Here is a data point: life exists now.

What can you learn from a single data point? It’s hard to go from one data point to understanding how a system works. But if you understand a system already, you can assess how likely that single data point is.

And if the data point is very unlikely, then what? Well, it’s still a single data point so nothing changes. But…maybe…if it’s surprising enough, then we can explore if our understanding of the system needs to change.

If that’s our data point, what system can we look at to contextualize that data point?

Universe

The universe is 13.6 billion years old. That is incredibly young. Sun-like stars are expected to continue to be created for 100 trillion years (that’s 100,000 billion). So we are only 0.01% through the phase of the universe where life-as-we-already-know-it could be supported. It is wild that we exist at such an early time.

Since our existence is random, why should we exist at such an early stage of the universe? You could argue that I could say that about any time, but we live in a very special time in the universe. Currently, we see a sky filled with galaxies. There are trillions of galaxies visible to us and we have catalogued millions of them already. Within a trillion years though, we expect the universe to expand so much that the number of visible galaxies will plummet. Each cluster of galaxies (called a group) will become fully separated from all other groups. One galaxy group will not be able to observe any of the stars/galaxies in another group.

In 1 trillion years, the visible galaxies will go from looking like the current observable universe (right) to the local group (left). It is very different! (source)

This means the number of galaxies future lifeforms will be able to observe will go from trillions of galaxies to ~100 galaxies (the size of a group). That is a very different universe they will observe. Will they even be able to build a model of how the universe works without being able to see the wide array of stars and galaxies that we see?

A trillion years sounds like a lot but that is only 1% of 100 trillion years. If life is random and equally likely in this time period, 99% of life will exist in that future. Isn’t it wild that we don’t live in that future? We get to see a bountiful sky.

Let’s put our conspiracy hats on for a second. If it is surprising that we exist in such an early universe, what changes in our assumptions could make our existence feel less surprising? Some possibilities:

  • Maybe the universe won’t change as much as we think. Dark energy is the main reason we think the universe will dramatically change with time. And yes there are many many things that confirm the existence of Dark energy but…y’know, it’s called Dark Energy.
  • Maybe the universe will change much sooner and will change enough that existence will no longer be possible. If life-supporting physics is only possible for a short period of time, that would explain why we exist now and not later. False vacuum, anyone?
  • Maybe the universe is more cyclical. Maybe it only lasts, say, ~20 billion years and re-big-bangs. It would explain why we exist now, because now keeps happening over and over. If it re-big-bangs exactly the same, maybe I write this exact post over and over again too.

Alright, maybe that’s enough conspiracy-hat time. There are other rare things about our time and it wouldn’t be reasonable to tie those to our existence. For example, solar eclipses won’t happen in 0.6 billion years. And Saturn’s rings didn’t exist 0.1 billion years ago and will not exist in another 0.3 billion years. Yet we managed to thread the needle and live in a time to experience both.

A perfect solar eclipse and Saturn’s rings - both are temporary. As the moon moves away from the earth, it will stop covering the sun fully. With time, Saturn’s rings will crash back into Saturn.

Though now that I think about it…maybe we exist now because it’s just a cool time to be around.