Could you swim under Australia?

Is it possible to swim under Australia? I mean islands are not connected to the core of the earth so you could actually swim under them. Well it isn’t possible because islands are like upside down mountains but… Basically, is Australia attached to the core like all other countries or is it an actual island? [...]

Is there a limit to how fast a man can ever run?

Given that Olympic World Records are constantly being beaten, is there actually a limit as to how fast a man can ever run? Paul Warner

How does a helium balloon’s flight compare to a plane’s?

If you were travelling in an aeroplane at say 500mph at 25,000 feet, and next to you was a small floating balloon of helium which was in mid air and not touching anything (and assuming nothing interfered with the balloon) would the balloon remain next to you throughout the journey or would it end up [...]