17 thoughts on “Alien Stellar Engines”

1. Back when the Gamma Ray Observatory’s BATSE instrument was first producing data the until then undetected Gamma Ray Bursts caused quite a stir as they were not predicted.

   We were students and offered to the scientists the hypothesis that these were warp signatures of advanced alien races. We got a lot of chuckles for it.

   1. … the until then undetected Gamma Ray Bursts …

      Not quite true. GRBs were first detected by the Vela’s, although the discovery wasn’t published for seven years due to the Vela constellation’s primary purpose.

      http://en.wikipedia.org/wiki/Vela_(satellite)#Role_of_Vela_in_discovering_gamma-ray_bursts

      “On July 2, 1967, at 14:19 UTC, the Vela 4 and Vela 3 satellites detected a flash of gamma radiation unlike any known nuclear weapons signature.”

2. There are a few astronomers already searching for alien megastructures.

   http://www.citizensinspace.org/2013/05/finding-advanced-extrarerrestrial-civilizations/

3. I don’t see how this proposed “stellar engine” would work, however. Seems the light pressure would push the mirror out of position much more rapidly than it would move the star. Am I missing something?

   1. yep, you’re missing gravity

      1. That mirror is a light sail which does overcome gravity. Any gravity, because even the slightest push changes the orbit. I believe Ed is right.

         1. there’s more (or maybe less) to it than an orbiting object. if it was orbiting in the Keplerian sense then the thrust would be changing directions, and result in no net acceleration over one orbital period . . .

            1. How could it not be orbiting in the Keplerian sense?

               Another name for not orbiting is falling.

            2. Then again, orbiting is falling as well.

   2. P.S. the linked article is fairly wrong about how a Shkadov thruster generates force. it is *not* by radiation pressure on the surface of the star. see here for a quickie: http://www.daviddarling.info/encyclopedia/S/Shkadov.html

4. Sir Isaac would have never imagined such an application

   Really? The author is a mind reader and not just any mind either.

5. The idea is kind of interesting. A generation ship on steroids.

6. It would be impossible to build a solid structure of that size anyway. Regarding whether it is possible to make such a structure work: Imagine a Dyson swarm with each unit (or at least a high proportion of them) having a large mirror attached to it. It would be possible to arrange that the mirrors were always pointing in one direction in the sky. This would produce a (small!) thrust from each unit, from light pressure.

   The coupling between this huge array of mirrors and the parent star would simply be gravity. As long as the thrust from the mirror is considerably lower than the gravitational force between the structure and the primary, then the system remains bound. What is needed here is the precise opposite of what is required for a lightsail ship; for one of those, one needs a light structure compared to the thrust.

7. Oops. One more thing: It might be better to generate the thrust another way. Using the sunlight power collected from a Dyson swarm to produce a really big laser beam focused on one small spot on the star might well turn the star itself into a reaction engine.

   1. Deliberately causing a solar flare massive enough to move a star is medically contraindicated.

      1. I never said it wasn’t dangerous 🙂 . However, how big the flare needs to be depends on the timescale on which one wants to work.

      2. is medically contraindicated.

         We wouldn’t be fools! That’s what cool shades are for!

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