# Where does the energy within atoms come from?

Most kinds of energy I know about involve a finite measurement and are transferred. In other words, energy in the universe is finite and is not lost or gained but only transferred through space one way or the other.

I was contemplating how an object, a table for instance, in order to apply enough outward force to hold an object off of the ground must have a sort of energy keeping all of its atoms together.

Atomic bonds involve energy, I assume.

My question is how does this energy work?

• where does it come from?
• is it infinite?
• how/why is that energy different from other kinds of energy?

After-thought:

I notice there are some things in physics, such a gravity, that we know a whole lot about how it behaves but close to nothing about why it behaves in the first place. Perhaps this is one of those things.

• related: physics.stackexchange.com/q/126512/58382 and links therein – glS Feb 6 '15 at 20:52
• once the object is at rest on the table, and the system table+object has reached equilibrium, there is no energy exchange between the two. Remember that the exchange of energy due to a force, i.e. the work done by it, is given by the product of the force times displacement. So no displacement implies no work done, i.e. no energy exchange. About the after-thought (V5) see this Phys.SE question – glS Feb 6 '15 at 21:10
• So you're telling me that a 500 gram object on a table requires zero energy and no force exerted by the table to counteract the constant force of gravity? Seems like energy in some form must be constantly be necessary in oder to hold the atoms together and keep the table from cracking in half. – CuriousWebDeveloper Feb 6 '15 at 21:16
• be careful not to confuse force exerted with energy exchange. There are forces between object and table. Mostly gravity pushing the object down and electromagnetic repulsion pushing it up (plus the effects of the Pauli exclusion principle, see linked question). But this does not mean that there is an exchange of energy. There is one if you put on an object too heavy for the table to hold, in which case energy is exchanged in a variety of ways when the table breaks. This is because in the latter case the object on the table is not in an equilibrium position – glS Feb 6 '15 at 21:23

First of all I recommend you to see in Internet Richard Feynman's WHY". It is exactly what he discusses, our questions about why.

An electron in an atom has two major types of energy, kinetic and potential. The first one is due to the fact that the electron performs a motion, e.g. if we calculate the average of the absolute square of the linear momentum of the electron in the ground state of a Hydrogen atom we find $< \hat {P^2} > \ = \ \frac {\hbar ^2}{a_0^2}$,

where $a_0$ is the Bohr radius.

The potential energy comes from the fact that between the electron and proton there exists an electrostatic field.

Now, why does the electron have a movement inside the atom? If the electron were localized at some time to a fix position, the uncertainty principle tells us that its linear momentum could have any value and it is not clear if the electron would remain in the atom.

Where from comes the potential energy: there are a couple of fundamental interactions with which is endowed our universe, and the e.m. interaction is one of them, see in Internet Richard Feynman's WHY. The types I recall are e.m. interaction, strong, weak, and gravitational. As Feynman explains, the existence of these interactions are fundamental axioms of our universe.

By what the energy in atoms (molecules) differs from other energies? Gravitational energy is due to just another type of interaction with which our universe is endowed. Strong interaction is what keeps together the components that constitute the hadrons (protons and neutrons) and the residual strong interaction keeps the hadrons together in the nuclei.

• Interesting info, especially regarding endowed interactions. That makes sense that at some level, there has to be a set of fundamental, inexplicable laws that "create" physics. But small question: hundreds of years ago we thought the atom was indivisible. Is it not possible that these endowed interactions are levels above other, deeper core fundamental interactions that we just don't know about yet? – CuriousWebDeveloper Feb 6 '15 at 21:37
• @CuriousWebDeveloper VERY possible. – Sofia Feb 6 '15 at 21:39
• @CuriousWebDeveloper : for instance, until now we accepted that bodies have to possess mass and there came one Higgs and told us that there is a boson that facilitate this. We also believed that electron is a fundamental particle and scientists already hold that the electron can be broken (with the cost of tremendous energy invested, i.e. what keeps the matter in an electron together is a force much stronger than the nuclear). – Sofia Feb 6 '15 at 21:43
• @Sofia to what theory are you referring to when talking of the inner structure of an electron? – glS Feb 6 '15 at 22:46
• @glance nothing organized so far, as I understand. An acquaintance of mine told me that scientists deal with the issue/question of the internal structure of the electron, and he sent me an article. It is very interesting. To tell you my own impression, it is that the electron should have an internal structure, otherwise it wouldn't have a magnetic momentum, but I don't deal with such things. As I understood it cannot be named a theory for the moment. If you are interested I can send you the article if there is some means here to attach an article. – Sofia Feb 7 '15 at 0:17