10. QUANTUM STORIES
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We all know the CIA introduced LSD to America, right? But did you know that they also wanted to introduce quantum entanglement and mind control? This episode revolves around an interview between John and David Kaiser, an American physicist and science historian. With David’s help, we take a look at how quantum evolved over the 20th century in both Europe and the US (and yes, even how the CIA and mindreading played a role). He also dives back into the topic of entanglement (or as Einstein called it ‘spooky action at a distance’) and sheds some light on the groundbreaking work of John Bell (who gave his name to the all-important Bell’s Theorem).
David Kaiser is an American physicist and science historian. He is also a Professor of the History of Science, Technology, and Society at MIT. David is the author of multiple books, including “How the Hippies Saved Physics”.
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David Kaiser: You know, it's a story that brings in the really dramatic disruptions just as recently as, say, over the 20th century, world wars, rise of fascism, nuclear age, and things that really were cataclysmic, and not just, you know, a sort of bump in the road. And so we see, one things that I find really, frankly, inspiring as an historian, let alone as a working scientist, is to see, you know, ordinary people really doing extraordinary things in difficult circumstances.
DK: And sometimes against really quite difficult odds, you know nudging, nudging this collective body of knowledge forward. They don't get all the answers they don't live to see near the final information we all dream of. And yet they as a community, they can kind of cobble some things together, get confidence on here and clear up some confusions there, and hand that off to the next generation and work hard as teachers and as mentors and, and try to keep this collective inquiry moving.
DK: And I find that longer view frankly, very inspiring, even though it involves stories of sometimes harrowing, and sometimes not such great people or people making not such great decisions. But overall, when I take a longer view, I do see it is very much a kind of storytelling adventure, this this quest to learn about the world.
John Holten: The Quantum stories we tell ourselves. When I first heard the title of David Kaiser’s book How “Hippies Saved Physics”, I knew I had to read it for these episodes. If Mundi wanted to set us off on a journey to find out about quantum, we’d have to trace it’s almost 100 year journey since its discovery.
Eva Kelley: And if it is a kind of magic, or a way of understanding the world and universe, just how did it come to be discovered in the first place? Because it seems like it’s pretty far out there in a way, not very intuitive. But at the same time, it’s also a really human disposition to try and explain things that cant be explained.
JH: Featuring David Kaiser, who is Professor of the History of Science and of Physics at MIT, this is episode 10 of second The Life Cycle: Some Quantum Stories
[Intro: The Life Cycle, a podcast about the future of humanity]
JH: David Kaiser is an excellent storyteller himself: and extremely well placed to tell the history of quantum because he’s also a physicist. His book from 2012 ‘How The Hippies Saved Physics’ tells how a crucible of time and place led to a massive series of jumps in understanding, and how iconoclasts and free-thinkers were willing to push the boat when it comes to science and its applied uses.
I started off by asking him to paint the picture as it where of where quantum physics came from in the first instance.
DK: Sure, you know, I'd be happy to. So you know, it's true that the, what we now recognise is quantum theory really coalesced over the first quarter of the 20th century, really roughly between 1900 1925/26 In round numbers. Of course, there was more work to be done. But it's really an amazing, fervent of activity during those first roughly 25 years of the 20th century, which as we know, we're quite dramatic times in Europe and elsewhere. And a lot of the work that we look back on was indeed being done by people based throughout Europe, including Britain, not exclusively, there were certainly people who were doing important work, who were who had come from United States who'd come from Japan, who had come from actually quite further afield. Many of them in that period, went to study and work in Europe.
DK: So Europe was still in some sense, a central place for working it out, even though it involves people from really genuinely a worldwide community. The other thing that I find really fascinating looking back on that era, is that the folks who were cobbling together quantum theory, most of them knew each other and they knew each other actually pretty well. It wasn't a huge community yet. It was several dozen people who we might recognise in hindsight as the kind of core group again, many, many more folks were contributing something. But the really central figures who did most of the work that we now celebrate in our textbooks and work hard to study and learn ourselves. That really was not a huge group in that in those early years, and they did tend to know each other they tended to study with each other they tended to visit each other, you know, by rail, they would trade 10s of 1000s of letters when they weren't sitting side by side or taking walks, you know, together.
