[Karls48 (Karl)]

Originally Posted by sjastro

From the frame of reference of the spaceships, the questions have no meaning if it was possible to travel at the speed of light (which it isn't). Both spaceships and the distances they travelled would be length contracted to zero. There would be simply be no spatial dimension in the direction of motion for both spaceships. The spaceships would behave as photons.

The speed of light from the cars headlamps is constant irrespective of whether the car is in motion or not. Additive velocities don't apply to light.

Regards

Steven

Travelling at speed of light - Relative to what? The Earth, some distant galaxy receding from the Earth faster then speed of light or centre of the universe?
If Big Bang theory is correct the only meaningful measurement of time, motion and distance is referencing it to the point in the universe where the Big Bang occurred, (and the time and space come to existence).