The Simulation Problem

(No, not this)

I’ve been struggling with this problem for a while now every time I sit down to start playing KSP. As you may know, I am a huge space enthusiast, and a stickler for realism when it comes to portraying space and science topics. Then, of course, I also like playing fun video games. So I’m fundamentally at war with myself when I ask myself: how much realism is enough?

The key here is not striving for realism, but making it feel realistic. This means simulating what I know, and glossing over that which I know nothing about. Yes, this is lame. Additionally, there are some things that take far too much effort to simulate realistically — engine physics, weather patterns, n-body gravitation, physiology.

This problem has been eating away at me enough that I haven’t actually been able to play KSP. I tried a variety of different play styles, but ultimately I got stuck on one problem: I wanted my rockets to be as small as possible, and to take the optimal ascent route.

As I began researching this problem, I realized it was not trivial. In fact, planning an ascent path is quite complex, and the equations have a large number of parameters. Another compounding factor was that there is really no good documentation on the internet about ascent patterns. I’m not sure if this is because that information falls under some sort of ITAR restriction, or just because nobody is interested in it. I wasn’t even sure how to start thinking about it. I knew there was something called a “pitch-over maneuver”, but how does it work? Do they pitch over at a constant rate starting at some altitude, or is a more complex function? Are there multiple pitch-over functions? I could find nothing that answered this.

The second problem was that it is not easy to simulate rocket ascents. You have to account for the curvature of the Earth, so it is not a ballistics problem but a set of differential equations in a polar coordinate system. I tried some basic solution in both Scilab (a free version of Matlab) and in Python, but in both cases the complexity of the problem became so great that I threw up my hands before reaching a satisfactory solution. I mean, it’s hard enough if you consider one stage, but once you consider that a rocket can have any number of stages, the design space spirals out of control.

The design feedback loop

This problem would not stop bothering me. Every time I sat down to play KSP, I realized I was sitting down into a self-imposed math nightmare. Then after that nightmare was solved, I would still be stuck with a inability to truly simulate all the aspects of spaceflight I wanted to simulate, at least not without a lot of work making my own mods.

The moral of the story is: you can’t trust the system. don’t mix realism/math and videogames.

(There is another corollary problem, which is that Reality Is Unrealistic. We have these notions of how phenomenon look drilled into our heads by TV and movies, but the truth is often different and less COOL. Unfortunate that we have been trained to have that heuristic for coolness. TV Tropes says it best. An interesting example is Star Citizen, which shows the ship engines as firing all the time — even when they are off in the physical simulation — because it “looks cool”. Sigh.)

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Interstellar: First Impressions

Don’t worry, I haven’t come here to moan about scientific inaccuracies. In fact, I’m here to analyze why I liked Interstellar in spite of it’s inaccuracies. And boy were there problems with this movie. There were bits that felt way off key, like the exploration of love as a transcendent metaphysical bond. There were moments when I was jarred from immersion, such as the Endurance falling out of orbit when Mann crashed the Ranger into it, or the frivolous astrogation (“If we slingshot around this neutron star here…”), or LITERALLY EVERYTHING ABOUT THE BLACK HOLE.

Honestly, Interstellar does one type of science fiction well – using speculative science and technology as a foil for exploring contemporary issues (like the changing of textbooks to say the moon missions were faked. That was an interesting addition). For the first half of the movie, I thought it was pretty hard sci-fi, but I eventually realized it was a little bit softer; overall, it fell somewhere between Star Trek and 2001 (I know, not a very helpful range). So my intense desire for scientific accuracy fell by the wayside.

It focuses on a wide range of topics: man’s relationship with nature, the need for an exploratory drive (and the fragility of that same drive as a cultural artifact), the nature of time in human relationships, and unfortunately something about love and gravity. Because it hit this wide range of topics, it seemed a little unfocused, although the movie was long enough to say something meaningful about each.

I might be giving the movie a more generous pass because it looked and felt fantastic. The range of sound was stupendous, and the use of sound was spot on. The movie does not twist itself for sound, sound plays to the movie. What do I mean by this? The rumble of the engines overpowers dialogue, non-diegetic sound abruptly cuts off with the end of a transmission, and Matt Damon gets blown up mid-sentence. And, of course, external shots of the spacecraft have no sound, and inside the spacecraft you can hear the thump of the thrusters. I was a little disappointed at how quite the inside was when the engine were off, though. By all accounts, space habitats are quite loud due to the constant fans and other machinery that make the space livable.

I feel like much of the movie walked the line between freaking awesome and too unrealistic. For instance, the giant waves on the first planet. Sure, there were huge tidal forces. But aren’t waves formed by wind, not tides? Also, why wasn’t there a huge back current in the spaces between them? Whatever, this is a severe case of Fridge Logic. Oh and the bit where everyone died from the black hole’s radiation and tidal forces (hint, this didn’t actually happen). I enjoyed all the graphics of the spacecraft though, and I found it very interesting to be able to identify what elements came from where (both actual and concept designs).

The biggest part of the movie that was completely unrealistic was the black hole, but this is OK. One of the points of speculative fiction is to change one thing about the universe and see how it plays out. In the case of Interstellar, the change was that gravity is actually magic. Basically. So you can’t fault them for having a magical black hole.

But the ending was very awesome, although I almost died from the whiplash. Like 2001, the movie just suddenly decided to go all trippy on us. Which I didn’t mind. I totally saw the whole “the 5th dimensional beings are actually transcended humans from the future” thing coming though. I also have a kickass theory about that part: the robot talking to Connors in the black is actually the 5th dimensional humans communicating with him, not the robot.

Ultimately the best way to describe Interstellar is that Gravity and Inception had a baby, and it didn’t inherit the awful movie gene from Gravity. So go see it.

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