You’ve also supported the more practical aspects of space exploration, funding SpaceShipOne. What was it like to watch SpaceShipOne take off?
I just remember being so nervous when that thing flew, hoping everything was going to be OK. I had never done anything to put anyone’s life at risk. When you are debugging a program, if it blows up, OK, you get an error message on the screen. If something goes wrong with a rocket, it’s usually... bad. Very bad.

What do you think of Richard Branson and Burt Rutan’s effort to turn SpaceShipOne into a commercial venture?
Burt Rutan is a genius of aeronautic design; I remember him scribbling some designs for the first version of SpaceShipOne that weren’t that far from how it ended up. If you are going to do something like that, he’s one of the few people in the world who could pull it off. Branson’s proposed SpaceShipTwo is still using the fundamental technology from the SpaceShipOne project, just of much bigger breadth. I think it’s going to be great if people can buy a ticket to fly up and see black sky and the stars. I’d like to do it myself—but probably after it has flown a serious number of times first!

Do you support NASA’s plans to send humans back to the moon and on to Mars?
You have to make an argument—which I think people do make with some persuasiveness—that this is about having an aspirational vision. Don’t we get the same data back if we have a little track vehicle running around Mars with a TV camera? I think there is actually a difference, having a human being out there. But I’m always fascinated by technical challenges. Human beings are fragile things, and for the period of time it takes to get them to Mars and back you have dangerous radiation from the sun and the galaxy. We have to think about issues like that. As a species, we’ve always been discoverers and adventurers, and space and the deep ocean are some of the last frontiers. I’m less certain that someone is going to be selling beachfront property on the Martian sea.


"The chance that we are going to pick up the phone and an alien is going to be on the other end is small, but it is certainly worth it."

The projects you have funded so far cover a wide range of fields. What are the criteria you look for?
I ask myself: What are the great questions in science, the knowledge that we are just scratching the surface of? The chance that we are going to pick up the phone and an alien is going to be on the other end is small, but it is certainly worth—on a modest scale, for me—seeing if we can enable some of that research. There are these greenfield areas like the human brain, systems biology, ­understanding how cells work internally, and how the proteins interact inside the cell. That’s an area I’m thinking about. Then there are the global issues we have today: global warming, the environment, and disease. I don’t know that I could make a difference in theoretical physics; that’s basically a bunch of mathematical and theoretical geniuses at different places. I’m not sure how anyone could make them work any faster than they are.

When you fund the Brain Atlas or SpaceShipOne, do you think of them as investments or philanthropy?
I think of them as philanthropy, but then the next thought is, Is there a way to make this thing self-funding? In the case of biological research, it means that you are either going to have to carve out some patents or try to create funding from other foundations or the government. I think we are going to have success with the Brain Atlas because the capabilities that we have demonstrated are pretty unique. But with that project we haven’t taken the route of getting proprietary intellectual property—not that I’m excluding it. Most of the things I’ve ever done, I try to capture some value and keep it going. And my gosh, look at Microsoft. In 1975 it was three guys, and now it’s 70,000.

When you and Gates started out, how ambitious were you?
We knew that microcomputers with software on them could have some impact, and certainly they were cheap. A big part of the success of Microsoft was that every year, the chips our software ran on got faster and cheaper. They doubled in capability every 18 months under Moore’s law. Even to this day, every year they get better and the price doesn’t change. It’s amazing, and that was a huge driver of our success. When we were starting Microsoft, we were thinking if we were really successful we would have something like 35 employees. On the other hand, in the back of our minds we were thinking, “Wow, if a lot of people bought a cheap computer . . . ” We had glimmerings of it.

How did the collaboration between the two of you work in those early days?
We split the programming tasks. I was familiar with the software that ran on mainframes and minicomputers that will let you emulate chips. And Bill bit off some of the really complicated stuff and did a great job architecting the overall design of the Basic program. Bill was always very focused on the external relationships and the business management part of it, whereas I was more attracted toward seeing where the leading edge of the technology was going. So we were a good complement to each other.

Do you guys reminisce about the old times?
Yes, we always have a laugh because it’s hard to explain the incredible level of fun we had. We talk about how Bill would sleep on the carpet at the office. The secretary would come in and see Bill’s feet sticking out of the door. We were very hard-core. Our only recreational activity was going to the movies. And then we would program until two, three, four in the morning and then get up fairly late, go back, and do it again. We just loved it. We had a great time.

In a weird way you and Gates still seem to follow parallel paths. Do you ever talk about entering a philanthropic collaboration?
We are always looking to find some areas of overlap in our philanthropic stuff. We’ve had so much success doing things before; it feels good. Recently we’ve been talking about doing something together on the frontiers of energy.

What are the biggest questions on your mind right now?
The health of the planet, whether it’s ocean health or energy. Should nuclear energy make a comeback? We have an investment in a fusion energy company that is quite interesting.

What kind of fusion research are you investing in?
The company is called Tri Alpha Energy [which finances aneutronic fusion, a process that emits protons rather than neutrons, potentially making it much more efficient than current concepts]. Fusion has been predicted to be just over the horizon for decades now, so whenever you see an interesting alternative approach, you think about it. There has been a lot of discussion recently on fission reactors, and I have been involved in doing some survey meetings recently. I think Bill is intrigued by that too. But it’s really speculative.

So you’ve got computers, sports, boats, space, science, rock and roll. Is there any childhood love you have left to get into?
When I was 7 or 8 I became fascinated with hot rods. I don’t own one. But I’m not as fascinated by them as I am by many other things. So no Model T with the super V-8 and the flames painted on the side. In life, you need to pick your spots.