Hacker News Reader

Comment by A2017U1 | Hacker News Reader

A2017U1·

With a constant 1g acceleration up until near the speed of light you can cross the observable universe in a human lifetime.

To the other side of the galaxy it would be 12 years

https://en.wikipedia.org/wiki/Space_travel_using_constant_ac...

View on HN

And what does modern physics say is necessary to maintain a constant 1g acceleration for years at a time?

A ball of iron the size of Earth. I'll show myself out now.

To reach close to the speed of light (~0.9c?) it'll take about 1 year before turning off the engine, and then another year of deceleration if you're planning to do anything else besides travel around at relativistic speeds.

Going to Mars using antimatter with the same 1g acceleration the entire time (reversing half way) will take a few weeks and require a small fraction of a gram of antimatter.

Ignoring the significant engineering problems like heat disappation, storage if it's not used instantly, you could get two years worth of thrust from antimatter measured in grams and cross the galaxy in just over a decade, in Earth time the trip would be >100,000 years.

You'd have to start braking halfway through to end up at your destination.

Any such spacecraft would be destroyed by the first grain of dust it hits

Isn't the milky way 100000 light years across?

Time dilation: At a constant acceleration of 1g, 100k galactic time reduces to 12 years ship time. Cf the link provided in the comment you're replying to.

As you approach the speed of light, the time observed by the traveler ticks slower, so you can travel vast distances in short observed time periods. So the people on the ship would spend 12 years, a manageable time period, but us more or less stationary observers would still see 100000 years pass.

Reply on news.ycombinator.com