Breakfast in London and lunch in Sydney isn't quite just around the corner yet, but plans are afoot to get us to the other side of the world in the time that it takes for a round trip on the Northern line. It's all about the scramjet.
A scramjet - or supersonic combustion ramjet - is mechanically very simple. It has no moving parts and takes all of the oxygen it needs to burn hydrogen fuel from the air. This makes it more efficient than a conventional rocket engine as it does not need to carry its own oxygen supply, meaning that a vehicle using one could potentially carry a larger payload.
The British-designed Hyshot III, tested over the weekend is hoped to be the forerunner of scramjets that will one day drop passengers back down in Oz before they even have time to finish a movie.
In the first instance, these would probably be used to launch satellites into low-Earth orbit but many have speculated that they could also allow passenger airlines to fly between London and Sydney in just two hours.
Sounds a trifle sci-fi-ish, but then again so did the British Rail thermonuclear powered flying saucer that got us into the office this morning...