Real linguists tested how Rocky understands Grace in Project Hail Mary — and split on the verdict

But while the rest of us were buying plush versions of him, actual linguists were doing something far funnier: peer-reviewing him. Several language professionals have now formally examined how a human teacher and a five-legged Eridian learn to talk to each other — and they did not walk away with the same grade.

The defense: this could actually work

The strongest case comes from the people who built the thing. The film hired conlang royalty David and Jessie Peterson — the duo behind Dothraki and High Valyrian — to design Eridian as a real functioning language: three "vocal instruments" playing over each other, seven notes each, two lines carrying vocabulary and a third handling grammar. Crucially, they designed it so you'd only need relative pitch, not perfect pitch, to parse it — meaning an ordinary musical human could theoretically learn it.

Could you, though? David Peterson told Scientific American he'd back himself:

"It's not too tough. You get used to it."

And he's not alone on team plausible — linguist Daniel Hieber, who went through the story's language-contact scenes line by line, lands on a straightforward yes: the broad strokes of how Grace and Rocky bootstrap communication hold up.

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The prosecution: objection, Hollywood

Other linguists pulled out red pens. The complaints, compiled:

• The speed. Grace goes from zero to fluent-ish absurdly fast, ditching his translation software early like a man who "got the gist" of Mandarin over a long weekend. Linguistics professor Betty Birner has pointed out the story shortcuts the brutally slow reality of language acquisition for narrative pace — and that math, the film's icebreaker of choice, isn't the guaranteed universal language sci-fi wants it to be.
• The thumbs. Rocky instantly reads a thumbs-up as approval, then spends the film confused by thumbs-down — which, per Birner's reading, is accidentally the most realistic bit: why would an alien share our "up equals good" metaphor at all?
• The downgrade. The harshest critique says the story sells the Eridians short. One linguist's scathing breakdown argues that a species with perfect memory and lightning cognition deserved more than adorable broken English:

"Weir could have created a much more strange and beautiful language for the Eridians."

The verdict (there isn't one, that's the fun part)

So the split, roughly: the language itself — surprisingly legit, lovingly engineered, learnable by a motivated human with decent ears. The learning montage — generous to the point of fantasy. Rocky's translated voice — either a charming character choice or a subtle demotion of the smartest guy on the ship, depending on which expert you ask.

Personally, I find it deeply soothing that the nerd fight of the year is over whether a jazz-chord spider learned English too politely. Amaze, amaze, amaze.

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