What happens when a star gets too massive for the energy it contains? Those are the principle figures that brought some people to wonder what happens next.
Picture a nice hot and humid day. Hot air rises, and hot humid air does as well. But when it rises, it may reach a place where the temperature and pressure are low enough that the water vapor condenses, and clouds are formed of the water droplets, but if they grow numerous enough to coalesce so that the air current can no longer keep them suspended, then they fall. If the hot humid air plunges swiftly into a very cold mass, then we have an expression for that, a cloud burst.
Now picture something like this in a very massive star. When the star reaches some critical point, there may be an explosive event, such as a super nova. There is the outflow, the implosive force, an inflow, and at some point, this starburst is more than just the outflow we see, but a residual body that we don’t, directly, see.
Subrahmanyan Chandrasekhar was a mathematician who explored the numbers and determined that there was a tripping point, a star with residual mass below the Chandrasekhar Limit, and the result would be what we call a white dwarf. If the mass is above that limit, then the collapse is greater.
What takes place is a change of the atomic structure. Most atomic particles, like neutrons and protons, take up space in the form of a zone of influence. The packets of energy we call electrons were assumed to take up solid space because of the appearance of physical properties. These properties were first observed by the size of the orbital shells that those packets of energy had above an atom’s nucleus. Given certain conditions, some of the atomic particles can make substantial changes. Einstein popularized it with the E=mc2 formula to represent how mass can be converted to energy or the other way around. The famous “transporter” fiction of Star Trek (“Beam me up, Scotty”) uses this, converting the mass of a person to energy, beaming it to another location, then reassembling it, voila, into the original human, or whatever.
Now if the star’s remaining mass, after the critical event, is within certain ranges, then the energy of the star’s gravity squeezes the elements not only into a solid, but collapse the areas of influence. Electrons squirt out and the element nuclei rub shoulders more directly. But the mass is so massive that this is not enough. Protons collapse, spitting out photons and electrons, turning into neutrons. So the star then becomes a very hot mass of neutrons. We call that a neutron star.
But what happens if the mass was even greater? Neutrons may not be able to hold their structure when the mass of massive stars is really enormous. If the mass is so great for that to happen, then the gravity of the mass will be so great that photons (light) will not be able to leave the star. The star becomes black. Einstein pictured gravity of astronomical bodies as depressions in the fabric of space. The mass of this star residue depresses space as if it punched a hole in it. The “black hole” moniker was an inevitable result.
If I may, I suggest a book by Kip Thorne, Black Holes and Time Warps: Einstein’s Outrageous Legacy (New York: Norton).
