- Bionics: Johnson is basically saying that we have seen no evidence that a superhuman bionic man/woman could be created. He mentions the increasingly sophisticated use of prosthetics, but is correct in noting that there are weak spots in that chain, and thus someone with a bionic arm won't really be guaranteed any advantage unless they become one of them full-replacement cyborgs from Ghost in the Shell. I'll admit that SF has probably gotten a lot of this wrong, but there's much more to bionics than just superhuman beings. In a more general sense, bionics is about applying natural biological systems and methods to the engineering of electronic or mechanical technology. And in general, this is something we've already done a lot of (for instance, velcro and lots of flight related innovations derived from birds). Even in terms of medicine, stuff like cochlear implants are rapidly approaching the point where the deaf can hear better than unmodified humans (there are, of course, other drawbacks to this). I know nanotechnology is used as a form of magic in some movies, but there is a ton of potential there. And something like a Respirocyte could theoretically result in "superhuman" powers simply by increasing the amount of oxygen stored in red blood cells. So no, I don't see the bionic man or woman anytime soon, but I don't think it's an unreasonable topic for SF.
- Uploading, or cloning for that matter: Johnson notes that this isn't impossible, just that they're also not "any kind of ticket to immortality for the simple reason that neither an uploaded version of your mind nor a clone with all your memories is you: they are both copies of you". This is an excellent point, and I do believe he's very right. While I'm willing to go along with the ride in a book like John Scalzi's Old Man's War, I seriously doubt the subjective experience would be anything like what Scalzi describes (he handwaves the whole thing by explaining that consciousness is transferred, so it's like a cut-and-paste, as oposed to a copy-and-paste - there's nothing left in the old body. I can see how that sort of thing would be appealing to people though.) Interestingly, Scalzi proposes something completely different in The Android's Dream, where the artificial consciousness is most definitely a copy (and we're never entirely sure how good that copy really is). Anyway, Johnson does wonder why anyone would even want to do such a thing, and I do take a bit of an issue with that. I'll expand on this later in the post, but interstellar space travel seems much more hospitable to some sort of electronic being than it does to biological lifeforms (again, more on this later). Another reason, assuming that the artificial construct can sustain creative thought, it might be nice to keep some folks around after they are gone. Maybe that would be a disaster - maybe Einstein would be a tremendous douchebag if he were still alive in mechanical form today, but it's probably something worth trying. In the end, I certainly wouldn't call this an unquestioned assumption. There exist lots of counter-examples, including the recently reviewd Diaspora, where artificial consciousness seems to have lots of advantages over biology (more on this in a bit).
- Sensors: I completely agree with Johnson here. The non-trivial challenges to sensors are numerous and I don't see them ever working the way they're portrayed on tv or in movies (books tend to be better, but still).
- Space Combat: Another one I mostly agree with, especially given the way it's portrayed in most SF. This is a topic already covered on this blog (and others mentioned my post) years ago, so I'll leave it at that. I do think there's a fantastic movie to be made in the mold of The Enemy Below, but in space and with realistic physics (with some handwaving around the energy and motivational aspects of the whole thing - it could be entertaining, but it probably couldn't be wholly accurate).
- Sol III: Quite frankly, I don't think I've ever seen this one before. The convention of naming the star, and then each planet around the star getting a number (i.e. the eighth planet orbiting the star Omicron Persei is referred to as Omicron Persei 8) does seem common, though I don't find it all that troubling. I can see how it would be a pet peeve of someone though.
Matthew Johnson lists out several Unquestioned Assumptions of Science Fiction. It's an interesting list, though it suffers from the same problems all lists suffer from: I don't agree with some of them, and I think there are some rather notable omissions. So let's get started: