[marcosdumay]

For an observer in the ship, obviously. Here, outside, it will be more like 200 thousand years, and constant 1g acceleration is impossible.

You are also forgetting how hard it to maintain that 1g of acceleration for a long period.

[shiftpgdn]

Just 1000 years for a stationary observer vs 22 years for a astronaut under 1g constant acceleration. It's not that radical.

[aardvark179]

The diameter of our galaxy is about 100,000 light years. Unless you've got some way to go faster than light then you're 2 orders of magnitude out on your estimate.

[JoeAltmaier]

That's ignoring relativity! For the astronaut, travelling at near C, dilation will occur and it will seem to be less time.