[cheryl j (OP)]

That is what Twitter OMG Facts Animals claims. Wikipedia says "the invention of the pet door was attributed to Isaac Newton (1642–1727) in a story (authored anonymously and published in a column of anecdotes in 1893) to the effect that Newton foolishly made a large hole for his adult cat and a small one for her kittens, not realizing the kittens would follow the mother through the large one."

Other physicists also constructed cat flaps, but Heisenberg found that when two cats went  through them they formed a wave pattern and were no longer good at catching mice. 

[christycurtis]

That is what I also read, but I think he focuses on his major inventions.