DK: So they were it was a community that really the inner circles of whom really knew each other well. And that doesn't mean they always got along. Sometimes they knew each other so well that they had fights all the time. But the point is, they really knew each other face to face. And that starts to change. Over later decades, as the community itself grew as the disruptions in Central Europe especially really thrust many folks further away from those close knit geographical regions.
JH: It’s worth jumping in here and to name some of this inner circle: for the first 25 years of the 20th century traditional physics was questioned by what would become known as ‘old quantum theory’, Max Planck, Albert Einstein, Niels Bohr, Arnold Sommerfeld and many others, all produced work that questioned the ability of traditional physics to account for reality. By 1925 Werner Heisenberg and Niels Bohr proposed a new interpretation of quantum mechanics (because there are more than one) and it became a core field in the area, it was dubbed The Copenhagen Interpretation because that’s where Hesenberg was based at the time.
EK: Perhaps somewhat fittingly for a quantum group, if you look on wikipedia, you’ll read: ‘There is no definitive historical statement of what the Copenhagen interpretation is.’ The people that are associated with it disagreed on a number of things. They didn’t call themselves the Copenhagen interpretation, they were more grouped together as that by outsiders, maybe for convenience. Some things that are characteristic about it we saw in episode 9, including how intrinsically indeterministic everything is, the importance of measurements and the principle of complementarity, which states that objects have certain pairs of complementary properties that cannot all be observed or measured simultaneously.
JH: And what Professor Kaiser really drives home is the philosophical nature that led to and fed the entire quantum project. This is something that would get lost initially when the centre of gravity changes from Europe beforeWW2 to the USA in a post WW2 era.
DK: That’s right. And I should go back and say, you know, going back to those earlier years in the 19, teens and 20s, and even into the 30s, you were asking, was there a kind of philosophical style of research. And I think there really was not for every single person, you can find a range or spectrum even then, which is how you need that in a healthy scientific community, a range of perspectives. But certainly many of the folks whose names we still rightly remember and celebrate as some of the most important contributors to quantum theory or modern physics more broadly, they really, many of them thought of themselves as doing as as part of their job was to be philosophically minded. That that was what they valued as part of their role of being talented physicists, of course, they had to be very good at mathematics.
DK: They had to be creative in manipulating equations. But for many of them, they thought that wasn't enough, it wasn't that wouldn't suffice. And they had many that had been raised studying philosophy even as high school students and these very elite gymnasium and so on, they'd studied, you know, traditions in German idealistic philosophy, from really their teenage years.
DK: This was a this was, in some sense, a native, you know, a kind of familiar mode of inquiry. Einstein was deeply taken with Immanuel Kant as a young person and then had a reading club for fun with some of his college buddies. Reading the works of the Viennese philosopher Aaron smock, Niels Bohr, who was raised in Copenhagen came from an academic family, he was immensely influenced by a mentor who was another Neo Kantian philosopher. Wolfgang, I'm sorry, Verner Heisenberg was the son of a classics professor, and recalls reading, you know, Plato's Timaeus, on a rooftop. And these people really think they thought part of their job was to bring a kind of overt philosophical investigation to their efforts to understand nature.
JH: This echoes what we were talking about back in the pub in London with Mundi. Philosophy might not be the same as magic, but to understand the make-up of reality, to be able to weave the story of the physical world as it where, you quickly come up against the big metaphysical questions.
