At the time, one of the biggest problems in physics was the “Blackbody spectrum”, which describes the spectrum of electromagnetic wavelengths emitted by a Blackbody. The problem with it was that the emitted spectrum was not explainable by known physics. Einstein achieved a breakthrough by considering light not just as a wave, but also as light quanta. Although this idea sufficiently explained the Blackbody spectrum, physicists (at least almost) unanimously rejected it. The fight between the “light is corpuscles” and “light is a wave” faction had been decided a century ago, with a clear victory for the “wave” faction.
I thought blackbody radiation was Planck, not Einstein.
I went a few times but eventually got grossed out by all the mold. (At least they don’t sell live pangolins there.)