Astro2110 – The Solar System

When Cristopher Nolan’s Interstellar hit the theaters in November 2014, I decided to wait for reviews from my friends. My friends, most of whom were pursuing Electrical Engineering and Physics majors, had this to say about the movie after they watched it: “Meh, too many logic holes”. So I skipped the movie; but over the year my curiosity and anticipation grew as I kept hearing positive recommendations from many others. So I picked up the movie when the DVD was released last month.

My verdict: I was disappointed. Why? Because I did not understand the movie. Don’t get me wrong; the performance by Matthew McConaughey and Michael Caine was polished, the cinematography was spectacular, and the CGI was fully convincing. But it was my incomprehension at the science presented in the movie that marred the experience. I was fully aware that the movie was a fiction, not a science documentary. But when you have experts like Kip Thorne, a theoretical physicist at Caltech, as a consultant for the movie, you are bound to expect better or easier to understand justification for the “fictitious science.”

Here are a few of the things in the movie that I could not understand

The worm hole shown as a 3D tunnel

For a brief amount of time, the movie showed the Ranger’s passage through the wormhole as going through a tunnel. Suppose we collapsed space to a 2D plane. Even if we assumed the worm hole to be a 3D tunnel between two points of the folded 2D space, the “tunnel” would become a 4D space in reality, at least according to the movie’s explanation. An instantaneous warp to the other point in the universe, and not 3D tunnel, perhaps would have been more plausible for visualizing purposes.

Visualization of the wormhole concept

Ranger requires booster rockets on Earth but not Mann’s and Miller’s planets

The spacecraft Ranger required propulsion from booster rockets to reach escape velocity when launched from Earth. However, it seems that Ranger did not require any booster rockets to leave Miller’s and Mann’s planets. The fact that the astronauts’ walk composure looked the same as they did on Earth indicated that the planets’ surface gravity is similar to that of Earth. One way to address this discrepancy is to assume that the planets were significantly smaller than Earth. Escape velocity rises with sqrt(m/r) while surface gravity rises with m/r^2, where m = mass of planet and r = radius of planet. Hence, decreasing the radius of a planet for a given mass increases surface gravity much faster than it increases the escape velocity. But then again, does planetary formation allow for such dense planets?

The Ranger spacecraft

Frozen Clouds on Mann’s planet stay afloat despite 80% Earth Gravity

Let us just ignore the first discrepancy: Dr Mann (Matt Damon) reveals to Cooper (McConaughey) that the planet does not have surface. So it is like a Jovian planet? Yet its outer atmospheric conditions are similar to a terrestrial planet? What cannot be ignored is that the solid frozen clouds on the planet are defying gravity. What is holding them up in the skies?

The frozen clouds on Mann’s planet

Time dilation within the black hole Gargantua was only a few decades

We shall simply ignore that as soon as Cooper in his ship came near to the event horizon of Gargantua, differential gravity would have elongated him into a spaghetti. What is also incomprehensible is that even after spending a few minutes inside singularity itself, less than a 100 Earth years have passed: Cooper’s daughter is still alive, probably in her 100s. Bear in mind that on Miller’s planet 1 hour equated 7 Earth years just by being close to Gargantua. Due to the inverse square law, gravitational field strength increases exponentially as one approaches the source. Not even considering singularity, just by being near the event horizon for a few seconds should have caused thousands of Earth years to have passed.

The black hole Gargantua

If you think I am mistaken in explaining the scientific holes in the movie, please feel free to correct me in the comments.

References

http://www.motherjones.com/media/2014/11/interstellar-movie-science-david-grinspoon-inquiring-minds

http://www.quora.com/Interstellar-2014-movie/Why-did-it-take-two-rocket-stages-to-lift-off-the-Earth-and-get-to-the-Endurance-orbit-but-just-Ranger-rocket-engines-to-lift-off-Millers-planet