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what hello and welcome I am Caitlyn saxs
a senior producer for Nova and today we
are going to be having a conversation
with David Kaiser and we're going to be
talking about the fundamentals of
physics and by that I mean the
fundamental physics group and that's
physics uh with an f f y s i KS we'll
explain that in a bit but these were a
group of physicists who held quite a
reputation as the hippies of physics uh
but who also help catalyze the
advancement of quantum physics so we're
going to get into that we're going to
delve deep into some trippy stuff like
the nature of quantum entanglement and
how these aspects of nature are being
used in technology today so David Kaiser
is a professor of the history of Science
and a professor of physics at MIT he's
the author of several award-winning
books on the history of modern physics
including how the hippies saved physics
science counterculture and the quantum
Revival uh the subject of which we will
be talking about today of course he's
also featured in a number of NOVA
documentaries including particles
Unknown about nutrino Einstein's
Quantum Einstein's Quantum riddle what
what is the universe made of and most
recently this year's decoding the cosmos
I have to say when I um started to look
up how many films David has been in I
just stopped there I figured that's
enough but every time we at Nova talk to
David our mind is blown that's why we
put him in so many of our films some of
which he has actually helped Inspire so
my goal for this conversation today is
to share that with you to try to blow
your mind um without the use of any
psychedelic drugs uh or whatnot so David
thanks for joining us today are you are
you up for this challenge are you ready
to blow some Minds well I'll do my best
and Kaitlyn thanks so much for inviting
me on it's always r a treat to be able
to talk with you and all the colleagues
at Nova so thank you thank you um so
first little housekeeping um this is a
live conversation so to the audience
watching live if you have uh questions
for David please just drop them in the
chat and we will try to get to them all
right so David first let's let's start
with the basics what what was this
fundamental physics group yeah well as
you say they they spelled physics with
an F that already gives you an
indication they were they were open to
having a pretty fun time they didn't
take themselves too seriously and that's
part of what drew me to them actually
when I was working on this project so
the fundamental physics group was an
informal group they weren't formally
organized in any way it was a rag tag
group actually you know not quite a
dozen people um and they all kind of
found each other in the San Francisco
Bay Area uh in the early and mid 1970s
they began having regular meetings uh
most of the time every Friday afternoon
for some big open-ended discussions
about basically how does the world work
what's the world made of things like
what's how do they best try to make
sense of things like quantum theory
which was is then as now can can keep us
up scratching our heads at night um and
so uh so they they were a group of
people almost all of whom had either
completed phds in physics or in the
process they were active grad students
at the time but they were finding a kind
of frustration with the typical way that
that young physicists were being trained
especially in the United States at that
time uh they had all entered the field
with these you know dreaming big big
thoughts about about quantum theory
about relativity about black holes about
the Big Bang about these really deep
deep kind of Juicy stories of of how the
world works and they each found in their
kind of formal training especially at
the PHD level that it seemed to them at
least kind of narrow it seemed to kind
of cut out some of these bigger what if
or how does it all work kinds of
questions that had helped Inspire them
you know when they were young kids
teenagers and so on on their own
combined with that they had the the the
remarkable bad fortune of trying to
enter physics at what turned out to be
one of the worst times to try to get a
job as a young physicist is through no
fault of their own the entire field
especially in the United States although
it turns out similar Trends in many
parts of the world at that time there
was a kind of um rapid cut in the demand
for young physicists not just in
university positions to become young
professors but also in industrial labs
in government Labs there was just a huge
huge fall in the demand and the supply
was was exploding so it was a really
tough time to make a kind of typical
career in physics and these folks
decided Well well they weren't finding
their main questions answered in their
kind of typical
curricula they some of them felt like
what do they have to lose because the
typical career path was shifting kind of
under their feet and so they kind of
bumbled along and found each other
through the kind of accidents of history
and they made a little kind of study
group a discussion group in um in
Berkeley California and one of the
topics they were most excited about was
quantum entanglement and then and then
you know topics that would spring out
from
there um so I want to get to Quantum
because that requires a pause to try to
wrap our heads around it and I will say
despite having made a film on it I still
haven't wrapped my head around it I
don't know if anybody has actually fully
wrapped their head around quantum
entanglement But first you also
explained in your book um you know in
the 1970s is there's a growing New Age
movement pulling in some aspects of
Eastern mysticism and they're also
seeing something um really appealing or
some alignment with with the principles
of quantum physics can you explain a
little bit like what what was it that
they were seeing in quantum physics yeah
I I should start by saying it's a great
question Kaitlyn so you know the group
was is about you know again maybe 8 to
12 kind of core members and they were
kind of accordi and week by week more
people come and go but there was a core
group and even among that group there
was a wide range of opinions the their
own opinions or ideas would change um
over time so so even though it's not a
huge group there was variety among them
and for some of them just as you say
they got very very interested really
enthusiastic about all kinds of um
spiritual and and intellectual
Traditions beyond the ones that they had
experienced through their kind of
typical training uh and for some of them
ideas from various strains of Eastern
kind of spiritual or mystical Traditions
really really excited them like um
Confucianism like uh Daoism or Buddhism
Confucianism they're not the same as
each other those Traditions uh and some
of these folks got excited about trying
to do a kind of compare and contrast so
they some of them really became um you
know they would read a lot of books that
go to go go to lectures in the Bay Area
at a time when interest in these topics
was growing especially in the San
Francisco area at that time so one of
the things that got some of these folks
excited like like FR of COA who's a
member of this group uh he was
originally actually from Austria but was
at that point doing a post-doctoral
fellowship uh in in
California in Santa Cruz not so far from
Berkeley uh and so froff was really
noticing in his EXP ations there were no
there ideas at least in some of these
Eastern traditions of a kind of
underlying wholeness a kind of uh hidden
connectedness among things that might
appear to be separated that was one
thing that really resonated with frof as
a young person because it seems to be
parallel at least with ideas that he
really was grappling with day by day in
areas of quantum theory that in Quantum
in tanglement but not only in that is
there a kind of um could could the you
know could the whole be more than the
some of its part parts we might say and
that was something that he was he was
exploring or getting exposed to in his
reading in his lectures and in his own
um increasing kind of meditations and so
on that's an example he went on to write
a bestselling book about that called the
da of physics that as far as I know is
still in print speaking of a blockbuster
International seller but it was really a
kind of pet project a passion project of
copras because he was trying to really
sit with these two different sets of
ideas that to him seemed maybe to have
things to offer to each other so that's
a quick example um that that
a kind of notion of subject and object
might not be the same as a kind of
typical or traditional uh Western View
is there a role for the Observer that
might have an impact in what even gets
counted as being observed or what we
attribute to being something as a part
of objective reality are we bringing
something to that controversial
questions to this day in the in the
topic of quantum physics but again in
the 70s was getting some of these folks
really interested about possible
connections or at least parallels with
things were just beginning to
explore so it sounds like the idea of
quantum entanglement which I want to get
into in just a moment but basically the
idea that things can communicate faster
than the speed of light and also this
idea of the role of the observer in a
system are things that um both the
physicists of and I don't know what
you'd call them philosophers of the day
were very uh interested in so let's get
into what those are exactly from a
physics
perspect physics perspective
the quantum entanglement start at the
beginning this this came about what in
the early
1900s yeah I really gets articulated in
the 1930s mid 1930s so long before the
hippie days that were otherwise that
we've been talking about and in fact
entanglement is in that era was most
closely associated with names that
really we do know that we think of as
kind of unhp is like Albert Einstein and
Arin Schrodinger uh they each had kind
of Bohemian streaks in their own day but
they certainly weren't 1970s California
hippies let's be clear about that and so
uh what they were doing they weren't the
OG hippies right right that's fair to
say I think they'd agree with that
statement too if we could ask um but
what they were doing they were you know
these were some of the most important
architects of quantum theory the H1
Nobel prizes uh for their work
contributing to quantum physics also
it's important to remember is that both
Einstein and even Aaron Schrodinger by
this point became pretty convinced
Skeptics or critics of quantum theory so
