Here are the answers I give to this question.
- Carl Sagan's "Cosmos" and/or David Attenborough's "The Living Planet", in which they express pure unabashed enthusiasm for science. These were among a handful of television programmes that I was allowed to watch as a child, aside from the news and "The Muppet Show". (I re-watched "Cosmos" recently and found it a little creepy. He never stops smiling.)
- My grandfather. He was an artist, but he was also a craftsman with an abiding interest in science and engineering. He helped me make some wonderful models in primary school - a slice of clay painted to show the layers of the Earth's interior, dioramas of dinosaurs, a papier mache volcano.
- My mother the librarian. She brought home stacks of books for me, gradually tailoring them to my growing interest in science as I aged.
- The desire to do something "difficult". I found I could get good marks in most academic subjects without exercising the full capacity of my brain. Science, especially chemistry and physics, proved more challenging and hence more fun. We got to build things! Make dangerous compounds! Carry out controlled explosions! What wasn't to like?
- The desire to know more about the way the universe works. There are so many questions. We still have so far to go before we can start exploring our solar system, let alone our galaxy, in person. I want us to survive long enough to be able to make all those wonderful science fiction fantasies we have come true. It won't happen in my lifetime, but I'm happy knowing that in my tiny way, i'm contributing to the process of inching toward that goal.
- The knowledge that I'm doing something that gives people hope for something more than just surviving on this small dirty rock/beautiful blue marble.
Here are the answers I don't give, but are also true.
- The desire to travel. Let's face it, you need money to travel. If you haven't been born to parents who are able and willing to help you do so, you'll have to earn enough to do it on your own. Science, engineering and IT, if you develop your technical skills well enough, allow you to either fund your own trips abroad or go to conferences.
- The desire for creature comforts. I could survive in a tent with no hot water and access only to chemical toilets. I just don't want to, or at least not for longer than a week. Again, this comes down to money. I like my lifestyle. I wouldn't, at this point, be willing to live in a cramped flat trying to scrape a living off one of my less developed skills (writing, photography, painting), which is why they are hobbies.
- It passes the time in a stimulating manner.
The truth, then, is a complicated mixture of selfishness and altruism, but does anyone really want to hear that?
Bonus weird anecdote: My first outreach event this week was at the ScienceAlive centre in Harlow, Essex. A man came up to me afterward urging me to vote Republican "so they won't cut NASA's budget". Given that NASA's budget was at a high of 4.4% during the Apollo mission and has been on the slide pretty much ever since, I don't think that logic works too well. (Also, no.) I won't be basing my decision exclusively on what happens to NASA's budget (Also, NO.) What gives you the right to tell me how to vote after I've given a talk on Cassini at Saturn - and after I've told you our team's funding doesn't come from NASA - anyway? (Did I mention, no?)
It transpired he'd been watching Fox News. May the heavens preserve the UK from the incursions of Fox News. The Daily Mail is quite enough, thankyouverymuch.
Bonus anecdote #2: My second outreach event was at a secondary school in Tottenham, London, to a bunch of Year 9 students (about 14 years old). The organisers neglected to tell me that I wasn't going to be speaking to the top set, but rather to an "aspirational" group. Read: kids with behavioural problems. I figured this out about halfway through my talk, but damn, that was unnecessarily exhausting without the forewarning. It's always harder talking to a disaffected audience. That doesn't mean I don't believe it's worth doing. But at least if I know this in advance, I'm mentally prepared for the two or three people who clearly don't want to be there and aren't afraid to show that they couldn't care less that I've given up my time to come and speak to them.