# Today's $1000 Question: How does the Atomic Force Work? This topic is 4812 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic. If you intended to correct an error in the post then please contact us. ## Recommended Posts I would like to know if someone can explain me how the atomic force works. I am especially interested in an equation. We have equations for gravity, the electrical force, etc... But I never actually saw an equation for the atomic force. I don't have$1000 to give you, however, so you're going to have to settle for my gratitude ;)

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Do you mean the strong nuclear and weak nuclear forces?

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If that's what you mean than this should explain it: Fundamental Forces

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The link didn't show up :(
Here: http://www.egglescliffe.org.uk/physics/particles/nuclearforces/nuclear.html

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By "atomic force" you mean strong force? (i.e. force that acts between quarks, and also keep nucleus)

I think there is no nice equations, because: it works only on short range, where you have to deal with quantum physics and where force carriers are (comparably) heavy.
Take for example electromagnetic forces. At big ranges with big charges you have nice equations. But force is not just some force attracting stuff together. It is transmitted by force carriers (electromagnetic forces is carried by photons). For electromagnetic force, nice equations is only approximation to what really happens. Same for strong force, except there is no nice equation.

Some info:
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html

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Quote:
 Original post by DmytryTake for example electromagnetic forces. At big ranges with big charges you have nice equations. But force is not just some force attracting stuff together. It is transmitted by force carriers (electromagnetic forces is carried by photons). For electromagnetic force, nice equations is only approximation to what really happens. Same for strong force, except there is no nice equation.

that made me think: could the same be said about gravity? the graviton still isnt proven, is it? but if it were, how does that match up with einsteins interpretation about curving spacetime? extending the parralel, thatd mean the other forces could probably be tought of as curving spacetime aswell, no?

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Quote:
Original post by Eelco
Quote:
 Original post by DmytryTake for example electromagnetic forces. At big ranges with big charges you have nice equations. But force is not just some force attracting stuff together. It is transmitted by force carriers (electromagnetic forces is carried by photons). For electromagnetic force, nice equations is only approximation to what really happens. Same for strong force, except there is no nice equation.

that made me think: could the same be said about gravity? the graviton still isnt proven, is it? but if it were, how does that match up with einsteins interpretation about curving spacetime?

As I understand, quantum gravitation is one of the biggest problems of physics. Graviton should be a quanta of gravitational interaction, like photon is quanta of electromagnetical.
Quote:
 extending the parralel, thatd mean the other forces could probably be tought of as curving spacetime aswell, no?

Probably not - with gravity there's some really weird things happening (for example with orbit of Mercury), and them is explained by general relativity. On other hand, electromagnetic interaction does not exibit such strange effects.(i.e. there is different strangeness)

Besides, there is another very interesting thing: Other forces are interaction between some sort of charges, whereas gravity is interaction between energies*. There is only two known phenomena that works this way: inertia and gravity. And them are just too equal for concidence. It always makes sense to try to reduce two phenomena to one**, and that's what general relativity is all about.

*any form of energy - rest energy (as given by e=mc^2), or energy of photon, or whatever else. Note that energy depends to frame of reference, so it must have something to do with spacetime. It is probably possible to treat energy and impulse as sort of charge, though it will be very unlike any other charge.
**like electrical field and magnetic field.

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it just seems wrong two phemonena that appearently have completely different roots, like gravity and electromagnetism are so similar at the surface. it does feel like there should be a reason for that.

meh i know too little about all this.

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The reason I asked about the *strong* nuclear force is because I'm looking for a way to approximate it.

I am programming a simple simulator with the aim of simulating some basic elementary particles (electrons, neutrons, protons), and build virtual atoms using them. I won't try to be perfectly physically correct because I feel it would never end.

I will basically be simulating particles as points. So there will be no collision detection. And each timestep, all particles will apply their relevant forces to all other particles. In my case, I will worry about gravity, the electric force and the nuclear force, which will keep the nuclei from breaking apart... But I will also want to do something to keep electrons from crashing into the nuclei.

I'm mainly interested in a formula to compute the force (in terms of newtons) between particles. I'm also curious as about whether or not the nuclear force could be strong enough to keep electrons from crashing. Because then if they go too close to the nuclei, they will get bounced off.

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Quote:
 Original post by Eelcoit just seems wrong two phemonena that appearently have completely different roots, like gravity and electromagnetism are so similar at the surface. it does feel like there should be a reason for that.meh i know too little about all this.

Yes, it seems strange to me too. But on other hand, inverse squares law (at surface) is natural for fields that sorta conserve something. For example, "field" of bullets shot in random direction by the shotgun (in space), assuming bullets don't disappear and no new bullets is created in the space. Number of bullets per squared meter per second decreases as 1/r^2 .
Another example, apply simple "blur filter" to floating point image many times (to all image except some black and some white pixels used as sources as field). Gradient of resulting field will obey 1/r law in 2D and 1/r^2 in 3D. (with certain filters there could be anisotropy, but even in this case law will hold at least for parallel distance vectors) Seems that it doesn't matter what filter is used as long as filter doesn't change "brightness".

edit: another great example is things like deformations. Like heightfield of soap film - gradient obey 1/r law (on surface(pun intended)). I'm is not very sure about small 3D deformations in materials but it seems to me that there is some inverse squares law too.
Or sound, also inverse squares.

[Edited by - Dmytry on October 8, 2005 1:32:32 PM]

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