they helped build this amazing edifice
and then over the intervening decade
from the 1920s to the 1930s and indeed
Beyond Einstein and schinger each
started kind of nursing these really
significant questions and even kind of
doubts crit
criticisms and so each of them began
thinking about what we now call quantum
entanglement partly because they were
convinced this couldn't be real in the
world they were trying to sus out do
does quantum mechanics predict such
strange sounding things and if so isn't
that a problem for quantum theory right
so so they're helping to articulate
things we still read their papers with
great profit to this day exceptionally
clear from the 1930s but their goal was
not to say hey there's this cool feature
quantum theory isn't that great their
goal for each of them Einstein and
ringer both and they're kind of egging
each other on through letters of the
time was to say this sounds just too
strange to be real it sounds like spooky
ghost stories as opposed to real physics
nonetheless what they began to to
identify is that if one took the
equations of quantum theory really at
face value as it had been worked out
already in the 1920s and 30s
quantum theory seem to suggest that
under certain circumstances if there
were two little bits of matter two
particles two um to things we could
imagine performing measurements on or
interacting with in a laboratory if they
moved very far apart arbitrarily far
apart um that they would still retain a
kind of connectedness so they weren't
clear at the time was did it involve
actually communication the word that
you'd used um there's some kind of
connection in fact as Einstein iously
called it dismissively in a letter to a
friend it looked like a spooky action at
a distance for him that was not terms of
Praise that it would looked like it was
like ghost stories of weirdness so the
idea was the equation suggested that
there was a kind of again that that a
Quantum system was more had more to it
than just adding up everything you might
know about one piece and adding what you
might know separately about a second
piece that there were connectedness or
correlations or connected behaviors that
the equation suggested could be real uh
beyond what you would ever be able to to
kind of think about in a classical
physics or say in a Newtonian
system and for for Einstein as for
Schrodinger this spelled trouble not
excitement um nonetheless I wrote these
papers in the 1930s actually was
schinger himself who coined the term
entanglement in English he had just fled
his job in Berlin because of the rise of
the Nazis he was doing more and more
work in the English language Schrodinger
coined the term entanglement Einstein
had likewise fled uh Berlin um earlier
and had resettled in the United States
so the two of them were now exchanging
letters across the Atlantic Ocean and
really kind of as I say kind of coaxing
each other to articulate their
criticisms of quantum theory around
topics like entanglement so that's where
this topic kind of stays so a number of
of the earliest kind of proponents for
quantum theory like Neils bore and his
younger colleagues M Heisenberg WF gang
poy a lot of these uh folks were were
kind of not too impressed with
Einstein's critique um they some of them
wrote their own responses that frankly
are hard to follow today and some people
call the responses kind of muddled it
was kind of you know a debate that
seemed not to go anywhere and so
Einstein and bour remained lifelong
friends but they never convinced the
other of how to think about Quantum the
about topics like entanglement in
particular and basically they both died
having not convinced the other over
after discussions that had had unfolded
over decades nearly 30 years uh soon
after each of them actually had passed
away as it turns out a much younger
physicist and member of the next
generation named John Bell who's
originally from Northern
Ireland was kind of dissatisfied by the
state of play by the state of discussion
of these topics and so he read
Einstein's paper very very carefully the
so-called epr paper Einstein had written
this paper with two younger colleagues
um uh Boris Podolski and Nathan Rosen we
usually use their initials
E this is the paper saying that quantum
entanglement proves quantum Theory there
is a problem with Quant quantum theory
that that's exactly right so that's
right so the epr paper published in in
in Spring of 1935 that's Einstein
podowski Rosen identifies this strange
prediction quantum theory and says
that's like too bad for quantum theory
right and so so John Bell much later was
reading that paper with great great
interest he read and was really
dissatisfied with Neil's B's response
that also had been published in in the
1930s and so B returned to this with
let's say fresh eyes younger generation
not quite beholden to the same um sort
of all the same assumptions that had
animated the ear earlier folks and what
bell did was he realized there might be
a way to really test this this question
and not just argue late at night through
kind of C cigar smoke um among friends
which is how Bor and Einstein tended to
talk about it Pipe smoke or cigar smoke
and so John Bell says maybe we could
actually force a showdown maybe there's
an empirical contrast between a world
that behaves the way Einstein assumed it
would have to and a world that would
obey these strange looking equations of
quantum theory and so Bell divide what
we now call in his honor Bell tests he
said maybe there's a way to actually
subject Paris of particles that have
been prepared a certain way conduct a
series of measurements on each member of
the pair and and try to understand
whether their behavior really lines up
is correlated in this much stronger set
of correlations that quantum theory seem
to suggest so what he did is he
basically took the the core ideas that
Einstein and Podolski Rose and had put
forward in the 30s and tried to codify
them what bell did was kind of codify
them any theory of nature that obeyed
what Einstein and his colleagues
considered kind of um um you
non-negotiable they core principles that
must lead to different predictions for
real experimental outcomes Bell is the
one who really first showed this
compared to the Now by that point fairly
standard predictions from the equations
of quantum theory and if when design
these clever experiments and conduct
them very carefully maybe we could sus
that out so that's what Bel did he
published that article in late in um in
uh in the year of 1964 so almost 30
years after the epr paper and schinger
similar work from the 30s uh and then um
this amazing body of work which now we
teach all our students we consider one
of the most significant papers in the
history of modern physics John Bell's
article uh it went nowhere it was
completely ignored in its early days in
fact uh it was published in 1964 it
received zero citations in the worldwide
sent of literature the next year he
received one citation two years later
and that was by John Bell himself it was
a self- citation no one was picking this
up literally no one uh and then what
caught my eye was the first among the
first to begin to pay attention was this
group that you and I began talking about
just a few minutes ago the group that
had called themselves the fundamental
physics group uh in
Berkeley this I mean the fundamental
Mysteries of the universe why was nobody
paying attention to that for a a
generation or more
it's a good question and that's partly
what I tried to explore in in the book
that you mentioned a lot I think a lot
of it has to do with the changing way in
which uh physicists were training newer
physicists and the changing kind of
landscape in which young physicists
found themselves during the period
between the 1930s and the 1960s or
really 1970s a lot changed in the world
a lot changed in physics in between one
of the big ones of course being the
second world war these enormous um
weapons projects uh like the nuclear
weapons project headquartered at Los
Alamos the Manhattan Project in the US
uh and and these you know huge kind of
Applied Physics projects that that
really enveloped a generation or two now
what happened especially in the United
States not only there coming out of the
second world war was a pretty
significant
reorientation in what seemed to count as
worthwhile physics I should clarify most
physicists in the United States were not
working on weapons projects after the
war the weapons projects continue to
grow the supply of young physicists grew
faster so it's not that everyone was
working on bombs afterwards at all those
projects were going strong but it was a
minority of the population but there was
a a kind of ripple effect nonetheless
and that really caught my eye when I was
wearing my historian's cap if you look
at changing textbooks in quantum theory
look look at changing lecture notes look
at changing homework assignments and
these things you we have paper traces
this was long before the internet so
people had to write stuff down like z o
which was the best thing for historians
paper trail all over place you see this
transition in what sort of is is taken
to count as as really kind of worth
celebrating or worth focusing on in
training young scientists young
physicists in particular so it's not
that they all started focusing narrowly
on nuclear reactions or let alone weapon
stuff but there was a focus on a kind of
pragmatic approach that we the the
attitude became it was often kind of
caricatured by the saying shut up and
calculate which was attributed to F and
it's not clear if ever said it but it's
it rang true with an attitude that he
and many many of his generation would
try to instill in their own students
their job is not they argued to stay up
late at night through the cigar smoke
arguing about what it all means but
actually to say let's put these
equations to work let's find new
phenomena build new things and let's ask
different kinds of questions not bad
questions I want to be clear in many
ways this was a golden age for physics
United States more Nobel prizes than
ever before people were finding really
important things that we still take for
granted and teach our students today it
wasn't bad physics it was a different
set of
priorities
so is it safe to say that physicists of
that day were creating Technologies
advancing science that relied on these
fundamentals of quantum physics to be
true they just weren't asking why they
were true I think that's a good gloss I
think that's exactly right that's
consistent with you know the questions
they were asked for their homework
