I'd like to add something to the other hints
The largest of boards
it's a plank, which is a word play on Planck
my length is real small
A well-known professor, a rock without roll.
Einstein literally translates to "a rock"
A black body's spectre by my law is bound.
Planck famously was the first to correctly describe black body radiation https://en.wikipedia.org/wiki/Planck%27s_law
My famed equation with E is profound.
almost everybody has heard of E=mc^2
QM's foundations by us were laid out.
Our golden medals deserved were, no doubt.
both Einstein and Planck pioneered in Quantum Mechanics and won a nobel prize for discovering energy quantization and describing the photo electric effect