Abstract
Lisa
Randall is a theoretical physicist working in particle physics and cosmology.
She was born in Queens, New York City, on June 18, 1962. Lisa Randall is an
alumna of Hampshire College Summer Studies in Mathematics; and she graduated
from Stuyvesant High School in 1980. She won first place in the 1980
Westinghouse Science Talent Search at the age of 18; and at Harvard University,
Lisa Randall earned both a BA in physics (1983) and a PhD in theoretical
particle physics (1987) under advisor Howard Mason Georgi III, a theoretical
physicist. She is currently Frank B. Baird, Jr. Professor of Science on the
physics faculty of Harvard University, where he has been for the past a decade.
Her works concerns elementary particles and fundamental forces, and has
involved the study of a wide variety of models, the most recent involving
dimensions. She has also worked on supersymmetry, Standard Model observables,
cosmological inflation, baryogenesis, grand unified theories, and general
relativity. Consequently, her studies have made her among the most cited and
influential theoretical physicists and she has received numerous awards and
honors for her scientific endeavors. Since December 27, 2010 at 00:42 (GMT+7),
Lisa Randall is Twitter’s user with account @lirarandall. “Thanks to new
followers. Interesting how different it feels broadcasting on line vs.via book
or article. Explanations? Pithiness? Rapidity?” is her first tweet.
Keywords: Cosmology; Interview; Particle
Physics; Lisa Randall; Theoretical Physicist;
Who
are you?
Lisa Randall.
Professor of Physics at Harvard University. And I'm also the author of Warped
Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions.
That's always a complicated question. The first part's easy. I'm from Fresh
Meadows, New York. It's a part of Queens, sort of on the outer edge of Queens
towards Long Island. And how does it influence who I am today? Well I think
growing up in New York can't help but influence who you are. Even though I was
in Queens, I went to high school in Manhattan. But also I was subject to the
____________ of being in New York. I was joking with a friend recently. I think
my first day of school didn't exist because it was at the time of the teacher's
strike. So I think that was characteristic of sort of a sense of uncertainty
that existed around that time. So I think the fact that it was a bit of a
bizarre educational system in the beginning probably influenced me; but also
the fact that it's an intense community where there's lots of bright people
around. For me, I think going to Stuyvesant was just nice to get away from the
more insular area of Queens that I was in. And I think basically having ... And
we did have some good teachers. And not everyone, but some of them were good.
And I think it definitely just influenced how seriously I took academics. You
know I just always liked school, so I looked reading. I liked math. It wasn't
as much science. I think I liked math. I remember liking math more than ... The
science we learned was a little bit diluted. In third grade we dug up an ant
hill and just looked at it. You know that was ... that was counted as science.
So it wasn't really all that technical. But I think I liked just ... I liked
math. I liked the fact that it had answers. You know you didn't necessarily
need a great teacher. You could still learn the math, which was nice. But I ...
but I was a big reader too, so I just liked all that when I was a kid. Well you
know it doesn't happen at once I think. You sort of go ... I mean it's funny.
You're going into science thinking that you'll have some impact that's sort of
more permanent maybe, that you'll find some truth. And then you realize that
truths get overturned, and it's not so easy. And it's not so obvious what will
be there. But I think the fact that you can work things out, that you can test
them, there's something very reassuring about that. It's not ... it isn't just
opinion at the end of the day. For a while it is opinion until it's tested. But
at the end of the day it's ... it's ... it's not opinion; or at least we'd like
to believe that. And I think it's true, and I think it's been well-tested in
many aspects of what it's predicted. So there is still that ... Even though
what ... what doing science is about is sort of answering questions you don't
know the answer to, at the end of the day you sort of have this overriding
belief that some things will be known. Well I mean in a broad sense we're trying
to understand ... I do theoretical particle physics, first of all. And so we're
trying to understand the substructure of matter. That is to say we're trying to
understand what are matter's most basic elements. How do they interact? We're
also ... The kind of work I do also interfaces with cosmology at times, understanding
what's in the universe; how it's involved; how do you explain the properties of
what we've observed there as well. So a lot of what we're doing is trying to
extend beyond what we know. There's something called the standard model
particle physics, and it tells us about particles called "quirks",
like those inside the proton neutron; particles called "leptons",
which are like an electron; and it tells us the four forces that we know about.
And we're trying to get beyond that. We're trying to understand questions like,
“What are masses? Why are they what they are? How are those masses related? Why
are they related in the way they are? Are the forces related in some way? Where
are they unified?”
What
impact does your work have on the world?
