Over at Do the Math, Tom Murphy has an interesting piece about a semi-formal survey of physicists he conducted, and those physicists' opinions about the achievability of various advanced technologies and situations. The physicists covered the gamut from undergraduate majors to grad students to full faculty members. The results are discouraging for those who -- like me -- were promised flying cars when we were young. The surveyed physicists saw self-driving cars being generally available within 50 years. Everything else on the list -- fusion energy, lunar colonies, contact with aliens -- were "out there" tech or applications, and a lot of things -- artificial gravity, warp drive, teleportation -- were in the "not going to happen" category.
Tom provides lots of caveats. He cheerfully admits that he's isn't a survey expert, and may have screwed up the structure of the questions. The choices for time frames are quite broad: less than fifty years, more than 50 but less than 500, more than 500 but less than 5,000, and so forth. The physicists put fusion energy into the second of those categories; both 75 years and 475 years in the future fall into that band. He identifies an "expert gradient" pattern: the graduate students are more pessimistic than the undergrads, and the faculty members are even worse. Tom even references -- in more polite terms -- the old saw that science advances one funeral at a time.
Like me, Tom thinks that our current high-tech society faces a number of difficult fundamental challenges in this century. He takes a more global view than I do. When he considers potential energy sources, for example, he often looks at global needs. I admit to being a lot more parochial than that. I think that there are big chunks of the world that have very little chance of maintaining their current population level and maintaining (or achieving) a high-tech society, so we need to be looking at regional solutions. For example, India will have problems because of its large and growing population.
Africa will have problems because of the lack of existing
infrastructure. And so on.
The good news -- if you can call it that -- is that exotic new science doesn't appear to be necessary for some regions. One of Tom's most interesting posts is the concluding one in his examination of alternate energy sources, an energy matrix that compares those sources on several measures (availability, potential size, etc). Tom's conclusions? Electricity is a solvable problem. A relatively small number of technologies, most already in existence, will probably suffice. And that transportation is a hard problem, as electrification is more difficult (compared to heating/cooling, lighting, etc). I agree with those conclusions for some regions.
One of the regions that I worry about is the US's Eastern Interconnect. Almost 70% of the US population lives in the states that make up that area; in 2010, those states were responsible for 72% of all US electricity generation; and also in 2010, 73% of that electricity came from coal and nuclear power plants (50% coal, 23% nuclear). Over the next 25 years, the large majority of those nuclear plants will reach the end of their operating license extensions, and it seems unlikely (at least to me) that very many of them will be allowed to continue operation. The Eastern Interconnect accounts for 80% of coal-fired generation in the US; any major reductions in coal use to address climate change and air pollution issues will fall very heavily on the Eastern Interconnect. It's not clear to me where adequate supplies of electricity are going to come from.