S:What is the roundest thing in the universe?
S: Yep
P:  I'm just saying
S: Oh no, Phill!
Not at all
P: You should see it when- ah, no,  uh, the roundest thing in the universe?
S: Yeah
A: Ball bearing
S: Bearings are quite round, but they-
A: I followed a ball bearing once
P: Do you mean smoothest, most round?
S: Well yeah, the most purely, purely round in other words
Cause if you, well-
P: Cause the Earth is- a thingie as it's squashed, it's not round
S: No, that's right, it's an oblate spheroid
P: Whoa-ho Nelly Furtado
He's got a word for everything
R: Is it a-a-a liquid drop, a water drop?
S: They can get jolly round
They can be very round
Very nice! We're actually further out of space than Earth, beyond Earth
It's a cosmic phenomenon
J: Is it a black hole?
S: It's that kind of a deal
R: Ah it's those erm... space helmets, those big round space helmets with the things on the top
J: Is it er... the thing called the Genius Point? Is it the point
at which the- to which everything...
S: Sucked in
J: ...goes to ultimately?
S: Not that. It's when a supernova
has a gravitational collapse, it turns into something called a...
...neutron star.
J: Yeah
R: Ah, the neutron star!
A: They're really round
P: That's not round!
S: No that's what-
That's a supernova I think. That's a supernova. Going supernova.
P: Then show us the round thing!
S: He's very upset, aren't you?
P: Yes!
S: It only has a diameter of about 15 miles or so
and there isn't one near enough to be able to see it with a naked eye
J: Have you ever noticed how we always have to take Stephen's word for it?
S: But what's interesting is that
if I had a thimble-full of a neutron star, it would weight more
than a mountain.
P: Yeah but you don't
R: I'll tell you what, imagine how confused the old woman darning your socks would be
if you had a thimble-full of it
She was just trying to fix a hole and a pwhmf
was all space and time coming out of the thimble
That's no way to treat the elderly
S: You're right
A: You put a thimble down and no one could pick it up
S: No one, no, not at all
J: Not when you've got a good cleaning lady
you want to hang onto them, you don't want to mess them around, no.
"I'm leaving Mr D." "Why?" "Well because of all this space business
with your thimbles, I don't like it."
S: It might have double the mass of the sun
but it's only 15 miles across, roughly.
And the highest mountain on it is 5mm,
so it is superbly round.
Because- as opposed to the Earth,
which, although the Earth is jolly round, apart from the flat bits at the top,
the point about the Earth is that it is actually jolly smooth compared to, say,
a billiard ball.
P: Smoother than a ping pong ball
S: Yes, now why is that? Than a snooker ball...
P: I'm sorry I did not know there would be a follow up question.
R: Why is the Earth-
S: If you were to scale-up a snooker ball
to the size of the Earth, the mountains and
trenches would be huuugely greater
than our highest mountains or deepest trenches, i.e. the little pits
that you can see when you examine a snooker ball closely,
if scaled-up to the size of the Earth, would be gigantic
so the Earth in that sense is smoother than a billiard ball.
