5 C
Saturday, November 26, 2022
Dr. Brown: The birth, death and rebirth of stars????

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the Infohealth series at the Niagara-on-the-Lake Public Library.  

Dr. William Brown

Special to The Lake Report

As stars go, our sun is a middling-sized affair, fated to end its days as a source of energy for life on our planet sometime in the next several billion years. 

A gloomy prospect perhaps for those who worry about such catastrophic events in the far distant future, well beyond any prospect of life as we know it and certainly the existence of our species, homo.

But that’s what happens when stars run out of hydrogen – their chief source of energy. For it is through the fusion of hydrogen to form a helium and in the process, the conversion of a tiny bit of hydrogen’s mass into an enormous amount of energy, that our sun creates all the energy necessary for life.

The reason for which is obvious from Einstein’s most iconic equation, E = mc2, where E stands for energy, m for mass and c2 for the speed of light squared. It is the last factor – the speed of light squared – that explains the conversion of even the tiniest bit of matter into such an enormous amount of energy and why nuclear bombs are so powerful. 

The earliest stars that formed a million or so years following the Big Bang, were often simple giants, composed mostly of hydrogen and some helium but as yet, none of the elements we associate with life – oxygen, carbon, nitrogen and phosphorus from which billions of years later, first RNA, then DNA would be composed.

Because of their huge masses and therefore enormous gravitational forces, those giants burned fiercely and quickly through their supply of hydrogen over hundreds of thousands of years – not the billions of years, more typical of smaller stars such as our sun. 

Most giants collapsed into themselves and exploded in supernovas, generating yet higher temperatures and through a series of nuclear fusions, created heavier elements scattered by the explosion about the former star’s neighborhood, where they were picked up by newly forming stars.

The latter incorporated those elements and through later generations of stars and repeated nuclear fusions, including those produced by the collisions of neutron stars, eventually created all the natural elements of the periodic table. Evidence suggests that our sun is the third in a series of stars in our neighbourhood of the Milky Way.

The sun is slated to lose much of its hydrogen and therefore mass and gravitational force, over the next few billion years. In the wake of those changes, the sun will likely expand to engulf the inner planets as far out as Earth and possibly Mars – and along the way, burn off Earth’s atmosphere and water and put an end to whatever life exists on our planet at that time, before finally, over a few more billion years, collapsing into a cooling, dense white dwarf of a star. Based on good evidence, that’s our fate.

Other stars may – if their remaining mass is large and dense enough – collapse the nearby surrounding space (and time) about themselves to become a black hole or perhaps, as was observed recently, create a hybrid of a black hole and what was left of a nearby star. 

And sometimes giant black holes gobble up nearby stars – a form of cosmic feast or even murder, if you’re inclined to be theatrical about such matters. Personally, I think the universe is mute on such matters, except for gravitational waves picked up on Earth as faint chirps – all that’s left – of signals generated billions of years ago far, far away by gigantic collisions between pairs of black holes or neutron stars or other cosmic events on a grand scale. 

Recently a radio telescope in Penticton, B.C., detected a “huge radio flash” generated by a magnetar – a “dense, spinning ember wrapped in intense magnetic fields” left behind after a supernova explosion, yet another example that the more astronomers look, the more surprising and stunning the universe becomes. 

* The NOTL library’s upcoming six-week series on physics in September and October comes courtesy of Zoom and reminds us that not so long ago, in 1900, little was known about the universe writ large and nothing about the quantum world, except for the electron. You might want to tune in.