Science Forums 2

[CraigD]

Originally Posted by wade_b

Which sounds like it [Einstein’s box] COULD apply to the emdrive?

No, not according to a usual resolution such as the one in post #31

The Einstein’s box thought experiment (this particular one – there are actually several that commonly go by the name) – which can, with very precise equipment and instrumentation, by physically performed – is exactly analogous to the simpler example of a box inside a freely moving box, which I’ve sketched in the image attached below. It moves the outer box a fixed distance, then the system is “used up”, and before it can be used again, must either be reset, which returns it to exactly its starting position, or mass removed and added to it from outside, which defeats the premise of it being a closed system.

What makes Einstein’s box a trickier riddle is that it’s less intuitive that shining emitting light from one object onto another which absorbs the light (a more difficult feat than it sounds at first hearing, as most objects ultimately emit about the same amount of light they absorb) actually transfers mass between them, than it is that moving a small massive box from one end to another of a large hollow box transfers mass within it.