"the one who said they built a Michelson interferometer in a day in their physics lab" Maybe you should check with them too: it's possible that they have also

"the one who said they built a Michelson interferometer in a day in their physics lab" Maybe you should check with them too: it's possible that they have also built "a" Michelson interferometer (just like Thorlabs kit features one) but maybe their setup was in spite of that insufficient to perform the needed measurements in the way needed for the valid execution of a Michelson-Morley experiment? Historically, Michelson constructed his first interferometer in 1881 in Potsdam, Germany: https://arxiv.org/abs/2111.12176 https://arxiv.org/abs/2111.12176 Inventing it was obviously necessary but not sufficient for a valid Michelson-Morley experiment, which was correctly finished only during 1887 in Cleveland, Ohio.