Sunday, November 22, 2015


Space! The Final Front... wait a moment,

I'm sorry Dave, I'm afrai.... no, not that one,

So, in some ways this movie, Interstellar, reminds me a lot of other space movies we have watched this semester. Though the resemblance is much closer to 2001 than Star Trek. Where Star Trek goes to great lengths to appease fans and Hollywood rather than physics, 2001 and Interstellar went to great lengths to keep the physics intact, with only minor gimme's for Hollywood's sake. Of course, that is ignoring the whole, "Fall into a black hole, discover it is a created 3-D tesseract designed by super advanced humans some indeterminately long time in the future just to make sure Matthew McConaughey got to send a message to his daughter that saved the human species" ridiculousness. (Time paradox anyone?)
But, Kip Thorne worked hard to make sure the movie was as close to physically accurate as possible, and he did a good job. One of the most fascinating parts of the movie to me was the planet referred to as "Miller's planet", after the explorer that landed on it. Orbiting close to the super-massive black hole called Gargantua, there were many oddities about this planet as a result of it's orbit. The first one, is the passage of time on the planet. Being that close to a black hole, the gravity of the black hole causes time to run slower on the planets surface than away from the black hole. According to the movie, one hour on the surface of the planet is 7 years back on earth or on the space ship.
Location of Miller's orbit

In Kip's book on the physics of the movie, he states that in order to have that much time dilation, The planet has to be incredibly close to the black hole. We already knew that, but Kip goes into a bit more of the implications there of. So, in the movie we see the giant waves that seem to circle the planet and pass by any given point once every hour, based on time given in the movie.
These waves dwarf any waves we have ever seen on earth. For comparison, the largest wave seen on earth was 100 feet tall. These waves are estimated at around 4,000 feet tall. So, it seems pretty obvious that these waves are caused by Gargantua's massive gravity, which is why they dwarf our own waves, only created by the gravity of the moon, which is minuscule by comparison. But a good question to ask is exactly how they are formed. Well, the first part of the puzzle is realizing that Gargantua pulls Miller into the shape of a football, like so:
Any one up for some handegg?
As you can see, this causes massive bulges on the planet, which is why most of the planet is only about knee deep with water. However, assuming the planet is tidally locked to Gargantua (which is necessary for the planet to not shake itself apart), why do the waves move? Without the planet rotating, the "waves" would just stay in place, making a really awesome planet wide ocean that is about knee deep at the equator, and thousands of feet deep at the poles. And while that would be awesome, and more habitable than the reality, that's not how the planet is depicted in the movie.

Instead, Kip proposes the planet is tidally locked to Gargantua, but rocks back and forth. If this is the case, then a possible explanation is a phenomena called tidal bores. In essence, tidal bores are what happens when the tide changes rapidly enough or with enough force to create waves that move with the tide. On earth, these are at times spectacular, but rarely devastating or dangerous to those outside of the flow of the water. However, a tidal bore caused by Gargantua's massive gravity, could result in the massive, 4,000 ft tall waves every hour.
Tidal Bore on Earth
Finally, there is an interesting observation that Kip makes in his book. If we make an assumption that Miller's planet was formed while the universe was still young, say around 12 billion years ago in Earth time, then following the time dilation of Miller, then at "present day" when Cooper & co make it to the planet, it is only 200,000 years old. It is interesting to think that they could have set foot on a planet that in the universal sense is incredibly young, and undeveloped. That's some time travel crap right there.

1 comment:

  1. Excellent post! You've really maintained an outstanding blog all semester.