assignments the way the textbooks were
being kind of Rewritten in the Years
after the end of the second World War I
think it's exactly that there's another
part that really intrigued me that I
think at least accentuated those Trends
and that's that coming out of the second
world war physics enrollments were
growing like crazy they in fact physics
was the fastest growing field of study
in the American University system of all
the fields around every field of study
was growing it was a huge influx of new
students thanks in large measure to
things like the GI Bill lots of people
who' served in the second world war now
have the opportunity to go to college
and some of wouldn't have had that
opportunity um if they hadn't served and
if there hadn't been this GI Bill huge
rapid rapid exponential growth in the
American University system and again
plays out with different rhythms in
other parts of the world as well uh
certainly very similar growth in the
Soviet Union at the
time um and then kind of uneven in other
places anyway even as as as every
department is growing none grew at a
faster rate than physics partly because
of those of the drama of the wartime
projects after the end of the second
world war these once highly top secret
projects like radar and the man
Manhattan Project were kind of unveiled
selectively unveiled and young
physicists became you know um kind of
heroes or were treated at least as as
cultural celebrities in a way that's
sometimes hard me and my colleagues to
imagine today they were some of them
were treated as really just like
basically like movie stars um and so the
enrollment were booming like never
before so that we treat you like a movie
star David I appreciate that you're no
of a movie star
well uh yeah the word Nova there seems
to M to play a role there Caitlyn anyway
no disrespect to my friends in Nova it's
not quite the same red carpet anyway I
love it but the point is it was really
kind of cultural phenomenon in the 40s
really into the 50s where even when when
like Time Magazine would conduct polls
of like you know the most prestigious
profession nuclear physicist would be
ranked like among the top three we
were're not there these days right um so
it was really a cultural phenomenon as
an educational phenomenon um and so the
the kind of floodgates opened so if you
ask yourself what's it like to teach you
hundreds of students in a class on
quantum theory when before the war it
might have been dozens you know as a
teacher I would imagine asking different
kinds of questions it's hard to grade
300 essays until what it all means
multiple choice you go to multiple
choice or you do you know really good
there was a there was a a collection of
really Exquisite calculating skill again
I want to be clear it's not like good
bad it's shift in what gets prioritized
and that post-war generation many of
them got extremely good at calculating
and doing kind of quantitative
math-based problem sets and that's not a
bad thing that's incredibly important
for for physics but what got kind of
shunted what got lower priority and kind
of pushed to the side and sometimes
actively denigrated but just kind of
squeezed out pedagogically as well were
these much more open-ended kind of
philosophically flavored questions about
let's try to ask qualitative questions
about what what it means for the world
to behave that way so I think a lot lots
of pushes and pulls on that generation
coming out of the second World War uh
and Bell was really educated in that era
he was one of the
outliers in fact John Bell recalled
later in his life that he was actively
advised not to pursue these
philosophical sounding was it all mean
questions because it would hurt his
career and he went on to an extremely
prestigious career as a let's say a kind
of straightforward particle physicist he
used equations of quantum theory
brilliantly there effects named in his
honor in in kind of mainstream nuclear
produ PHS to this day but it was really
a kind of side interest that he learned
to kind of keep quiet
about even though today we now realize
this was just absolutely foundational
you know uh mindboggling
work um I really want to get to the
quantum entanglement explanation but
just building off that for a second as a
historian of
science
um you you've seen
how this sort of anatomy of Paradigm
shifts in in in thinking and and is this
how it always happens is always these
outliers
or if you have any any commentary on on
what it actually takes to make big
shifts well that that's really
interesting so I I think there I don't
know it always takes that I think we can
find examples so this wasn't unique
let's put it that way this was the only
time we found that kind of outlier but I
think what what I find most interesting
as an historian is that it's almost
never the work of one
loansome you know genius or outlier or
anything else but we we a lot of the
work that my historian colleagues and I
really have fun trying to do and it
involves kind of detective work is try
to understand what are the shifting
institutions in which that work was
being done or uh in contrast to which
the outlier you know was positioning
themselves you know in contrast so that
what what was the taken for granted path
and how was that reinforced for example
through teaching through pedagogy
through the pattern of support you know
Financial or otherwise for certain kinds
of questions and so the the the outliers
first of all are almost never working
alone and secondly they're they're in a
kind of they're situated um in in a kind
of social universe that also is not
static doesn't sit still and that's
Again part of what really grabbed me
about the the the the shifts we're
talking about now you know the the
second world war drove in the United
States an unbelievable infusion of cash
in the sciences and in higher education
like literally never before and it
didn't last forever and it began to
rever the fortunes reversed equally
quickly so to shockingly fast with these
exponential drops in things like support
uh you know roughly a quarter Century
later so it's it's these kind of amazing
play of ideas and curious personalities
and ideas that are you know kind of
delicious and strange and hard to get
our heads around those aren't bubbling
up in in a vacuum they're also kind of
taking place uh aside some really
sometimes quite dramatic shifts in how
we get the work done yeah I I really
appreciate that and it's something that
we at Nova I think over the last few
decades have Al start to appreciate
moving away from this sort of Lone
genius model for how uh science is
Advanced because for the most part it
it's actually not and you know a few
often a few people get the credit you
know the Nobel Prize goes to just you
know a couple names right um but it's
the way new ideas get created is through
inter interaction it is and and what and
what are the conditions to allow those
interactions that accentuate some that
might make put a strain and sometimes
beyond the immediate control even the
immediate recognition of the folks that
we otherwise I think you're right tended
to to focus on maybe a bit too narrowly
yeah let's pause on the history for a
second I want to come back to it but
let's do a dive into quantum
entanglement terrific great this
phenomenon is hard to understand yeah uh
but you probably more than most people
have experienced trying to explain it so
what's what's your I don't know what's
your three minute uh explanation yeah it
it's it is it's just it's wonderful um I
think and also it is still kind of
beguiling it's it's not straightforward
and yet as as as I think you're already
setting us up we have better evidence
now than ever before it's it really
seems to be how our world works and so
it's worth you know three minutes maybe
even four um to try to to try to get our
heads around it so the idea really is
that
um that we we often make a lot of good
progress enormous progress over
centuries and centuries in fact trying
to understand the properties of one say
object one hunk of matter and how that
hunk of matter might interact with
another hunk of matter but each carrying
their own properties with them and
property sounds very abstract uh that
means if we're talking about little
particles what is its value of it spin
along the X Direction let's say that's a
fundamental property of many types of
quantum objects kind of intrinsic AGN
momentum we can measure it extremely
accurately in Laboratories now it's not
a hard notion even for undergrads to be
able to interact with
so one way we try to describe things
like uh little bits of matter is with
their spin spin along a certain
direction in space is spinning up or
down with respect to say the the X
Direction and so we might think that we
have two particles we could just
attribute a spin to each particle
separately and then ask about you know
um the combination their effects and
that's exactly where things start to
break down that what what B tests and in
this area of entanglement seem to really
accentuate is that the value that we
measure of say the spin of one particle
over here is going to be bound up in
ways that people found and still find
very hard to to Really wrestle with what
we measure here seems to depend on what
happened over there and the over there
could be across a a crowded laboratory
space a couple you know feet or meters
apart in principle according to Quant
the it could be across the Galaxy and
that's where it starts hitting up very
hard with other things that we take for
granted like local causes yield only
local effects if I if I hit something
here something shouldn't change there
instantaneously it should take time for
some physical process of information or
force to move through space over time
it's that conjunction of ideas that
anagement really forces us to to to
question let me unpack that a little
further if I were to take prepare these
particles send them off in opposite
directions and then perform a
measurement over here on particle a I
say oh I see it spin is is spin up along
the X Direction just having perform that
measurement is now going to change the
the measurement outcome for what a
colleague is going to find arbitr far
away now what I can't do is use that um
to send information we can't communicate
within Tang although people very smart
people have tried for a long time to
find a way to do that what it does is it
changes the the statistics the
correlations between the measurements
that we measured and so if I only am
sitting at one box and I see a stream of
particles coming at me I measure the
spin spin up spin down spin up spin up
