cynar , 9 months ago

The maths is wrong, though the idea is correct. At 0.5C, the length compression is approximately 86.6%. Basically, the star 1 ly away now appears to only be 0.866 ly away.

From outside, you took 2 years to get there. By your ship’s clocks, you took 1.73 years to get there.

The effect gets stronger as you approach C. At 0.99C, time passes at only 14% the speed it passes for an observer. The distance also shrinks to only 0.14 light years.

This calculator lets you play with the numbers. https://www.omnicalculator.com/physics/time-dilation

Time dilation and length contraction are fundamentally linked. The change is the same in both, so that C is always constant, at any speed.