Is it possible to use force to reduce the empty space in an atom?

Question

Atoms are mostly empty space (at least from what I've heard) so is it technically possible to shrink the space between the electrons and the nucleus of an atom?

Answer 1

The concept that atoms are 'mostly empty space' is misleading, and not really true. To talk about what is empty space and what isn't, you need to somehow distinguish between some part of space being 'occupied' or 'not occupied', and at the level of elementary particles, it is not clear how that distinction should be made. If all you have are point particles, then you might as well say that an atom is not just 'mostly' empty space, it is 100% empty space. However a more correct view would be to consider the wavefunction of an atom, in which case you'll find that the wavefunction is a continuous, 'space-filling' function - an atom contains no empty space. It is fully occupied by the wavefunction. Read this answer for a very good description.

As to your question, yes you can 'compress' the wavefunction by applying an external potential to the electron. This can be done using electromagnetic or gravitational forces. Even though it is difficult to 'shrink' an atom by more than a tiny fraction in the laboratory, it is possible to 'squish' it by a small amount, and instruments sensitive enough to detect this shrinkage are available. This is, for example, how the Zeeman effect works.

Answer 2

Atoms are not mostly empty space - they are full of fields. They are usually said to be so to emphasise the extremely small size of the nucleus in relation to the atomic size.

It is possible to make atoms smaller. We see this in nature, in the description of neutron stars where atoms have collapsed under gravitational pressure and protons absorbing electrons become neutrons.

In a sense, we can think of a neutron star as a single giant atom - obviously, immensely larger than the usual ones!

The periodic table starts with the stable atoms - Hydrogen, Helium, Lithium - and so on. Then we get to radioactive elements where the balance of forces in an nucleus - the electroweak and strong - becomes unstable and particles are ejected from the nucleus. We then get a huge stretch - going by atomic number - where nothing is possible - but then the atom becomes large enough for the gravitational force to become effective and this then restores stability. But at this point, protons are not possible any longer and we get what are called neutrons stars. We can carry on, building larger and larger atoms but then neutron degeneracy pressure is no longer strong enough to resist the increasing gravitational force and we get a black hole - which in this picture is just another type of giant atom.

When we think that the classical picture of a black hole is determined wholly by its charge, mass and angular momentum - we see just how close this is to a description of an elementary particle like an electron or a proton - which is also determined by its charge, mass and angular momentum (notwithstanding more precise descriptions due to chromodynamics. The point being that elementary particles are determined by finitely few parameters - and quarks fit this description just as well as protons at a different scale).

Answer 3

you can indeed significantly squeeze out a lot of the empty space inside an atom through the use of powerful explosives. the so-called "Fat Man" atomic bomb which was dropped on Nagasaki used a sphere of chemical explosives to compress a subcritical sphere of plutonium beyond criticality and thereby trigger an atomic explosion.