# Driving force of an electron on earth **URL:** \ **Category:** Factual Questions\ **Created:** [December 13, 2021, 7:56pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004 "2021-12-13T19:56:07Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [December 15, 2021, 4:47pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/21 "2021-12-15T16:47:51Z")
It really comes down to electrons in atoms being constrained to having certain energies, and a change in electron energy can only happen if the energy imparted/removed is exactly equal to the difference between those energy levels. At the scale of electrons, gravitational interactions are so weak that they never impart enough energy to transition an electron between allowed energy levels, so gravity might as well not exist as far as an atom’s orbital electrons are concerned. ---
**Author:** ![gdave](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gdave/32/3683_2.png) [@gdave](https://boards.straightdope.com/u/gdave)\ **Post date:** [December 15, 2021, 6:18pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/22 "2021-12-15T18:18:41Z")
> [@Riemann](#): > > Well, it does in the sense that the ball hits the ground. But I’m not really sure what OP is asking here. Not the OP, but I’ve got to admit, as a layman, I’m confused by your confusion. If I throw a baseball while I’m standing on the ground, it slows down and (eventually) falls to the ground, and rolls to a complete stop. If I emit an electron through whatever mechanism, the electron apparently just keeps going. It doesn’t seem to behave anything like a baseball or any other sort of projectile that most of us non-physicists are intuitively familiar with. I believe what @Lucas_Jackson is asking is why an electron’s behavior appears to be so different from the behavior of objects us non-physicists are familiar with. Why does a baseball (or a canonball or whatever) slow down, fall to the Earth, and stop, while electrons (which many of us non-physicists envision as tiny balls, and yes I realize that’s not right) don’t? ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 15, 2021, 6:31pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/23 "2021-12-15T18:31:15Z")
> [@gdave](#): > > If I emit an electron through whatever mechanism, the electron apparently just keeps going. No - in that scenario, an electron is influenced by gravity in just the same way as a baseball. A free electron and a baseball traveling at the same speed through a vacuum absent any force other than gravity would follow the same path. But most electrons in our environment are not free, and few of those that are free are moving at the speed of a baseball or in a vacuum or free of any other force. Electrons _are_ influenced by gravity, but gravity is a very weak force, and typically will just be _irrelevant_ to any account of the behavior of an electron. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 15, 2021, 6:51pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/24 "2021-12-15T18:51:31Z")
> [@gdave](#): > > I’m confused by your confusion. I’m asking exactly what OP seeks an explanation for. His macroscopic analogy is a baseball - but what is he suggesting that’s analogous _to_ - what electron behavior does he want an account of? Electrons in an atom? Electrons in a metal or in an electrical circuit? Free electrons in some context? What, exactly? ---
**Author:** ![gdave](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gdave/32/3683_2.png) [@gdave](https://boards.straightdope.com/u/gdave)\ **Post date:** [December 15, 2021, 7:00pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/25 "2021-12-15T19:00:23Z")
Well, for that, I’ll let @Lucas_Jackson clarify for themself. But I’ve got to add, it’s issues like this that sometimes make these kinds of threads really frustrating for non-physicists like me. There are definitely knowledgeable posters here who will really go out of their way to explain concepts to laypersons (including you in some other threads I’ve read). But then there are instances like this, where it seems like it’s not at all clear to the layperson asking the question how to even ask it the way you want it asked. Just to be clear, I don’t think you or anyone else owes anyone a response - we’re all just voluntarily hanging out on a discussion board. But it can get frustrating seeing a response that’s little more than saying, “Your question is unclear”. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 15, 2021, 7:06pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/26 "2021-12-15T19:06:36Z")
