If there is life on Mars already, not just a few bacteria hiding deep in the rocks but cities and roads and the whole civilisation thing, the implications are profound.

Not only does it mean that life has arisen and flourished on the Red Planet, but that NASA is involved in a conspiracy that makes climate change deniers look like geniuses.

It wasn’t entirely clear how NASA didn’t want us to see the evidence, since the images in the video were from their own public resource pages, but the UFO Channel presenters promised to reveal all, and I was sure that such respectable-looking guys as these wouldn’t lead me astray.

And respectable they were. “Distinguished” springs to mind. They spoke well, their suits were nice, glasses just right, enough to set any deluded space cadet – even one as gullible as me – straight about the lies of those evil people at NASA.

But it was the hair that won me over. Silver not grey, wavy not curly, without doubt the most credible hair I’d ever seen.

Apparently, NASA is trying to conceal the existence of pyramids, large sculptured faces, statues, buildings, cities and machines that have appeared in photos returned from Mars.

And after carefully viewing the video, I can now reveal that the proof that these objects are indeed alien artefacts is... they look like them.

A bit. The fact that they don’t look like them completely only proves even more that that’s what they really are. If you disagree, you’ve either let them fool you, or you’re in on the conspiracy.

To think here I’d been, taking NASA’s word that these things were just piles of rocks or strange geological formations, when all along they were evidence of intelligent life on another planet. Amazing.

I felt such a fool.

Subsequent photos of the same objects at higher resolution or with lighting from a different angle, in which the objects look less like pyramids and flying saucer maintenance depots than, say for example, piles of rocks, were not fully explained.

No doubt time was pressing or the UFO Channel would have covered this detail, and detail it can only have been for, as I say, their hair was just perfect.

Something bothered me, all the same. There are some things that look like other things without actually being them. What if these things on Mars were like that?

You might be walking down the street and see a pile of leaves shaped like a small elephant with two trunks and an extra leg. It could be a pile of leaves, or it could be a deformed dwarf elephant with leaves stuck all over it. You can’t really tell just by looking.

You nudge the object with your foot, and it breaks up into a flurry of leaves. There’s no elephant there.

The point is, even facts are just guesses. Piles of rock are plausible things to find on Mars.

The things we see there could still be artefacts, which the Martians, realising they’d been spotted, concealed before better photos could be taken.

The dwarf elephant could have teleported itself away just as you reached out your foot to kick the leaves. You can’t actually prove anything either way.

Science isn’t about proof. The whole world, everything you’ve ever done, could be just a vivid dream from which you’ll awaken tomorrow morning to find that you’re actually a leafy sentient dwarf elephant living on Rigel 4 who just ate one too many Denebian burritos last night. You couldn’t prove otherwise.

Everything we do is based on weighing the evidence, and deciding what is most probable.

People don’t handle probability well. You might have a one in a million chance of winning the lottery. You see a big number but, after all, somebody’s got to win it and it might as well be you. So you buy the ticket.

But if someone said, “I’ll give you a million dollars if you can get in your car blindfolded and drive it round the block without hitting anything,” you’d be much less likely to have a shot at it.

We make judgements about the world. It’s actually all we do. Artefacts or rocks, look at the evidence, think about probabilities. But in the end it’s your choice what you want to believe.

Conspiracy theories about aliens on Mars aren’t evil. They’re the response to a mind-numbing world by people with numb minds. Many indeed are those who need to feel (as an admittedly slightly mad musician named Roger Waters once termed it) “that warm thrill of confusion”.

For all the beauty of the view, here at the edge of infinity is a cold and scary place to stand.