 I have a kind of security mindset so I'd noticed that the university had some pin codes on some of the doors and I realised that this code is a four digit code but basically there was no like button to press entered to let you in. You know if the code was 2345 it would let you in whether you typed 1, 2, 3, 4, 5 or whether you typed 2345C so it occurred to me there would be a kind of master code like a single long sequence that included all permutations of four digits. So I wrote a bit of software to create this and printed it out on a single sheet of paper about two-thirds of a sheet and I tested it on another door that I wasn't supposed to have access to. And it worked, I got into the room. What was this room you got into? I've been trying to switch to the first place you wanted to discover. It was a kind of research lab with some parallel computers in it that was accessible to postdocs or something. Are we rolling guys? Yeah, good to go. Okay, fantastic. Let's play some Jenga. I'm not sure what the rules are because it's like... When I played it as a kid I think it was you were only supposed to use one hand or finger and then there were certain things about you know not doing the easy blocks but I literally went from the easiest blocks right away. Okay. So let's jump to hash cash. Was there an aha moment during this process or was it a long arduous process similar to picking a lock? I was interested in cryptography so I happened to have been reading about hash functions and the birthday collision. It's from the phenomena that if you have a room full of people at a party or something there's a question which is how many people need to be in the room before there's 50-50 chance that they're two people with the same birthday. You know you think well it's got to be related to 365 because the number of days but actually it's a lot smaller it's like 23 people or something counterintuitive. 23? Yeah so it's low. It's because the people are like pulling a dice out of a bag or something right so they got random birthdays and as you get more of them there are more potential birthdays for them to collide with. So overall it ends up being a lot less than you'd expect. So anyway with hash functions you could take your time here. Oh wow okay that's there. No I'm not sure that one's going to go. Yeah okay we've got one more left there you go. Besides reading about hash functions and this birthday collision the hash functions are much more permutations than the number of birthdays obviously right so there's you know trillions and trillions of permutations but it did occur to me that you know if you've found such a collision it's like almost computationally impossible at the time particularly you could instantly prove it to anybody and you could instantly verify this enormous amount of work. And then I was also running a remailer which is a way to have privacy for email and there were people spamming through it which was a nuisance and because it's related to anonymity you couldn't block their IP address or email and stuff like that right so I was trying to think about a way to solve the spam problem that didn't involve blocking IP addresses so those two ideas came together and that's where hashcash came from. All that looks risque. There you go. Pressure's on okay. So when people see a finished system like hashcash it looks kind of simple and elegant right in like wow that's pretty simple I can understand that and then their intuition is you know I could have built that. People were trying to make electronic hash systems from hashcash from after that like 1997, 1998 and so on but it was quite hard to do. They didn't get implemented because they weren't fully decentralizable and you know as as Bitcoin came to adopt it done by a massive amount of computers in 10 minutes and that that's obviously a much higher amount of work. I held my breath. One of the nice things about Bitcoin is it's understandable at lots of different levels right you can understand it from a user level or from an economics level it's surprisingly complex to fully appreciate all of it you know including the game theory and things like that. Obviously you're very busy with satellite projects putting Bitcoin in space. Why do we need Bitcoin in space? There's a few reasons. One is because it's cool and you can. Why do I do anything right? Yeah and sure. No shit! Oops. I mean I expect to lose there with the man that is you know building blocks better than most people. And another is that you get some kind of privacy because the receiving is anonymous. Yeah just more more Bitcoin. More Bitcoin. More blocks.