The thought experiment in special relativity became more widely known when a Northern Irish physicist, the originator of what  included a modified version?
Bell's spaceship paradox Bell's spaceship paradox is a thought experiment in special relativity. It was first designed by E. Dewan and M. Beran in 1959 and became more widely known when J. S. Bell included a modified version. A delicate string or thread hangs between two spaceships. Both spaceships now start accelerating simultaneously and equally as measured in the inertial frame S, thus having the same velocity at all times in S. Therefore, they are all subject to the same Lorentz contraction, so the entire assembly seems to be equally contracted in the S frame with respect to the length at the start. Therefore, at first sight, it might appear that the thread will not break during acceleration.
Aether theories Aether theories (also known as ether theories) in physics propose the existence of a medium, the aether (also spelled "ether", from the Greek word (αἰθήρ ), meaning "upper air" or "pure, fresh air"), a space-filling substance or field, thought to be necessary as a transmission medium for the propagation of electromagnetic or gravitational forces. The assorted "aether theories" embody the various conceptions of this ""medium"" and ""substance"". This early modern aether has little in common with the aether of classical elements from which the name was borrowed. Since the development of special relativity, theories using a substantial aether fell out of use in modern physics, and were replaced by more abstract models.