After Elon Musk appeared on The Simpsons last night and jetted off at the end of the episode in his Dragon spacecraft, Lisa points out that "for a man who likes electric cars he sure burns a lot of rocket fuel." Musk apparently heard this parting shot as a slight against his technological prowess and took to Twitter to point out why electricity will never get people off the planet:

If u saw @TheSimpsons and wonder why @SpaceX doesn't use an electric rocket to reach orbit, it is cuz that is impossible — Elon Musk (@elonmusk) January 26, 2015

Musk goes on to explain: "Reason is Newton's Third Law. In vacuum, there is nothing to "push" against. You must react against ejected mass … Ion thrusters are great, but have extremely tiny force (photon thruster even less). Must have more thrust than weight or you don't go up." He also notes that another futuristic trope for getting off the planet — the space elevator — still needs a lot more research into the raw materials before it'll actually work:

And pls don't ask me about space elevators until someone at least builds a carbon nanotube structure longer than a footbridge — Elon Musk (@elonmusk) January 26, 2015

It wasn't just electric rockets that were suggested in the Simpsons though. Musk arrives in the town as an inventor out of ideas but is soon inspired by Homer’s free-form rambling and ends up overhauling the nuclear power plant and installing electric, self-driving cars in every home. There are gags about violin-playing quadcopters, self-packing luggage, and even a working hyperloop (although it's no monorail).

Overall, Musk is given the usual celebrity treatment: there's a couple of good-humored jokes about his status as world's best inventor ("You’re the guy who put wheels on luggage!?"), but it's mostly just compliments dressed up as criticisms. His dedication to saving the planet for future generations does end up putting current Springfielders out of work however, and Musk is soon given his marching orders by Homer — blasting off once again in the Dragon spacecraft. On Twitter though, the inventor had a few more words of wisdom for those trying to get into space without rockets: