Clarke's third law is largely about fiction. It's a rule of thumb for writers, not a rule for reality.
In reality there are limits; there's no reason to think technology can improve indefinitely. We may still be far from those limits, as e.g. Drexler's books show, but fundamental rules such as "Effort requires energy input" are unlikely to ever change, and it's equally unlikely that most modern scientists would regard limit-tech as being magic.
As for the average guy on the street, he probably considers computers to be magic...
Humanity has existed for a hundred thousand years and civilization for ten thousand and you think two hundred years of the scientific era has us within spitting distance of the end of knowledge? We can't even come up with models that consistently explain what little we're able to observe like gravity at all scales. As long as gaps like that exist we know we're wrong at a fundamental level. We could be as wrong as Newtonian physics or we could be as wrong as a bunch of Flatlanders. There will be limits, but they may be so far beyond our ken our current brains aren't even capable of understanding them.
I think the argument isn’t that we’re in spitting distance of the end but that we can, if you will excuse the metaphor, recognise the distant peak of the mountain representing it.
Even extrapolating Moore’s Law’s exponential growth of x2 per 1.5 years would still take ~200 more years to reach the limits of computation — Improvements to particle accelerators aren’t anywhere near as rapid — so we have a long way to go before we reach the end of experiment even if we improve as fast as possible and have almost no surprises.
Not that I disagree with your general premise that some massive surprise could be waiting for us; I happen to think there is, and I get the impression that it’s totally unconventional in the physics community to say “at least one of GR and QM is wrong, but we don’t have any experiment that tells us which”.
> Not that I disagree with your general premise that some massive surprise could be waiting for us
I hazard that should we find such a surprise, it will be under somewhat extraordinary conditions not commonly found in nature, and quite likely ill-suited for power generation on the nanometer scale.
I’m not a betting type, but if I had to take a bet I would expect it to be ~”and this is how the conditions of the Big Bang can be recreated and exploited to make something that looks like a star but which will exist forever. Also the interior of our fake star is now a new universe 50 billion light years across even though the outside circumference is ten light seconds.”
Not very useful for cell-scale engineering. Might count as “magic”, but the bigger-inside thing is a serious idea for making the Alcubierre drive less unphysical.
We do have that kind of knowledge when it comes to thermodynamics and the limits of computation, though. And Newtonian physics was incomplete, not wrong.
While the law is interesting, it mostly applies to science fiction. We can't presume that said sufficiently advanced technology is physically possible -- in fact, the opposite seems decently likely.
I'd like to think that we have a certain level of understanding of topics like the conservation of energy. We understand that it is possible in theory to liberate enormous amounts of energy from the rest-mass of ordinary matter. However, we also understand that, in general, matter is stable, and this liberation takes place either very slowly, or under extremely energetic conditions. We also understand that building microscopic structures capable of resisting extreme conditions is an extraordinarily difficult engineering problem. Nanostructures that could bring these conditions about? Even more so.
Our level of understanding seems, broadly, a better level of understanding than a 16th century layperson would have of topics like the existence of electromagnetic waves and electricity, let alone the batteries, semiconductors, and software applications of semiconductors which ties them together.
He'll think more or less the same thing that 99% of people in the 21st century think.
That is, very few people know -- or care to know -- how their cell phone works. Those on this forum, of course, do. But, to the average man-on-the-street, its magic.
The difference is that a modern person knows that if they really wanted or needed to, they could find resources to explain how their phone works (beginning with electricity, electronics, programming, etc.)
The 16th century guy would be at a disadvantge for he'd correctly intuit pretty fast that nobody on the planet knows how it works and there is nowhere to get the info.
To be clear, I'm not saying that no magical-ish tech will ever exist in the future. I'm specifically doubting the physical possibility behind the imagined gray goo tech.
In reality there are limits; there's no reason to think technology can improve indefinitely. We may still be far from those limits, as e.g. Drexler's books show, but fundamental rules such as "Effort requires energy input" are unlikely to ever change, and it's equally unlikely that most modern scientists would regard limit-tech as being magic.
As for the average guy on the street, he probably considers computers to be magic...