No, no, it's the Nitrogen.
The flying unicorns eat nitrogen, see (that's how they fly) and when they fart, it makes the air glow around them.
Ever see a rainbow? Unicorn diarrhea.
:m:
Light at Light Speed
- Thread starter Bowser
- Start date
The flying unicorns eat nitrogen, see (that's how they fly) and when they fart, it makes the air glow around them.
Ever see a rainbow? Unicorn diarrhea.
:m:
tashja
Registered Senior Member
James, please help me understand this:
A Feynmam diagram describing the space-time processes of two electrons exchanging a virtual photon, emitted at A and absorbed at B.
''thus for this example, the virtual photon is not restricted to travel at exactly the speed of light for the entire time it travels between the two particles. But special relativity says that if it is traveling faster than light, then in some frame of reference it would appear to be going backward in time. If it is going backward in time, then it can be emmited at A and absorbed at B. In other words, in the second diagram, the virtual photon is traveling faster than light.''
Q:So, do photons travel faster that light between particles and sometimes at less speeds, too?
''The self energy of the electron (an electron interacts with its own EM field) by emitting a photon and then capturing it again.''
Q: How could a electron catch the same photon it emitted? The electron would have to be moving faster than the photon, no?
A Feynmam diagram describing the space-time processes of two electrons exchanging a virtual photon, emitted at A and absorbed at B.
''thus for this example, the virtual photon is not restricted to travel at exactly the speed of light for the entire time it travels between the two particles. But special relativity says that if it is traveling faster than light, then in some frame of reference it would appear to be going backward in time. If it is going backward in time, then it can be emmited at A and absorbed at B. In other words, in the second diagram, the virtual photon is traveling faster than light.''
Q:So, do photons travel faster that light between particles and sometimes at less speeds, too?
''The self energy of the electron (an electron interacts with its own EM field) by emitting a photon and then capturing it again.''
Q: How could a electron catch the same photon it emitted? The electron would have to be moving faster than the photon, no?
tashja:
There's a difference between virtual photons (like the ones in Feynman diagrams) and real photons (like the ones that you see or that carry radio signals). Real photons never travel faster than light. In fact, they always travel at exactly the speed of light.*
Real photons can carry useful information from place to place. Virtual photons, on the other hand, are more like carriers of electromagnetic forces - for example, they "tell" two positively-charged particles to repel one another by carrying a kind of message from one particle to the other. We can detect real photons with our eyes, a camera or whatever. We can't detect virtual photons, because they spring into existence only for a tiny fraction of a second, do their job then disappear again. If they were detectable they would violate conservation of energy, effectively acting like energy appearing out of nowhere.
In quantum physics, a photon actually doesn't have a well-defined path through space. A photon is, in some ways, a wave of probability that is spread throughout space. An equivalent way of looking at it is in terms of Feynman's "sum over histories", in which you can consider the photon to simultaneously "explore" all possible paths between the point of emission and the point of detection or absorption.
In the Feynman picture, a photon doesn't have to travel in a straight line between its emission and absorption points. Some of the paths it explores will be straight lines, but some will be curved paths and some will be circles or spirals or squares or any shape you care to name. So, an electron can catch its own photon just by the photon travelling in some kind of loop and coming back to the electron.
For real photons, if the photon is unimpeded between two points then when we add up all possible probabilistic Feynman paths the end result is the same as it would be if a point-like particle had travelled in a straight line between the two points at constant speed. (*This is the more complex explanation referred to by the asterisk above.) The curvy paths kind of cancel each other out when you do the Feynman sum. When you're dealing with virtual photons to calculate something like the self-energy of an electron, things are quite different.
So, in short, when you're dealing with the quantum field theory picture of photons (e.g. Feynman picture), you're getting into rather complicated and technical territory, and the rules that apply to the real photons you're familiar with don't exactly apply to virtual photons.
