[ozziegooen]

"In the 19th, with trains, they reached 60 mph. In the 20th, with jet aircraft, we could travel at 600 mph. Can we expect 6,000 mph in the 21st?" The 21st century still has 90 years left in it. We have no idea what technologies will emerge in that time. If a technological Singularity occurs, well...

[demallien]

Yes. If we ever manage to build a space elevator for example, it will open up the entire inner solar system for exploration / colonisation, at which point the people that continent hop today will be able to world (planets and large moons) hop tomorrow, with a corresponding jump in the maximum speed that a person will travel at...