StarTalk Radio host Neil deGrasse Tyson took to Twitter on Monday, December 21 to deliver his first impressions of "Star Wars: The Force Awakens."

The new droid in the movie, BB-8, has stolen everyone's heart, but Tyson pointed out that the robotic ball would have had some trouble keeping up with the other characters:

We're assuming that Tyson is talking about this part:

Before getting into Tyson's criticisms, it's worth noting that the rolling robot really does work.

The filmmakers revealed a working prototype of the droid before the film was released. They created a robot version of the droid for the movie and there's even an app-controlled toy robot that seems pretty fun.

There's actually a whole website dedicated to explaining how it works.

bb8 r2d2 YouTube/Tested

That said, BB-8 is pretty poorly designed, according to NASA roboticist Brett Kennedy.

"Looking at the BB-8 droid I would have to say the physics, it doesn't follow particularly well," Kennedy said in a video for Wired. "Trying to roll up and over anything is extremely difficult."

The problem, Kennedy said, is that with only one wheel like BB-8 has, you'd easily get stuck.

Depending on what kind of material the robot's main sphere made of, Kennedy also noted that it would likely have trouble getting any traction over surfaces like sand.

The droid could function fine on flat, uniform surfaces though. Kennedy compared it to kicking a soccer ball. But in "Star Wars," the characters of course don't stick to uniform, flat surfaces.

"How many places do you think that you've got enough flat ground that you can actually roll a soccer ball," Kennedy said.

It's no secret that Tyson loves "Star Trek" way more than "Star Wars," so we were expecting him to be pretty hard on the movie.

But even though he went after BB-8's plausibility as an all-environment droid, even Tyson can't deny the droid is adorable: