EDGE 33 January 20, 1998

THE THIRD CULTURE
"INTELLIGENCE AUGMENTATION"
A Talk with Patty Maes
I'm from Europe, I love eating a lot of food that some Americans
would think is disgusting, like brains, kidney, etc. I love getting
recommendations for the kind of restaurants where I can find liver
and rabbits, and so on. I want to get recommendations from other
people whose tastes are similar to mine. This is exactly what these
software agents do.
THE WORLD QUESTION CENTER - III
Pattie Maes, Anne Fausto-Sterling, Stephen H. Schneider
THE REALITY CLUB
Stewart Brand, Paolo Pignatelli, Duncan Steel
(6,545 words)
THE THIRD CULTURE
"INTELLIGENCE AUGMENTATION"
A Talk with Patty Maes
Pattie Maes came to the United States nine years ago to work with
Marvin Minsky and Rodney Brooks at the MIT Artificial Intelligence
Lab. She had received her Ph.D. in AI at the University of Brussels,
and was attracted by Marvin and Rod's more alternative view on artificial
intelligence, and artificial life. After working for the AI lab
for two years she moved to MIT's Media Lab, which is more interdisciplinary
than the AI lab, something that attracted her given that she has
varied interests. She used to be happy just doing research, but
given that her research is finally applied anyway, she realized
that she would only be happy if her work made it into the real world,
and so that's one of the reasons that she started Firefly, a start-up
which sells software that allows Web sites to personalize the interactions
that they have with the visitors of their Web sites. An example
is Barnes and Noble, a Firefly customer.
Barnes and Noble uses the tools to recognize individual people
so that they can provide personalized service to those people. Maes
points out that it used to be the case that many years ago you would
go to the corner bookstore and the owner there would know you, would
know what you have bought before, they would know about your interests
and they could give you personalized service and say, "Hey, did
you know there was a new book by Isabelle Allende?" They know you
have an interest in certain types of writers. She believes that
Web sites will have to provide that same kind of very personalized
high quality service on the Web, because this will be one of the
ways in which they can distinguish themselves.
"If Barnes and Noble on the Web knows me," she says, "knows what
I'm interested in, can help me find the stuff that I'm interested
in, can tell me hey, you've bought the other Isabelle Allende books,
did you know that she has a new book out, or did you know that there's
another author very similar to Marquez, etc., that just published
a new book? If I get that kind of personalized service, even though
in this case it's implemented by an algorithm rather than by the
corner bookstore owner, I'm going to be much more loyal and go to
Barnes and Noble because they give me this personalized treatment,
they recognize me, they greet me, they remember what I've bought
before.
JB
PATTIE MAES has been at MIT's Media Lab as a faculty associate
professor for six years. She also started her own company two years
ago, Firefly Network, a spinoff of the work that she does at the
Media Lab. She remains a director of Firefly, and works there half
a day a week.
"INTELLIGENCE AUGMENTATION"
A Talk with Patty Maes
JB: Let's start with Firefly and work backwards. What are you doing
now?
MAES: I started out doing artificial intelligence, basically trying
to study intelligence and intelligent behavior by synthesizing intelligent
machines, I realized that what I've been doing in the last seven
years could better be referred to as intelligence augmentation,
so it's IA as opposed to AI. I'm not trying to understand intelligence
and build this stand-alone intelligent machine that is as intelligent
as a human and that hopefully teaches us something about how intelligence
in humans may work, but instead what I'm doing is building integrated
forms of man and machine, and even multiple men and multiple machines,
that have as a result that one individual can be super-intelligent,
so it's more about making people more intelligent and allowing people
to be able to deal with more stuff, more problems, more tasks, more
information. Rather than copying ourselves, I'm building machines
that can do that.
We've been using many techniques in this nascent field of intelligence
augmentation. One technique is that you rely on software entities
which we've termed software agents that are typically long-lived,
continuously running, fairly simple, and that can help you keep
track of a certain task, or that can help you by automating that
task, or semi-automating it so it's as if you were extending your
brain or expanding your brain by having software entities out there
that are almost part of you that are looking out for your interests
and helping you deal with multiple tasks.
