麻豆传媒

I DON鈥橳 know about you, but for me, every week of 2020 has felt extremely long, especially since the coronavirus pandemic has gotten under way.

As I am not an essential worker, I am currently spending most of my time at home. I try to focus on my work on both science and the philosophy of science, but then I inevitably check the news. Each update seems to make the week drag on for longer and longer.

The reel of bad news may feel like it is never-ending, but one of the ways that I have tried to keep things in perspective is by thinking about the different timescales on which things occur in the universe.

As an early universe cosmologist, I know, for example, that cosmic inflation happened in a fraction of a second. Cosmic inflation of space-time, the fabric of our universe, is one of the first things that ever happened. This was a period in which space-time, like the number of cases of covid-19 in many areas when it first got off the ground, grew exponentially. The more space-time there was, the more space-time grew.

The rate of space-time expansion during inflation was so quick that it grew faster than the speed of light. This might be surprising to hear because we are all so used to the idea that nothing goes faster than the speed of light. This is the case for things that live inside space-time, such as people, planets and spaceships, but there is no such limit on space-time itself.

We currently believe that inflation lasted from around 10^-36 to 10^-33 seconds after the big bang. Not only did space-time grow faster than the speed of light, but this period of expansion was extremely short. A week of this outbreak is essentially an eternity in comparison.

So perhaps cosmic inflation isn鈥檛 the best way to maintain perspective on human timescales, but what about stellar astrophysics instead? Stars like our sun have lifetimes of about 10 billion years, which is very close to the current age of the universe. This scale is difficult for humans to fully comprehend.

Interesting things can happen towards the end of stars鈥� lives. They initially shine because they are 鈥渂urning鈥� hydrogen 鈥� essentially an atomic reaction that fuses hydrogen atoms together to produce helium. This releases energy, some of which we observe as photons, particles of light.

鈥淵ou鈥檝e probably been trying to avoid people outside of your household for a couple of white dwarf pulsations鈥�

In the case of the sun, this process has roughly another 5 billion years left to go. If you, like me, have been socially isolating for around five weeks, this means that the sun still has about 50 billion of your lockdown periods so far left before it reaches the end of its life.

Eventually, the sun will start fusing helium into carbon. This process will begin in our sun when it has about 100 million years of life left, which is about a billion times as long as the period that we have been in isolation for so far. These processes certainly put our wait into perspective.

Yet such prolonged timescales aren鈥檛 the only ones that are relevant to stellar evolution. Although helium to carbon conversion will continue for at least 100 million years, the transition to this process will begin with a helium flash that will take place in just a few minutes.

We have been stuck in lockdown for a lot longer than this, of course, but at the very least we can say that we won鈥檛 be in social isolation for the time that it takes for the sun to start making carbon!

The helium flash isn鈥檛 the only stellar process that can take just minutes. When the sun finally dies, it will leave behind a remnant known as a white dwarf. This is a very dense object made of hydrogen, helium and carbon, and when white dwarfs are the by-product of stars at least 10 times more massive than the sun, they contain a good amount of oxygen too.

These white dwarfs can experience instabilities that will be familiar to people who have been to the beach: just as an ocean鈥檚 waves are partly the result of gravity, white dwarfs experience waves caused by gravity in their interiors. Such waves then cause pulsations in the brightness of the white dwarfs, and these can be around two weeks long.

So one way to think about how long you have spent in physical isolation is to compare it with this phenomenon: so far, you have probably been trying to avoid contact with people outside your household for only a couple of white dwarf pulsations.

It may not be your first instinct to use these references, of course. But if you are losing your sense of time or feel as though this outbreak is messing up your natural biorhythms, it may help to try and reframe the timescales involved in terms of cosmic phenomena. It is helping me, anyway.