spin up spin down I look it seem seems
to be a completely random set of
basically plus ones and minus ones as
far as I can tell there's no information
conveyed When I Look only at one box
that I have access to what's really
remarkable is that when my colleague who
might have been on alphas and Tor takes
a jet back uh and we compare our
notes only when we see the complete set
of that experiment what questions did I
ask what measurements did I perform
round by round over here what
measurements did my colag can perform on
her particle over there time and time
and time and time again that when that
we see when we each ask certain
questions in common we got related
answers we went when we asked different
questions those answers also lined up in
a spooky way so the particles were
behaving as if they somehow shared joint
properties even though we only saw
random noise at one box at a time is a
random box at each random outcomes at
each box it means I can't send a message
to her saying oh you know go um you know
change your stock portfolio because the
correlations only come from seeing the
combination of measurements performed
and outcomes received nonetheless when
we perform that when we get all the log
books together we find that the
particles are behaving in a correlated
way that far exceeds whatever could have
happened by chance if each of them had
definite properties on their own if I
just try to say each particle had a
value spin before I chose to measure it
I literally get the wrong answer my
friend and I together get the wrong
answers and so by attributing sort of
fixed properties to a particle that are
that are revealed by my measurement by
just making that assumption even saying
I don't know what it is I just assume
there's a value that gets revealed I get
different answers for the combined
experiment when I bring all the log
books together then I then then what
quantum theory predicts that might still
not be as clarifying as we'd
like but yeah so I want to get back to
the history because essentially and I
see why hippie's New Age movement
Eastern missm could see something
appealing here right basically physics
seems to be telling us that there is
some sort of way that particles are
communicating instantaneously which has
a lot of parallels sorry sorry sorry k i
be careful with the word communicating
because one of the things that came out
actually of this group's work was
something we now call the no signaling
or no communication theorem so so it's
not it's not like put it the way it's we
can guard against the following we've
done this with real experiments now for
Generations um decades now if it were
communication then we might expect
communication to have to um involve say
sending a signal even one bit a zero or
one from this side to that side and as
far as we know communication has a speed
limit the speed of light given
relativity and so we're able to do these
experiments shutting experimenting far
enough apart from each other the two
boxes two detectors
there's not time for a single light beam
a single you know status update on on
Facebook to get from that device to that
device so so they're not communicating
and then lay on top of that we have no
useful information we only have one box
so we can't receive a signal from the
other side know is so so what is the
verb what are they yeah it's it's
dissatisfying um I I tend to use the
word correlated uh but because
correlation implies you need the whole
set to then find these patterns you need
both
right um as opposed to like I just got
you know a message in my in my in my ear
yeah or or behaving as one system almost
their behavior is correlated that's
exactly right so the behaviors what we
what we measure will show patterns but
we can only sus out those patterns
frustratingly and yet bizarrely when we
bring the two sets of of kind of log
books together um and so and that wasn't
clear I should say even clarifying that
was part of what the work of this group
that we began talking about really
really did uh one of the members of that
group uh who was
um an enthusiastic participant in their
discussions Philipe abart who is a staff
scientist at the Lawrence Berkeley
National Laboratory and would meet with
them often he actually was responding to
these really joyful very clever thought
experiments that members of the group
other members of the group were coming
up with exactly to try to send messages
they wanted to have a kind of fast and
light Telegram and Philly Bart published
one of the first ever demonstr that even
according to quantum theory that
shouldn't work that won't work because
you need to you know bring both boxes
both log books together so we know that
I can say that with a straight face like
oh well there's a no signaling theorem
because the work of groups like like
this fundamental physics group because
it was not straightforward actually John
Bell himself ended his classic 1964
paper worried that maybe this did leave
the door open to fast and light
communication because it was because it
was so you know difficult to sus out so
I don't mean to make it sound like it
was so straightforward over the work um
over in that case about a decade and
then the decades ever since then people
clarifying that it's not exactly
communication but there's something
certainly spooky or unexpected that
still
happens so we left the the story the
history at at um John Bell has sort of
um envisioned a hypothetical way that
this could be experimentally tested
where do the fundamental physics group
come in what what happens next that
actually changes the field right so one
of the people who discovered John Bell's
article which otherwise as head was
really being ignored largely ignored in
the literature was at the time a PhD
student named John clauser clauser was
at the time at Columbia University in
New York uh in the late 60s and early
70s and he basically found Bell's
article by accident he was in the
University library and he found a funnyl
looking Journal Bell published his
article not one of the mainstream
journals for all kinds of reasons we can
talk about and basically as a kind of
study break from his main dissertation
project young John clauser found this
weird looking journal on the shelf and
he kind of took it took it off the shelf
and in great Serendipity you know kind
of semi- randomly it fell open to her he
he flipping through found this strange
sounding article by John Bell Bel the
title of Bell's article mentioned was it
Serendipity or was it uh quantum
entanglement right we'll never know
that's right I I can't rule out either
but it was certainly not he wasn't he
didn't go looking for it I'll put it
that way it's not that clauser had
already heard about the article because
few people heard about it so by whatever
wonderful spooky actions um clauser
found John Bell's article and got very
excited this this looked like the kinds
of big you know how does the world work
kinds of questions that had attracted
young John clauser to study Physics in
the first place so as clouds recalls he
rushes back to his dissertation advisor
look at this amazing thing we could do
these experiments John Bell was a
theoretical physicist clauser was a
budding experimental physicist so Bell
had had identified a type of experiment
perform it he wasn't prepared to do it
himself CU oh we we could do that and
his advisor said that looks like you
know kind of philosophy or not what we
should be doing do this straightforward
project on very very important topic um
but do this other work and don't bother
me with these philosophical Trifles at
least as clauser remembered really just
a strong brush on so nonetheless the
topic kind of got under clouser's skin
he wrote letters to John Bell uh asking
if other experimentalists had taken it
on Bell was delighted to hear from
anyone let alone an actual
experimentalist that no one's done it
maybe you could do it that would be
amazing and so they have a little kind
of pen pal correspondence and then
slowly again through kind of Fun
accidents uh John clauser has put in
touch with other young folks the few
exceptions who also had kind of found
John Bell's article there's a group in
the Boston area uh and and a few others
so John Bell as John Claus completes his
dissertation gets a postto at Lawrence
Berkeley laboratory so to do his kind of
mainstream to continue his mainstream
research
well he gets there just to the
laboratory like most of his going
through a huge downturn in fortunes
there's lots and lots of kind of you
know spare time because the funding has
been cut way way back so he has
permission of his new supervisor new
postdoctor supervisor to spend kind of a
little portion of his time on this kind
of pet project could one design a kind
of bell test and really do it and to his
credit his advisor Charles Town said
sure you can spend some time in that cuz
you know we're not at capacity and
Charles towns went further and enabled
um a PhD a new PhD student at the time
to start working with John clauser uh
and so the two of them were able to work
on these first ever you know Bell tests
clauser recalled that he basically got
good at dumpster diving like there was
not like he got grants from you know the
federal government to do this thing it
was like what could he scrap for spare
parts and there are photographs that I
love of him actually literally duct
taping equipment together in this uh in
this kind of leftover space of the lab
um but nonetheless together um Stuart
Friedman the grad student and and John
clauser were able to do the first ever
Bell test and they found against what
clauser had hoped for uh exactly the
correlations that quantum mechanics
predicts I should say both John Bell and
John clauser hop this would be a way to
show that Einstein was right and that
quantum theory wasn't really true after
all it wasn't as true as as um as
correct as could be but there was
something maybe wrong and that
entanglement would be entanglement tests
would be a way to to to reveal that
quantum theory is not the last word and
instead ironically clauser and uh and
his colleague um younger colleague
Stewart Freeman actually found beautiful
beautiful scen results everybody wanted
to be on team Einstein everyone not
everyone but but some of these is Iconic
guys yeah yeah uh and so to to to turn
that story forward uh that so clauser
basically shared the Nobel Prize in 2022
for an experiment that he hoped we give
opposite results maybe we all make such
mistakes in the lab is pretty great so
um so that's an example of how the topic
began getting local attention now Cloud