One of the limitations of our minds as they are now, is that we're
good at doing one thing at a time and keeping track of one thing,
but the nature of our everyday concerns is very different, and we
have to deal with multiple problems and do a lot of multi-tasking
and continuously keep track of all these different things. It's
something we're not good at, something we're not made for. But we
can extend ourselves, or augment ourselves, by having software entities
that are an extension of ourselves and act on our behalf. It can
be very simple things, like a very simple monitor, for example,
that monitors for you whether there's still milk in your fridge,
and that reminds you when the milk is running out, and even reminds
you at the right time, when you are driving past the supermarket
or when you're in the supermarket.
JB: Smart refrigerator?
MAES: I have a two-year old who drinks a lot of milk, so it's
one of the concerns that I have to deal with, one of many concerns.
Instead of having to check every morning and every evening and try
to keep remembering how much milk there is in the fridge, why can't
the fridge do this for me? That's a simple example, but I would
be very happy if that problem were solved and I didn't have to worry
about that. Our lives are full of silly little problems like that
but they matter a lot - - we have to deal with them. To a large
extent these little extensions of ourselves could deal with such
concerns, or could help us deal with them. The digital equivalent
of this, is the monitors that keep track of your stocks or something,
and tell you if a certain stock that you own has been rising more
than usual or down more than usual, things like that. So I have
this vision where we could extend or augment our minds by these
software entities that help us, that know what we care about, what
the problems are that we are trying to solve. Every one of them
may deal with a very specific small problem, and they don't even
have to be intelligent, and they're trivial to build, but I think
they would make a huge difference in our efficiency, the efficiency
of our lives.
JB: What technology is involved?
MAES: The example I gave of the milk is a very simple one. In
other situations it may be something more complicated, like we build
agents that monitor your reading habits, or, say, news
reading habits. They may pick up a certain regularity in what you
read, like maybe you own a lot of Apple stock and you want to make
sure you see every article about Apple, and you read every article
about Apple in the newspaper. That could easily be automated. We
built agents that monitor what you read, keep track of all of that
and memorize it, and then discover patterns that you read
every article about Apple Computer and then offer to automate
that for you and to highlight those articles in the newspaper so
that you definitely won't miss them.
JB: How do you read the newspapers?
MAES: This only works for electronic newspapers. We have prototypes
of these kinds of systems and, you can just monitor what a person
reads and try to infer from that what it is they're interested in.
You can also ask them for more explicit feedback, and ask them,
did you like this article, do you want more of this kind of articles
in the future, or was this something that you didn't like even though
you read it. That's going a step further. It involves the use of
machine-learning techniques. A lot of that kind of work is finding
its way into products like Microsoft's Office 97 where there is
a simple form of an assistant which monitors what you're doing,
which knows about typical patterns of activities that you engage
in and which gives you help which is contextualized, based on data
it has about sequences of action that people engage in when involved
in a particular task.
JB: Are we talking about anthropomorphic assistants?
MAES: Agents are not necessarily personified. It won't necessarily
look like a cute character on your screen there's no reason
nor need for doing that. For example, the Firefly work doesn't have
any kind of personification, and still there is a system there that
helps you in a personalized way. The two are orthogonal issues,
and it's up to a designer of an agent to decide whether it's appropriate
to use personification or not. In most of the work that we've done
at our lab, the agents are not at all personified. In any event,
I'll be happy to anticipate all of Jaron Lanier's comments and talk
about them in the interview.
JB: Debate with an empty chair?
MAES: Jaron and I already had our debate on Hot Wired's "brain
tennis" pages. We've already gone through this whole thing. But
let me continue. I talked initially about very simple agents that
would be completely programmed, like the milk monitor in your fridge;
I talked about agents that can do some machine learning and that
can pick up patterns and offer to automate them. A third approach
that we have been pursuing the most actively is one where agents
are not necessarily smart at all themselves, but what they do is
they allow you to benefit from the intelligence of other people
that have solved the problem that you are currently dealing with.
Take for example the buying of a car. I went through the process
of trying to figure out what car to buy just a couple of months
ago. I didn't know what methods to use, I didn't have a clue about
what car I wanted to buy. I did a lot of research on the Web. The
first problem was finding what Web site was worth going to in terms
of car information, or new car information. Then I had to learn
what the different Web sites could offer me; which ones have good
reviews, which ones give you the information about actual cost and
prices of new cars.
