push" light around, just abosorbtion or redirection.
3. A massive object can never catch up with light to apply force to accelerate it.
Finally, just use your imagination why something with mass can not reach the speed of light. If the speed of light is always observed to be constant IN EVERY FRAME OF REFERENCE a massive object could possibly have, then how is anything going to catch up with it. To clarify, picture a monkey chasing a dangling banana that is just out of his reach because it's attached to a helmet on his head. No matter how fast that monkey goes he'll never get that banana.
Originally posted by Jwprox
Conceptually these are some answers to your questions that do not even require math. (Although a thorough understanding of the algebra in special relativity will formally show you)
Think of 3 things:
1. Definition of mass.
2. What happens when a photon hits a massive object.
3. What will never happen when massive object is trailing a photon.
1. Mass is anything with resistance to acceleration, accleration is change in velocity... You can not accelerate something with a constant velocity like light can you?
2. Light is absorbed or reflected by mass, but that does not mean it has changed velocity. Either it gets taken in or spit out. So there is no real way to "push" light around, just abosorbtion or redirection.
3. A massive object can never catch up with light to apply force to accelerate it.
Finally, just use your imagination why something with mass can not reach the speed of light. If the speed of light is always observed to be constant IN EVERY FRAME OF REFERENCE a massive object could possibly have, then how is anything going to catch up with it. To clarify, picture a monkey chasing a dangling banana that is just out of his reach because it's attached to a helmet on his head. No matter how fast that monkey goes he'll never get that banana.
There are monkeys that eventually give up chasing dangling banana's, they get together and some of them obstruct the banana's path by forming a perfect circle around the monkey that has a banana dangling from its helmet, one monkey take's position at the centre of the circle of monkeys, then as the monkey with the nana rebounds off the circle, eventually the monkey with nana will cross the central monkey's path, he then just picks the fruit when it comes to him!
If only we could explain the whole of physics using monkeys and bananas.
You can quote me on that.
raptor5618
Feb10-04, 12:08 PM
I read this thread with a great deal of amazement. To think that someone would ask a question, get an answer and then say thats not it stupid is just a bad joke. Ok maybe the answer did not seem right but they did not counter it with reasons for feeling they were wrong and in some cases just saying why which is very much like a child. A discussion does not include ridicule or personal insults. To ask for help and receive it only to personally put down the person trying to help shows that this person is totally without class. They have worked on this for 10 years so why are they not explaining the answer to his own questions. Also I was just reading that a theory or proof cannot come to be unless there is a way to try and prove it wrong. So to say that the laws that have been created might be wrong well my thought on that is NO Kidding. Based upon what was observed and studied to day they seem pretty good and may continue to be good but who knows what the future will hold that may explose errors in what today seems perfect. He wants logical proof well protons go the speed of light. Why because they can. Why cant an object with mass go the speed of light. Never saw any going that fast so it must be impossible. No math not fancy manipulations.
Yep he may know more, be smarter, have the formulations that will turn physics on it head and you know what I think about that. Good for you. Because if you act in your life like you do here my guess is that you never have talked to anyone for more than a few moments where they were not trying to get away from you. There is far more to life than what degrees you hold, how high your IQ is and all the books your read and understand no matter how easy or hard. I am thankful that there are people who put forth this effort and work to understand the world around us. But at this point in time I think that it is foolish to think that we know more than a tiny bit of how everything works. So in the scheme of all knowing we know very little. even you.
I would think you are a self proclaimed teacher as no real teacher would use your techniques. Ridicule is not a motivator. I also have seen a total lack of reasoning behind why you feel an answer is flawed. Kind of remindes me of the old skit from Monty Pythong. "Yes it is, no it isnt"
ranyart
Feb10-04, 01:04 PM
Originally posted by Jwprox
If only we could explain the whole of physics using monkeys and bananas.
You can quote me on that.
[:))]
Originally posted by raptor5618
I read this thread with a great deal of amazement. To think that someone would ask a question, get an answer and then say thats not it stupid is just a bad joke. Ok maybe the answer did not seem right but they did not counter it with reasons for feeling they were wrong and in some cases just saying why which is very much like a child. A discussion does not include ridicule or personal insults. To ask for help and receive it only to personally put down the person trying to help shows that this person is totally without class.
I have to agree with you. I read this article with complete shock. There were so many people in this article who tried to help answer Tenzin's question. He, however, rejected the help because it was not in the right format. Others tried and were shot down as well, even though they meant good intentions. These people were taking time out of their day to try to explain concepts, and they should at least deserve at least some respect. When I dont understand something, I accept all the help I can get, whether it be mathematical or philisophical-ish concepts. Its kind of a shame when these discussions turn into flame wars.
Tenzin on renormalization:
Originally posted by tenzin
Don't worry your level of math does not impress me. I know more than I have let on. I learned QED renormalization in about 15 minutes of reading a book I just picked up off the shelf.
Tenzin on why the speed of light is invariant:
Originally posted by tenzin
Lethe had nothing to do with my thinking. I have been considering this for over 10 years.
i especially liked how it takes him 15 minutes to learn renormalization (which is a pretty hard subject!), but after 10 years of thought, he still can't grasp special relativity (which is not very hard!)
but yeah, i agree with your sentiments. i was quite shocked when i spent time on what i thought were informative and helpful comments, only to be insulted and accused of ignorance.
just imagine, this guy is a teacher!!!
Adrian Baker
Feb13-04, 12:21 PM
Originally posted by tenzin
The electron is a particle. It is not a wave because something can not be both.
Well I was diffracting some electrons the other day and when I turned up the accelerating Potential , the diffraction increased... How do particles do that then?
An electron may perhaps not 'be both' but that doesn't mean it must be a particle either!
I found the following particularly amusing, in re: learning renormalization:
Any person who inderstands the probablity of coin flips can understand QED.
Apparently he didn't catch the fact that renormalization really has nothing to do with probability, showing a bit of confusion with the notion of probabilitic dynamics (basic quantum mechanics) and convergent Feynman integrals...
Also, anyone who claims to be an excellent teacher -- and in the same breath calls their audience stupid -- is really demonstrating their true colors.
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