This question already has an answer here:
The famous double slit experiment shows how light behave like a wave when sensors near one slit are on and recording vs not recording. I didn't find a lot of details, but especially given the case that something similar could happen for light traveling around the universe... it raises for me the question:
What if someone/something recorded the particle at the slit or not with a 50% chance of recording. Supposing we wouldn't/couldn't know which it is, it should behave like a wave (my expectation). Couldn't we possibly later open that box and ask/check if it was actually recording or not?
More accurately, would the results change if we could and could not later know if the sensor was actually recording or not?
I know of the delayed double slit (especially the Experimental delayed-choice entanglement swapping) but here I'm not asking regarding time travel but more regarding possible knowledge or lack of it. Because if anything that could observe light would force it to collapse, it seems that it could tell us if something observed that particle, ever (ok no need to put aliens here but it could).