Danny Hillis registered the third domain name on the internet. You read that correctly — the third. In today’s talk, given at TED2013, he shares what a different world the online community felt like at that point in time.Danny Hillis: The Internet could crash. We need a Plan B To underscore the point, Hillis brought a book onstage with him. It’s the ARPANET Directory, a list of every person who had an email address in 1982.

About the size of a high school’s Parent-Teacher Association directory, Hillis says that the heft of the book makes the online community of the time seem “deceptively large.”

“There’s actually only about 20 people on each page — because we have the name, address and telephone number of each person,” says Hillis, thumbing through it. “And everyone’s listed twice because they’re there once by name and once by email address.”

He continues, “There were only two other Dannys on the internet then. I knew them both.”

When Hillis picked his domain name, Think.com, the only options that were taken were BBN.com and Symbolics.com. It occurred to Hillis to make some additional selections, but he felt that would violate the take-only-what-you-need ethos that permeated the internet then.

Danny Hillis: Back to the future (of 1994)“I thought, ‘There’s some really interesting names out there. Maybe I should register a few extras just in case.’ But then I thought, ‘Nah, that wouldn’t be very nice,’” he remembers. “That basic feeling of trust permeated the whole network. There was a real sense that we could depend on each other to do things.”

Hillis’ point is that trust was built into the technical protocol of the internet. While that was fine when it existed on a small scale, now it includes billions of users and an unquanitifiable amount of machinery and infrastructure. The entire system isn’t just vulnerable to attack — it’s even vulnerable to mistakes. To hear why Hillis thinks we’re setting ourselves up for a disaster, perhaps one even bigger than the financial meltdown, watch this talk. It’s a bold call for us to make a backup system should the Internet crash. A must-see for anyone who has hopped online today. Which, naturally, includes you.

Watch the talk »

Want to take a closer look at the ARPANET Directory? Here is a snippet view in Google Books. And, it’s searchable. In fact, here is Danny Hillis’ entry.