قالب وردپرس درنا توس
Home / Science / Exploding black dwarfs could be ‘the last cool thing to happen in the universe’

Exploding black dwarfs could be ‘the last cool thing to happen in the universe’



The artistic conception of a dark brown dwarf, which may resemble hypothetical black dwarfs, is expected to exist in the far future.

The artistic conception of a dark brown dwarf, which may resemble hypothetical black dwarfs, is expected to exist in the far future.
Picture: NASA / JPL-Caltech

Dr. Elliot said in his famous poem: “This is how the world ends,” Not with a bang but a whimper. “Scientists now consider the heat death of the universe a whimper, but a new theoretical analysis predicts that the universe will breathe its last time in the form of an explosive black dwarf.”

Trillions of trillion years from now, long after the last stars die, the heaviest black dwarfs will begin to become supernovas, according to new. research published in the Royal Astronomical Society’s Monthly Notice. Black dwarfs are the frozen remnants of white dwarfs, which are themselves the ruins of low-mass stars. The study’s only author, astrophysicist Matt Caplan from Illinois State University, said that these explosions would be “the last interesting thing to happen in the universe,” as he said. explain in an ISU press release.

The universe could end in any wayBut the best prediction for now is that it will continue to expand long after everything within it is torn apart, including galaxies, solar system, stars and even atoms. By the time the black dwarf is about to appear, the universe will be “cold and lifeless,” Caplan wrote in an email to me.

“The expansion of the universe would have long ago separated all the remaining objects by such enormous distances that no light could be reached from one object to another,” he said. he said. “Every object will find itself in a universe completely devoid of anything else in all directions. It will be cold and close to absolute zero ”.

When surviving stars switch to supernovae, it is due to the excess iron in their cores – the result of internal nuclear reactions. The same cannot be said for smaller stars, which eventually burn and shrink to white dwarfs. In theory, white dwarfs will eventually lose their luster and freeze in the far future, converting into black dwarfs.

“Without a source of heat, they cool forever until they turn ‘black’ and no longer shine,” Caplan said. “It’s like taking a hot pan out of the oven – all it can do is cool.”

These hypothetical objects would be roughly the size of Earth but about the same mass as our Sun. Crucially, nuclear reactions would still take place inside these dense frozen worlds, but at a significantly slower rate than normal. And as the new study predicts, these reactions will lead to a steady accumulation of iron, albeit at enormous cosmological intervals. With this in mind, Caplan gathered numbers to estimate how long it would take these black dwarfs to produce enough iron to trigger a supernova explosion.

Answers, at 101,100 “Hilariously long,” Caplan said. The age of the universe is close to 10ten years, so if you try to write down 101,100 it would have 1,100 zeros and “take up most of a paragraph,” he explained. Or as Caplan put it on the ISU release, “it’s like saying the word ‘trillion’ almost a hundred times.”

Importantly, these explosions will occur only among the largest black dwarfs, namely those with masses between 1.2 and 1.4 times the mass of the Sun. These supernovae – the last ever to happen in the universe – will eventually stop at around 1032,000 years from now, after that time the universe will truly be a quiet and peaceful place.

Caplan said his analysis took into account the effect of the expanding universe. However, “if the dark energy is different from what we suspect, then the expansion of the universe could destroy black dwarfs long before they have a chance to explode,” he said. Furthermore, Caplan’s calculations are based on our current understanding of nuclear physics, astrophysics and cosmology, but to be fair, scientists cannot be sure whether the laws are Whether physics and cosmic constants will remain the same in the far future. For example, it is possible that the universe will not exist at this future intersection.

“Some theories of particle physics predict that protons are essentially unstable and will decay, although this has yet to be observed or confirmed. If that were the case, all matter would ‘evaporate’ long before any black dwarf explodes, “Caplan said.” That’s just an example. In a sense, our understanding. The distant future depends entirely on our understanding of the laws of physics today, and the small changes in physics we know can have enormous consequences for fate in the end. of the universe and its content. “

Although Caplan said these black dwarf supernovae would be “the last interesting thing to happen in the universe”, we asked him if something could happen after this period.

“It depends on your definition of interest,” he said. “If a cold iron ball floating in a universe that is completely causally separated from all the other objects is ‘interesting’, then I think you might find something interesting. taste. “

Okay, fair score. But if there is any consolation in all this, it is that the universe will continue to expand forever, at least according to some theories. It would be dead, cold and lifeless, but at least it would be around here.


Source link