If you extrapolate from the last hundred years of progress to the next hundred, it's plausible that there will be at least as much technological progress as the

If you extrapolate from the last hundred years of progress to the next hundred, it's plausible that there will be at least as much technological progress as these ideas would require. The problem with such prognostication isn't so much that these things can't happen. It is that unexpected events that will happen first turn the future in a different direction.