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Author Topic: Do electrons move faster than light?  (Read 6193 times)

Offline Eric A. Taylor

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Do electrons move faster than light?
« on: 05/08/2010 19:13:54 »
I've read that when a photon with the correct energy hits an atom, the electrons in the atom will move to a higher orbit. But they do it without moving through the gap between orbits, rater they go from the lower orbit to the higher instantly WITHOUT going in between. Does this mean the electron in moving faster than the speed of light? Or is the distance so tiny we can't measure a time unit that small? What is the shortest time unit measured? If the electron is moving faster than light is it possible to get a macroscopic object (like a star ship) to make a "quantum leap" to other stars?


 

Offline lightarrow

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Do electrons move faster than light?
« Reply #1 on: 05/08/2010 20:30:28 »
An electron in atom is not a point particle, it's "smeared" in all the orbital (simplistic explanation). So you cannot say that it "goes from one point to another". You can say that its wavefunction changes in a new one whith different energy and different values in space, no much more than this.
 

Offline JP

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Do electrons move faster than light?
« Reply #2 on: 06/08/2010 02:42:53 »
I think the question is still interesting, even with orbitals.  Each orbital has an expectation value of position (representing an average of position) and it's usually this expectation value which can't change faster than the speed of light would allow.  Or put another way, if you jumped from one spherical (angular momentum = 0) orbital to another, would the expected radius of that orbital change faster than the speed of light? 

I don't know the answer off the top of my head.
 

Offline Eric A. Taylor

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Do electrons move faster than light?
« Reply #3 on: 06/08/2010 10:01:51 »
An electron in atom is not a point particle, it's "smeared" in all the orbital (simplistic explanation). So you cannot say that it "goes from one point to another". You can say that its wavefunction changes in a new one whith different energy and different values in space, no much more than this.

I understand that electrons are not points. I'm not sure it's correct but when I picture an atom in my mind I see a tiny particle, or cluster of particles tightly packed together (neutrons and protons) surrounded at quite a large distance (relive to the nucleus) by a fuzzy shell or concentric shells that is the electron cloud. When the photon hits and interacts with the atom this shell gets bigger.

What I'm wondering is does this change in wave function happen instantly or is there a split second when the electron cloud disappears then reappears in the higher orbit. If "orbit" is the correct word. I've heard particle physicists call it an "orbit" but it doesn't mean the same as when an astronomer uses the term. Sort of like "calculus" has different meanings in dentistry and mathematics.

Considering a dentist is a doctor do they have to know how to DO calculus as well as knowing how to remove it?
 

Offline Farsight

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Do electrons move faster than light?
« Reply #4 on: 06/08/2010 10:47:36 »
I think an interesting way to think about this is via the de Broglie atom:



The electron isn't a point going round like a planet, it's "smeared" like lightarrow said. The de Broglie atom shows integer numbers of wavelengths. Now take a look at the picture below:



When the electron goes to a higher orbital, that "quantum jump" is like "changing gear". But IMHO it isn't moving faster than light. IMHO an electron can never move faster than light because as per the evidence of pair production and annihilation, we actually make electrons out of light. 
 

Offline JP

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Do electrons move faster than light?
« Reply #5 on: 06/08/2010 11:45:53 »
One possible answer has to do with the energy-time uncertainty principle--basically in order to absorb a photon of a precise energy, the electron needs to see the incoming light field for a short window of time (enough time to see a few wavelengths of the field pass by).  This means that on average, the electron will take a bit of time to make the jump, and that probably saves it from jumping at faster than the speed of light.  This doesn't really answer any details about the process, though.

To give details, I've also found this highly technical article: http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html

The article is probably a bit heavy, but stress the point that the quantum jump isn't instantaneous, and that over a short period of time, it switches continuously from being in orbit A to being in orbit B, so that at some point in between it's halfway in state A and halfway in state B.  (The physical meaning is that it's originally 100% likely to be found in state A, and later 100% likely to be found in state B, but in between it could be found in either state A or state B). 

An excellent question, though!  My undergraduate (and even graduate) level courses on quantum mechanics didn't really go into how these jumps happened.
 

Offline flr

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Do electrons move faster than light?
« Reply #6 on: 06/08/2010 17:11:12 »
For example the transition time for electron to jump from 2p back to ground-state (1s) is about 1.5 ns.

But from what I understand, that is not the 'jumping' itself or the time of the 'jumping' process, but rather a statistic estimate of the average lifetime of electron in the excited state 2p, and this time is millions of time larger than the time required for electron to jump between the two orbits while the light (of a certain visible frequency) is spontaneously emitted.     

 

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Do electrons move faster than light?
« Reply #6 on: 06/08/2010 17:11:12 »

 

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