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Wednesday, July 17, 2024
Dr. Brown: From millions and billions of years to nanoseconds, time is all relative

Within a trillionth of a trillionth of a second, something very tiny, very dense and quantal in nature, inflated faster than the speed of light into something very much larger, jampacked with a dizzying array of elementary particles and forces, which we now recognize was the earliest universe.

Or at least that’s what some of the best minds in physics believe happened 13.8 billion years ago in what famously became known as the Big Bang.

But imagining trillionths of a second, never mind a trillionth of a trillionth of a second, is well beyond my imagination and probably yours.

In my life, I’m aware of hours and days, and because I’ve reached my early 80s, perhaps more aware of years, but not so much, seconds and certainly not thousandths of a second.

Yet in my days as a neurophysiologist, I regularly recorded electrical signals generated by single nerve and muscle fibres, each of which lasted only a few thousandths of a second.

And if that’s not short enough for you, some physicists and engineers regularly work with times as brief as nanoseconds (billionths of a second) or less, events much briefer than anything we’re aware of in daily life.

For most of us, time is a precise quantity which we observe by the movements of the second hand, and the long and short hands of traditional clocks – or these days by the passing of digital numbers on our watches or other digital devices.

And if we’re runners or bikers, we can track our times to several decimal places. The underlying assumption, of course, is that time everywhere is the same – a second is a second – wherever we happen to be.

Records in sports are based on that assumption, especially the 100-metre dash where the difference between the winner and second place may be measured in hundredths of a second or less.

Perceptions of time are another matter. Mountaineers who have fallen and survived to talk about it, sometimes report that what was a few seconds for the actual fall seemed slowed and stretched out enough to see their life scroll through their mind – what some refer to as time dilation.

There's also stretched time. For example, once I dreaded an upcoming, thoroughly overbooked clinic full of challenges, many of which required plenty of time to deal with.

Yet, once into the clinic, instead of feeling overwhelmed, there seemed more than enough time for everyone and every problem despite what turned out to be the heaviest clinic of the year.

Or perhaps the opposite sensation occurs: time seems to speed up or “fly.”

Time scales vary with what we’re looking at. The time scale for the universe and geology is measured in billions and millions of years, human evolution by millions and thousands of years, and our lifetime by years.

For example, our sun was born roughly five billion years ago and is slated to go on for another seven to 10 billion years. In the case of tectonic plate movement, the distance between North America and Europe increases by a barely noticeable inch a year.

However, looking back 100 million years, the two continents once touched and 200 million years ago, Earth looked much different. There was one giant land mass, a state to which Earth’s land masses will eventually return, an example that illustrates how very slow changes played out over a long time lead to major changes.

When we look at the Niagara region, everything seems so permanent – Niagara Falls, the Niagara River and Lake Erie and Lake Ontario. Yet, all were created during and immediately following the last glacial period and will surely change once more when the current interglacial period merges into the next ice age.

When, not if, that happens, nothing will remain the same – not the lakes, rivers, lay of the land nor any human-made structures.

On the scales of the universe, geology and evolution, major changes usually take a long time – with some exceptions. Stars run out of hydrogen and if they are big enough, they end in supernova explosions.

And while it's true that some geological changes play out slowly over long periods, sometimes changes are explosive, such as volcanic eruptions, which if too many occur at the same time, as happened in Siberia over 200 million years ago, can lead to severe climate change and major extinction of species in the seas and on land.

Or out of the blue, a large meteorite might strike the Earth as happened 66 million years ago, after which the dinosaurs were gone (except for the ancestors of birds) and the evolutionary gates opened up for opportunistic animals such as lemur-sized primates and their descendants two million years ago, the earliest members of the “homo” genus in Africa.

Eventually, this led by chance and natural selection to modern humans.

Lots to think about when it comes to time.

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.  


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