re: 3 Body Problem - Netflix

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1. The nano-fiber sail ship. It needed a thousand nuclear detonations to reach 1% light speed correct? How would they have placed let’s say the last 200 or so warheads so far out so quick? At that point where the sail ship would be and how fast it was moving would have taken normal propulsion well over a decade to get there to put the warheads in place. Didn’t make sense to me.

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They wound up only getting 300 warheads, which is why they had to reduce the mass of the capsule so much. That said, it’s an interesting question. Using some pretty big assumptions:
- Assuming ~17 km/s capsule velocity at the end of the conventional burn
- Assuming linear acceleration with each successive detonation
- Assuming the warheads are evenly spaced
- Assuming ~10 seconds between the first and second detonation

.. then the capsule’s velocity would increase at roughly 10 km/s with each detonation, putting it just over 1% speed of light after 300 detonations. After the first detonation it would be traveling at roughly 27 km/s, and would travel 270 km total between the first and second warhead. 270 km/warhead * 300 warheads = 81,000 km total travel distance.

That’s actually… not that far. Earth is 150 million km from the Sun. Using the same 17 km/s post-burn velocity for the warheads, it would only take about 80 minutes for one of them to travel 81,000 km. Of course, there are other considerations:
- The warheads have to decelerate, which will increase their travel time.
- The acceleration after each detonation probably isn’t linear. So the capsule velocity probably increases by more than 10 km/s after the first detonation.
- I didn’t rewatch the scene to check the time between the first two detonations.

I actually think the bigger technical issue would be the precision required to position each warhead in the exact location required to pass through the hole on the sail. I think a more realistic failure mechanism would have been a warhead that barely missed the hole and collapsed the sail rather than a failed cable connection.

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Also the name of the show. Is that just a reference to 3 Suns in the system the aliens reside in?

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It’s a reference to the classical physics problem that the San-Ti face as a civilization. There is no known mathematical solution for the movements of objects in a 3-body system, due to the chaotic way in which the gravitational fields interact. Here’s an image from Wikipedia that sort of illustrates the issue:

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then the capsule’s velocity would increase at roughly 10 m/s with each detonation, putting it just over 1% speed of light after 300 detonations. After the first detonation it would be traveling at roughly 27 km/s, and would travel 270 km total between the first and second warhead. 270 km/warhead * 300 warheads = 81,000 km total travel distance.

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Wouldn’t it be gaining speed after each explosion and covering more distance exponentially? The last 50 or so detonations would be much further apart if we are figuring 10 seconds in between detonations. Or the detonations if kept at the same distance apart would begin to be close to simultaneous.

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What exactly is the issue they are facing? Is the chaotic gravity going to eventually rip their planet apart?

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They show it in the VR game. Flash freezing, flash heat and yes eventually, one of the suns will consume the planet most likely. The issue is that they can't plan or do anything because they don't know when the next extreme weather event will hit. 5 years, 5 minutes, 5 seconds.

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What exactly is the issue they are facing? Is the chaotic gravity going to eventually rip their planet apart?

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So the issue is that their planet’s “orbit” (if you can really call it that) around the 3-star system is chaotic. The stars are moving chaotically relative to each other, which causes the planet to wander somewhat randomly through the stars’ gravitational fields.

This presents two major problems:

1. Their civilization keeps getting wiped out due to the unstable orbit - in one era the entire planet freezes because it’s too far from the stars, while in another era the planet gets covered in firestorms because it’s too close. Then there’s my personal favorite, the situation where gravity inverts due to a syzygy (the three stars align, causing their combined gravitational pull to exceed the normal gravity at the planet’s surface). Every time they get wiped out, they have to rebuild their civilization. Hence the slow rate of technological progress that they mentioned. Colonizing a habitable world in a stable orbit will allow their civilization to thrive without the constant resets.

2. At some point, the chaotic orbit will cause their planet to crash directly into one of the three stars. This will wipe them out for good. Since the movements of the stars/planet are unsolvable, they don’t know whether it will be next week or a a billion years, but they know it will happen.

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Why couldn’t they just help guide the probe where it needed to go?

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I mean they’re 4 light years away…

And it wasn’t actually a guidance issue anyway, at least as depicted on screen. It was a mechanical failure.

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It seemed like they had control over most all electrical components on earth. And that was pretty far away too.

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Because the sophons are on earth, not in space.

Are you sure you watched the right show?

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Second. I don’t think I understand the headset VR “games”. At first I thought it was the aliens tasking the humans to solve a problem they couldn’t inside a game scenario. Are the just for communication or do they have a larger purpose i’m just not seeing.

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vr headsets were tech trisolaris shared with a faction of humans that supported the aliens as overlords basically.
in the books the vr sets were more to help recruit - more like screening for 'like-minded' folks, and for some communication purposes. a good vehicle to understand the depth of the problem trisolaris faces.

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So the wallfacer stuff. They have to come up individually with a way to fight the aliens but never talk about or act on it until it’s time to put it in action? How does that work? What if something needs to be constructed? Someone explain this to me.

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they are basically little dictators appointed by an international body that don't have to explain anything they are doing unless its excessively resource consuming without directly contributing to progress of the mainstream defense plans. they are allowed (and enabled/supported) to do pretty much anything that isn't a war crime or crime against humanity. A wallfacers plan needs to be a secret.
if something needs constructed, good. its part of the wallfacer's plan. even if it seems like nonsense, resources are mobilized to achieve the wallfacers request.

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they are basically little dictators appointed by an international body that don't have to explain anything they are doing unless its excessively resource consuming without directly contributing to progress of the mainstream defense plans. they are allowed (and enabled/supported) to do pretty much anything that isn't a war crime or crime against humanity. A wallfacers plan needs to be a secret. if something needs constructed, good. its part of the wallfacer's plan. even if it seems like nonsense, resources are mobilized to achieve the wallfacers request.

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Gotcha. They just can’t reveal the ultimate goal of the plan. They can have all the set pieces in place just not say what they will ultimately do.

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Thanks for this. This clears up another question I had. Considering how devastating these “orbit” issues are how do any of them survive to start over? Or is that a big spoiler reveal?

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I haven’t actually read the books, so I couldn’t spoil anything if I wanted to.

My assumption was the real San-Ti did something similar to the “dehydration” process we saw in the video game.