Hello, I hope you can help with my question!! I am a 27 year old amateur theoretical physicist about to start a bachelor's degree in physics as a mature student... I have just been going over some bits of Einstein's theory of Special Relativity and have noticed something odd that has confused me! The theory initially states that there is no absolute frame of reference in the universe. Ok, so let's say astronauts Mary and Dave are floating next to each other in space, Dave turns on his jet pack and flies off at 500,000mph. Mary will see Dave as being thinner as he will be experiencing length contraction. So then, shouldn't Dave see Mary as being wider, as in comparison to her, he is thinner?! Instead, it could just have easily been Mary who was accelerated away from Dave, as observers they would still be equal, although in this scenario Dave would see Mary as being thinner! I am confused!! This has also brought about an interesting thought experiment. If someone were to make a million identical metal cubes and blast them off into space in a million different directions at different speeds, then by measuring which one looked biggest couldn't we potentially find a direction of motion (relative to us) that is actually an absolute point in space, i.e. the biggest cube is not actually moving in space? Thank you for your time and help!!