Victor Garber as Martin Stein has been a welcome presence in both The Flash and in DCs Legends of Tomorrow. His delivery, his dialogue, and his mannerisms make him one of the most entertaining parts of any show hes appeared in so far. And that continued here with a monumental putdown of Ray Palmer. When it was questioned as to what 1975s Stein would know about alpha particles, the older Stein instantly quipped to Palmer, I was researching alpha particles when you were eating crayons. Touché, Martin. Touché.