I dealt with this problem for a month or two, and I accumulated
a lot of information about new cars and about car information on
the Web, where you should go first and second and third etc., and
then once I decided what car to buy I also gathered information
about the exact cost of that car to the dealer, what the lowest
price was that I could possibly get away with and how to get the
best deal. I learned about the different dealerships in and around
Boston for the particular Saab I wanted to buy. It's such a shame
that someone else cannot benefit from all that work that I did .
Wouldn't it have been great if something would have recorded some
of my experience and some of what I learned so that then that knowledge
would be available to another person who is going through exactly
the same problem? We are a social species, and we can benefit from
each other's intelligence and each other's problem solving. Very
few of the problems that we deal with, very few of the tasks or
activities that we deal with are completely original in the sense
that nobody else has ever faced that same problem before. Almost
every problem that we deal with is something that hundreds or sometimes
even millions of other people have dealt with before.
It would benefit society if we could more easily reuse the knowledge
and experience other people have gained about problems. This is
one of the ways that we have built software agents - they don't
necessarily have any information themselves about what you do when
you want to buy a car, but what they do is monitor, and collect
a lot of information about people solving problems, and then give
you some of that condensed information and especially patterns that
it finds among many people solving that problem.
JB: But, Pattie, you're not average, and besides, everyone wants
to learn from geniuses.
MAES: Often people want to learn from people like themselves,
or from people that they want to be like, or people they want to
look like, and to some extent this is what these agents do. They
figure out which people you should be drawing from, and they also
gather some of the information, and allow you to benefit from the
problem solving that other people have done when they dealt with
a similar problem.
JB: How do you know who the other people are?
MAES: You may not necessarily need to know, although in some of
our algorithms you can specify the kind of people you want.
JB: Take the example of the Zagat restaurant guides. You assume
that the people rating the restaurants are hip foodies who know
at least as much as you do about restaurants. If you didn't have
that orientation, you wouldn't trust the book and you wouldn't buy
and use it.
MAES: This is a great example because in choosing a restaurant
you don't want a recommendation based on the average of what other
people do, but you want to get recommendations from people like
you. The collaborative filtering software which we developed at
MIT and which Firefly commercializes, does exactly that. We have
a restaurant site on the Web called Boston Eats. You can go there
and tell the system which restaurants in Boston you like, and whether
or not you have very expensive taste or if cost isn't an issue for
you; etc. If a student goes there and tells the system what restaurants
they're interested in they may say they prefer cheap restaurants
because they're on a budget. So you may not want to get recommendations
based on their opinions and they may not be very interested in your
recommendations for more pricey restaurants. In short, you want
to get recommendations from people that have similar tastes as you
do. I'm from Europe, I love eating a lot of food that some Americans
would think is disgusting, like brains, kidney, etc. I love getting
recommendations for the kind of restaurants where I can find liver
and rabbits, and so on. I want to get recommendations from other
people whose tastes are similar to mine. This is exactly what these
software agents do. If you tell the system which restaurants you
like and dislike, and everybody else does the same thing, then the
system can identify who your taste-mates are, who the people are
who have the most similar taste as you do, the people who like and
dislike the same kind of restaurants. The system will only look
at their opinions about restaurants that you don't know to give
you recommendations, so you get recommendations from the people
that like the same kind of restaurants that you like. The agents
themselves don't know anything about restaurants, but what they
do know, what they can analyze, is which people are similar to which
other people, and which people you should listen to, which people
should give you recommendations, which other people's problem-solving
and opinions you should rely on.
JB: Could it be that one of the reasons you seem to attract a
lot of flack is that by calling these algorithms "agents" they become
personified. Some critics would claim that these so called agents
make us less human not more human.
MAES: The reason why we use the word agent is to emphasize that
you are delegating something. Whenever you delegate something there
is a certain risk involved that whoever or whatever you delegate
to may not do the task exactly the way you would have done it. In
that sense I think it is appropriate to use the word agent, so that
people keep in mind that there is an entity, acting on your behalf,
doing things on your behalf, and so things may not get done exactly
the way you would do them if you were to do it yourself. It's an
agent in a sense that a travel agent is an agent, or a real estate
agent is an agent; they work for you, they know something about
your preferences and interests etc. with respect to the problem,
but still, if you had enough time to do the job yourself, you may
do a better job of it. Another reason we use the word agent is that
we are changing the traditional notion of software. So far people
have mostly used the metaphor of a tool to describe and build software.