Bohr and Heisenberg for their part and their uncertainty principle was in a sense the end of determinism. The uncertainty principle, which for a little reminder, was outlined in the last episode, episode 9, states that the more precisely the position of some particle is determined, the less precisely its momentum can be predicted from initial conditions, and vice versa. This shattered the clockwork universe that Newtonian Physics promised. And it was part of Einstein and Schrodinger’s initial beef with quantum mechanics. But this more philosophical aspect to it all didn’t really survive in America, at least not at first. Professor Kaiser told me how the Second World War changed priorities:
DK: When we get into a very different era, the years soon after the Second World War, especially in the United States, when physics was now unbelievably popular as a topic of study in the way it never had been, even in Europe, certainly never in the United States. It became one of the most popular subjects for young people to study, partly because of the dramas of the end of the Second World War. That what looked to many people at the time was celebrated as the kind of road to victory with physicist leading the development of things like nuclear weapons in the in the decades since then historians and scientists have reevaluated some of those claims.
DK: But certainly at the time, it looked like physicists built the bomb and the bomb ended the war. That each of those claims is has been, let's just say more complicated now. But at the time, that seemed like such a straightforward equation. And young people were flocking to physics and other areas of engineering, in record numbers in the United States, universities were expanding exponentially quickly. It was physics done in a different mode, or maybe I say the range of kind of what looked like reasonable approaches had had sort of shrunk. So it wasn't they were doing on unimaginative physics. But they many, many folks in United States stopped valuing the kind of philosophical engagement that it seems so important, really not so earlier before. It wasn't like it had been 100 years that had gone by it had been maybe 15 years, it wasn't such a big change.
DK: And yet suddenly, the style of what counted as really valuable or what was valued in physics, especially United States in the face of these booming booming enrollments, people teaching auditoria full of physics students at a time and not small seminars that really changed what seemed important what seemed teachable. How do you have debates about Neo Kantian philosophy with 300 students at a time it's pretty hard.
DK: And so again, I want to say it wasn't sort of good versus bad physics, but it's certainly a pretty dramatic shift in style. And you can see that in textbooks in homework assignments assigned to PhD students in the nature of the papers, they published in the journals. A pretty dramatic shift over a pretty short timespan to become this kind of pragmatic, almost anti philosophical approach to push, push through the equations, and as many of us to say, get the numbers out. Or another popular phrase was shut up and calculate, which was, you know, maybe no one ever really said that. But that seemed to capture sort of the ethos of the time.
JH: So this was a really good time to study physics: there were many enrolments and exponential growth in its popularity. But by the late 1960s there was a reversal of fortune for physics: And at the same time there was the rise of the counter culture and the youth moment and there were also protests against the Vietnam War draft.
EK: And students were not excused from the draft right, they had to fight in the army?
JH: Yeah, and funding was turned from open ended unclassifiable research that had been in place after WW2 to way more specific, weapon oriented research. And as we saw in episode 3: Getting There with regard to space and ballistic rockets, there had been, or was at the time a growing relationship between the military industrial complex and scientists.
EK: So there was this strong reaction against the presence of the military on US campuses, because they were influencing what departments were researching.
JH: By the 1970s there is less money to go around. Kaiser points out that there was space again to start thinking about new ways to relate to and reflect upon nature. Departments were smaller in size, class were much smaller and begin to reflect 1930s style of teaching and philosophical musing that you had earlier in Europe.
DK: You have a bunch of students and faculty who don't want to work on projects that have even even an association with with these worldly affairs like nuclear physics, a lot of research in nuclear physics had nothing to do with weapons, but even that whole topic, some people said, I want to get as far from that as possible. I want to dream of of celestial I want to think of, of relativity and the solar system and the galaxies, I want to think about the deepest mysteries of quantum theory, topics that had really been kind of pushed to the sidelines through much of the 1950s and 60s. And so the topics that somehow garner attention start to shift the environment in which these young people are going to study it has shifted. And you see a kind of opening up again, or a broadening of what seemed like they might be legitimate styles for trying to learn about your the natural world.
JH: At this point, I wanted Professor Kaiser to tell one of the stories that he’s so good at delivering, to help explain this new shift in research and how the spirit of the age led to some pretty weird uses of quantum mechanics.