There's a difference between virtual photons (like the ones in Feynman diagrams) and real photons (like the ones that you see or that carry radio signals). Real photons never travel faster than light. In fact, they always travel at exactly the speed of light.*
Real photons can carry useful information from place to place. Virtual photons, on the other hand, are more like carriers of electromagnetic forces - for example, they "tell" two positively-charged particles to repel one another by carrying a kind of message from one particle to the other. We can detect real photons with our eyes, a camera or whatever. We can't detect virtual photons, because they spring into existence only for a tiny fraction of a second, do their job then disappear again. If they were detectable they would violate conservation of energy, effectively acting like energy appearing out of nowhere.
In quantum physics, a photon actually doesn't have a well-defined path through space. A photon is, in some ways, a wave of probability that is spread throughout space. An equivalent way of looking at it is in terms of Feynman's "sum over histories", in which you can consider the photon to simultaneously "explore" all possible paths between the point of emission and the point of detection or absorption.
In the Feynman picture, a photon doesn't have to travel in a straight line between its emission and absorption points. Some of the paths it explores will be straight lines, but some will be curved paths and some will be circles or spirals or squares or any shape you care to name. So, an electron can catch its own photon just by the photon travelling in some kind of loop and coming back to the electron.
For real photons, if the photon is unimpeded between two points then when we add up all possible probabilistic Feynman paths the end result is the same as it would be if a point-like particle had travelled in a straight line between the two points at constant speed. (*This is the more complex explanation referred to by the asterisk above.) The curvy paths kind of cancel each other out when you do the Feynman sum. When you're dealing with virtual photons to calculate something like the self-energy of an electron, things are quite different.
So, in short, when you're dealing with the quantum field theory picture of photons (e.g. Feynman picture), you're getting into rather complicated and technical territory, and the rules that apply to the real photons you're familiar with don't exactly apply to virtual photons.
Motor Daddy
Valued Senior Member
James, Are you still working on the problem from post #22? I figured by now you would have some type of explanation as to why my numbers are wrong. Good luck, as those numbers are the very definition of distance and time. There is no such animal as the relativity of simultaneity. There is absolute simultaneity in the universe!
Motor Daddy
Valued Senior Member
I don't post meaningless rubbish, I post facts. The facts are posted in post #22. If you disagree with them, tell me exactly where the numbers are wrong, and tell what you think the numbers are. Those numbers are the very definition of distance and time. Any other numbers and you've stepped outside of the definitions, which would make you wrong.
tashja
Registered Senior Member
Photons has two aspects. One aspect is connected to the speed of light which is not dependent on finite reference. The other aspect is connected to its wavelength/frequency, which is dependent on reference.
The photon sort of has two legs, which strattle and connect finite reference with the speed of light reference. Its C-leg will see infinite time and space contained on its point-instant reference, allowing this leg to be everywhere in the universe at the same time. It other leg is finite and will take on different characteristics within space and time dependent on the reference. It will appear at a given place in finite reference.
All photons have the C-leg in common. However, the finite leg is based on position in finite space and time while being reference dependent. The last statement further breaks the finite leg into exact position in space-time, yet variable with respect to wavelength-frequency based on reference.
The photon sort of has two legs, which strattle and connect finite reference with the speed of light reference. Its C-leg will see infinite time and space contained on its point-instant reference, allowing this leg to be everywhere in the universe at the same time. It other leg is finite and will take on different characteristics within space and time dependent on the reference. It will appear at a given place in finite reference.
All photons have the C-leg in common. However, the finite leg is based on position in finite space and time while being reference dependent. The last statement further breaks the finite leg into exact position in space-time, yet variable with respect to wavelength-frequency based on reference.
No. I didn't even bother reading that post in full, because I know it will just repeat the previous misconceptions of yours that I dealt with at length in a previous thread.
Where you went wrong is the same as where you went wrong last time, and the time before that, and the time before that.
