What is in the space between atoms?

I understand that molecules are constantly being formed from collisions and such, but what I do not understand, is, on a tiny level, within the level of the atom, what is in between? 'Air' is not the answer, what if we were talking about the molecules and therefore the atoms between air! What's there! Is it matter? Is it just 'nothingness?' Is it subatomic particles?

Similarly, what is space? For example, in outer space, there is ideally a vacuum. What is in a vacuum, if not atoms? What is in space, if not atoms?

I have had these questions for as long as I could comprehend 'open space.'


  • 1
    $\begingroup$ It's basically just vacuum. Nothing more. $\endgroup$ Jun 5 '17 at 4:57
  • $\begingroup$ In that case, what's in a vacuum? $\endgroup$
    – Equinox
    Jun 5 '17 at 4:58
  • 3
    $\begingroup$ Literally nothing at all $\endgroup$ Jun 5 '17 at 4:59
  • 2
    $\begingroup$ Well, there are electromagnetic and gravitational fields and such. Even in deep space there these things as well as particles of matter (mainly H and He), cosmic radiation, dark matter, etc. But I think you are asking what lies between any two things, which is nothingness. Probably a better question for physics.se or astronomy.se, depending on your angle. $\endgroup$
    – airhuff
    Jun 5 '17 at 5:06
  • 4
    $\begingroup$ I'm voting to close this question as off-topic because it is about physics $\endgroup$
    – porphyrin
    Jun 5 '17 at 6:51

From a chemists point of view, nothing. There are no particles or molecules, there are only (sometimes) photons carrying the electromagnetic signal between molecules. You could, even say that virtual particles constantly fill (and leave) this space, provided some shielding from the electromagnetic radiation (however I believe this usually happens inside atoms, between orbitals). You can also say there are gravitational fields between particles/inside the atom too, but they aren't actual particles (at least ones that we have not found).

From a physicists point of view, there's everything. What we perceive as "empty space" is just a blank piece of paper waiting to be written on. Over on the Physics SE a question similar to this has been answered. Essentially this "empty" space is full of potential energy, fields waiting to be simulated (typically by energy) to create particles.


Our best understanding is that the Universe is composed of fields. So, I guess you could look at "space" as being a 3-d volume slice of the 4-dimensional space-time manifold which does not contain matter (although matter is "just" another field, it is one of the most localized fields (by localized I mean has a well defined (and measurable) position)). Sub-atomic particles are ...hmmm...embodiments of their respective fields - it doesn't really make sense to logically separate the particle from the field. Virtual particles exist in empty space, or looking at it another way: no space is empty. We also believe space possesses an energy density (a constant energy density), but that's a bit more difficult to pin down. To answer your more philosophical question: what is in a vacuum if not matter, I guess I'd say it's "potential" - not in the sense of potential energy (although there is that) but in the sense of an ability to form virtual particles (as long as they obey the laws of physics (quantum mechanics)). Unfortunately, the reality is that not only can you not really separate space and time, but you can't separate space-time from energy. For instance, a photon experiences no time and the space in the direction of a (relativistic) particles velocity is compressed - the idea that these slices are fixed or constant in dimension is inconsistent with Relativity. So, in a sense, space is subjective: it depends on the observer. In artsy-craftsy language: space is the canvas upon which nature draws.


Not the answer you're looking for? Browse other questions tagged or ask your own question.