EK: How weird? Is this where the hippies come in?
JH: More like spies at this stage - the CIA - rather than hippies. Cause actually the ‘hippies’ in his title is a bit of misnomer. Although there are definitely some free-spirited, new age actors in the pages of the book. But this particular story showed just how hippy thinking pervaded not just society at the time, but also the military industrial complex. It takes place at the Stanford Research Institute, which was located in Menlo Park, CA. It's the R and D agency that works for a lot of companies throughout the years and government agencies. And actually one example of its work is, if you recall back in Episode 2, we talked about how Walt Disney used Werhner Von Braun to create the Tomorrowland section in his new park.
EK: Yeah, the original Disneyland in California.
JH: Exactly, that opened in the 1950s. Well it was the SRI that chose that location after it was commissioned by Disney to find the best spot. They’ve done a bunch of stuff: SIRI on Apple was an invention of a company created by the SRI which they sold to Apple. Also Uri Geller was even brought there in 1972 to have done some of his out there thinking. But anyway, the CIA were worried at the time that the Soviets were way ahead in the field of mind control. And so inspired by quantum non-locality, they wanted to conduct ‘remote viewing experiments’. I asked Prof Kaiser to tell me the story:
DK: Ya no, I be glad to it's really, it's one of these moments, we have to stand back and say, Was that really going on behind the scenes? and it really was. and so, exactly, as you say, by the late 1960s, and accelerating it throughout the 1970s, there was a concern among at least some experts within the US military, that the Soviets were somehow much more advanced than the United States was on on topics like mind reading, let alone mind control what things that are often called Para psychology, or ESP and so on.
DK: And now I want to be careful to say I'm not endorsing that view I'm saying that it was it is now well documented through things like Freedom of Information Act and you know, once once classified studies we now know some more about that, that there was at least some you know, interest in and frankly some real investment with with real money behind it. If you adjust for inflation, it looks like you know, budgets in the millions of dollars, not billions, but millions you know, substantial money around trying to really accelerate US based efforts in in things like extrasensory perception or mind reading are these non standard topics, I'll call them again without uncertain endorsing them myself.
DK: And so one of the things that happened was, the representatives from the CIA, and also from the Defence Intelligence Agency, which is a similar version of the US has many similar, you know, agencies, sometimes they compete with each other. So each of these groups, as it turns out, got involved in trying to support a kind of accelerated programme and basically mind reading or reading minds at a distance. And some of the folks I was writing about in this book, were trained in physics and had PhDs often for very, very elite programmes in physics. But they had, they sort of entered the field, just as the bottom fell out, just as funding dried up from more traditional sources, as jobs as traditional academic jobs were, were very, very, very hard to find.
DK:And so they kind of banded together and made a kind of informal discussion group in Berkeley, California, to talk about all kinds of things that they had found squeezed out of their own training, when they were young students in physics, including PhD students, things like how do we make sense of these strange equations of quantum theory, and for some of them, not all, but for some of them, they were curious or certainly open to a wider range of new age, or countercultural ideas like maybe ESP is real, and maybe we can explain it using quantum theory, not just observe it, but maybe even account for it.
DK: If we're going to be good empirical scientists, some of them said, then let's conduct our own experiments and come up with our best, you know, scientific explanations. So that really captured the imagination of some members of this kind of ragtag group who were basically frankly down on their luck, PhDs from from great programmes, and not traditional scientific careers, to march into next. And so some of them basically got hooked up with CIA or DIA related funding to help do these so called Remote Viewing experiments, just as you said, and the idea was, could maybe not every person, maybe some people are especially susceptible, especially especially capable of essentially receiving you know mental imagery or some kind of messaging from another mind far away. And that's what it was called remote experiments.