this in
Berkeley he befriended I just want
emphasize that that was a Nobel prize
winning experiment it turned out to be
with the passage of in this his case
exactly 50 years so if you are willing
to wait you know that was it was not
seen and in fact again not only were
people still not paying much attention
to John Bell's article people didn't pay
much attention at the time to the to the
fredman clauser experiment it was
published in our most prestigious
Journal unlike John Bell's article and
yet it was again roundly ignored you can
tell that by citation analysis there's
correspondence from the time that John
claer himself shared with me and other
historian colleagues this was still kind
of dismissed by most kind of you know
mainstream physicist in fact John claer
never got the kind of position in
physics he had hoped for he never got a
university professorship and some of the
letters around his early applications
make it clear is because they thought he
was working on a kind of important
merely philosophic on a strange topic
which 50 years later you know earned a
share of the Nobel Prize um so that's
seems kind of hopefully that's humbling
for some of our department heads in the
world today anyway the point is clauser
really had caught the bug he now was
able to do this remarkable experiment
that was not getting a lot of attention
one place it did get attention was his
own backyard in Berkeley and he began
meeting up with this fundamental physics
group he was a kind of charter member
with about eight or 10 of of other kind
of new friends who all the others of
whom almost all of whom were actually
coming from theoretical physics they
were intrigued by Quantum in Tangent in
Bell's article and now they had one of
the world experts uh at their disposal
meeting John clauser and together they
met you know every Friday for years to
to kind of wrestle with this some of
them thought this might lead to things
like faster and light
communication uh and some of them
thought even further maybe this would
lead to things like an explanation from
mind reading maybe the communication is
between you know entangled particles one
of which is in my mind and one of which
is in your mind uh and so some of them
took this into even more let's say uh
new Agy kinds of directions they were
they were immersed in a kind of hot bed
of new age um enthusiasm in the Bay Area
clauser I think to his credit had a kind
of open mind about that he wasn't s of
convinced about New Age stuff but he
also said what do we know more than once
and he would participate every week and
would they would go and have study
sessions at other plac places in the Bay
Area like The eln Institute and CLA
would go time and time again and he
would say you know he he as far as I can
tell was let's say um curious but not
dogmatic in either direction some of his
his discussion mates became um much more
convinced and then maybe unconvinced and
convinced again you know there were kind
of strong ideas strong passions the
point is the group was didn't feel Bound
by what counted like to be a
straightforward question they said if
we're not if most of us aren't going to
get the kinds of careers that we wanted
anyway
and these questions seem worth pursuing
and curious they would kind of let their
curiosity drive them and they were
combine that with this really grounded
discipline study of of they could push
the equations around some of them could
do world class experiments so it's that
combination that really grabbed me of a
kind of open-minded
curiosity uh combined with the
discipline to see it through and so they
weren't just like musing they weren't
just having the late night dormatory
room chats they were open to that and
they were doing the homework right and
they were trying to say well if we take
this seriously here's what my
calculation suggest I could imagine a A
variation on that experiment they were
trying to do both and that I found
really
exciting so I hear that these
experiments really helped kind of prove
that
um that the universe is spooky that
these phenomenon seem to be real but
does did that have a direct correlation
to the um applications it sounds like
there were applied physicists already
kind of working on applications that
relied on the underlying physics um or
did this work also help Advance the both
sides of the equation I think I think
it's that it really had a knock on
effect for for both sides I mean there
weren't a lot of people at the time in
fact none that I can think of frankly
who were trying to exploit quantum
entanglement for new devices at that
time the topic was really just not of
much interest either way and so part of
what happened and partly why I got
excited to write the book was you start
seeing this early group of the kind of
eccentrics um and then with their
correspondence Network you could see a
small number of other physicists some of
whom were more had had closer ties to
the mainstream and had their own range
of you know Curiosities and interests
there's a kind of dispersed community
that begins to to talk together um some
of whom start doing followup very
brilliant followon experiments uh beyond
the the original one that John clauser
and Stuart Freeman had done and that
includes people like Alan aspe who who
then shared the Nobel Prize in 2022 a
little later it involved people like um
like Anton Zinger so there are people
and others who begin doing more
experiments um kind of riffing on the
pattern but trying to do even more
clever versions of the freedan clauser
experiment there are theorists who begin
trying to really sit with these
challenges from the Berkeley group why
can't we use quantum entanglement to
send messages fast and light if we can't
um does that help us understand other
features of Quantum Theory and new ideas
came out from that something called the
no cloning theorem was one as a direct
response to these kind of clever
provocations so you see this unfolding
again over kind of the next decade from
the mid 70s into the mid
80s and that's when you start seeing now
a kind of critical mass in a few Pockets
not still not um on the mainstream in
most textbooks um but enough people now
Beyond just this this eccentric Berkeley
group who begin wondering maybe if this
really is true of the world could we put
it to work does it become a resource and
not just a curiosity and so you start
seeing an effort to do things like
Quantum encryption which is happening
the first theoretical protocols being
formulated in the mid 1980s exactly
Downstream from a decade 10 years worth
of really trying to wrestle with both
the first Bell tests and these really
clever ideas about the relationship
between quantum entanglement
communication and relativity and so
encryption Quantum encryption becomes
really the first one of the first kind
of efforts to apply entanglement in a
new kind of device and that's actually
going yeah go ahead can you explain that
a bit how does it use entanglement in
device yeah so the idea the core idea
between behind encryption is again to
say that these uh entangled particles
share features together and so if
someone wanted to kind of um eases drop
on a signal typically for typical
signals we can we we have one source
beaming out say radio beacons and if
someone wants to kind of intercept that
radio Beacon can get a sneak preview
right uh because the radio Beacon is
sort of a basically classical system and
so what you do here should have not
won't won't show up over there if you if
your beacon instead are quantum
particles in the special entangled State
then their behavior is correlated and if
someone Taps into this particle here
that affects the behavior over there
right so it changes the it it basically
alerts both sides that someone's
actually tapped your line it announces
the fact of eaves droping which
classical signals are much harder to to
to verify that and actually erases or
scrambles the hope for message anyway so
eavesdropper doesn't get the message
because they've messed up that special
just kind of delicate Quantum State and
they've announced their presence in
brief so that really relies on these
really wonderful but strange properties
of say pairs of entangled particles
which you don't get through kind of
classical communication channels and
that was again trying to play with this
idea of entangle particles kind of one
Quantum state that some distributed
through space combining that with you
know how do we communicate from this
side to that side the kinds of questions
that among others this Berkeley group
had been really putting their putting
their finger on and trying to push push
push roughly 10 years later some other
clever folks some of whom had been in
touch with that with that uh Berkeley
group in the early discussions they turn
it around and say oh actually this
becomes a way to protect information as
opposed to a way to send it somehow by
Magic so and then now that becomes
that's really a kind of worldwide
billion part of a billion dollar
worldwide industry now that's one
example are there so Quantum encryption
is one example what other um
applications of quantum entanglement are
we seeing now so another big one yeah
another big one there are several
another big one is actually on Quantum
Computing which is not quite as far
advanced in terms of kind of entering
the kind of everyone getting to buy one
on Amazon but Quantum Computing is an
area that's also a subject of enormous
effort and enthusiasm and funding and
support in universities in government
labs in private Industries um everywhere
in many many countries um and and at the
core of of many many kind of quantum
algorithms is again these kind of
entangled States these now we call them
Bell States they're trying to use these
pair these special prepared kind of
pairs of
particles can really kind of take
advantage of their connectedness so
instead of having lots of particles lots
of bits calculating kind of in parallel
on their own um you actually get can get
these for certain certain kinds of tasks
you can exploit the connectedness and in
some loose sense uh exploit the fact
that that one state is again more than
the sum of its parts you're getting kind
of more computation out from one
entangled system than you would ever get
from having two kind of separated or
classical bits there's much more to it
but the point is that a lot of the kind
of speed up or the power behind many of
the um algorithms that are designed to
run on quantum computers really comes
from exploiting this connected these
Bell States so that's that's another
kind of um kind of on the horizon not
