The Death of Galaxies
Within the super clusters there are all types of galaxies. The spirals continue to create new stars in their spiral arms. With the Hubble Space Telescope (HST) we have been able to prove this by measuring the color of the light from spirals. It is blue, meaning they are full of young, new stars.
Ellipticals, on the other hand, are red. In stellar evolution, red stars are old, dying stars. Remember, ellipticals used all their star making material up in their first few million years of existence. Ellipticals are dying galaxies.
But not all spirals are blue. HST has shown that the bulge in most spirals shines with red light. All the stars there are old and dying.
And HST has also found some red spirals. Old galaxies that have used up all their star making materials and are slowly dying. As star formation ceases, the dead spirals become lenticular galaxies, losing their spiral arms.
If our current view of the universe is correct—that it is flat and expanding at an ever increasing rate--eventually all galaxies will meet that fate. Gigabillions of years from now, the last new star will be born in a galaxy far, far away, and gradually the stars will become white or brown dwarfs, neutron stars, or black holes.
As these dead and dying stars pass near each other, one is accelerated and the other slowed. The accelerated star speeds out of the galaxy, and the slowed one spirals into the massive black hole at the center of the galaxy.
After another many gigabillions of years, the universe is populated only with free dead stars and massive black holes.
After 1032 years, the protons that make up all matter and the black holes begin to decay into leptons (a basic subatomic particle like a quark—the electron is a lepton). Eventually, after 10100 years, even these decay into photons and neutrinos (particles with virtually no mass). The universe has reached a state of maximum entropy. It is dead.
Not all cosmologists share this theory. A very few still feel the universe is an oscillating universe. That is, at some time in the far distant future, the expansion will cease and all matter will begin falling back in on itself in what has been called ‘the big crunch.’ Proponents of this theory point to what is happening with our Virgo super cluster as evidence this may already be happening. The tens of thousands of galaxies in the supercluster are all falling in on themselves.
The end point of this theory is all the matter in the universe will crunch itself into a singular point, and explode out again in another big bang to create a new universe.
And in fact, evidence from the HST indicates the current expansion only began some eight billion years ago. Before that, gravity was slowing the expansion.
Still, most cosmologists consider the Virgo ‘collapse’ a ‘local’ phenomenon, and subscribe to the expansion theory. They do not know, however, what is causing the galaxies to rush away from each other at an increasing rate. It appears that at some demarcation time in the universe, gravity reversed itself, and instead of pulling matter together, began pushing it away.
One theory suggests the culprit is dark matter. But if gravity reversed itself in the past, might it do so again?
Perhaps when the Webb space telescope goes into orbit, we will find out.