DK: And so the idea was one person would sit in a darkened room with, you know, helpers, sort of noting down what they say they see or think about in their mind, while another person went around the Bay Area, and sort of looked very intently at various landmarks. There's a famous clock tower on the campus at University of California, Berkeley, there are, you know, benches in parks near golden, near the Golden Gate Bridge.
DK: And so this was being done on the kind of, you know, in sometimes highly classified forms on it with taxpayer dollars to see could one exploit basically long distance espionage and the idea, you can see why this might have appealed to the CIA, or the Pentagon during this very scary Cold War moment. What if once someone could get signals from what the Soviets were doing at some highly classified Research Centre, you know, behind their borders? Could one somehow could trained field agents do espionage at a distance.
JH: So needless to say the experiments weren’t all that successful, although sometimes people did seem to draw a similar picture to the places the subjects were sat looking at for hours on end.
EK: That sounds fun, maybe we should do that once.
JH: Yeah. You could sit somewhere in London and then I’d think about what you’re looking at.
EK: Yeah!
JH: It would be a fun way to spend an afternoon.
EK: But yeah, it’s cool that the CIA were inspired by quantum mechanics.
JH: Yeah it was the age of trying anything to get one over on the enemy, like flying to the moon or developing LSD. There was a lot going on between the two superpowers. But this led Professor Kaiser to get very excited about one of your quantum friends Eva, entanglement, and I love the way he talks about it:
DK: And so, so part of what attracted some of the physicists I was writing about, not all but certainly some of them, was that they thought this might not only be replicatable, this might be a phenomenon that people could really do at least some people, but they thought they could explain it using quantum theory. And this gets to one of the most delicious, counterintuitive concepts of the heart of quantum theory that I still just love and it's still pursue both. In my physics research and as an historian, this notion called quantum entanglement, so Einstein himself helps to clarify as a concept ultimately to reject it. Same with similar with Aaron Schrodinger, some of the giants of quantum theory, elucidated this notion even back in the 1930s. And it's a winded up striking both them and frankly, many of their colleagues is just just too strange to be true.
DK: Einstein famously dismissed it as spooky action at a distance. So this is, this is maybe what the equations predict, but that can't be right. That can't be how the world works. And that's part of what energises group many decades later, kind of underemployed physicists in the San Francisco Bay area. They were just mesmerised by this concept of entanglement at a time when very few other physicists were paying attention to it. And they thought, if entanglement as described by quantum theory were real, could that open up still other more more strange sounding phenomena? entanglement Sounds pretty strange on its own. If we take that seriously, where else might it lead us? Could it actually account for things like correlated brainwaves among humans across great distance?
DK: The idea behind quantum entanglement is that pairs of particles, at least if they're prepared a special way should show really strongly correlated behaviours, even if they're arbitrarily far apart. And that's what really made Einstein so uncomfortable. You know, what we mostly remember Einstein, for in physics is his gorgeous theories of relativity. And relativity is really all about local causes yield local effects, if we had to boil down relativity, it's local, local, local. You change something here, it's going to take some time for some influence, to move through space before somewhere else could be affected by it. That's, in some sense, the heart of relativity. And quantum entanglement, at least seem to be intension with that. And that's what I saw himself began to recognise and made him so uncomfortable with quantum theory more generally.
DK: Well, these folks in the 70s came, came to it with maybe a more open mind and said, you know, maybe entanglement, as described by quantum theory is how the world works. In fact, one member of this group who was a much more agnostic on the mind reading stuff, but was it was enamoured with entanglement, a physicist named John Clauser, conducted with it with a partner, Stuart Friedman, the first ever real laboratory experiment to try to see as entanglement happening in the world, as described by quantum theory, or what a more Einstein like theory, account for the data.
DK: So this group was was was, you know, eyeballs up to their eyeballs and thinking about quantum entanglement. And some of them thought, if entanglement really is a feature of the world, as these new experiments seems really to lend more evidence toward, then maybe some quantum particle lands in the mind of, you know, one person sitting in a darkened room that's entangled with some particles in the mind of the distant viewer, and so on. So they were some of them at least wanted to push the implications of entanglement as far as they could. At a time when, when entanglement in general, or even the broader kind of philosophical interpretation of quantum theory more generally, this was still kind of on the outs for mainstream physics. And they were among the kind of early adopters saying this stuff is fascinating. It's important, and it could lead to even more interesting questions.
