In 2000, personal computers were becoming faster fast—something like five times faster every five years. This was a trend that had started no later than 1985, and people had got used to it. They felt this would continue to eternity; that if you needed a faster computer, all you needed to do was wait a while and technology would deliver it.
In that year, while I was studying computer science, it was explained to me that there was a theoretical limit to how fast a computer could be. Large computers had already reached that limit. Personal computers still had some way to go, but it was a matter of a few years until they’d also reach it.
Sure enough, my 2014 computer still feels very fast in 2019. You could barely use a 1995 computer in 2000—if you installed any recent program, you were in trouble. Personal computers stopped becoming faster around 2005–2010, as we knew they would.
Why am I saying all this? Because some people think that the solution to the batteries’ problems—long time to charge, small specific energy—is to wait until technology makes them better. But current technologies have theoretical limits; and new technologies are unproven.