Popular science fiction is full of examples of people and objects being shrunk down to the size of insects or smaller.

Let us assume that everything is shrunk. Thus an animal would still contain the same number of cells in its body. Also, each atom and molecule would shrink.

Assumption: Physics has advanced sufficiently to be able to make a stable local change in fundamental forces and/or a local change in cosmological constants.

Question: What local changes in forces and/or constants have to be made to cause the shrinkage?

  • 1
    $\begingroup$ By "atoms shrinking" are you referring to the sub atomic distances decreasing universally? $\endgroup$ Sep 29, 2018 at 12:41
  • 2
    $\begingroup$ You would be talking about shortening the wavelength of the election, so it resonates in orbits closer to the nucleus of the atom. However, decreasing the wavelength requires increasing the energy, do the electrons would be more likely to escape. Someone with some serious math juju needs to run the numbers $\endgroup$
    – pojo-guy
    Sep 29, 2018 at 12:57
  • $\begingroup$ Besides shrinking the atom by getting the electrons closer, is there any answer involving making the electrons repel each other less (less distance not power) so the atoms can approach each other closer before they are "locked" against each other? $\endgroup$
    – Demigan
    Sep 29, 2018 at 15:26
  • $\begingroup$ One version of what this would like can be found in Philip Latham's short story "The Xi Effect" where everything shrinks. $\endgroup$
    – a4android
    Sep 30, 2018 at 4:55

3 Answers 3


The only scientifically sound approach I am aware of is to expand space. We know that space is expanding in all directions at a rate virtually undetectable on human scales. If scientists were to be able to identify how this occurs, they might be able to reverse the process locally. Such an shrinking would interact with the world like looking through a lens. If you had a grid of squares 1m on each side and intersected at right angles, and it went through this area, it would appear from the outside as that pocket of space has more grid-squares than the surrounding area.

This counterintuitive result comes because while space is expanding, the laws of physics governing molecular forces aren't. Hubble's Law shows that space is expanding at somewhere around 72 km/s/Mpc. That means two objects that are 1 megaparsec apart find the expansion of space increases the distance between them by 72km/s. One could use these numbers to determine that New York and Los Angeles are separating at a rate of 300um/year due to these effects, but that would not quite be accurate. It would be more accurate to say the points in space where NYC and LA are at this instant are separating at that rate. The actual physical cities don't stay on those points; they move. The distance between them is governed by the molecular forces within the earth. These entities made out of atoms and molecules sort of settle into the expanding space they inhabit. The effects would appear as though there was an ever-so-slight force tugging apart the molecules, but this would be dominated by the inter-molecular forces we know and love today.

So your "shrunk" creatures could simply have had space locally shrunk around them. This would result in there being more apparent space, locally, than there "should" be if you assumed space was flat. They could then go about their merry way, because we didn't change any laws of physics. We just changed the shape of space.

The drawback is that any physical interactions most travel through this field. If you want a Honey I Shrunk the Kids moment when a giant ant terrorizes the heros, do it from afar. As long as the ant is outside of this distortion, it will look gargantuan from inside. However if the ant tries to move to attack the heros, it will have to go through this shrinking space field, and will appear to be the "proper" size for an ant by the time it arrives to bite their heads off.

As an added bonus, you would get an extra check-mark's worth of believability. There are many undeniable effects in physics which are irreversible over the global scale, but are trivial to reverse locally. The march of entropy is, to the best of our knowledge, unassailable globally. However, locally we reverse it all the time. Our refrigerator chills things locally by globally increasing entropy. So it is at least plausible that an expansion of space, which is currently believed to be unabating, could be locally reversed by causing an expansion somewhere else. We don't have any clue how this could be done at the moment, with modern physics, but we didn't understand how heat pumps worked until the mid 1700's either!


The equilibrium of forces keeping us as we are, are very delicate and complex. It is unlikely we will be able to produce Pym particles, unless our fundamentals of particle physics change somehow.

To make a body become smaller through the forces acting on molecules, without changing mass, you either add pressure - which can cause them to change shape or react in different ways - or you reduce temperature, which will cause most substances to shrink. But we've frozen animals to little above absolute zero, anf they didn't shrink enough to fit the rule of cool this question implicitly requires.

To make individual atoms smaller, we need to increase the constant for the electromagnetic force, but the same force also affects molecular bonds and doing so would change all of chemistry in ways that we could hardly predict.

The only option left is to change the properties of space. We could use an Alcubierre drive to make a body seem smaller, since the drive will contract spacetime. But we would need the body to be moving at what would seem faster than $c$ relative to us, and upon contact with another body, both bodies would be obliterated.

So no, sorry, that is not viable in any way we can conceive.


The diameter of the nucleus is in the range of 1.7566 fm ($1.7566 \cdot 10^{−15} \ m$).

The diameter of an atom ranges from about 0.1 to 0.5 nanometers ($1 \cdot 10^{−10} \ m $ to $ 5 \cdot 10^{−10} \ m$).

You see that there is a lot of empty space down there.

You just have to make the electrons orbitals closer to the nuclei (or better, move the higher probability cloud closer to the nucleus), and you will get rid of a lot of empty space, thus shrinking the size of any object where you are applying this feature.


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