JH: So you heard just earlier Prof Kaiser mention the names John Clauser and Stuart Friedman. And as we mentioned at the end of episode 9, in 2022 the Nobel Prize for Physics was awarded to John Clauser (along with the French physicist Alain Aspect and Austrian physicist Anton Zeilinger). And we can take some solace Eva from this John Clauser!
EK: Oh yeah, why is that?
JH: Because after he got the call from Stockholm, he gave an interview to his local newspaper The Mercury News, and I read this, and in it he admits that he initially found quantum mechanics to be daunting—even though he was going to go on and spend his life working in this field—and had to repeat a course in Advanced Quantum Mechanics three times before he passed.
EK: Ha, I don’t blame him.
JH: No, to be honest with you, right now neither do I. Well anyway, Clauser appears a lot in Professor Kaiser’s book, and he really does seem to be a great physicist and part of this group David Kaiser is talking about, these early adopters prepared to try and chart entanglement. Indeed, the Nobel committee awarded the prize in 2022 for this very work: they gave it to him "for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science".
EK: “The violation of Bell inequalities.”? What’s that, I don’t like the sound of it
JH: No neither do I. Prof Kaiser paints a picture of how great John Bell was.
DK: John John Bell was really just an extraordinary physicist, of this sort of postwar generation. So he was, you know, a generation younger than the Einsteins and Schrodinger to the world, he was taught by members of their of their generation. So Bell was really coming of age, in the 40s and 50s as a young physics student himself. He was originally from Northern Ireland, I believe, from Belfast, he made most of his career at CERN.
DK: He, as a very young student, got also puzzled, really grabbed by some of these broader philosophical kind of what what does it all mean questions that quantum theory was had been inspiring again and in in the earlier generation, Bell was was really just dissatisfied with the kind of path responses that he tended to get to these deeper questions when he asked his physics teachers, you know, but what if we take these equations of quantum theory seriously? What how do we make sense of them? in a in a more interpretive vein. And he was basically told as many people in that generation were, you're gonna ruin your career, rather than saying, here's the answer you're looking for. It's like, that's just not real physics anymore. Right was was as a paraphrase, at least the way that Bell himself remembered it many years later.
DK: And again, there's much evidence that that was the prevailing attitude during the sort of 50s and 60s era. So he followed good advice. He became a very accomplished physicist in more mainstream topics and high energy, particle physics and nuclear physics. That's partly why he wound up spending so much of his time at CERN, doing really important work and in what we would call mainstream particle physics.
DK: Many things for which he is still remembered even there. And yet he kind of nursed this this side interest, a kind of hobby that really stretched from his undergraduate days about how to make sense of quantum theory in a deeper, interpretive or philosophical way. And it was in the midst of some of those thinkings in the mid 1960s, really on his own, when he came up with what we now call Bell's theorem in his honour, or more specifically, these bell tests that he really devised in a brilliant, brilliant, imaginative leap.
DK: So he wrote this paper late in 1964, he was actually on sabbatical and travelling around the United States. And was was so self conscious that this paper was so outside the mainstream that he didn't, he sent it to a strange or a little known journal that didn't charge what were called Page fees, because most journals then would charge authors to pay to get their work published, and Bell who didn't want to ask his US hosts to even pay their fairly modest fees.Because he figured this would be a look like a nonsense paper. So that's how much on the outs this was as late as 1964, when he published this paper that now is just an absolute landmark of modern physics. And everyone has to know this paper, we rightly returned to it all the time. So So again, just a marker of how on the outs this work seemed at the time.
