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Started by uranrising on Mar 4, 2021 10:39:23 AM
A science joke

Just come across a joke I'm hoping one of the scientists here can explain.

Q. What happens if you put a black hole into an indestructible dustbin?

Dayraven - 04 Mar 2021 10:45:06 (#1 of 86)

Much more of a thought experiment than a joke, I think. Black holes do emit radiation via quantum effects (it's called Hawking radiation). So since it can't absorb the indestructible dustbin, it's going to emit radiation out of the top because that's the only place it can go, giving it motive force.

Post by deleted user
Tomnoddy - 04 Mar 2021 10:51:45 (#3 of 86)

Nowhere else for it to go in an indestructible dustbin. Well, it might start a journey to the centre of the earth.

ZimAgain - 04 Mar 2021 11:16:07 (#4 of 86)

It's obviously a disparaging reference to Romulan spaceships.

TommyDGNR8 - 04 Mar 2021 11:21:00 (#5 of 86)

If the bin doesn't deform, then I suppose you could imagine the black hole sucking in everything above it and hence sucking itself off the ground.

Not terrifically good science, and certainly not a great joke, I'd posit.

FleurDuMal - 04 Mar 2021 11:22:44 (#6 of 86)

There's no such thing as an indestructible dustbin, so the joke doesn't work. The dustbin would simply be absorbed into the black hole.

dreams99 - 04 Mar 2021 11:23:10 (#7 of 86)

It was on the BBC2 scientists tell jokes prog. It was the only one met with bewilderment (rather than sheer cringe)

hailesaladdie - 04 Mar 2021 11:23:48 (#8 of 86)

A black hole sucking itself off? Missus!

pranzingfrogg - 04 Mar 2021 11:24:16 (#9 of 86)

It’s a variation on the paradox of irresistible force v immovable object, innit? If the object moves, it isn’t immovable, if it doesn’t the force isn’t irresistible.

TommyDGNR8 - 04 Mar 2021 11:24:52 (#10 of 86)

BBC2 scientists tell jokes prog

Y'see? There are good reasons why I leave "popular culture" to the likes of Laz.

CloakAndDagger - 04 Mar 2021 11:25:26 (#11 of 86)

There's no such thing as an indestructible dustbin, so the joke doesn't work.

There's also no such thing as talking sausages, but that joke's a belter.

uranrising - 04 Mar 2021 11:37:48 (#12 of 86)

Same with talking animals entering a bar..

PS. Many thanks for the explications.

champagnerocker - 04 Mar 2021 11:44:53 (#13 of 86)

Or the sodium ion that walks into the bar and complains that he has just lost an electron.

Lento_ - 04 Mar 2021 11:45:06 (#14 of 86)

The smaller a black hole is, the quicker it emits radiation.

According to a black hole calculator thing I found on the web, a black hole with a radius of 0.5 metres (to fit in a bin) would weight about the same as 56 Earths and radiate all that mass as energy in just 3 seconds.

It wouldn't be so much "taking off" as "blasting the Earth in to tiny pieces while accelerating itself to something close to the speed of light".

CloakAndDagger - 04 Mar 2021 11:45:46 (#15 of 86)

Tricky to fit that on a slip of paper inside a cracker though.

TommyDGNR8 - 04 Mar 2021 12:40:34 (#16 of 86)

An indestructible cracker?

Dayraven - 04 Mar 2021 12:44:36 (#17 of 86)

That's not a cracker. That's just an er.

RosyLovelady - 04 Mar 2021 13:08:47 (#18 of 86)

Remind me, someone: what does happen when an irresistible force meets an immovable object--is it just a lot of heat or summat?

hailesaladdie - 04 Mar 2021 13:09:49 (#19 of 86)

The unstoppable force stops, the immovable object moves.

Dayraven - 04 Mar 2021 13:15:20 (#20 of 86)

It's a philosophical paradox. The scientific answer would be more that neither of those things are known to exist.

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