> [@gdave](#): > > But then there are instances like this, where it seems like it’s not at all clear to the layperson asking the question how to even ask it the way you want it asked. I’ve put a lot of effort into trying to give helpful replies to this thread, as have others, trying to guess various aspects of electron behavior that OP might be trying to understand. But apparently none of these answers were helpful. So it’s really a _very_ straightforward question - what is it that electrons are doing (or that you think they are doing) that you want explained? I’ve already just addressed this one: > [@Riemann](#): > > > [@gdave](#): > > > > If I emit an electron through whatever mechanism, the electron apparently just keeps going. > > No - in that scenario, an electron is influenced by gravity in just the same way as a baseball. A free electron and a baseball traveling at the same speed through a vacuum absent any force other than gravity would follow the same path. ---
**Author:** ![gdave](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gdave/32/3683_2.png) [@gdave](https://boards.straightdope.com/u/gdave)\ **Post date:** [December 15, 2021, 7:11pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/27 "2021-12-15T19:11:21Z")
Sorry, I was myself just trying to help the OP. I personally don’t have a question. I’ve just seen more than one thread like this, where there is an obvious disconnect between the OP and experts who are trying to answer their question. Apparently none of my posts were helpful, though, so please disregard them. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [December 15, 2021, 7:21pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/28 "2021-12-15T19:21:20Z")
**Gdave** I understood what you were trying to do. I’ve been trying to do the same. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [December 15, 2021, 7:42pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/29 "2021-12-15T19:42:44Z")
> [@DocCathode](#): > > Newton’s laws work great- unless you get near light speed or get down to quantum scale. Hold up here. Newton’s laws work great, always. For example, an electron in an atomic orbital does not have a net force on it and does not accelerate. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [December 15, 2021, 7:43pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/30 "2021-12-15T19:43:29Z")
I happilly admit my error. As I said, I know just a bit and hunger to know more. ---
**Author:** ![Tfletch1](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tfletch1/32/5340_2.png) [@Tfletch1](https://boards.straightdope.com/u/Tfletch1)\ **Post date:** [December 15, 2021, 7:52pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/31 "2021-12-15T19:52:36Z")
Elementary particles don’t have the same properties as those described by classical mechanics. I don’t know if all of them move, like those that provide forces for other particles (some of the bozons). However, photons (particles of light) are bozons that move at the speed of light in a vacuum. The mass particles are known as fermions, which make up the elementary particles of the atom. Negatively-charge electrons (negatively-charged) are held in their orbitals by electrostatic attractions of the positively-charged protons. They still move around within the confines of their orbitals. I think these tiny particles always have kinetic energy because the universe is always increasing its entropy (different types of energy states). This explains brownian motion of microscopic particles or diffusion of gases or solutes in a liquid. So all small particles are naturally in motion. Even at absolute zero temperatures (−460 °F) electrons will still move. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [December 15, 2021, 7:56pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/32 "2021-12-15T19:56:22Z")
> [@Tfletch1](#): > > Elementary particles don’t have the same properties as those described by classical mechanics This seems to contradict what **Pleonast** said. I’m confused (more than usual). My flight is boarding so I have to go for now. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [December 15, 2021, 8:03pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/33 "2021-12-15T20:03:30Z")
> [@Riemann](#): > > I’m asking exactly what OP seeks an explanation for. His macroscopic analogy is a baseball - but what is he suggesting that’s analogous _to_ - what electron behavior does he want an account of? I apologize for the confusion. I’ll try to clarify. I was reading about atoms - specifically Hydrogen atoms. It was explained that an electron “orbits” the nucleus at about 2,200 kilometers per second. That’s pretty fast. It’s not shooting through space in a straight line at a constant speed (that I could understand), it’s circling a center. The moon circles earth because it’s falling into earths gravity well (sorry for the macro example). Does the electron circle the nucleus due to a similar mechanism? If it does, then it seems like there might be some sort of drag associated with this behavior given that electrons have mass. (to reiterate, I know almost nothing about this stuff - especially QM) And apparently some have been doing that for billions of years. That’s a long time with no decay. That is what sparked my question. I’m not suggesting there is paradox or anything, I’m just trying to understand. Thanks for all of the explanations so far. It’s been enlightening. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [December 15, 2021, 8:13pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/34 "2021-12-15T20:13:20Z")
