I misrembered, it remains roughly the same volume, until 1.6 juipiters of mass, at which point the effect of gravity from each additional hydrogen is greater than the intermolecular forces and additional hydrogen would cause it to compress more than it would grow.

The increased mass increases the force of gravity on the outer particles which ends up reducing the radius more than the increase due to the layer of new hydrogen, IIRC.

Imagine a stack of glass cups. It gets tall enough that the bottom glasses break under the weight of the new glasses. Tada!

The volume of Jupiter is mostly gas. If you increase the mass enough, at some point the higher gravity and thus higher pressure at the center causes a phase change of enough mass (from gas to liquid or liquid to solid) that the lost volume from the phase change exceeds the original volume of the added mass.

It's like pushing a bunch of origami paper into a box until a bunch of them collapse and fall flat instead of filling the volume.

Is your friend the same crazy person I know who doesn't eat meat? Are they crazy?

_i don't know why your comment made me think of that reference _