quite on the Shelf yet today
technology so what do you think the
future might look like with respect to
how Quantum Technologies might change
the world I mean we're we're living
right now through what seems to be like
an AI Revolution it seems like it's
changing a lot is there going to be a
Quantum Revolution where just the fabric
of the way Society works it changes
because of these
Technologies I I likely so but it's
going to come in way in stages I think
most you know big changes tend to
actually so one is I think we're we one
one thing that people would love to be
able to do if they can get kind of
robust quantum computers to really run
uh on a larger scale would be to start
simulating Quantum
materials as we've been saying now
quantum mechanics just says that matter
behaves just differently than than kind
of large blocks of matter behave that
otherwise are otherwise described so
well by classical physics
and so our computers to this day our
ordinary computers are really good at
simulating ordinary matter even that's
hard but we've got really good at it
they get really really bad very quickly
at simulating Quantum states of matter
because of these kind of exponential
kind of uh connectedness let's say and
that really just swamps what our even
our best supercomputers can do today
quantum computers would so to speak
speak that native language of quantum
theory itself so one hope would be to
have a just an unbel ably improved
ability to understand materials at a
quantum mechanical level maybe even
design materials maybe that gets even a
few steps down the road to things like
Pharmaceuticals I don't know but what do
we want to do I mean if if matter is
made of quantum objects can we learn to
understand and maybe even manipulate
Quantum objects Quantum materials in in
a in a in a in a in a kind of more
thorough grounded uh first principles
way with a with a ability to simulate
those that equals our kind of
imagination let's say that's that would
be one great thing so like a quantum
computer could run a fusion reactor
because it's a Quantum process or
something like that maybe so maybe so or
or or would it help us understand again
some maybe bioactive molecules better
than we able to now things like that
would there would there be some sort of
spooky kind of blackbox aspect to how
quantum computers actually do their
Computing the same way you know AI is
kind of a black box right now I I think
that's probably right and and so it it
that's right so people spend a lot of
time trying to understand a design and
understand Quantum algorithms but as
these go up to scale I think one would
likely start to find things like we find
you know um huge machine learning
algorithms or behind things like gener
AI that really um exceed a kind of human
interpretability or human explainability
I would expect the same thing to happen
as these Quantum algorithms again grow
in their own
complexity what do you think um what's
your expectation for the timeline when
we might actually
see uh See this in our lives It's Tricky
for Quantum encryption I think it's it's
it's already in some sense here it's in
it's in pretty Advanced beta testing I
have friends and colleagues who have
done this uh as kind of demonstrations
but in not just in pristine laboratory
conditions real world demos with
kilometers and kilometers of fiber optic
CA strung through cities not just in in
you know kind of laboratory or
university buildings and showing that
encryption systems really do work as
designed um and they can be deployed um
not quite at scale but beyond only kind
of control controlled conditions so I
think encryption is frankly further
along in getting closer to something
that could really be of commercial and
governmental use for good or ill I mean
I'm not sure that's a great good thing
frankly um but um but nonetheless I
think it's much closer Quantum Computing
I think one of the big limits maybe the
biggest limit so far is not designing
real really cool algorithms not
designing the code we love to run on
these things but getting enough of these
very kind of delicate Quantum States
these so-called cubits or Quantum bits
to maintain their special Quantum State
because you know basically heat and
noise are the enemies of of quantum
coherence so to really put it another
way we work really hard when we do these
these experiments to reveal quantum
entanglement like modern day Bell tests
we have to Shield our Quantum particles
against all kinds of disturbances
against noise and so imagine trying to
do that with lots and lots and lots of
these Quantum particles these Quantum
entangled particles because many many
kinds of effects of the environment will
tend to wash out that special Quantum
State and therefore wash out that kind
of quantumness that you want to
exploit so forgive me if this is a
little bit of a one1 question but when
does something become Quantum I mean
obviously we don't see don't see we
don't see our uh stuff in our world
regularly entangled is there a reason
for that or is there a line at which
physicist to say this is quantum this is
not it's it's the opposite of a one1
question that's still have to frankly
it's it's a deep question um and so I'll
give you a shallow answer but I'll just
say that that the there is no single
kind of dividing line it depends on you
know the system and the means with which
you're interacting with it nonetheless
one of the great kind of races that's on
today again involving some of my very
dear colleagues and friends to see
exactly how large how many moving Parts
a system they could make that still
shows the unmistakable quantumness and
when does the classical description kind
of take over and and become you
thoroughly adequate and that's that's a
moving Target we know that if we want to
describe a single atom at a time we're
not going to be able to do it with
Newton's physics we know just as you
said we want to describe a huge
collection of atoms then we do really
well with classical physics and where's
that line is it you know 10 atoms is it
100,000 atoms is it 10 million atoms and
that I think really becomes kind of
context specific but part of the the
kind of virtuosity is to be able to
demonstrate robust Quantum behaviors for
systems that have lots and lots of
quantum moving Parts but not so many
that it's kind of tipped over and the
quantum just kind of washes out so again
that's a bit of a vague answer but I'll
just say it's a live issue uh and part
of what what uh even for those
demonstrations part of what tricky is
that as I say kind of an impacts of the
environment which can take many forms
tend to wash out the special quantumness
of one system or or of these complicated
many art systems so that's what's what
what creates one of the main drags on
quantum computers is is how many of
these so-called cubits of these
specially prepared Quantum states can
you keep in their quantumness in their
Quantum State before they before that
kind of washes out and and there's
special
bell-like Behavior Quantum Behavior no
longer becomes usable because it's been
kind of diluted because the entanglement
been kind of spread out among so many
partners that it no longer has that
specialness between these two uh members
of an entangled pair so again that's a
bit of a of a of a of a imprecise answer
but I think the biggest challenge right
now is just is maintaining large numbers
of the stuff on which you could run
Quantum
algorithms So speaking of things losing
their Quantum state or changing them
there's another aspect of quantum
entanglement that is strange which is
about how the Observer can affect the
system uh which is troubling in some
ways can you explain a little bit about
that yeah that's another one that that
sort of won't go away and I should also
say it doesn't command a single answer
you're among experts in the field it's
an area people still really get rightly
troubled by and many people have their
own favorite answers but they all
they're not it's not the same answer so
again if if we take the the equations of
quantum theory at face value it
certainly looks as if and many people
smart people including noo laureates
have have described quantum theory as
somehow relying on the Observer to
produce um a certain outcome that we
choose what measurement to perform and
therefore the outcomes of measurements
are sort
of unavoidably dependent on our choice
at least of what to do how we chose to
intervene what what setting we set on
our on our measuring device and
therefore what answer we got especially
if we combine that with what we talked
about somewhat time ago about in
tanglement that we no longer can
describe these Quantum atics as just
having fixed properties that our
measurements happen to reveal right it's
that that really puts the tension on
what's often called the measurement
problem that we chose what measurement
to perform and that revealed a definite
answer it's not that we get a a fuzzy or
squished out answer we get a real answer
might not have gotten the same answer
you know the next time around so so what
role did we play in kind of manifesting
or bringing forth a particular
measurement outcome because we chose
form of measurement so some people take
that and say one one person in
particular Eugene vigner but that was
just really uh um unavoidable and that
somehow human consciousness had a role
to play in quantum theory vigner I
should say won the Nobel Prize in
physics he was not a dummy his ideas
commanded lots of attention including
from this Berkeley group some of them
were enamored of that is there a reason
why human consciousness should be
somehow written into the equations of
quantum theory they were intrigued I
don't think they quite succeeded at that
but they were intrigued by that question
these days that line of thinking is much
less um popular let's say among experts
in Quantum theor it's not that it's been
sort of disproven necessarily but other
folks have found other other
roads one that's popular and it's not
one that I particularly endorse but gets
a lot of people excited is something
called the many worlds interpretation
which basically says that um that all
the answers are chosen it's just that
the Universe kind of splits in some
sense every time a measurement is
performed so that our human
consciousness me here also winds up
splitting and along this path or in this
you know this track there's a version
it's all self-consistent there's a
version of me that found the electron
spin up but at that moment there was a
split and there's a version of me in a
track that with which I had no longer
