Einstein’s greatest legacy- How demons and angels advanced science

Thought experiments are common in theoretical physics today. Physicists use them to examine the consequences of a theory beyond that what is measureable with existing technology, but still within the realm of that what is in principle measureable. A thought experiments pushes a theory to its limit and thereby can reveal inconsistencies or novel effects. The rules of the game are that a) relevant is only that what is measureable and b) do not fool yourself. This isn’t as easy as it sounds.

Something I run across often is someone with a “great new theory” (at best one of those descriptions is true) or a scenario that supposedly tears down a pillar of physics (usually relativity), who doesn’t realize that a thought experiment doesn’t (dis)prove anything, because absent any comparison with experiment, all a contradiction shows is that your thought process has some problem — it’s pretty easy to assume contradictory things, which wreak havoc on thought experiments. (For the relativity folks, it’s usually a subtle assumption of absolute simultaneity)