Indeed, yes, the force in this case happens to be gravity. The amount of matter contained is normally so big so as to generate a gravitational field capable of over-riding standard intermolecular bonds, though it must be noted that the strength of the gravitational field decreases linearly with distance from the edge of to the centre of the sphere.

Why it doesn’t just collapse from the beginning of its existence is a matter of stellar physics; when clouds of hydrogen become sufficiently large, they become hot to the extent of being able to initiate nuclear fusion; the energy generated creates a huge outward pressure, which inflates the star to a very large size. This pressure gradually drops over the life of a star, then increases again as it turns to helium fusion, and so on.

When stars collapse, fusion processes no longer take place, which means that outward pressure no longer exists, meaning that there’s nothing but intermolecular forces to keep the star from collapsing in on itself; but by now it’s too late and the implosion begins. If the mass of the star is above three solar masses, the star becomes a black hole and relativistic effects occur very noticeably.

One more observation; Boyle’s Law only holds for ideal gases under classical circumstances. For more complicated gases, this relation doesn’t hold (though a more accurate approximation may be made using the Van Der Waals model), and particularly when we are dealing with small quantities on the nanoscale, quantum effects have to be taken into account, and this is where things get really complicated!

Jamie

All would info would be great.

Regards,