Speed of Electrons

[Airbrush]

Anyone know what the average speed of an electron? For example, the speed of electrons in the atoms of some common solids, liquids, and gases at room temperature?

[ajb]

The drift velocity of electrons in a wire subject to an external electric field is of the order meters per hour.

[Airbrush]

Thanks for the info. I was thinking of the speed of the electron in orbit around a nucleus. How many revolutions per second? What is the average circumpherence of an electron's orbit? Then I can calculate the speed in orbit.

[ajb]

Thanks for the info. I was thinking of the speed of the electron in orbit around a nucleus. How many revolutions per second? What is the average circumpherence of an electron's orbit? Then I can calculate the speed in orbit.

 

I think this is a question motivated by classical thinking. I don't think you can really answer this in the context of quantum mechanics.

[granpa]

the speed of the electron in the ground state of the bohr atom is alpha*c

alpha=1/137

[ajb]

the speed of the electron in the ground state of the bohr atom is alpha*c

alpha=1/137

 

 

This is based on the Bohr model. We know that the Bohr model fails to give the correct angular momentum of the ground state of the hydrogen atom. As such, I am very reluctant to attach too much physical significance to this speed.

[Klaynos]

I would echo ajb's reluctance. The Bohr model is incorrect.

[Airbrush]

So all we can say about the speed of an electron is that it moves less than the speed of light? How about an approximation? About half light speed? Or very much slower? It doesn't have a very great distance to travel to be high revs per second.

Edited March 31, 2011 by Airbrush

[TonyMcC]

Perhaps the electron doesn't move at all ? Perhaps we cannot think of it as a small body in orbit around the nucleus? http://www.newton.dep.anl.gov/newton/askasci/1993/physics/PHY112.HTM

Edited March 31, 2011 by TonyMcC

[timo]

So all we can say about the speed of an electron is that it moves less than the speed of light?

Unless you can define what the speed of an electron around the nucleus is supposed to be (note that the electron is better described as a cloud around the nucleus than as a point rotating around it), you can't even say that.

Edited March 31, 2011 by timo

[Klaynos]

Of course we could look at it like this....

 

The electron is a standing wave around the nucleus.

 

Standings waves are by their very definition stationary.

 

Therefore the electron has no speed.

 

But this is also wrong. The problem here is the electron isn't a classical thing, you can't think of it like that. Which is annoying!

[Mike Smith Cosmos]

Of course we could look at it like this....

 

The electron is a standing wave around the nucleus.

 

Standings waves are by their very definition stationary.

 

Therefore the electron has no speed.

 

But this is also wrong. The problem here is the electron isn't a classical thing, you can't think of it like that. Which is annoying!

 

 

 

Surely if we cannot pin the electron down to some understandable form , we are in a ( blindfolded ) position of not understanding exactly what makes the whole of chemistry, much of physics, much of the workings of the universe, work.

 

 

.

Edited April 1, 2011 by Mike Smith Cosmos

[imatfaal]

Surely if we cannot pin the electron down to some understandable form , we are in a ( blindfolded ) position of not understanding exactly what makes the whole of chemistry, much of physics, much of the workings of the universe, work.

.

 

Fun and kinda scary ain't it?

[ajb]

So all we can say about the speed of an electron is that it moves less than the speed of light? How about an approximation? About half light speed? Or very much slower? It doesn't have a very great distance to travel to be high revs per second.

 

 

Again, this is all thinking very classically.

 

Surely if we cannot pin the electron down to some understandable form , we are in a ( blindfolded ) position of not understanding exactly what makes the whole of chemistry, much of physics, much of the workings of the universe, work.

 

Quantum mechanics is what is needed.

[swansont]

Surely if we cannot pin the electron down to some understandable form , we are in a ( blindfolded ) position of not understanding exactly what makes the whole of chemistry, much of physics, much of the workings of the universe, work.

 

Is there some guarantee (of which I am unaware) that we can understand "exactly what" makes everything work? Or even what "exactly" means?

[Mike Smith Cosmos]

Is there some guarantee (of which I am unaware) that we can understand "exactly what" makes everything work? Or even what "exactly" means?

 

 

 

Surely it is the "lot" of scientists to discover and find out how the universe works! If not, how can we learn to harness the "goodies", move and exist.

 

"Exactly " means more than a superficial level of understanding.

 

Guarantee toward understanding. Well there's a thing ! If not, then we must remain like the Eloy or whatever they are called in H.G.Wells the time machine. Those below the earth and those above ( the Eloy ) just wandering about accepting everthing at face value , smiling. ( Perhaps that is the better state to be in )

 

.

[swansont]

Surely it is the "lot" of scientists to discover and find out how the universe works! If not, how can we learn to harness the "goodies", move and exist.

