Dinosoaring through time

Text: Boris van Meurs. This article previously appeared on the Faces of Science blog of NEMO Kennislink. Photograph above article: Internet Archive Book Images, via Wikimedia Commons

The fact that the past no longer exists is quite annoying, at least as far as my research is concerned. I happen to study the history of the Earth from a philosophical perspective. It’s a little jarring to have to admit at parties that you’re doing research on something that doesn’t exist.

Come and join me in a time machine, together with Saint Augustine. Source: Internet Archive Book Images, via Wikimedia Commons

How do you study something that no longer exists? In this blog post, we’ll be travelling through geological time with an unexpected guest. A mediaeval bishop who had no notion of fossils or the Big Bang will explain to us why our relationship to the past is highly problematic.

Time machine with bishop

Welcome to our time machine. Enter Saint Augustine (354-430). Saint Augustine is an important figure for the Catholic Church. In his Confessions, he shares how he grew from a rebellious youngster into a virtuous Christian.

One of the chapters is devoted entirely to time, and Augustine is not afraid to get feisty and completely overturn all our ideas about time.

Time doesn’t seem to exist for Saint Augustine. But then what happened to the millions of years of the Cretaceous? Source: E. D. Cope, Public domain, via Wikimedia Commons

Two parts of time never exist. The past exists no longer , and the future, does not exist yet. Now, if something consists of non-existing elements, then that thing itself cannot be said to not exist. Imagine I give you a pair of Christmas socks, of which one no longer exists, and the other doesn’t exist yet, you’ll be going home with cold feet.

But there is of course a third ‘element’ of time: the present. The present, according to Augustine, is constantly changing, so that nothing remains the same – and therefore nothing ’is’ in the present either. When you say ‘now’, the present moment is gone before the word has rolled off your tongue.

Time, it seems, doesn’t exist at all. So what is it that I’m studying, day in, day out?

It’s (not) gonna be a long, long time

However, Augustine is not yet done assaulting the notion of time. For example, he asks himself whether a ‘long’ time can ever exist, as when we say that one hundred years is a long time.

Saint Augustine joins us for an under-water exploration. What to do with the time when the Mosasaurus and the Ichthyosaurus were alive? Source: Heinrich Harder, Public domain, via Wikimedia Commons

This problem is rather important for geologists, who love long times. The Cretaceous, for example, lasted approximately eighty million years. The Earth was formed 4.6 billion years ago. If we want to say something about this kind of time frame, there has to be such a thing as a long time.

The critical Augustine asks himself when exactly a long time is ‘long’. To answer this question, we must explore a number of options, he says. A time can be long in the past, the present, or the future.

Can a time be long in the past? No. Because once a time is gone and in the past, it no longer exists. It feels like a very long time when I was cleaning the kitchen yesterday, but yesterday no longer exists. And if yesterday no longer exists, then neither does this long time. And if this time does not exist, it cannot be long. (No more than a non-existing Christmas sock can be big or small.)

Can a time be long in the future? Actually, no. Because if a time does not yet exist, then it does not yet exist. Kind of logical. You may be looking forward to celebrating your birthday next year, but you’ll still have to wait for some time before you turn a year older.

The present has no duration

So time cannot be long in the past or in the future. The present is our last hope. Can a time be long in the present?

Imagine we say that a million years is long in the present. Clearly, these million years are not all happening at once. Of the million years, one must be the current year. That year is the one that exists at this particular moment. For example, it is now 2021, and the year 1,002,021 will only exist in the future.

Does this solve our problem? No, because within this year, not all months, but only one month exists, and within that month, only one week, and within that week, only one day, and within that day, only one hour, and within that hour, only one minute, one second, one nanosecond, et cetera, et cetera, all the way to infinity and beyond.

In Augustine’s words:

In fact the only time that can be called present is an instant, if we can conceive of as such, that cannot be divided even into the most minute fractions, and a point of time as small as this passes so rapidly from the future to the past that its duration is without length. (401) Source: Saint Augustine. 2015. Confessions. Translated by R.S. Pine-Coffin. London: Penguin.

In other words, the present is not long either, since it lasts less than a moment. A long time can therefore not exist in the past, nor in the future, nor in the present.

Saint Augustine in the time of the dinosaurs. Source: Édouard Riou, CC0, via Wikimedia Commons

But then what happened to the millions of years of the Cretaceous? How can the long, long history of the Earth exist?

Conclusion

Bye, bye, dinosaurs. Bye, bye, hundreds of thousands years’ long solar cycles. Your time does not exist. Nowhere can time have a ‘long’ duration; not in the past, not in the present, and not in the future. Also, it seems I don't have a good pitch for promoting my research at parties.

And yet, this is unlikely to cause an epidemic of depression among the geologists and historians in my audience. We may be unable to see the past, but we can bring it back by studying its traces: a rock, a fossil, an old book. This allows us to speak of the past without literally bringing back all those long gone years.

Hurrah for science, for remaining utterly unaffected by my philosophical mutterings, and bravely continuing to speak of things that do not exist (such as the past).

And yet... What is it that we’re speaking of exactly? How do you talk about a time that no longer is? Where do they go, these moments that pass us by? Where is the past, that no longer exists but still seems to be working just fine?