Usually we think of software as passive. You have to turn on and
instruct it to do something and then it will do it. The agents approach
to software is different in the sense that the
agents are continuously running. You don't want to have to start
up that agent in your fridge that's watching the milk, it should
continuously be taking care of that particular task for you, so
it's long-lived software that is continuously running. That is very
different from the kind of software that we've been using in the
past, and that's another reason why a different term is appropriate
- you have a different kind of relationship with this software.
To rephrase McLuhan, every extension of ourselves is an amputation,
and that's very much true for every technology that we invent that
automates some things on our behalf. Take the pocket calculator.
People today don't want to live without it any more, and most of
us either have one on our computer that we can use or one on our
desk. We've delegated the task of doing calculations to the pocket
calculator, and this extension of ourselves also has meant an amputation,
because 20 or 30 years ago people used to be able to do all these
very complicated calculations in their head. They had all these
tricks, these heuristics that we don't even know anymore. We've
lost these as a population. The pocket calculator, a technology
from which we derive benefit, is also an amputation which has made
us less good at performing that a particular function.
It's important to keep that in mind, that if agents automate a
certain task for you, then you may not be very good at that task
anymore because you rely on the agent that is automating it for
you, and after awhile you no longer know how to do it yourself.
I don't care if I don't know how to do a lot of tasks any more.
I don't need to be good at checking whether there is milk in the
fridge; I'm perfectly happy delegating this to some technology and
being less good at that. For other tasks, in other domains, you
want to be careful, either because you may not want to lose the
ability to perform the task yourself, or because the agent is not
perfect enough to delegate the whole task with satisfactory results.
Examples include finding new music or deciding what news to read
in a newspaper. You don't want to have an agent telling you exactly
what articles you should be reading - you always want to be doing
some browsing yourself, because otherwise there's this risk you'll
get tunnel vision. The agent gives you gives more of the kind of
articles that you like and over time you get a narrower and narrower
selection of news. In the end you read just one type of story. This
can be dangerous. It's important in that case to design the whole
system so that the agent is only used as assistive technology. This
is a problem that can be solved in the design of the interface with
the agent.
To illustrate this point, we have built a software agent that
makes a personalized newspaper for a user in two different ways.
In the first way this agent takes all the news articles, picks the
ones that it thinks you'll be interested in given what it knows
about what you've been reading in the past, and it then gives you
a personalized selection. This approach involves a risk that you
are never even going to do some browsing yourself, and you're just
going to read what the agent has presented to you, and then you
get that tunnel vision problem. However, you can build that same
agent by just having the agent highlight in the newspaper the articles
that it thinks you will be interested in. It doesn't change the
newspaper. You will still see all the articles in the newspaper
have that element of serendipity, but the agent assists you, because
it has highlighted these articles. Even if it's in very small print
or it's on a page somewhere deep in the newspaper, you won't miss
it, because you could just go through the paper and see what all
the highlights are and make sure you've definitely read the stuff
that you have a long-term interest in. It's important for us as
designers of agents that we keep these issues in mind, and that
we come up with interfaces like the highlighting interface that
avoid the problem in which the extension becomes an amputation.
JB: On a Utopian level you're talking about designing agents at
MIT Media Lab as pure research. That's a very different situation
than the real world where these technologies are going to be implemented
by corporations that are interested in selling things. Unless you
configure your own agent, or you retain a service where the agent
is strictly controlled by you, the computer user is going to be
served by an agent of a search engine company or a bookselling company
or a catalog company, etc. Once such corporations find out you want
x or y or z, you begin to lose what remains of your privacy, then
you lose your identity by becoming an economic cipher to the new
band of info-transactional conglomerates. You're going to be targeted
for direct mail, unsolicited email, and pretty soon they're selling
your home phone number, your blood type, your medical profile. And
if any governmental agency wants your information, you better believe
they will be able to get it without the benefit of a subpoena.
Another problem is that one of the characteristics that agents
seem to have in common and which again distinguishes them from other
software is that they know about you. But would they know if you're
a jerk and would they tell you if they did?
MAES: That would be nice actually. But let me first answer your
concerns. What is important is that the information these agents
have about you is yours and only yours; it is completely up to you
to decide and specify who gets access to what information. This
is one of the reasons I talk of these agents as extensions of yourself.
There's a lot of very personal information in your head, and you
control what information you release to whom.
JB: Don't you think that it's naive to think that's going to happen?
