My problems with kurzweil lie with regards to the great complexity barrier and the laws of physics. Many individuals assume we'll still be making grand discoveries centuries from now, that may be the case if somehow we couldn't go beyond human lvl intellects. Currently the complexity of our tools, of the information that is now at our disposal is growing exponentially. We've had to become ever more specialized and it's now becoming nigh impossible for any single individual to keep up with much more than just his field of expertise. Even amongst the various fields, it is now only a few that are able to truly excel and dominate their particular field, given the vast amount of knowledge that has been accumulated in most all.
It seems reasonable to suppose that we need to transcend the limitations of "brains as they are" to cope with advances in the amount of information available, and, more importantly perhaps, to be able the clearly visualize complex solutions that today, to the best of us, may be quite hazy.
IF we can significantly exceed the human intellect limitation, and cope with the ever increasing complexity, we should hit another wall, the laws of physics. Unless, revolutionary insights that allow us to basically modify and alter the physical laws to our whims lie in store, we will most likely encounter that with the laws as is, we'll probably reach the limits of the possible technologically speaking, given posthuman superintelligence shortly after, probably a century or two at the most.
That's true, and some things we presently imagine to be practical may turn out to be "practically" impossible, such as the repair by nanotechnology of a hundred trillion synapses, so as to restore, atom by atom, the cryopreserved human brain, with even approximate "atom by atom" fidelity. (As just one illustration of a possible difficulty, information fundamentally necessary to such a standard as "atom by atom" fidelity might be virtually "reduced to noise", even in what appears to be a well preserved, vitrified brain, at least, it is not presently possible to demonstrate otherwise.)
At the same time, perhaps it will be possible to reconstruct even a somewhat damaged brain by nanotechnology to emulate the original, where sufficient memory is conserved to satisfy the practical goals of "reanimation". These realizations, both as to the impracticality of repairing biological brains and the comparative ease and desireability of "uploading" might be of such a complexity that they could only be reached by intellects brought forth in the attempt to generate these emulations, as suggested in an early story titled
Nothing's Impossible.
And, if the very worst were to occur, such that the transhumanist's vision of identity survival by way of information alone (including some measure of genetic information) were to be all that was possible, and uploading "didn't work" either, then perhaps the scenario presented in another early fictional work (
Travelling) might be more realistic:
In either case, personality survival by one standard or another might be achieved (though it might not be recognized as such by many living today). One thing we must take into account is that the standards by which "personality survival" are measured in the future will be those accepted then, not those that are most prevalent now, even among "transhumanists".
I agree with him, that we are in store for a great wave of change, as is. Given that in less than 50yrs we are likely to possess the ability to enhance or trascend the limitations of the human intellect, our tools are also becoming ever better, and our information/knowledge of the world increasing exponentially. What I've trouble seeing is the exponential progress continuing indefinitely without further discoveries hinting at new laws or ways to change the laws themselves. Some of the comments I've heard from kurzweil hint at him believing higher intellects will find ways to get around the laws as we continue to progress, but that is not necessarily the case.
If we get a "spike" that seems to be like an upward leap of almost unmeasuable steepness at some point, perhaps that would be enough specification of a "singularity" for any practical purpose.
Certainly, the central figure in the above story
(Nothing's Impossible) found, looking back historically, that when the entire world "rushed to upload" and they all moved their identities into "hyperbrains" over a period of just a few years, something took place that, looking forward from today, we would be likely to describe as a "singularity".
boundlesslife