… can you determine *WHEN* intex exist by sitting alone in your room contemplating time and chance?

Conundrum Three

A physicist by the name of J. Richard Gott III thought so. He attempted to demonstrate, solely through an analysis of time and chance, that humankind will never make contact with offworld minds. More precisely, he contended that there is not and never will be a galaxy-wide civilization. Gott called his chain of reasoning the Delta T argument, though it’s also known as the Doomsday argument.

Gott first got the idea while visiting the Berlin Wall in 1969. Because the Berlin Wall was built in 1961, it just so happened that he showed up during the eighth year of the wall’s existence. Using this temporal fact alone, could he estimate when the wall would fall? He believed he could, using a mathematics of possibilities.

Imagine: two possible timelines.

In Timeline 1, the Berlin Wall exists for ten years.

In Timeline 2, the Berlin Wall exists for a billion years.

You randomly stumble upon the wall in year 8 of its existence. Is it more likely you are living in Timeline 1 or Timeline 2?

If your intuition tells you it’s more likely you’re in the ten-year timeline, linear statistics backs you up.

Now imagine: an infinite number of possible timelines for the Berlin Wall. Every possible duration from eight years to eternity. Once again, you stumble upon the wall in year 8. Which of these infinite number of possible timelines are you living in, most likely?

You might guess you’re in a timeline where the Berlin Wall will fall soon. So did Gott. He ran the numbers and calculated a 95% chance he was in a timeline where the Wall would fall within the next 312 years after he observed it in 1969. And the wall did fall twenty years later, in 1989.

Gott used the same logic to predict the fall of Stonehenge. He randomly visited the enigmatic British landmark about 4,000 years after it was constructed by the druids. From this fact alone, Gott calculated there was a 95% chance that Stonehenge would last another 150,000 years. As I write this, Stonehenge endures.

Gott grew ambitious. Most scientists who hunt for intex stalk them in space; Gott elected to stalk them in time. Gott applied the same mathematics of possibilities to the question of when in our future timeline we might contact extraterrestrials. His starting assumption: we do live in a galaxy with intex who are detectable by us. (They’ve observably colonized our region of the galaxy, or sent forth discernible probes, or because they’ve transmitted energy signatures or communications perceptible from Earth.)

Imagine: two possible timelines.

In Timeline X, a detectable civilization exists in our galaxy for ten years (maybe ten years after its inhabitants start broadcasting radio messages, the civilization destroys itself through nuclear Armageddon).

In Timeline Y, a detectable civilization exists in our galaxy for a billion years.

You wake up this morning and observe that for as long as you’ve been alive you have never detected any signs of extraterrestrial life. Is it more likely you are living in Timeline X or Timeline Y?

Using the same statistical reasoning he applied to the Berlin Wall and Stonehenge, Gott crunched the numbers and calculated that 98.6% of all sentient beings who will ever live in our galaxy will come into contact with (or inhabit) a civilization of median size or greater, and that the population of the median civilization will be stupendous: quadrillions of beings, far more than the number of neurons in our brain.

But we do not appear to be living in an interstellar civilization with quadrillions of citizens.

Ergo, reductio ad impossibilem, Gott concludes it is extremely unlikely we will ever contact intex. According to his math, we are alone in the void and will remain lonesome for eternity[1].

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[1] I think there are some irredeemable flaws in Gott’s approach, mostly due to his reliance on linear statistics. If you want to catch the mind of intex, you need more than time and chance and linear thinking. The Doomsday argument does not make its way into intex theory. It does incorporate one indispensable element of intex theory, however.

You. Right here, right now, reading about intex.