Indistinguishable From Magic by Robert Forward
The first four chapters of this book are available free online at:
The chapters in this book alternate between essays on possible future tech and SF short stories in which elements of the essays are illustrated. Each essay has a particular topic and the short story which follows it relates to the topic of the preceding essay.
The pairs of essay and story are:
The story centers on a boy and his family who work in scientific / hi-tech professions. The family takes a vacation to visit Mars, which does not seem to be very developed yet as a colony. Much of the story gives me the feeling of a "Juvenile" or "Young Adult" title; however the amount of jargon and concepts might be a bit steep for that age group.
Both the essay and story describe a variety of possible uses of antimatter for generating electricity and propulsion for spacecraft. To one degree or another, some of these are supposed to be within current science and technical capability, assuming a vast initial outlay of funding. For instance, to make cost-efficient production of antimatter for fuel could require a power plant with the capacity to supply electricity for an entire city as just one of the expenses. So, political and financial plausibility are major factors as well as technical issues.
One thing I found interesting about the essay was that among the various Earth-to-space structures discussed Forward does not talk about "space elevators". He seems to essentially dismiss constructing buildings from the surface to orbital heights based on the strength of potential materials. However, at the very end of the article he suggests "space fountains" could be used to help hold up miles-high towers, which might eventually be built up to the top of the atmosphere. He never says whether such towers could provide any benefits for "space elevators" beyond what could be accomplished by the "fountains" by themselves.
There are a number of proposals in the essay. The story only presents the idea of something similar to a “satellite” maintained at the necessary altitude by upward pressure from a ground-based “fountain”.
Most of this section is not about starships as most people tend to think of them. This is mostly about any sort of spacecraft that goes beyond our solar system. Both in the essay and the story, he favors very small, unmanned probes propelled by a “light sail”-like arrangement. There’s more here of technology that is easily accessible given the necessary funding. And as the story suggests, the project could have some return on investment other than knowledge.
Much of this involves ways in which we might counterbalance the attraction of gravity in a given situation. We’re not necessarily talking about flying cars using some new force of nature that is repulsive. For instance, we’re shown how an ultra-dense material could create a gravitation field around itself that, if properly positioned, could cancel out the Earth’s gravity in a limited area between the Earth and the dense object. There are also some more hi-tech ideas.
5) Black Holes
Forward presents the concepts behind black holes and some ways they might be used. In particular, possibilities for microscopic black holes are considered - for instance, Hawking Radiation. He also argues that black holes would be useful to observe in order to extend our knowledge of physics, leading to advances in applied physics.
The accompanying story presents ideas for a different kind of spaceship propulsion, ideas on constant acceleration and portrays some interesting (if not entirely convincing) aliens.
6) Space Warps And Time Machines
A number of space and time “short cuts” are discussed and the issues associated with them. Any possible method of achieving these seems to require extreme measures – and that often means incredibly vast engineering feats. The concepts covered in this section, such as gateways for quick hops from star to star, may appeal the most to readers of galactic SF.
The story “Twin Paradox” struck me as being more about “first contact”, an interesting view of a galactic civilization’s view of newcomers and the “twin paradox” of relativistic time dilation. A nice story, just not about “space warps” and not about “time machines” in the usual SF sense.
7) Future Speculations
Some more extreme speculations on possible future science. These are topics that many scientists prefer to avoid, such as free energy and ESP. Forward says these areas probably are just wishful thinking, but he wants to suggest how science might try to investigate the possibilities.
8) Faster Than Light
This chapter discusses issues in FTL in general. Some methods to get around the speed of light were previously considered in earlier chapters, such as Space Warps. Here, Forward looks directly at FTL communications and travel from various angles.
At least a couple of the SF stories in the book are good as stories (not just as educational tools). However, the book as a whole might be disappointing if read primarily for fiction. The non-fiction material covers many areas of SF-type science. Some of the possible solutions do require science and engineering more exotic than building a Ringworld.
Readers interested in this kind of non-fiction may also be interested in Lawrence Krauss’ The Physics Of Star Trek