Motor Daddy
Valued Senior Member
I didn't expect any sort of real response, people believe what they want to believe. Instead of saying it's wrong, or boring, show me in black and white why my numbers are wrong and tell me what you think the numbers are. Anything less is avoiding the facts as posted.
You're still ignoring the response in post #28, MD.
Your numbers appear to be a correct elementary exercise in the mathematical world of Euclidian spacetime.
Good for you.
Are you able to repeat the exercise in the mathematical world of Minkowski spacetime?
And how do you tell which mathematical world matches the real world?
The [post=2662612]Relativity of Simultaneity[/post] thread has been waiting for your reply to that question for six months.
Your numbers appear to be a correct elementary exercise in the mathematical world of Euclidian spacetime.
Good for you.
Are you able to repeat the exercise in the mathematical world of Minkowski spacetime?
And how do you tell which mathematical world matches the real world?
The [post=2662612]Relativity of Simultaneity[/post] thread has been waiting for your reply to that question for six months.
Motor Daddy
Valued Senior Member
Pete, I haven't seen your numbers of Einstein's Chapter 9 yet. Let's see 'em. I showed you mine now you show me yours! Chicken? You can't show legitimate numbers for the exercise because there exists no relativity of simultaneity. I'll eat you alive if you dare to try.
...
Your use of high school algebra, combined with a profound lack of physics understanding will make this appear so; but only to you.
Everyone else with even a cursory understanding of physics will be left simply shaking their heads and feeling slightly embarassed for you....
Motor Daddy
Valued Senior Member
Show me the numbers. Enough of the small talk.
Neddy Bate
Valued Senior Member
Hey MD, how are ya?
Your calculations are based on the assumption that the embankment is at absolute rest. But what if the embankment is located on earth? Then, according to your own ideas, you'd have to consider the speed of the earth rotating and revolving around the sun, right? So now you have to pick a location on earth, and recalculate everything based on the time of day, season of year, etc.
And you really can't assume that the sun is at absolute rest, because it is revolving around the Milky Way Galaxy. So you'd better start Googling all of those speeds, and fix your calculations.
Also, don't forget that your approach doesn't work well for 3-dimensional problems.
I look forward to your seeing your new calculations. Have fun!
Motor Daddy
Valued Senior Member
Hey MD, how are ya?
Your calculations are based on the assumption that the embankment is at absolute rest. But what if the embankment is located on earth? Then, according to your own ideas, you'd have to consider the speed of the earth rotating and revolving around the sun, right? So now you have to pick a location on earth, and recalculate everything based on the time of day, season of year, etc.
And you really can't assume that the sun is at absolute rest, because it is revolving around the Milky Way Galaxy. So you'd better start Googling all of those speeds, and fix your calculations.
Also, don't forget that your approach doesn't work well for 3-dimensional problems.
I look forward to your seeing your new calculations. Have fun!
Hi Neddy Bate, how are ya? Long time no see. I'm doing fine.
I personally don't assume the tracks have an absolute zero velocity. I am working Einstein's example, and the ONLY possible velocity the tracks can have is an absolute zero velocity. Why is that, you might be asking? Because the lights from A and B on the embankment impacted the embankment observer simultaneously, and the lightening struck A and B on the embankment when the train's A and B coincided with the embankment's A and B. That is one point in time, not two, so the embankment MUST BE at an absolute zero velocity. MUST BE! Einstein's thought experiment has many flaws, it's actually laughable.
Thanks for playing, though. By all means, feel free to play again if you think you have a valid point.
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Right off the bat you state something that is counter to all experimental evidence. You state that an observer on the train will not see the speed of light as c (I assume we can neglect the affect of the atmosphere on the speed of the light in this example). You assert that he will measure it as something less than c because of the speed of the train. All experimental evidence indicates that the speed of light is indepent of the observers motion. Does that mean that the if the light was in the front of the car then the speed of the light would exceed the speed of light to the back wall?? What is your evidence that this supposition has any basis in reality?