I don't know. You
know for one thing it turns out which ideas turn out to be right. I think that,
you know, at this point though, one impact is just it makes people think about
broader questions. I mean it's ... I mean one of the nice things, it expands
your horizons. That wasn't meant literally, but in the sense that it's nice to
think ... I don't know. I mean some ... I guess people are different. Some
people like to think they know everything, and some ... For some people, I
think it's nice to think there's all these questions that we don't know the
answer to. I mean there could be extra dimensions in space that we just don't
know about. And certainly in the history of physics there have been many things
that have been discovered that no one would have anticipated. No one
anticipated quantum mechanics, but it was discovered and people put it
together. And so I think just the idea ... It's a little bit humbling, but in
an interesting way, to think about the number of questions we know the answer
to; but look at the number of things we don't know the answers to. And so I
think just being able to think about these in an intelligent way, to ask these
questions, and to, you know, hopefully to think more scientifically about them;
not just to think in a sort of "new agey" kind of way, but to really
think about what these things could mean.
Do
you have a crative process (on scientific work)?
You know it's pretty
random. A lot of the time you just hear about an idea and you're mulling it
over and you think oh, you know, I could do this a better way. Or this could
have this implication. It's not just one thing. A lot of it is ... I think ...
I think one thing that it's ... I think a lot of creative people ... But
different creative people work in different ways, but I think some just have a
lot of ideas in their heads sort of buried. So when something comes up, you can
sort of automatically make connections. And so sometimes it's sort of piecing
things together. And of course that always turns into something else. But
realizing oh, for example, if there are extra dimensions, maybe it can have
implications for particle physics to solve this problem that I've been worried
about for years. So to be able to make connections and to sort of recognize
good ideas, I think that's another thing, to really listen. Sometimes it's
really easy to dismiss an idea, and sometimes they should be dismissed. But to
really listen and be aware of sort of the full range of implications of some
thoughts ... of some particular ideas. So I think that's important too.
What
the risks of scientific innovation?
I'm a little bit
hesitant to overstate the risk because some science is risk and some science is
not. I do think that probably biological advances will entail ethical consider
... issues. And I don't mean that we shouldn't be doing certain types of
research. But in the end we should be able to evaluate. For example if we do
understand genes, how much do we want to be able to engineer? I mean those ...
I don't know that that's a risk, but I think it's important to be able ... that
there's a systematic way of asking these questions and that they're on the
table. There probably are risks to the environment. There probably are risks to
our food supply. And it's not necessarily from science, but sort of how science
is applied in sort of more agricultural and industrial sort of contexts. There
probably are risks associated with antibiotic resistant bacteria. There are
risks of that sort. But a lot of the risks, I think, have to do with how things
are applied in general. And I think that has ... I mean it's not just that
science research could be controlled, but perhaps industries using scientific
analysis should be better controlled. For example, you know, bio engineered
food, it's not that it's necessarily bad, but there should be some way of
regulating it to see if it is bad or not. And right now it's not ... I mean so
I think the risks are sort of that things are changing so fast that sort of
regulation doesn't necessarily keep up with it. So that's probably more of the
risks at this point.
What
is human nature?
You know I think
we're inclined to sort of generalize from ourselves because we know ourselves
the best. But then people go out and do mysterious things and you think,
"Oh wait. That's a bad person. I don't know where that bad person came
from." So I think ... You know I think we have good impulses and bad ones.
I mean I think given all things being equal, we'd wanna be generous and do good
things, and make things better. But I mean ultimately we're selfish and greedy,
and a lot ... and not always bright. Some people are small and some people
aren't. And I think ... And some people wanna know the answers, and some people
just want the simplest thing. I mean some people are lazy and some people are
energetic. I don't think there is any single way that human beings are. There's
really a bunch of different ways.
What
makes a science-literate citizen?
Well the first thing,
this is one thing I always say when I'm asked this question, is it would be
nice if people understood numbers at a very basic, elementary level so that
when any issue, not just a scientific, but especially a scientific issue, is
presented, we don't have to say, “Some people think this and some people think
that.” We can say, “Seventy eight percent of the people think this, or this is
known at 90 percent confidence level.” And for people to have some idea of what
that means so that we can describe ... I mean there's always this hesitation
when something isn't 100 percent known. And nothing is ever 100 percent known,
and we can test it to some degree of precision. And it would be nice to be able
to speak in those terms so that rather than say, “Some people think this or
some people think that,” or, “Maybe it's true or maybe it's not,” that we can
really put ... attach numbers to that. And I think it would give rise to much
more intelligent debates on many subjects. Because the way everything is
presented today is sort of in black and white terms. And it would be nice to be
able to evaluate. And it's an interesting thing. I mean I had a friend who used
to do that to me. You know he would ask a question and he would say ... and I'd
say, “Well I don't know the answer to that.” I'd say, “I don't know whether
that's true or not.” And he'd say, “Well, you know ...” but he sort of was a
gambler. So he'd sort of say, you know, “What kind of odds would you put on it?”
