Alex McColgan

Let's say 70% of intelligent races reach this level.

Finally, how long do civilizations survive?

For this number, sadly we do not even have a single example.

We do not know how long our race will survive until we die out, by which point there will be no one left to write down the final figure.

However, although there are numerous dangers that could end us as a species, ranging from meteor strikes, nuclear war, or even solar flares, the longer we are able to survive, the more likely it is that we will go on surviving.

This is because once humanity spreads out, we become more and more resilient to a species-threatening catastrophe.

If we are on multiple planets, a comet hitting Earth would no longer threaten the survival of our species.

If we are in multiple solar systems, a solar flare would no longer be able to get all of us.

Species could, in theory, reach a sort of immortality level in this way, lasting for potentially billions of years, as long as they could get out of the danger range.

Let's be optimistic and use this figure.

What does that give us for the Drake equation?

Based on these assumptions, our answer is zero in our galaxy.

If civilisations lived for trillions of years, which is longer than the universe has existed for, we'd still be at zero for these values.

Given these odds, our chances of ever hearing from another civilisation is next to non-existent.

But that's just the thing with this kind of estimate.

If we instead assumed that life arising was certain, and that intelligence arising was certain too, our final answer for even a 1000 year civilisation would no longer be 0.

Instead, that comes to an answer of 9 in our galaxy.

9 intelligent races who might be up in the stars right now trying to communicate with us.

and if races routinely do make it to functional immortality to the point where their civilizations last for billions of years, then we would see as many as 9,450,000 in our galaxy, or more.

I know these are hypotheticals, but I find this very interesting.