Geoffrey Landis—NASA scientist, hard science
Nick Beckstead—Research Fellow, Future of
Humanity Institute at Oxford University; Trustee for the Centre for Effective
Purpose of the call: I
contacted Dr. Landis to learn about the feasibility of space colonization
(especially interstellar colonization) and who the most informed people on that
Why this person:
Anders Sandberg recommended that I speak with him. According to Wikipedia, Dr.
Landis works for NASA on planetary exploration, interstellar propulsion, solar
power and photovoltaics.
We discussed Dr. Landis’s views about the feasibility of
interstellar colonization, the main potential show-stoppers that might make
interstellar colonization impossible, and other informed people on these
issues. We discussed making machines that continue to function for long
interstellar voyages, building ships that humans could survive on for a long
time, developing advanced power sources, finding habitable targets,
interstellar matter, radiation, and the will to do it. In Dr. Landis’s view,
interstellar travel will be extremely difficult, but it’s definitely possible
These notes were
compiled by Nick Beckstead and represent the major points made by Dr. Landis in
Do you believe that, eventually, interstellar colonization will be possible
if people have the will to do it?
Dr. Landis believes that interstellar colonization will
eventually be doable.
Some aspects of interstellar flight will be technically
extremely difficult, but it is definitely possible in principle. The basic
physics is straightforward.
We are just beginning to get a statistical sense of what
other planets in other solar systems are like. We don’t currently have a good
sense of how many of many of these solar systems are habitable or could be made
Why might space colonization (especially interstellar colonization) be
impossible? (Alternate framing: Imagine you learned that space colonization
wasn’t technologically possible for us, even in principle. In your mind, what
are the most plausible reasons that could be true?)
There are many unknowns. Some potential challenges include:
machines: Interstellar colonization may require making machines that will
work for hundreds, thousands, or tens of thousands of years. Few machines can
do this now, but perhaps appropriate repair systems would solve the problem.
This is something that has not been done, and it’s not clear that it could be
survival on a space colony: It hasn’t been demonstrated that people can
live on a space colony, and someone might be skeptical for this reason.
source: Enormous amounts of energy will be required, and it might require
fusion power. (Some other methods have been proposed as well, including systems
using lasers and particle beams.) But fusion power isn’t something we’ve
achieved yet. It’s plausible that we will, but perhaps we won’t.
potentially habitable target: Perhaps we won’t be able to find appropriate
targets. A random planet probably wouldn’t work. It isn’t at all clear yet that
there will be suitable targets. Terraforming might be a solution, but its
feasibility hasn’t been demonstrated. Alternatively, there could already be
life on other planets. New pathogens could be a major obstacle for people who
attempt to colonize other planets.
matter: There are good theoretical reasons to think there isn’t much
millimeter-sized gravel in interstellar space. But if there are sand-sized
particles, that would be a challenge for interstellar travel at relativistic or
near/relativistic speeds. Shielding may be a solution to this. Alternatively,
if interstellar travel must proceed more slowly, some possible solutions would
include (i) a generation ship, (ii) freezing people and re-animating them upon
arrival, and (iii) travelling with machines or uploads, possibly creating
biological humans upon arrival.
This looks like a problem that could be addressed through shielding. Dr. Landis
believes this problem can be solved by creating a strong enough magnetic field.
do it: Given the large costs and long time involved with space travel,
would people be willing to contribute the money and effort?
There is a lot of diversity in the world, and
Landis’s intuition is that enough people would want to do it. A possible issue
is that because it might require so much energy to do interstellar
colonization, anything that could produce that much energy could probably be
weaponized. Conceivably, there could be opposition from a larger group of
people uninterested in space colonization to creating something that could be
used to create a dangerous weapon. Alternatively, people might develop the
energy source in order to make a dangerous weapon, and that might be co-opted
for interstellar travel.
In 1968, Freeman Dyson looked at the economics
of interstellar colonization, and it was prohibitively expensive. But he
pointed out that there has been a long history of exponential growth in
economic productivity and energy production. If these trends continue long
enough, interstellar colonization will become much more affordable. On the
other hand, exponential trends will not last forever.
Dr. Landis said he could probably think of more potential
obstacles if he thought about it.
There’s a burden of proof issue that comes up with many of
these issues. When it’s physically possible to do something but we can’t
currently do it, does the burden of proof lie with those who would argue that
we’ll eventually develop the capability to do it, or the people who think that
we never will? There are people on both sides of the issue, but Dr. Landis
takes an intermediate stance in many of these cases. It might be feasible, but
we haven’t yet proven that it is.
I asked about lack of nitrogen as a possible obstacle, but
Dr. Landis assured me that nitrogen is abundant enough that this wouldn’t be an
If interstellar colonization is impossible for some unknown reason, how
surprising would that be?
It’s possible that there are unknown obstacles. Most of the
obstacles we’ve discussed seem like they could be overcome. If they can and
these are the only obstacles, that makes the Fermi Paradox more puzzling.
Someone could argue that this suggests that interstellar colonization is
impossible for some unknown reason.
Who are the most informed people on the question of the in-principle
feasibility of space colonization (especially interstellar colonization)?
In no particular order,
The Icarus Institute
The 100 Year Starship
Les Johnson and his Tennessee Valley Interstellar
The main classic is The
Starflight Handbook: A Pioneer's Guide to Interstellar Travel by Eugene
Mallove and Gregorty Matloff. It was written in 1989 but has held up well.
What is the range of opinion among these people? Who are the most credible
people arguing for in-principle feasibility? Who are the most credible
The people in the above groups would probably have opinions
that are generally along the same lines as Dr. Landis. Some would be more
optimistic, and some would be less optimistic. They would generally agree that
space colonization is possible in principle, and most of the disagreement would
be about how hard it is.
Most people at NASA generally haven’t thought deeply about
It’s hard to think of notable pessimists. Charlie Stross
wrote a good essay arguing for pessimism about space colonies, and he might be
a good person to talk to. (Nick raised Stross as the most credible pessimist he
was aware of.)
When thinking about interstellar colonization in the very long run, do you
imagine humans travelling long distances in spaceships, or something more like
von Neumann probes?
Dr. Landis would consider all of the following:
Flesh-and-blood humans who make it all the way
within their own lifetime (this is more feasible travelling at high speeds
and/or slowing down human metabolism)
A generation ship
Freezing people and re-animating them upon
Travelling with machines or uploads, possibly
creating biological humans upon arrival
Other “exotic propulsion” possibilities
Questions I sent to Dr. Landis prior to the conversation
Do you believe that, eventually, interstellar
colonization will be possible?
Who are the most informed people on the question
of the in-principle feasibility of space colonization (especially interstellar
What is the range of opinion among these people?
Who are the most credible people arguing for in-principle feasibility? Who are
the most credible skeptics?
Why might space colonization (especially
interstellar colonization) be impossible? (Alternate framing: Imagine you
learned that space colonization wasn’t technologically possible for us, even in
principle. In your mind, what are the most plausible reasons that could be
When thinking about interstellar colonization in
the very long run, do you imagine humans travelling long distances in
spaceships, or something more like von Neumann probes?