I’m Going to Whine About a Space Movie Being Inaccurate, and There’s Nothing You Can Do to Stop Me.
One of my favorite physics 1 projects was one that required us to use our newly-discovered physics knowledge to explore the world around us. It was an opportunity to find an example in the media where we could apply what we’ve learned to better understand things we took for granted. It gave us a chance to look at normal, daily events with fresh eyes, and maybe even learn from them.
Or, if you’re me, you use it as an opportunity to complain about a stupid movie.
What follows is one of my proudest papers: ‘G-Force and the Physics of Interstellar’. Also known as, ‘I’m a science student and I need to make sure everybody knows it.’ This is unedited and presented in the original format required by my professor. I’m hoping that, at the very least, this is interesting reading for beginning physics students.
Enjoy.
Description
For my example, I’ll be looking at the spacecraft Endurance from the movie Interstellar (2014). It is a unique spacecraft in that it rotates in order to imitate gravity for it’s passengers. (Of course, this is not the first time such a concept has been introduced — 2001: A Space Odyssey (1968) uses the same ideas, and more recently The Martian (2015).) My question is — given certain parameters by the makers of the movie, and estimating on others, how many gs are the astronauts experiencing in one of the scenes in the movie?
This particular question is noteworthy to me because of my long-lasting enthusiasm for space movies. It started with Contact (1997) when I was about 8, and went downhill from there. Someone once quoted their anonymous Astronomy professor as saying, “There are two gateway drugs to science — dinosaurs and space.” (http://thatssoscience.tumblr.com/post/118902737398/my-astronomy-professor-there-are-2-gateway-drugs) The latter was certainly true for me, and Contact (and Star Trek, and Firefly) were all at fault.
Fundamental Physics Principle
The most important principle being used here is the mathematics involved in acceleration and rotation. Specifically, that g-force can be equal to acceleration while traveling in a circle or taking a sharp turn. G-force is calculated by v²/r (velocity in m/s and radius.) The necessary velocity can be calculated by looking at the rotations-per-minute and diameter of the Endurance.
Visual Evidence
(WARNING FOR SUDDEN LOUD NOISE AT 0:16)
In this scene, they are forced to line up the Ranger with the Endurance, which (normally) rotates at 5.6 rotations per minute. (http://www.space.com/27694-interstellar-movie-spaceships-infographic.html) Because of the explosion, they are instead forced to match up with the hatch of the rotating craft. I would like to know how many gs they are experiencing, and whether it makes sense for McConaughey’s character to maintain consciousness.
Inquiry
The question I plan to solve is how many gs the shuttle that McConaughey’s character is in is experiencing. In order to solve this, I will be using data provided by the movie, and data provided by the movie’s creators after the fact. In the scene, the robot CASE tells us that the rotation of the Endurance is 68 rpm (rotations per minute). Alternate information provided by the movie creators tells us that the Endurance’s ring diameter is 210 feet. (http://www.space.com/27694-interstellar-movie-spaceships-infographic.html) Using this information we can calculate the velocity of the Endurance, and subsequently the necessary velocity for McConaughey’s shuttlecraft (a small and maneuverable Ranger) to achieve, and, using that information and the measurements of the Ranger, we can calculate the gs.
I was able to estimate the width of the Ranger by using a to-scale image that I found. (http://www.space.com/27694-interstellar-movie-spaceships-infographic.html) Knowing that the ring diameter is 210 feet, I calculated that the width of the shuttlecraft is approximately 22.4 feet (6.8m). I confirmed that this is more or less accurate while re-watching the movie by seeing the size of the shuttle in comparison to both the actors and the other spacecrafts.
Solution
Using the math and formulas shown below, I calculated the experienced gs as 34.69 m/s.
Reflection
Using the math and formulas shown above, I calculated the experienced gs as 34.69 m/s. This is, of course, physically impossible to endure, much less stay conscious during. I was immediately taken aback by my calculations and used a website to check my results (http://www.artificial-gravity.com/sw/SpinCalc/). It confirmed the numbers that I got, which only confused me further. How could the creators of this movie make such a massive mistake? I expected the numbers to be somewhat off, but to have a character remain conscious while experiencing a sustained 34.69 gs is so out of the realm of physical possibility that I’m disappointed in the results of my calculations.
I looked through the numbers I had initially, and I only used one piece of information not provided by the film or it’s creators — that the shuttlecraft diameter is 6.8m. However, this was based off of an official to-scale diagram (http://www.space.com/27694-interstellar-movie-spaceships-infographic.html), which means that while it might be off by a couple of feet, it’s not inaccurate enough that it would throw off the results to the point of physical impossibility. To put the results into perspective, a pilot that has experienced high-g training can endure about 9 gs before passing out (http://gizmodo.com/why-the-human-body-cant-handle-heavy-acceleration-1640491171). There are even videos online of people taking g-force tests, and they can barely stand a sustained 8 gs (http://www.businessinsider.com/how-pilots-survive-inhuman-levels-of-g-force-2014-11). Dr. John Stapp experienced 45.4 gs during his experiments, but only briefly, and he suffered lifelong ocular damage due to it. The 34.69 gs that McConaughey’s and Hathaway’s characters endured was for the entire duration of their reconnection with the Endurance (which I timed at a whopping 50 seconds), and McConaughey’s character not only stayed conscious during it, but piloted the spacecraft, demonstrating that he could still see and think.
In conclusion, Matthew McConaughey’s character should be dead, and despite the number of scientific inaccuracies in this movie, I find myself disappointed by there being yet another one.
