Do you really think the electric car can replace the combustion engine?
Tom Hale, NEW YORK CITY
Absolutely. I really do think we're headed toward a future that is 100% electric. Within 20 years, the majority of new cars manufactured will be pure electric. It'll take another 10 or 15 years beyond that for the fleet of existing cars to be primarily electric because it takes a while to switch out things.
What is Tesla's greatest challenge in terms of convincing consumers that an electric car is the best option?
Michael Brown, BOSTON
At this point, we don't have a lot of difficulty doing that. In the beginning, people didn't know what to expect. How do you charge it? Is it safe? But these are not huge questions anymore. These days, since we're only selling a roadster, our problem is convincing people to pay $100,000 for a car.
How come you're so damn smart?
Alex Arthur, LONDON
These are great questions! A lot of times I get asked, How come you're so damn stupid? I think it's got to be some combination of nature and nurture. Having a father who's an engineer is definitely part of it.
Were you considered a geek in school?
Ju Huang, STAMFORD, CONN.
When I was a kid, I would just walk around reading books all the time. And I was also the youngest kid in my grade, so I was quite small. I was kind of a smart aleck. It was a recipe for disaster. I'd get called every name in the book and beaten up. That was my schooling experience.
Did you ever doubt that you were going to succeed in your high-risk enterprises?
Anirudh Joshi, MELBOURNE
Absolutely. I always knew that there was a chance of failure in all my endeavors. But I felt that they were important enough that I had to try, even if I thought the probability of success was less than 50%.
Is there a technological limit to what you are capable of creating?
Patrick Scott, WASHINGTON
As long as it doesn't violate some law of physics or economics, I guess there's ostensibly no limit. One thing I know I could get right, though it sounds mundane, is to apply aerospace-engineering techniques to create a double-decker freeway with prefabricated, high-strength metal sections that are dropped into place to double up the lanes so you don't have traffic. I've had plenty of time to contemplate it on L.A. freeways.
Do you even come back to South Africa anymore?
Marshall Lambert, DURBAN, SOUTH AFRICA
I was born and raised in South Africa. But my brother and sister are in the U.S., and most of my cousins are in the U.S. Most of my family is here. I was hoping to go back to South Africa for the World Cup, but when I had the Tesla IPO, I couldn't go.
What advice would you give to young people in developing countries who want to be entrepreneurs?
Prakash Shrestha, KATHMANDU, NEPAL
Just go and do it. Try to get together a group of people to do something useful. This may seem like an obvious thing, but often people will organize into a company that doesn't produce anything useful.
SpaceX was founded with the goal of making humanity a space civilization. Are you hoping to see that?
Erik Kulu, TARTU, ESTONIA
If I live for another 40 years, then yes. The technological breakthrough that's necessary for that would be a truly reusable rocket system. That's so critical to lowering the cost of transport to the point where most people could go to space.
What's it like to work with NASA on a rocket project?
Todd Feltner, HAZARD, KY.
It's been great. They've been incredibly helpful to [SpaceX] as advisers, and obviously they're our biggest customer. There's definitely some resentment within certain quarters of NASA, but there's also enormous support. One shouldn't think of NASA as monolithic.