The problem with Kevin Kelly is that he tickles the part of your brain that wants more Richard Feynman, and then this.
This thesis is not new.
Kelly on the Future, Productivity, and the Quality of Life — January 2013
Guest: The basis of my non-worry comes from the fact that I think the idea of universal computation is a myth. And by universal computation is the belief that starting with the mathematical idea called Turing-Church hypothesis, which says any computation is equivalent to any other computation. The full version of that is: Any computation is equivalent to any other computation given infinite time and space.
From my original notes:
There was good stuff, but he also went on irritating rambles I wouldn't wish to consume again.
... The weirdest one is where he challenges universal computation as applying only when infinite in time and infinite in space.
Kelly seems not to comprehend the challenge involved in proving near-equivalency of computational systems (over any ingenious metric) in the finite case. You'd be walking straight uphill in the general direction of Chaitin's constant.
Although there are infinitely many halting probabilities, it is common to use the letter omega to refer to them as if there were only one.
Is lumping omega actually a real problem?
Kelly seems pretty sure that omega comes in flavours marsupial and mammal ("substrates").
Feynman had a supreme knack of not screwing this stuff up, even when he was skirting a field he really didn't know much about. He had such a strong sense of when his own feet were on solid ground, and was extremely clever is turning the discussion to where his solid footing generally carried the day.
Kevin Kelly not so much.