And it's interesting because you almost always do have in the back of your mind
some sort of probability. And so rather than just say, “I don't know,”
sometimes just say well, you know, “Maybe 70 percent chance that this is right.”
You know and it sort of makes you think a little bit more deeply about these
things rather than this very surfaced level which can be dismissive. So I think
that's really important, for people to just have a basic understanding of
numbers and what ... so they can understand scientific evidence better, what it
has shown. But also, I mean, there's obviously just some concepts that I think
it's important to know, particularly about issues that are relevant to our
society. I don't think that people necessarily have to know about theoretical
particle physics. I do, however, think that people who want to know about
theoretical particle (26:30) physics should have the opportunity to do so. I
mean that was one of the reasons I wrote a book, because it's such difficult
material that unless you can really give a lot of the background, explain
quantum mechanics, explain general relativity, he particle physics, I can talk
about extra dimensions in the way we're doing now, but it's nice to have this
deeper understanding that comes with really understanding the development of
physics; and understanding what are the questions we're trying to answer at a
deeper level; and why would we think this might be the right answer. But I
don't think everyone has to want to know that; but I do think that people who
want to should be able to. And these experiments are expensive, and they
involve lots of people. And so if we're asking for the government to support
it, it's only fair that we should tell people why they should be excited. It's
not just discovering Higgs particles. It's discovering new forces, new elements
of nature and what that can mean, what the implications are. Maybe it's telling
us about space time even. I mean it could be really just interesting and deep,
even if it's not changing our daily lives. But there are issues that do change
our ... that are important for our lives where the science can be really
complex too, such as climate change, which is an important issue. And it's
important for people to be able to sort of evaluate what's ... At this point,
almost all of the scientific evidence is given in a sort of “he said, she said”
kind of way. And it would be nice to be able to go a little bit more deep into
it. A lot of medical advances, it would be nice for people to, again ... to be
able to really evaluate what the evidence is and how many ... just what the
significance is for various studies.
What
is String Theory?
Well okay, so first
of all what problem is string theory trying to solve? String theory is trying
to reconcile quantum mechanics and gravity. And let's take a step back and see
what we mean by that, because in fact we do understand gravity. Einstein's
theory of general relativity describes gravity, and it's been tested. We've
seen evidence of general relativity. Quantum mechanics we know very well has
been tested on atomic skills. The point is that there exists scales that we
can't test. They're much too small for experiments to be done -- in distance,
or much too high energy -- where we wouldn't know how to make predictions. It
would look inconsistent. In other words, in the regime of large things where
cosmology or general relativity applies, we do fine. It's just quantum
mechanics is negligible on those scales. On small scales, atomic scales we can
ignore gravity because gravity is so weak. But there exists tiny distances or
very high energies where both forces (22:24) would, in principle, be important.
Those aren't ones where we can experimentally test; but even theoretically we
believe we should have a theory which could work at all distance scales. It's
just the fact that we haven't been able to make experiments to test those yet
doesn't mean there shouldn't be a theory that describes it. So people have been
looking for a candidate theory of what's called “quantum gravity” for some
time. So string theory is a theory of quantum gravity. Or it's a candidate
theory of quantum gravity. And it's based on the idea that fundamentally we
don't have elementary particles, but we have fundamental oscillating strings.
And particles are the oscillation of those strings. And if you ... You can say how
could we not notice those strings in the particles. But if you think about it,
if the strings are really tiny, they look like particles. We can't see it. To
see that it's actually a string, you'd have to see the additional oscillations
that a strong can have. And to do that you'd have to be able to test the
energies that it would take to make a string oscillate. And it turns out we
need to start having __________ approach anywhere near those energies at this
point.So essentially what we're doing is we're taking ... It's sort of an
interaction in the sense that we take some ideas from string theory, such as
extra dimensions and branes, and see what could be the implications for
particle physics. And if, for example, it was found that we were right, string
theorists would have to find ways to predict the kind of geometry we propose.
And if that ... After we did our work ... At first when we did it, everyone
said, “Oh this never happens in string theory.” But after we did it, people
found ways that this could happen in string theory. But also some of the more
theoretical work such as the infinite work dimension of space, maybe that goes
back to string theory. There are possibilities that people haven't thought
about yet. So ... and it goes back and forth.
Where
does the idea of multiple dimensions come from?
So you’re jumping to
multiple dimensions, which is also something I work on. And I kind of work on
it in connection with trying to answer some of those questions that we just
mentioned. But the idea of multiple dimensions has been around for ages in
terms of just mathematical concepts. But in terms of physics it was more recent
after Einstein developed his theory of general relativity. And it was observed
that his theory works for any number of dimensions. It doesnt have to be three.
