This TED Talk features writer and physicist Stephen Webb, recorded live at TED 2018.

I saw a UFO once. I was eight or nine playing in the street with a friend who's a couple of years older, and we saw a featureless silver disk hovering over the houses.

We watched it for a few seconds,

and then it shot away incredibly quickly.

Even as a kid, I got angry.

It was ignoring the laws of physics.

We ran inside to tell the grown-ups,

and they were skeptical.

You'd be skeptical, too, right?

I got my own back a few years later.

One of those grown-ups told me,

last night I saw a flying saucer.

I was coming out with the pub after a few drinks.

I stopped in there.

I said, I can explain that sighting.

Psychologists have shown we can't trust our brains to tell the truth.

It's easy to fool ourselves. I saw something, but what's more likely,

that I saw an alien spacecraft

or that my brain misinterpreted the data, my eyes were giving it.

Ever since, though, I've wondered,

why don't we see flying sources flitting around? At the very least,

why don't we see life out there in the cosmos? It's a puzzle, and I've discussed it with

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