> [@Tfletch1](#): > > They still move around within the confines of their orbitals. This statement is not correct. Yes, we often tell stories of electrons orbitting nuclei to give students a visualization, but the particle concept just doesn’t work in this regime. It’s better to think of a probability cloud, a cloud that is stable. It’s of course more complicated than that. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [December 15, 2021, 8:24pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/35 "2021-12-15T20:24:32Z")
> [@Lucas\_Jackson](#): > > I apologize for the confusion. I’ll try to clarify. I was reading about atoms - specifically Hydrogen atoms. It was explained that an electron “orbits” the nucleus at about 2,200 kilometers per second. > That’s pretty fast. It’s not shooting through space in a straight line at a constant speed (that I could understand), it’s circling a center. The moon circles earth because it’s falling into earths gravity well (sorry for the macro example). Does the electron circle the nucleus due to a similar mechanism? If it does, then it seems like there might be some sort of drag associated with this behavior given that electrons have mass. (to reiterate, I know almost nothing about this stuff - especially QM) > > And apparently some have been doing that for billions of years. That’s a long time with no decay. That is what sparked my question. I’m not suggesting there is paradox or anything, I’m just trying to understand. What you were reading was wrong to describe the electron orbiting at some particular speed. And you were right in wondering how it could do that for billions of years without orbital decay, but not because of any “drag”. The moon’s orbit for instance isn’t decaying due to any drag. It’s increasing because it’s getting energy from the slowing down of the rotation of the Earth, and once the Earth and the Moon are tidally locked the orbit will just stay the way it is “forever”, as long as outside forces don’t change it. (Like the death of the Sun.) The electron though is a charged particle, and charged particles that accelerate will radiate electromagnetic radiation, so though some physics was explainable by having the negative electron orbiting the positive nucleus just like a planet, it raised some issues, and the solution was the weirdness of QM. ---
**Author:** ![GeneralTang](https://avatars.discourse-cdn.com/v4/letter/g/97f17d/32.png) [@GeneralTang](https://boards.straightdope.com/u/GeneralTang)\ **Post date:** [December 15, 2021, 8:43pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/36 "2021-12-15T20:43:51Z")
> [@Pleonast](#): > > Hold up here. Newton’s laws work great, always. For example, an electron in an atomic orbital does not have a net force on it and does not accelerate. This is flat-wrong. Newtons “laws” are not true laws. They are approximations that work well in the human-scale world. They fail to be applicable at all to electrons in general. One reason, as discussed above, is that electrons don’t really have a position or orbit; they aren’t actually tiny balls, but are more like clouds of probability. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 15, 2021, 8:46pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/37 "2021-12-15T20:46:42Z")
> [@Lucas\_Jackson](#): > > The moon circles earth because it’s falling into earths gravity well (sorry for the macro example). Does the electron circle the nucleus due to a similar mechanism? If it does, then it seems like there might be some sort of drag associated with this behavior given that electrons have mass. Before talking about electrons, there seem to be some misconceptions here about macroscopic objects. Drag is not a property of mass, and is not caused by gravity. The moon does not experience drag - in the vacuum of space, it just keeps on orbiting (except at very long time scales when other small effects matter). Drag slows a solid object moving through a fluid. A moving object has to “push the fluid aside”, and there is friction at the object’s surface. Drag force is a function of the object’s shape and speed, not its mass. If you place a piece of lead inside a ball, that does not change the drag force on that ball at a given speed. So first of all, the question of whether an electron experiences drag is not related to whether it has mass or whether it is affected by gravity. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 15, 2021, 9:20pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/38 "2021-12-15T21:20:26Z")
