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Language: en
we have to talk a bit about the magical
the mysterious string theory super
string theory sure there's still maybe
this aspect of it which is there still
for me from an outsider's perspective of
this fascinating heated debate on the
status of string theory can you clarify
this debate
perhaps articulating the various views
and say where you land on it so first of
all I mean I doubt that I will be able
to say anything to clarify clarify the
debate around string theory for for
general audience part of the reason is
because string theory is a has been
something I've never seen the Iraq war
physics do it is broken out into
consciousness of the general public
before we're finished
you see string theory doesn't actually
exist because when we use the word
theory we need a particular set of
attributes in particular it means that
you have an overarching paradigm that
explains what it is that you're doing no
such overarching paradigm exists or
string theory what string theory is
currently is an enormous lis large
mutually reinforcing collection of
mathematical facts in which we can find
no contradictions we don't know why it's
there but we can certainly say that
without challenge now just because you
find a piece of mathematics doesn't mean
that it's applies to nature and in fact
there has been a very heated debate
about whether string theory is some sort
of hysteria among the community of
theoretical physicists or whether it has
something fundamental to say about our
universe we don't yet know the answer to
that question but those of us who study
string theory will tell you are things
like string theory has been
extraordinarily productive in getting us
to think more deeply even about
mathematics that's not string theory but
the kind of mathematics that we've used
to describe elementary particles they
have been spin-offs from string theory
and this has been going on now for two
decades almost that I have allowed us
for example to more accurately calculate
the force between electrons with the
presence of quantum mechanics this is
not something you hear about
in the public there are other similar
things the kind of that kind of property
I just told you about is what to call
weak strong duality and it comes
directly from string theory there are
other things such as a property called
holography which allows one to to take
equations and look at them on the
boundary of a space and then to know
information about inside a space without
actually doing calculations there this
has come directly from string theory so
there are there are a number of direct
mathematical effects that we learned a
string theory but we take these ideas
and look at math that we already know
and we find suddenly we're more powerful
this is pretty good indication there's
something interesting going on with
string theory itself so it's the early
days of a powerful mathematical
framework that's what we have right now
what are the big first of all most
people will probably that which as you
said most general public would know
actually what string theory is which is
a at the highest level which is a
fascinating fact well string theory is
what they do on the Big Bang Theory
right one can you maybe describe what is
string theory and two what are the open
challenges so what is string theory well
let the simplest explanation I can
provide is to go back and ask water
particles which is the question you
first ask me what's the smallest thing
yeah what's the smallest thing so
particles one way I try to describe
particles to people a star I want you to
imagine a little ball and I want you to
let this size of that ball shrink into
it has no extent whatsoever but it still
has the mass of the ball that's actually
what Newton was working with when he
first invented physics he's the real
inventor of the massive particle which
is this idea that underlies all of
physics so that's where we start it's a
mathematical construct that you get by
taking a limit of things that you know
so what's a string well in the same
analogy I would say now I want you to
start with a piece of spaghetti so we
all know what that looks like and now I
want you to let the thickness of the
spaghetti shrink until it has no
thickness mathematically I mean worse
this makes no sense mathematically this
actually works and you get this
mathematical object out it has
properties that are like spaghetti it
can wiggle and jiggle but it can also
move collectively like a piece of
spaghetti
then it's the mathematics of those sorts
of objects that constitutes string
theory and does the multi-dimensional 11
dimensional however many dimensional
more than four dimension is that a crazy
idea to you is that is that the stranger
aspect of string theory to you not
really and also partly because of my own
research so earlier we talked about
adding these strange symbols that we've
discovered inside the equations it turns
out that to a very large extent add
incres don't really care about the
number of dimensions they kind of have
an internal mathematical consistency
that allows them to be manifest in many
different dimensions since supersymmetry
is a part of string theory then this
same property you would expect to be
inherited by string theory however
another little-known fact which is not
in the public debate is that there are
actually strings that are only four
dimensional this is something that was
discovered at the end of the 80s by
three different groups of physicists
working independently I and my friend
Warren Siegel who were at the University
of Maryland at the time were able to
prove that there's mathematics that
looks totally for admission oh and yet
it's a string there was a group in
Germany that used slightly different
mathematics but they found the same
rizzo and then there was a group at
Cornell who using yet a third piece of
mathematics found the same yourself so
the the fact that extra dimensions is so
why they talked about in the public is
partly a function of how the public has
come to understand string theory and how
it's the story has been told to them but
there are alternatives you don't know
about
you