In the 1920s, a generation before the coming of solid-state electronics, one could look at the circuits and see how the electron stream flowed. Radios had valves, as though electricity were a fluid to be diverted by plumbing. With the click of the knob came a significant hiss and hum, just at the edge of audibility.

As soon as the printing press started flooding Europe with books, people were complaining that there were too many books and that it was going to change philosophy and the course of human thought in ways that wouldn't necessarily be good.

Particle physicists may freeze a second, open it up, and explore its dappled contents like surgeons pawing through an abdomen, but in real life, when events occur within thousandths of a second, our minds cannot distinguish past from future.

For much of the twentieth century, 1984 was a year that belonged to the future - a strange, gray future at that. Then it slid painlessly into the past, like any other year. Big Brother arrived and settled in, though not at all in the way George Orwell had imagined.

I keep track of my kids sometimes with social media. I have to check TMZ every morning to see what's going on, and then at night, I go to bed with Snapchat.

All the trends show that email usage among the younger cohorts of Internet users is declining. Whether it will take five or 30 years for email to go extinct, I'm not sure.

So the major obstacle to the development of new supplies is not geology but what happens above ground: international affairs, politics, investment and technology.

Google is already overflowing with incredibly creative bright groups already working on lots of the software problems of the world.