MAES: No it isn't, because in fact there is already a standard
that has been proposed to the W-3 consortium, the OPS standard
open profiling standards which has been proposed by Firefly
and Netscape, and then afterwards Microsoft joined as well. That
standard specifies how personal information about a user could be
stored in the browser, and it also specifies that information would
be the property of the user, and that the user will be able to specify
that every time a site asks for certain information for example,
the user will specify which information can be given to that site
and what can be given to that site. This is similar to cookies,
but cookies done in the right way. The difference between cookies
and the OPS standard is that you will know what the site is asking
for. A site is asking for my taste in x or y, or another site is
asking for my age, or my this or my that, and you can say no, I'm
not going to give it to you or if you think you can get a
value out of it, out of giving it to that site, you will give it.
Privacy is one of the primary problems we have to get right if
we want agent technology to be widely adopted, and so we've been
very concerned with this, even though as you say I'm a researcher,
and it's not necessarily my concern, we've been very involved in
this issue and making sure it will belong to the user, that none
of that information is accessible to anyone except the user, that
when it gets passed it is encrypted so it can't be stolen from you.
It's always made clear who is asking for it and for what, and you
have to give approval to anyone who asks for it.
THE WORLD QUESTION CENTER III
Pattie Maes, Anne Fausto-Sterling, Stephen H. Schneider
From: Pattie Maes
Submitted: 1.14.98
Here's my question for 1998:
"Computer networks allow large groups of individuals to organize
themselves and perform activities that were previously more centralized
in radically decentralized ways. Examples are publishing (who searches
libraries with old-fashioned books anymore?), editing (electronic
word of mouth becomes more important than the NYT or Siskel and
Ebert), commerce (are we going back to barter, getting rid of all
middlemen?), and so on. The result is a powershift from current
authorities (or centralized, hierarchical organizations) to decentralized
communities. I wonder what the limits are of such decentralized
organizations and what the role of current authorities and middlemen
will be in this new world?"Do new computing technologies create
or destroy jobs?"
Pattie
From: Anne Fausto-Sterling
Submitted: 1.14 .98
My question:
"Can we find a way of talking (and thinking) about complex developmental
systems (a.k.a. cells, organisms, communities, societies) without
falling into the nature vs. nurture trap and without resorting to
imprecise locutions such as "genes for...?"
Anne Fausto-Sterling
ANNE FAUSTO-STERLING is professor of medical science in the division
of science and medicine at Brown University. She is the author of
Myths of Gender: Biological Theories About Women and Men.
From: Stephen H. Schneider
Submitted: 1.13.98
Hi John, glad the question idea has taken off as well as it seems.
Sorry that when you first asked I was in a whirlwind of Kyoto activities
and dashed off a not-quite-question. Here as requested is a true
interrogatory form of the idea:
"Can we mitigate potential long-term, global risks that, for convenience,
we often deny exist (e.g., massive species extinctions or significant
climate change), without first being able to overcome smaller scale
problems made invisible by personal denial?"
Cheers, Steve
STEPHEN H. SCHNEIDER is a Professor in the Biological Sciences
Department at Stanford University, and the Former Department Director
and Head of Advanced Study Project at the National Center for Atmospheric
Research, Boulder; author of The Genesis Strategy; The Coevolution
Of Climate And Life; Global Warming: Are We Entering The Greenhouse
Century?; and Laboratory Earth.
THE REALITY CLUB
Stewart Brand, Paolo Pignatelli, Duncan Steel
From: Stewart Brand
Submitted: 1.13.98
(David Deutsch wrote:) "What's the copyright status of the list?
Ideally what I'd like to do is answer them and put the answers on
my web site. What do you think?"
I'd say the copyright status should be whatever encourages David
Deutsch and anyone else to answer the questions, anywhere, anyhow.
Stewart
STEWART BRAND is founder of the Whole Earth Catalog, cofounder
of The Well, cofounder of Global Business Network, and author of
The Media Lab: Inventing the Future at MIT and How Buildings
Learn.
From: Paolo Pignatelli
Submitted: 1.13 .98
In reply to the extremely interesting question posed by Colin
Blakemore: "(Colin Blakemore:) "Most human beings perform effortlessly
a variety of tasks that are computationally extremely difficult
(such as seeing, holding objects and understanding speech); but
they are generally poor and vary enormously in tasks that are computationally
easy (such as solving puzzles, doing mathematics and science). Given
that the latter skills are apparently as biologically valuable as
the former, does this disparity reveal a fundamental limitation
of the human brain?"
