Movie Science: Lightyear Top Fails

Did you catch the science error at the CENTER of the recent Buzz Lightyear Movie?


I just watched Lightyear with my girlfriend and had to pause and complain roooughly 37.2 times. It would make my old grad-school physics professor roll over in his grave. If he were dead. But let’s focus on the one, tiny little mistake that the ENTIRE movie’s plot revolves around!

Buzz is testing a spaceship fuel to see if it can get him to “hyperspeed”

Your mission is to accelerate through deep space, slingshot around alpha tecani, then through the deceleration rings back here to takani prime. Target flight prime: 4 minutes, 28 seconds

First off, that slingshot is impossible given how fast he’s going.

Fuel stable, increasing speed to .7c 70% hyperspeed

You’ve heard of e=mc^2? c is the speed of light. So they imply that hyperspeed IS the speed of light. Which really makes no sense if you’re talking about traveling between solar systems in short time frames. Doesn’t “hyper” mean more than? Unless some unexplained magic happens when they reach it?


Anyway. Buzz doesn’t quite make it all way there.

0.8c, pushing to hyperspeed

And that’s as fast as he gets. So not “hyperspeed”, but still amazingly fast. A speed where trying to use the sun’s gravity to change direction would be like… Indiana Jones trying to move the boulder by blowing on it.

But Buzz somehow slingshots around the sun and makes it back to the planet! Only to find…

Whoa diaz you grew a beard? how long was i gone? 4 years, 2 months and 3 days

But… but how??? Good thing they explain it!

time dilation what?

Yeah, that was my exact reaction! But probably for different reasons

time dilation is quite simple. As you approached hyperspeed, your time slowed relative to our own.

Technically true. SO far so good.

so during your mission, you aged only minutes, while the rest of us ages years

Hoooold up. Wait a minute.

That’s not how time dilation works. For there to be a significant effect, you have to be going REEEALLLY CLOSE to the speed of light.

For it to have been over 4 years back home? Let’s calculate how fast he would have had to go.

The results? In percentages of the speed of light?


That’ SO close to the speed of light, that if you were to go that speed and RACE a beam of light from earth to alpha centauri? You’d lose by only 1/4 milisecond.

Don’t get me wrong- noticeable time dilation DID happen to Buzz at his speed. But how much?

Even if he had spent his entire trip going at the full 0.8c, if 4 minutes and 28s passed on earth, he’d have experienced a whopping 7.44 minutes. Which leaves us with the question…

Can Pixar and DISNEY not afford to have someone on their staff who understands physics?

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