For 40-plus years, my career focused on clinical neurology and related aspects of neuroscience, both of which I enjoyed and enjoyed some success.

Then two books caught my attention: one by David Christian in 2011, “Maps of Time,” which covered all of history from the Big Bang to the present, and Chris Stringer’s 2012 book, “Lone Survivors,” which covered the human origins story.

Both books expanded my interests and perspectives and led to several six-week series at the library and later were expanded to cover the annual Nobel Prizes and writing my 2016 book, “Perspectives.”

But of all the interests triggered by Christian and Stringer’s books and many other related books, as well as primary sources, it was physics which most caught my interest.

Why? Because physics covered everything from the creation and evolution of the universe writ large, from the Big Bang to the present (and future), and the universe writ tiny, the subatomic universe of quantum mechanics.

The story of human evolution is important too because without modern humans, there would be no science and no one to understand what was happening in the universe — the universe would unfold without a witness.

More than any other field in science, physics is split between theoretical physicists and experimental physicists.

This was never more true than in the last century, especially in quantum physics where, except for bashing particles together from the early days of Rutherford to later times doing the same with far more expensive particle shooting galleries such as the massively large Hadron collider in Switzerland, much of the progress in physics came from the artful creation of mathematical models of atoms from the likes of Einstein, Bohr, Heisenberg, Schrodinger, Born, Dirac, Feynman and Weinberg, to list the major players.

Similarly, modelling the universe coupled with rigorous experimental observations brought enormous progress in understanding the origin and evolution of the universe.

But unlike chemistry and biology, theoretical physics fosters plenty of speculation, some so weird that it garners a lot of public attention for as long as the public attends to much in science.

For example, shortly after the Higgs particle was finally proven to exist, some physicists wondered what might happen if the Higgs particle, which is thought to confer mass on other particles, changed its mass and hence the mass of other particles.

They speculated that even though the likelihood of that happening was vanishingly tiny, on the time scale of the universe, it could happen — and if it did, the universe would vanish at light speed beginning where the change in mass began in the universe.

Doom speculation also centres on matter and antimatter — particles of identical mass but opposite charge.

Both are thought to have been created within the tiniest fraction of the first second in the universe and would annihilate one another, leaving no matter in the universe and no possibility of any stars or life of any kind.

That is, unless matter particles slightly outnumbered antimatter particles, leaving surviving matter sufficient to produce all the matter with which we are aware.

And there is some evidence from collision experiments in which protons are fired at other protons that some antimatter can be produced — let’s just hope they don’t create a chain reaction such as the speculative change in the mass of the Higgs particle.

Other speculations aren’t so crazy. Again, given the time scale of the solar system and especially the sun and Earth, for sure, there will be future extinctions, even massive ones, which in the past came close to destroying most of life on land and in the seas.

How do we know this? Because massive volcanic eruptions are natural events that have happened several times in the past and on minor scales continue, as we well know, wherever the Earth’s plates come together.

Similar reasoning suggests that a collision with a massive asteroid akin to that which struck the east coast of what is now Mexico will happen again — it’s simply a matter of time.

And what about extinction of our own species? Extinction is in the cards here too, because every prehuman species has gone extinct before, hence Chris Stringer’s 2012 book, “Lone Survivor.”

Of course, we don’t know precisely why we might go extinct at this time, but climate change would be a good candidate given that we are top predator and already we’ve done a good job of devastating ecosystems on which we so depend. We are like lemmings blindly running to a precipice few see or are willing to see.

The dilemma for humans is that even though we are highly intelligent as a species — evidence for which surrounds us in the many devices we play with and use — we are also incapable of getting along with one another, even in the short term. Humans are a quarrelsome, selfish, bullying and tribalistic species.

No need to go back to ancient times — look at the history of the 20th century and the first quarter of this century.

Countries spend billions and even trillions on arming themselves to the teeth and some aren’t hesitant to use them.

Even if war hasn’t broken out in the South China Sea yet or other seemingly quiet-for-the-moment areas of the globe, wars have a way of erupting — witness the simmering conflicts between Thailand and Cambodia these days.

We simply can’t get along with one another — that’s a fatal flaw for such a clever species.

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.