have any contact that in my conscience
found the outcome to spin down and so on
and so you can imagine this infinite
proliferation I find that pretty headyy
and pretty dizzying I have very dear
friends who think who think that's the
most straightforward way to understand
what quantum theory is telling us so
it's not that my Consciousness is active
in the world but in some sense my
Consciousness is bound up because it's
also made of quantum particles and all
this this entire Quantum assembly is
always doing self-consistent things but
I can no longer Trust
I can no longer send or receive messages
from these kind of now parallel tracks
that have somehow forked off now that's
a great way to make some pretty cool
science fiction some friends of mine
think it's a great way to describe the
natural world obviously that hasn't
commanded you know Universal Acclaim
either there's all kinds of things which
which get at exactly what you put your
finger on Caitlyn what is the role of
let's say the observer in in our in our
interactions with the quantum world and
I can see how the fundamental physics
group would see this as really
compelling because it seems physics
seems to suggest that we have a role in
in we have agency in creating the the
the uh universe that comes to be for
some of them I mean again that was at
least an an enormously consequential
question and a lot of them to their
credit didn't say ah I found the answer
I'm right they said that's a question
worth sitting with right and so I think
it was it was our openness to the
questions that I that again that really
um I just came to admire uh not all
their answers some of their answers I
thought were actually frankly pretty
silly some of them came to consider
those answers silly too over time not
all of not all again it was it was a
rich variety but to be open to ask
questions that otherwise seemed strange
or silly I mean a lot of questions seem
strange or silly at first and some of
those not all but some of those
questions when we bring our kind of
disciplined um thinking to them can
really surprise us and so that was the
that's what I found so frankly endearing
about the group so what happened to this
group did it disband did they all
just become popular phys what happened
yeah they again it was kind of accidents
of history that that by which they found
each other in the early mid 70s and then
by the late 70s early 80s they they
began to kind of you know go their own
ways um so some of them stayed in the
Bay Area uh some of them moved on
geographically um some of them became
kind of very clever Consultants we might
call them kind of entrepreneurs these
days all kind kind of tasks some of
which failed some of which you know
succeeded on the margins uh one of them
won the Nobel Prize right and so it
really it's a it's a huge range of uh
rags to riches to for some of them Rags
again or to others um you know a kind of
uh lasting place in in in our in our
understanding of of how we've come to
where we are today so and and many of
them I should say many of them are still
alive one or two have indeed passed away
only recently they were doing this when
they were in their 20s and 30s 50 years
ago and so many of them are around they
was around when was working on the book
and they were very generous with their
time when I had questions and and they
would always get back to me right away
and I had a chance to meet and and talk
with them and so and I still hear from
many of them to this day so you know
they're all I think all of them have
kept a sense of the Wonder I think
that's fair to say some of them have
pursued even more let's say heady topics
that are On The Fringe or the or outside
the
mainstream about say could we understand
UFOs are there ways to understand
relativity in non-canonical or non
unusual ways that might lead to strange
effects again I'm not endorsing those
claims but at least you can see them
puzzling through them um and and others
like I say have uh have now reached the
very Pinnacle of success in our field
like John clauser so it's it's a whole
range and their legacy is that physics
has continued to pursue these these
questions and I understand I want to
Pivot a little bit to talk a little bit
about your work so I know you were
involved at least in a in a in a as at
least in some respect with Quantum Bell
test a cosmic Bell test tell tell us
about that yeah I was so it was it was
really quite um it was one of the
adventures of my life it wasn't just a
highlight of my career it was even even
more special than that but I'd written
the book that we've been talking about
and then you know after it came out some
of the young physicist uh with whom I
work um had read the book kind of for
fun had a strange title and um you know
they were curious so they read the book
for fun and then we began talking about
well could we imagine redoing or doing a
new generation of bell test what using
what we all have learned in the interim
over the last you know several decades
not just about Quantum Theory but about
the structure of the universe so my
younger colleagues and I were coming at
this from astrophysics and cosmology not
first and foremost from quantum physics
per se and you know we've learned a lot
about the big bag about the the kind of
course of the universe over the last
almost 14 billion years about the kind
of causal structure which parts of the
universe uh could have interacted with
with other parts over time and so
working with Andy fredman and Jason
kikio uh they were at the time very
young post talks uh we began wondering
whether we could visit one of the most
stubborn kind of loopholes in these
generations of Bel test which was often
called um the freedom of choice loophole
or the Free Will loophole which is a bit
more um sensationalistic but the idea
was in any Bell test we have these two
devices and physicist locally at each
one have to choose what measurement to
form in real time before that a member
of the pair arrives and so it we have to
do something like flip a
coin and so um the question that was
identified in the mid-70s by people like
John clauser and talked about it and
debated it with people like John Bell
but was never really tackled in in um in
new experiments was how do we know that
we're using a Fair coin how do we know
there was no hidden coordination or
statistical correlation
between the choices of what measurements
to perform here and there which there
something in the shared past that could
have either tipped off the far side of
the order in which measurements will be
performed or maybe even nudged them both
you know relativity says that things
that are far part can interact it just
takes some time well we've had 14
billion years of time right since the
Big Bang so the question was could there
have been something in the shared past
some subtle effect that have been
overlooked that could have kind of led
to a correlation in the order in which
questions were asked even though those
devices are so far apart from each other
today and so we decided to turn to the
Heavens to turn the universe into a pair
of random number generators not flip a
coin you know in our in our local
laboratory but turn to random processes
far away and long ago on opposite sides
of the sky and that's what put the
cosmic in Cosmic Bell so we proposed
this um we wrote a paper saying this is
feasible there's light from very distant
quazars very bright very early galaxies
on opposite sides of the sky that lit up
so early after the big bang that they
had no chance to trade light signals
with each other the light would be
traveling through most of cosmic history
toward the Earth we use those as our
decision makers when we get this light
on our Mountaintop this moment that
light was emitted very early in Cosmic
history depending on the properties of
that light we receive that will tell us
what measurement to perform here on our
Earthbound and Tangled particle and so
on over there so want those qu our
signals to be as unentangled as possible
as uncorrelated as possible and the
universe is a big old place so it turns
out one can search for really distant
sources of light that were coming from
opposite kind of separated parts of the
sky and uh and then do an Earthbound
test that way so we patched this
idea so you're using the entire universe
in your
experiment 96% of it yes we use is this
the largest experiment ever done well
depends on how we how we characterize it
uh but it certainly was among the
biggest it was trying to push quantum
theory and relativity out of their
shared Comfort zones let's put it that
way right so was really trying to ask
questions about fundamental quantum
theory with some real inputs to the
experiment that span Cosmic scales
that's certainly right um so I don't
know if it was the biggest ever but was
certainly trying to do that in a in an
unusual way so as a theorist we said
this could work we pitched it to Anton
Zinger and he lit up immediately and he
got very enthusiastic he and his group
had thought similar questions as we then
found out so we put a team together and
we got finally got some generous support
from the National Science Foundation and
so we built this International
collaboration we really did this we did
a pilot test in uh Anton's home city of
Vienna and based on how well that one
turned out we did a big
test on the island of La Palma in the
Canary Islands with huge four meter
telescopes it was just a joy and that
was captured partly uh in this in this
Nova film uh Einstein's Quantum riddle
the the filmmakers are there they got
some I think breathtaking footage of
what it's like to work on a Mountaintop
Observatory which is just jaw-droppingly
beautiful they captured Us in moments of
real uncertainty uh we got bad weather
several nights we were Iced Out chased
down the Mountaintop Midway down because
the first few nights there were ice
storms and if we didn't leave we'd you
have to sleep in the telescope Dome
basically so it was really you know
wasn't so straightforward uh and and the
filmmaker was there to catch you know
kind of the highs and the lows both um
which I'm very grateful for because it's
you know I have my fond memories but I
can go back and watch the footage too
and say wow this really this is a team
of 20 people working literally Around
the Clock uh and and it was just a huge
Adventure you thank you for doing the
promo for me you did my
job if you want to check that out you um
that's on our website Nova maybe we can
drop the link in the chat as well um but
yes we did follow that experiment um a
few years ago that's right so what um