> [@Lucas\_Jackson](#): > > I was reading about atoms - specifically Hydrogen atoms. It was explained that an electron “orbits” the nucleus at about 2,200 kilometers per second. Let’s stick with this model for now, since at one time this _was_ the consensus model for the atom. Is the concept of drag applicable to the orbiting electron, and is this why the model failed? Drag occurs when a solid object moves through a fluid. And both a solid object and a fluid are _made_ of atoms. Drag is (crudely speaking) when a solid object’s atoms bump into the atoms of a fluid. But where the electron is orbiting, it is _part of_ an atom. The atom consists of a small and dense nucleus in the middle, surrounded by nothing but electrons. There is nothing else there for electrons to “bump into” to cause anything analogous to drag. So failure to consider drag is not the reason that this model failed. So we’re left with this model where the electrostatic attraction between the positively charged nucleus and the negatively charged electron could be analogous to the gravitational attraction between the Earth and Moon, and the fast-moving electron orbits forever in the same way that the Moon orbits the Earth pretty much forever. You could now jump back to post #4 for the reason this didn’t work. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 15, 2021, 10:50pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/39 "2021-12-15T22:50:43Z")
Newton’s laws are applicable in all regimes, provided that you formulate them correctly. For instance, it’s not always true that F = ma, but it is always true that F = dP/dt. It’s to Newton’s great credit that this universally-applicable formulation is how he actually originally formulated them. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [December 15, 2021, 11:09pm UTC](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004/40 "2021-12-15T23:09:56Z")
Pulling together a few things. We can call anything that is impeding or slowing down motion _drag_. We associate drag with aerodynamic drag in our usual experience, and frictional drag in general, but there are other ways we can cause drag and slow things down. Just about everything we know involves drag of some form. Even the moon orbiting, the planets orbiting, the galaxy rotating. Gravitational radiation causes a (ridiculously tiny) amount of drag that comes from gravity waves radiating energy out from a system. We see this is a more violent form with LIGO when it detects the insane energy released as orbiting black holes or neutron stars radiate out enough energy that their orbits decay and they merge. Gravitational frame dragging is another even more infinitesimally tiny but real effect. As noted above, a moving electron radiates energy. It isn’t that much different to gravitational waves, but does involve vastly more energy relative to the electron’s size. An orbiting electron should radiate energy, and this should mean it should slow down. But it doesn’t. This is a very fundamental question, and was one of the most perplexing facing physicists a century ago. It made no sense that the atom could exist in the manner it seemed that it did. The first clue came when Bohr came up with his analysis of the hydrogen atom, and the famous Bohr model. Something that gets taught at high school level physics. Bohr took a few very recent ideas and discoveries and made a significant breakthrough. He proposed a situation where the electron orbited the nucleus in a manner where the circumference of the orbit must be a multiple of the wavelength of the electron. This instantly meant that there were different orbits, orbits with different energies, and a rule that the electron could only move from one orbit to another by either adsorbing or emitting a photon with an energy exactly corresponding to the energy difference between those orbits (it is allowed to jump multiple orbits, not just go in steps of one at a time.) The extraordinary part about this model was that it almost exactly predicted the observed spectral emission lines of hydrogen. So it wasn’t just navel gazing, this was a big deal. Sadly the model didn’t scale, and when you added more electrons and tried to model other atoms, the results didn’t work. But it kick started the work of people like Schroedinger and Dirac which resulted in a theory that did work. That theory is modern quantum mechanics. As noted above, the idea that the electron orbits at a specific speed isn’t really correct. That is more a Bohr model version of reality. Useful, and worked in a limited case, but not the accepted version of reality. But the underlying point remains critically important. At very small scales things are quantised, and this imposes steps in changes of energy. These steps stop energy leaking at very slow rates, and stop electrons winding down, and impose similar bounds on the operation of other processes. [Previous page](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004.md?page=1) [Next page](https://boards.straightdope.com/t/driving-force-of-an-electron-on-earth/956004.md?page=3)