Watch Live Tonight: The Challenges of Interstellar Flight

If humanity ever travels to another star, the trip could take generations. Such a journey would present serious technological challenges, of course, but the social difficulties of keeping a large population happy and healthy on a spaceship could be no less daunting. Anthropologist Cameron Smith of Portland State University has studied these questions and will discuss the during a lecture at the Perimeter Institute for Theoretical Physics in Ontario that will be broadcast live here on this page.

Smith’s talk, “Interstellar Voyaging: An Evolutionary Transition,” will begin Wednesday at 7 p.m. ET as part of the presented by Sun Life Financial. The lecture will be viewable on this page as well as at . Online viewers can pose questions to Smith by tweeting to @Perimeter and using the hashtag #piLIVE.

spoke to Smith about what it will take to mount an interstellar voyage. Below is an edited transcript of the conversation.

Is it really plausible to discuss a multigenerational space journey? Are we even close to being able to do something like this?

I think it’s a very good idea to start thinking about it now, and to spend a century thinking about the genetics, the cultural implications, the propulsion and designs. I think it’s possible, but I think it should be done carefully. I don’t want to see a brief flurry of interest and then see it flare out—the American moon program did that.

One of your first projects in this field was to research the population genetics of a space colonization journey. What did you learn?

People have proposed that you could send fewer human beings and store frozen eggs and sperm and maintain viability that way. But there are cultural reasons why that’s not so great. I think we should go in populations that are culturally familiar. In evolution, generally speaking, radical changes in the short term are not too typically likely to work. And so I would propose a larger starship with tens of thousands of people aboard and let them sort out the new variety of social and genetic interactions that need to happen as they’re going. Don’t try to invent it all here.

What are the other human evolutionary challenges associated with such a voyage?

We also tend to think of how it’s done in low-Earth orbit, in microgravity, but that environment is so alien to the whole human experience that I don’t think that gravity environment is realistic to think about on a long-term voyage. Even on Mars it’s only one-third the gravity of Earth. You’ll also probably have a different breathing-atmosphere composition—probably higher oxygen content. This has to do with the pressure you have to maintain. So let’s say we have a slightly higher oxygen percentage—what’s the effect on the human body? That’s a big one.

If we could launch an interstellar trip now, would you go?

But it would be easier if I were married. I think it’s a very good project for family people. I’ve stayed by myself, I’m awfully busy, I’ve decided to pursue academic and other things, and I think it would be a lot easier for a person who has a family to consider going. You can still imagine your continuation through your children.

I’m surprised by that. For many people, getting your spouse to agree to go and deciding to put your family at risk could be the main barriers to making the trip.

In fact, I think it’s a moral imperative. To not look at and explore the universe around us, that’s indefensible. People assume the Earth is safe, just because it’s been a great place to live since the advent of farming. But geology shows us there have been five big extinction events in Earth’s history. So I think it’s morally acceptable to send people on these voyages, and I don’t think you’d have any problem finding volunteers.

With the recent movie , and what’s going on in spaceflight now, it seems like there is a lot of popular interest in interstellar travel and space colonization these days. Why do you think that is?

If you’re thinking about doing this, every aspect of life has to be considered, because it’s human populations in a completely new environment. So that’s one reason why it can be quite exciting to people. If we ever have a Mars colony, it’s not a mission anymore. It would just be living out your life. And so we have to have a cognitive shift on how we think about this, from short-term to long-term, and from individuals in space to families in space, and communities and larger cultures.