By a strange coincidence, only a few days after I read the proposal for a dark matter engine, I find on the arXiv another, probably even more significant proposal by Louis Crane and Shawn Westmoreland of Kansas State University: Are Black Hole Starships Possible? (http://arxiv.org/abs/0908.1803).
The gist of Crane and Westmoreland’s paper is that physics appears to permit the construction of small black holes that function as power generators and rocket engines of the highest possible efficiency. The technology required to construct and manage such an engine is impressive, but does not appear to be beyond the capabilities of the near to medium future. Our current understanding of the physics is not complete, so better understanding could rule out the construction of such engines, or make them even more difficult to make — or make them easier to make!
A black hole engine can perhaps be fed with mass to keep it going, it can be contained and steered with particle beams, and the energy it radiates can be used to manufacture more black hole engines. If possible, then, the black hole engine appears to be an ultimate technology. You build an army of robots near the Sun, they collect and channel solar energy to a sphere of gamma-ray lasers that implodes radiation to form a small black hole, you feed it and steer it, and then you use the first black hole to make as many more as you like. Each black hole produces enough energy to drive a heavy, shielded, human-crewed starship to relativistic speeds.
Although I am not competent to rule on the feasibility of black hole engines, I am competent to make the following observation. We are living in the critical decades that will determine the long-term future of the human race. In this and the next generation or so, we will probably know if dark matter engines, or black hole engines, or some other ultimate technology is possible for us — or not. We will certainly know if there are other water-bearing planets near us — or not. And we will certainly know if other technological civilizations are traveling in space near us (a black hole rocket creates a rather spectacular high-frequency gravitational contrail), or trying to signal us — or not.
These staggering questions can be arranged into a simple table that determines the alternative futures of the human race.
- If black hole engines are not possible and there are no neighboring technological civilizations, then it is up to us try to keep ourselves going in this one solar system. We have no choice, we must go into ourselves rather than out into interstellar space.
- If black hole engines are not possible but there are neighboring technological civilizations, then we try to keep going in this one solar system, but we also must deal with the consequences of unknown messages (possibly including detailed instructions for building aliens and a town for them from scratch) from beyond. It is our choice how we respond.
- If black hole engines are possible and there are no neighboring technological civilizations, then we have no enemies or competitors, and it is our choice to expand into interstellar space in a movement that makes all past frontiers paltry and produces a human civilization of hitherto unimaginable size and glory.
- If black hole engines are possible and we do have neighbors, then everything is up for grabs. The stakes are so vast we can’t even imagine them. We are instantly exterminated as dangerous vermin (black hole warhead approaching Earth at 99% c can’t be detected in time to stop it from literally shattering the planet); we find ourselves in a desperate war for survival with planets splattering left and right; we are enslaved or exploited by hucksters will millions of years of experience; we join a commonwealth with the wisdom to protect and nurture all members; starfarers are sparse enough to co-exist without war or politics; who knows!…. What happens may be our choice — or not.
By the way, I view the posting by reputable researchers of a paper such as arXiv:0908.1803 as an extremely encouraging sign of the times.