But people also think about extra dimensions because of string theory, which is
a candidate theory for unifying quantum mechanics and gravity, which seems to
require extra dimensions of space. But the other reason we think about extra
dimensions is because they might actually have implications for our world and
explain properties of matter that weve observed, and how they ... why masses
are what they are for example. Well theres a number of ways to think about what
dimensions are. I hope we all know where three dimensions are, which you can
say are left, right; forward, backward; up, down. And if you think about it,
three ... we say there are three dimensions of space. And sometimes we need
three coordinates to locate some objects in space. So you can say longitude,
latitude and altitude. So if there were more dimensions, you would need more
coordinates. Now of course for whatever reason we are not physiologically
designed to observe those dimensions, but that doesnt mean they dont exist. One
way of thinking about it is ... Maybe the best way of thinking about it is the
way that someone named ____________ did it in the late 19th century in a book
called . And he said suppose there were two dimensional creatures living in a
two dimensional universe? They would have the same trouble conceptualizing
three dimensions that we have when we try to conceptualize more than three,
such as four. And so he asked questions like,"What would observers in this
two dimensional universe see, say, if a three dimensional object like a sphere
passed through the universe? And what this flatland universe would see would be
a series of disks that grow in size and then decreased in size. In the same way
that we can certainly think about a two dimensional world inside a three
dimensional world, it could be that we observe three dimensions but really
there are more. And if a hyper sphere say a four dimensional sphere passed
through our universe, we would see a series of spheres that grew in size and
then decreased in size. The fact that we dont observe those extra dimensions
doesnt mean they dont exist. And they are hard to conceptualize. They certainly
are hard to visualize. But we can think about them mathematically and
conceptually without too much trouble. You want evidence, do you? Well we dont
know if theres evidence yet. So one reason we think about it is to decide what
would be the evidence. So how do we know if these dimensions exist? And of
course you cant answer that question until youve really thought it through and
thought how are they hidden; what would be the implications? And we havent seen
them yet. I mean the reasons that we think about it, like I said, are string
theory and the fact that they might have implications for our universe. But how
can we test whether it has these implications? Well what were going to do ...
not me but ________ will do is look for evidence of particles associated with
travel in the extra dimensions. That is to say if particles traveled in the
extra dimensions, there would be partner particles called “Kaluza-Kline
particles” that are like the particles we know about. They have properties that
interact similarly, but they have mass. And their mass reflects the extra
dimensional geometry. Thats because they have momentum in those extra
dimensions. And so what well do is look for evidence of these extra
Kaluza-Kline particles. And if we see them, and if they have the properties
that we predict, it would be evidence for extra dimensions.
What
was the greatest “Eureka!” moment in your career?
I mean, for any
problem you work on there's some moment where there's sort of maybe it's a
moment where no one else cares about, where it all fits together and I found
some simple way of doing something. There are also the models that people have
heard about such as the models about extra dimensions, something else that we
did having to do with a different way of communicating supersymmetry breaking. There
were a lot of eureka moments in that and making it work out and the fact that
we could all tie it together. So, it's hard for me to pull those out because a
lot of the time when you're working on something there's that one thing that
you get excited about.
Have
you ever been surprised by the result of an experiment?
I think one thing that
surprised us, Braman and I, when we were working together was this existence,
or the possibility of the existence, of an infinite extra dimension. People had
actually thought there were theorems that you couldn't have an infinite extra
dimension, that gravity would just look wrong, that there was no consistent way
to do it. And it was really interesting because we came across this by really
following the consequence of our equations to the end and there was just no
mistaking that it was allowing the possibility of an infinite extra dimension.
And it was interesting to go back and see what assumptions have been made that
made us think, or made other people think that it was impossible, and just to
see how the theory was almost smarter than we were and worked it out. That was
kind of fun.
Do
you believe in absolute truth?
Do I believe in
absolute truth? I believe in effective theories, so let me tell you what an
effective theory is. An effective theory says basically that I can ... If I
can't measure something, I don't have to worry about it in the sense that, for
example ... Let's take Newton's laws. Newton's laws work just fine. But we know
that eventually we have to take into account relativity, if things were going
really fast where we have to take into account quantum mechanics when we're
looking at really tiny scales. But for the scales we observe, you don't have to
worry about the fact that a ball is made up of atoms. It's perfectly fine to
think of it as a ball with some mass because you would never be able to measure
the effects of the atoms on the ball when you're just throwing the ball. So I
guess I believe that we ... There's a truth that we know because it applies to
the world as we've seen it, as we've measured it. That's not to say that there
can't be other underlying truths you could see if you could understand ... if
you could really see things better; if you could test them better; if you could
measure them better. So I think anything we know could be upset if you look at
regimes outside the regime of which we studied them. So ... But that's not to
say the truth isn't absolute. It's absolute in the scales that we've seen it;
but it's just not absolute in the sense of applying the most fundamental
skills.