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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

by A2017U1 8y ago

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_acceleration#Ship_reference_frame https://en.wikipedia.org/wiki/Space_travel_using_constant_ac...

jerf 8y ago
And what does modern physics say is necessary to maintain a constant 1g acceleration for years at a time?
- pacala 8y ago
  A ball of iron the size of Earth. I'll show myself out now.
- A2017U1 8y ago
  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.
noddy1w 8y ago
Isn't the milky way 100000 light years across?
- cygx 8y ago
  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.
- Xylakant 8y ago
  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.
unstuckdev 8y ago
You'd have to start braking halfway through to end up at your destination.
letitgo12345 8y ago
Any such spacecraft would be destroyed by the first grain of dust it hits

jerf 8y ago

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

pacala 8y ago
A ball of iron the size of Earth. I'll show myself out now.
A2017U1 8y ago
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.

noddy1w 8y ago

Isn't the milky way 100000 light years across?

cygx 8y ago
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.
Xylakant 8y ago
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.

unstuckdev 8y ago

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

letitgo12345 8y ago

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