 

No. It is the lot of scientists to discover how the universe behaves. One cannot be sure that the models scientists develop are how the universe actually works.

[Mike Smith Cosmos]

No. It is the lot of scientists to discover how the universe behaves. One cannot be sure that the models scientists develop are how the universe actually works.

 

Is this not the difference between a medical symptom being understood "behaves " and not understanding the underlying 'cause' "works ".

 

Surely it behooves us to get at the underlying 'cause' , "works", in science if we are ever going to manipulate the underlying "works" to our advantage .

 

 

.

 

Again, this is all thinking very classically.

 

 

 

Quantum mechanics is what is needed.

 

Yes, Fine . But I personally still have the need, the way my brain works , for me to contain ideas, and work forward, to translate the quantum concepts into a working Model.

This so, even if that model has all sorts of bits, waves and things hanging off it, unlike anything in the normal classical world, I still need a model or series of models.

The maths is all well and fine but much as I understand the operations of much of the maths, I am unable to keep a picture going in my mind when it all goes too convoluted. You mathematicians seem to be able to wander unruffled in a sea of equations. Very well done , but I need to pull some workable models out of this quantum jungle.

 

At a later juncture, and in another subject area, say September when I return , I would like to investigate this issue of :- are we using maths to describe reality, perhaps sometimes in an awkward way, or is maths the reality that underlays the universe?

Edited April 3, 2011 by Mike Smith Cosmos

[swansont]

Is this not the difference between a medical symptom being understood "behaves " and not understanding the underlying 'cause' "works ".

 

Surely it behooves us to get at the underlying 'cause' , "works", in science if we are ever going to manipulate the underlying "works" to our advantage .

 

That's moot. You can only develop science as far as it can be tested and is falsifiable.

[ajb]

You mathematicians seem to be able to wander unruffled in a sea of equations. Very well done , but I need to pull some workable models out of this quantum jungle.

 

To my knowledge, there is no experimental data that does not agree with the predictions of quantum mechanics to within acceptable experimental errors and the domain of validity.

 

Like it or not, non-relativistic quantum mechanics is a model that works extremely well.

[Mike Smith Cosmos]

 

Like it or not, non-relativistic quantum mechanics is a model that works extremely well.

 

 

 

Whats that supposed to mean ?

 

.

Edited April 4, 2011 by Mike Smith Cosmos

[ajb]

Whats that supposed to mean ?

 

I refer you back to my previous post.

 

 

To my knowledge, there is no experimental data that does not agree with the predictions of quantum mechanics to within acceptable experimental errors and the domain of validity.

[Mike Smith Cosmos]

<br>I refer you back to my previous post.

<br>To my knowledge, there is no experimental data that does not agree with

the predictions of quantum mechanics to within acceptable experimental

errors and the domain of validity. <br><br>

<br>I understand calculations are very very very precise in all quantum maths . They are usually around one particular feature of quantum mechanics as far as I can see.<br><br>What appears to be lacking are good models of quite what is happening ( acknowledged by such masters as Einstein, Feynman etc ). What is more; missing is some overall model /models that can draw it all together. I might be wrong. But if there were such models, why am I not hearing about it/them. All I seem to hear is " its in the maths". Unless, of course,  that  you convince me that maths is the very bedrock principles on which  <font size="3"><b>all</b></font>  is built. I concede maths is the bedrock of calculation and quantitative prediction. But I'm not so sure it is the bedrock of <b><font size="2">Reality</font></b>.      <br>

<br><br><br>eek!   What have I done <br><br><br>.<br><br><br> Edited April 4, 2011 by Mike Smith Cosmos

[swansont]

There is a model of what is happening: it's called quantum mechanics. Things are waves, and obey the relationships described by QM. You seem to want a mechanism to explain why quantum mechanics works that way. I can't help you. And until someone comes up with a way of testing ideas about such mechanisms, neither can anybody else.

[DrRocket]

Yes, Fine . But I personally still have the need, the way my brain works , for me to contain ideas, and work forward, to translate the quantum concepts into a working Model.

This so, even if that model has all sorts of bits, waves and things hanging off it, unlike anything in the normal classical world, I still need a model or series of models.

 

The model IS quantum mechanics. But it appears that you cannot accept QM as the model, because it does not admit of classical interpretations. In that case either you are doomed to never understand, or you will have to invent and validate some alternative to quantum mechanics. Since an army of professional physicists has found no alternative to quantum theory in roughly a century since its discovery, I would personally bet that you are doomed.

 

"There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe that there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper, a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I can safely say that nobody understands quantum mechanics." – Richard P. Feynman in The Character of Physical Law