I'll give an example (using a physics question that showed the conflict quite well).
Imagine a pole vaulter with a 5m pole who can run at 0.7c. He runs at a shed that is 4m long. An observer would see a point where he fitsthe pole into the shed due to the pole's length contraction. Relative the the pole vaulter, the shed contracts and he can't fit!
"They are both right from their frame of refrence." But they can't both be right. We end up with a paradox.
Imagine a pole vaulter with a 5m pole who can run at 0.7c. He runs at a shed that is 4m long. An observer would see a point where he fitsthe pole into the shed due to the pole's length contraction. Relative the the pole vaulter, the shed contracts and he can't fit!
"They are both right from their frame of refrence." But they can't both be right. We end up with a paradox.