Gravity.
I once had to spend half an hour in a bar, racking my brains for the dregs of my knowledge of GCSE physics so that I could explain to a colleague exactly why 'gravity' was not caused by the weight of the air in the atmosphere pushing everything down.

The penny dropped for him when I asked if this was the case, how do you think they walked on the moon?

His answer? "They wear big heavy boots!... Oh..."

I then had to try and explain the concept of mass causing a gravitational pull. I had to give up at that point when he just kept asking 'why?' and my knowledge and sketchy memory ran out.

I never pretend to be particularly smart, but the ignorance of some people is quite amazing.
(Woodlouse say it with flowers. Send her a Triffid, Sat 5 Mar 2011, 10:55, 11 replies)

Was he having you on?
There's loads of stuff that I will argue the case for in the pub to get a rise.

By the way it's the earth's rotation that makes gravity, that's why all planets spin.
( Ring Of Fire A petty, drooling belming butthurt retard., Sat 5 Mar 2011, 16:07, closed)

I thought it was because
the inside of the Earth is a big magnet and everything has varying amounts of iron in it. That's why things that have lots of iron like a car are really heavy.
( sandettie light vessel automatic New Twitter - @bollocksreally, Sat 5 Mar 2011, 17:18, closed)

Nope, it's inertia.
Everything is expanding at a constant rate, including the space between everything, so what you feel as the "pull" of gravity is actually the "push" of the earth's surface against your feet as it gets bigger.

You don't notice things expanding as you're expanding too, as is the space between everything, which is why the universe is not getting more crowded. Trains notwithstanding.
( argyleblanket The man on the roof works for me, Sun 6 Mar 2011, 12:50, closed)

partly true
there's also the pull from quantum strings.
( Ring Of Fire A petty, drooling belming butthurt retard., Sun 6 Mar 2011, 22:19, closed)

Unfortunately not.
I'm the same where I'll happily argue a fantastically wrong point just for the entertainment value. But there was no doubting the sincerity of his own conclusions in this case.

While I don't generally stroll around with a sense of moral superiority over all my peers there were in the case of this chap several incidences where he showed himself to be a several cards shy of a full deck.

As to the true cause of gravity, I'm not that bothered to look it up but I'm pretty sure that the conclusion that it's caused by rotation is bollocks. The rotation of planets would more likely seem to be a result of gravity rather than the cause.
(Woodlouse say it with flowers. Send her a Triffid, Sat 5 Mar 2011, 19:54, closed)

As any fule kno
It's because this country sucks.
( His Popiness the Hole Invaded Poland on, Sat 5 Mar 2011, 21:12, closed)

I hope they don't switch it to blow.

(Woodlouse say it with flowers. Send her a Triffid, Sun 6 Mar 2011, 18:27, closed)

Conservation of angular momentum.
Back when the Solar System was clumping together from the remnants of an old star, it was spinning. This was because the Milky Way was spinning. I don't really know why the galaxies spin. Think of a teacup ride at the fair.

Anyway, the spinning dust cloud starts to clump together to form the Sun and all the planets, and much like when an ice skater brings in their arms and legs during a twist to go faster, as they get smaller and denser, they retain all that spin. Hence, spinning planets. Except Uranus, which does spin, but perpendicular to the rest of them.

Plus, the spin means that gravity is very slightly counteracted at the equator by a tiny amount - xkcd.com/852/

SCIENCE!*

_{*(Mainly just regurgitating various documentaries, but I'm taking a degree to learn the math!)}
( Mr.Ons knows you can hear him, Earthmen., Tue 8 Mar 2011, 9:18, closed)

heavy boots!
www.milk.com/wall-o-shame/heavy_boots.html
(gtfomh, Mon 7 Mar 2011, 0:31, closed)

I may be talking out of my ample behind.
But isn't it a result of the curvature of space-time caused by sufficient mass? You're essentially 'falling' towards the centre of the gravity well. This is much easier to understand when it's represented in 2D.

For further mind-boggling lols, watch Episode 10 of Carl Sagan's Cosmos, and try to twist your head around 4-dimensional space.
( Mr.Ons knows you can hear him, Earthmen., Mon 7 Mar 2011, 14:15, closed)

You're talking balls
On rubber sheets
( Ring Of Fire A petty, drooling belming butthurt retard., Tue 8 Mar 2011, 6:37, closed)