May I have the honor of essaying a reply.
Computing devices are primitive, they are, in many important respects,
barely an improvement to the mechanical devices of Babbage. Faster,
yes, but better in being closer to us, to our intellectual world-
hardly! Present implementations of computation, the deterministic
and algorithmic machines we know today as computers, are but a first,
tentative step toward the goal of a computing device that more resembles
our brain and mind. There are still two models, however, representing
two different evolutions, one of evolutionary time so short as to
be "ex-nihilo", and one of a computing device either very fortuitously
born out of chaos, or otherwise evolved over billions of years,
from the first second of the Big Bang. The difference in complexities
that makes these two devices pretty much incommensurable. The future,
the information, knowledge and hope lie in the great works work
of the neuroscientists and geneticists. Last year's Dolly experiment
tells us, for example, that cell differentiation is more plastic
that we envisioned, which could mean that brain development of specialized
areas is also more plastic. This means that the complexity of evolutionary
development may also be greater than previously envisioned, since
the evolutionary tree has now many more possible branches, connected
by a more complex rule space (a field?) Perhaps there is hope -
the physicists are getting closer to some kind of unification, the
biological sciences are on their way to deciphering much that has
been screened from mortal eyes on the question, "who are we?", and
so perhaps the axiomatic sciences can look at the knowledge of their
confreres of the wider family of the scientific community, and propose
themselves the types of question agendas that we had with Hilbert
at the beginning of the century. These questions will have to do
with the nature of subjectivity and objectivity complexity and computation.
Questions on the difference between objective and subjective idealizations,
on their unification; on subjectively infinitely parallel processing
machines (relative infinities >from the "constructivist" approach);
on necessary and sufficient "seeds" of knowledge necessary for intelligence
evolution? (What are the natural objects, the equivalents to the
natural numbers of the Euclidians, and the natural rules, (the postulates)
that will bring the axiomatic sciences in convergence with the empirical
ones?) Certain concepts that we use today may be found to be useless
or impinging on our abilities to progress in our journey and adventure
to discovery , (communication bandwidth?), certain concepts deemed
province outside of science will need to be studied more deeply.
For example, we need to understand a lot more about "serendipity",
replaying the emotional experience equivalent to the debates regarding
God playing dice of quantum physics' debates) before we can imbue
machines with anything resembling our "intelligence" or "insight".
Colin Blakemore asks questions about what may be a partition theory
for the mind, a partition theory whose objects are knowledge machines,
"intelligences" or whatever one may call strategies for thought.
Just dreaming now, but wouldn't it be great if for our millenary
question proposals, perhaps in this venue, in part at least we could
pursue a common agenda?
Paolo Pignatelli
PAOLO PIGNATELLI, a cyber-entrepreneur, is proprietor of the virtual
Corner Store. He is a linguist, translator and scientist who previously
worked in image processing algorithms at Bell Labs.
From: Duncan Steel
Submitted: 1.14.98
Happy New Year (I think it's today on the Julian calendar).
Lewis Wolpert's question struck a chord with me:
"Why do people believe in things for which there is no evidence
and would it be a mistake to try and persuade them not to?"
I've been engaged for some years in trying to persuade people/governments
that there is a hazard to individuals/civilization/our species from
catastrophic impacts by asteroids and comets. But what I (and my
colleagues in such an endeavor) meet with is a total denial: that
there is no such hazard. Thus Wolpert's question for me has a corollary:
"Why do people NOT believe in things for which there IS evidence
and is it a mistake to try and persuade them to do so?"
Evidence = e.g. impact craters on Earth & Moon, asteroids & comets
flying by, impacts on Jupiter in 1994, geological and fossil record,
simple sums showing that a 2 km asteroid impact would release energy
equivalent to a million megatons of TNT, etc.
We have an awesome responsibility: so far as we know, we inhabit
the only planet bearing life (DNA) in the universe, and we are the
only species which can spread life/DNA throughout the galaxy. A
decent asteroid impact could put an end to that possibility, for
maybe millions of years.
Thus I have another question, which is actually more general than
just this topic in which I am interested (the hazard from big impacts):
"Why are we shirking our responsibility to the universe?"
Best,
Duncan
DUNCAN STEEL is a research scientist, broadcaster; author of Rogue
Asteroids and Doomsday Comets.