Mysteries of the universe are you trying
to solve now well there are a couple
left there's a few Mysteries left we're
not we're not going out of work anytime
soon you know one of the ones that I
find most delightful and challenging
really hard pivots a little bit away
from Quantum anagement but it still gets
to like what's the world made of I love
those kinds of questions and one puzzle
that's been with us for at least 50
years and has Trails even earlier around
the same time that the the fundamental
physics group was really forming and
beginning to wonder about Quantum
anagement people in other areas of field
began to realize that our universe is
chalk full of this mysterious stuff that
we now call dark matter we don't know
what it is and yet it seems to be
everywhere and it seems to really have
set our universe on its course in fact
we need now to un to to take into
account an enormous amount of dark
matter if we to understand how the
universe has evolved and in some sense
even why we're here without dark matter
it's not clear that galaxies could have
formed at least not at the same rate or
the same type that we you know have
today maybe our own Galaxy couldn't have
formed if there was no Milky Way galaxy
it probably wouldn't be a on or an earth
here you know for us to live on and ask
questions about the Universe I have some
dark matter here from physics at MIT I
Peter Fisher has a bunch on his shelf
too I recognize the box and
so here a very small amount yes there
there's approximately one per that
volume one that's that's that box is
great to show us just how thinly spread
out it is in our local setting there'll
be about roughly one you know kind of
one proton's worth one hydrogen nucleus
worth uh per kind of per box that size
um per cubic centimeter anyway so maybe
there's a few more than that but anyway
it's pretty thin on the ground but when
you add up how many cubic centimeters
there are in the entire universe this
stuff dominates it's more much more
about five times more Dark Matter per
per unit mass than all the ordinary
matter that we know about the entire
periodic table that Humanity spent a
couple hundred years piecing together in
testing thr in all the fancy stuff we've
learned about from the large hron
collider and experim before that the
higs BOS on neutrinos throw it in all
you want lots of great Nova special in
those too those make up roughly 20% by
mass of the stuff that's of the matter
that seems to fill our universe so we
have a big big challenge what is dark
matter okay well one of my favorite
hypothesis now is to say what if it's
not some exotic new particle that no
one's been able to find after 50 years
of careful careful testing What If
instead Dark Matter consists of ordinary
matter the stuff that we do know a lot
about that's locked locked up in unusual
gravitational States known as black
holes again lots of great Nova stuff on
black holes um but what if these are not
just ordinary black holes that we now
know a lot about what if these are
special black holes that formed right
after the big bang they're called
primordial or early Universe black black
holes they formed by by kind of doing an
end run by by by cutting out the typical
um life course by which ordinary black
holes are made these would have been
made long before there were atoms L
alone stars that collapsed to make
astrophysical or Stellar black holes and
stepen Hawking among others hypothesized
about these 50 years ago in the mid
1970s the idea was like quantum
entanglement kind of On The Fringe for a
long time even though Elite physicist
like in this case Steph Hawking had put
it forward it was seen as a curiosity at
best or a weird idea or not worth
pursuing and really over the last
roughly 10 years this hypothesis has
come roaring back uh into interest
partly because these other much better
motivated or seemingly better motivated
hypotheses like oh it's just some new
particle keep coming up empty it doesn't
mean the answer is Primal black holes
but it gets really intriguing because
now we know black holes are real that
wasn't so clear at all in 1974 we can
find other kinds of black holes now all
the time with amazing astrophysical
instruments we've learned a lot
theoretically anyway we know a lot we
know a lot about the early Universe what
could have led to the formation of a
population of these black holes early on
we just know more of these puzzle pieces
and a lot of them feel much more solid
than they did when this was merely
hypothetical 50 years ago so are you
saying there could be a primordial tiny
black hole in my office yes yes uh at
the very now it's not very like they are
among us they might be among us with
with very dear colleagues uh I've been
doing some work uh for on that exact
question as of others if all of Dark
Matter consists of these tiny black
holes they would have to have a mass
that was around the size of an asteroid
they'd be like big space rocks in Mass
but they're black holes which they've
condensed they've shrunk that mass down
to an impossibly small spatial size they
they're so densely packed you take the
mass of an asteroid a big Space Rock and
you shrink it down to the size of an
atom or smaller so it's a really really
amazing exotic object it has um very
interesting and strange properties so
now if that's all of Dark Matter then
you only need to sprinkle a couple of
those around the solar system to make up
for all the dark matter by mass that we
know has to be there because each one is
much more massive than say a typical
particle so the number per volume goes
down it's much less likely to have one
in your office Caitlyn very I don't
think there's something the mass of
asteroid in my office probably you you'd
know that you be tugging on you'd feel
it to be but but instead there should be
about one uh at least one or two Within
a sphere the size of say Jupiter's
orbit and it could be anywhere in in
that sphere right and it could be
zipping around at high speeds but you
can presumably detect that
astronomically then exactly right and so
we have this really fun paper uh that's
coming out soon actually coming out in
one of the physics journals saying if
that's really the case then there should
be observable signals of of visible
objects that we track with great care
like the position of the planet Mars
right thanks to 20 plus years of high
Precision Telemetry to Mars orbiters and
Mars rovers astronomers know the Earth
Mars distance to an incredible accuracy
centimeters amazing we know the distance
between Earth and Mars to one tenth of a
meter thanks to all these very cool you
know basically Space Program projects
that's amazing so now let's say some
little tiny black hole goes zipping
through this the solar system doesn't
hit anything right it's mostly passing
through empty space but it has enough
mass and it's going so fast it sets Mars
rocking just a little bit we're not
talking about a Hollywood Blockbuster
it's not Armageddon it's a tiny little
shift a kind of rocking motion that
would result in say the planet Mars but
we monitor Mars so well that that
rocking motion should indeed be
observable over not such a long time
period it should have a different kind
of rocking motion than if other kinds of
say space debris FL flu past so there we
have reason to think it could be
separated um from kind of other more
more mundane explanations for these kind
of um little Wiggles so this is the kind
of thing we we can now try to do other
colleagues wrote some really interesting
papers saying what about the GPS
satellite Network we know the positions
of of 30 satellites to about centimeter
accuracy and we've known that for
decades so we have kind of historical
Legacy data as well as going forward
they're tracked so carefully because we
need them for our navigation again if
some get a little wobble not a huge
effect would it show up in that kind of
system as well so there's hope to think
maybe we could test this bizarre
sounding hypothesis what if all of dark
matter is locked up in these tiny tiny
microscopic black holes formed by the
big bag it sounds like ridiculous we
might know we might be able to tell over
the coming decade or two and I find that
great fascinating so you think in the
next couple decades we'll have the
observations to sort of verify or
disprove this I think that's right I
mean I think if no such W wobbles show
up then that becomes a pretty tight
constraint if a couple wobbles do show
up then we'll have to play the usual
game well it re was it really a black
hole was a different mundane explanation
we overlooked it'll be hard but if you
find nothing that crosses the threshold
then it's going to be harder to account
for if all of Dark Matters black holes
so it really does seem promising as a
way to constrain and intriguing as a way
to at least get some hints If there
really were these these these wobbles
that could be found and that is on a
kind of decade long time scale not
impossibly far into the future but we
won't we won't know tomorrow but we
might really know something concrete
over the coming years
fascinating well we are already well
over time um David where can folks uh
keep up with your work going forward if
they want to um know the results of your
black hole tests and well you know I I'm
not on social media but I am uh I have a
website a very oldfashioned website uh
and I do keep that pretty up to date and
so all our physics papers are available
totally for free and open access on the
pre-print server even before they're
come out in the journals uh my
colleagues and I really is quite common
throughout physics to make sure that
anyone can see them without you know any
pay wall or restrictions I'm always
updating it there uh to papers I write a
lot of kind of more um accessible essays
about those things I also make sure
those are on the website and try to
share them that way too and of course I
love working with you and the team for
Nova and other fun things on YouTube so
hopefully that combination will will
help uh help folks who are curious
that's great yes uh you can watch any of
the films David appears in on our
website or on the PBS app if you want my
top pick uh for right now I would go
check out Einstein's Quantum riddle
because that delves into and explains
further what we just have been talking
about in this conversation today uh
David's also gonna appear in decoding
the universe Quantum coming up this fall
so stay tuned for that David thank you
so much for joining us as always a
pleasure to talk to you really Kaitlin
thanks it was really fun for me and I
hope folks enjoy the chat thank you
thank you