HOW does the universe end? According to astrophysicist Katie Mack speaking to Laura Whitmore on 5 Live on Tuesday afternoon there are five potential possibilities: vacuum decay (no Hoovers involved), heat death, the big rip (what it says on the tin), the big crunch and, rather more decorous sounding but no less deadly, the bounce.

All of them involve the destruction of everything, with only the bounce offering any hope for a sequel. Not that any of us will be around to see the climax, of course. It’s a while away yet. I think Mack said it was likely to be “10 to the power of 100 years” in the future. I’m a bit vague on the maths, but that’s a while away yet.

Such are the incidental pleasures of radio. It’s just on in the background and then suddenly you find yourself intrigued by something you had never thought of before. Such as what it might like to be a student scientist heckled by Stephen Hawking as Mack once was. Or thought she was. In fact, it was his voice box malfunctioning.

On Monday night I was in the car listening to On the Menu on Radio 4 where Adam Hart was talking about mankind and the animals that, from time to time, eat humans. Lions and tigers and wolves, oh my. It was a fascinating if, at times, horrifying programme – one tiger watched his potential dinner for a week, taking note of behaviour patterns. Turns out going for a toilet break outside at four in the morning every night is not recommended in some parts of the world.

Trophy hunting and human destruction of habitats both got a mention in a programme that was attuned to the social and environmental issues involved. And yet it was hard not to want to hear the next gruesome detail.

We’ve always been grub, it seems. The earliest humans were on the menu of, among other things, sabre tooth cats and hyenas larger than lions. Your best chance of escape back then? Climb a tree. So that’s where the idea of tree houses came from.