Several theories to date shed light on the various possibilities of how the universe would end. Apart from the common notion that it would happen way past the age of humans, every one of these theories is mind-boggling in itself. In a new research, scientists have now presented calculations for one of them - one involving black dwarf supernovae.
The new study authored by Matt Caplan, assistant professor of physics at Illinois State University, has now been published in the Monthly Notices of the Royal Astronomical Society. It focuses on the notion that the universe will eventually run out of energy, an event termed ¡®heat death¡¯ or the ¡®big chill.¡¯
The universe is known to be in a constant state of expansion. This continuous expansion is predicted to bring on the ultimate death of the universe.
The heat death theory suggests that due to enlargement, the density of the universe will decrease, to a point that the gas required to form new stars will run thin. No new stars will be born from this point on.
Eventually, existing stars will start dying and when they all die, their remains along with black holes, neutron stars and white dwarfs will be the only things left.
There are two known ways a star ends its life. Upon their age, massive stars explode in supernovae that leaves behind a black hole or a neutron star. Smaller stars, like our Sun, instead expand rapidly, eventually shrinking back down into white dwarfs.
These white dwarfs usually don¡¯t have the mass to go supernova. So they slowly cool down to the background temperature of space, eventually becoming cold, black dwarf stars. Since the process takes trillions of years and the universe is still only around 13.8 billion years old, it will be a while before the first black dwarf is seen.
In his study, Caplan hints at an astronomical event that will occur even after all the stars turn into their black dwarf state. Caplan suggests that even though it would be very cold and hence it would take a very very long time, fusion will eventually take place in these black dwarves too.
Caplan mentions quantum tunneling to be responsible for this.
Quantum tunneling is a phenomenon explained by quantum physics that has no explanation in classical physics. It is the finite probability of a particle to cross a barrier, which it could never cross as per the principles of classical physics.
Caplan implements this reasoning of quantum tunneling in the case of the black dwarf star. In a black dwarf, even though there should not be enough energy for this, nuclei inside it could spontaneously fuse together, eventually leading to a supernova just like those in the massive stars.
As per a report by Daily Times, Caplan mentions that ¡°only the most massive black dwarfs, about 1.2 to 1.4 times the mass of the Sun, will blow¡±. ¡°Even with very slow nuclear reactions, our Sun still doesn¡¯t have enough mass to ever explode in a supernova, even in the far far future,¡± he further adds.