DK: So Bell realised that there should be a way to empirically distinguish predictions from quantum theory compared to a more Einstein like model, where only local causes yield local effects by preparing pairs of particles in a certain way. And then conducting measurements on each particle at some distance from each other, and measuring a rate performing a range of types of measurements and not telling your partner what measurement you happens to perform. There should be an element of a kind of randomness of what particular property one person chooses to measure on one side, compared to what the partner measures far away. Then you bring both kind of logbooks back together and look at how often the measurements lined up.
DK: So to be just a little more concrete, you ask, in a sense, a series of yes, no questions. So you can compare the answers even if the questions were different. So if I asked you to do like ice cream sundaes, or frozen yoghurt, if I asked you to do like ice cream sundaes, you can say yes. If I asked you to do like chocolate chip cookies, you can say yes or no, I can compare how often you said yes or no, even though you are asked different questions than your partner, and that's what becomes actually really important.
DK: So you can you can compare the answers even as different questions were posed, which is like saying different properties were measured on each member of this pair of particles. And if they're if those particles are really behaving, as quantum theory says they should if they're genuinely entangled, then the answers should line up. Even when they're asked a range of distinct questions, their behaviours are so strongly correlated, they behave in such such a kind of lockstep way that their answers should line up more often than would then chance, as if there was some immediacy helping to line up their answers some kind of something that did not seem to obey Einstein's, strict stricture, say on local causes and local effects.
DK: So Bell said, I don't know if that's what will happen. That's what quantum theory predicts must happen. And now there's a clear way to distinguish that from from the predictions of rival theory. So we call these Bell tests, people have now conducted Bell tests for literally 50 years. The first one I mentioned by John Clauser and Sue Reagan was done 50 years ago. And there have been dozens and dozens and dozens of experiments. Since then, many types of physical particles, many types of properties, many types of detectors, every published result has been consistent with quantum theory. They every result rejects the kind of Einstein like predictions to high statistical accuracy.
DK: And yet each of these experiments has so far been open to these kind of loopholes, these logical little puzzles by which are really earnest Einsteinian hadn't were any left, a really earnest follower of Einstein's quite plausible ideas, could say, oh, well, I can explain why your experiments find those results. The world doesn't evolve according to quantum theory, that world really obeys an Einstien-like theory, and there's some extra thing you've left out or failed to shield against in your experiment, there's some way in which information could have leaked through without having to you to invoke this this funny notion of quantum entanglement.
DK: So that's what led my colleagues and I to try to do this kind of supersize experiment we called that a cosmic Bell test in Bell's honour. And the idea that, in brief is that the decision of what measurements to perform what questions to ask of each member of this entangled pair would be set not by something kind of local to our laboratory that could have been correlated with who knows what. That could have been all kinds of unnoticed ways in which information could have flowed before we even turned on our experiment.
DK: But rather, the choice of what measurements to perform was outsourced to the universe itself. We decided to turn the universe itself into a pair of random number generators. So we've performed real time measurements of light from a very distant galaxy in one direction of the sky on one side. And at the same moment light from a very distant galaxy and on the opposite side of the sky, like they've been travelling toward the earth for most of the history of the universe, almost stretching back to the time of the Big Bang itself.
DK: So that the light what was happening at that galaxy over there hadn't had time yet to talk to, to share any information, either with our experiment on the ground, or with with a very distant galaxy on the opposite side of the sky. Since really almost at the time of the Big Bang, pushed it back about, well, about about 8 billion years in what experiments we wound up doing out of a 14 billion year old universe.
DK: And so the idea was to say, Can we shield against an Einstein like mechanism, a kind of local causes kind of explanation, while still trying to test for whether the quantum theory predictions hold up, and they held up absolutely, beautifully, stunningly beautifully. The measurements on these entangled particles on the ground, actually, on this beautiful mountaintop observatory in the Canary Islands.
DK: The measurements showed exactly the correlations, the patterns that quantum theory predicts, while having shielded against these kinds of local or Einstein like explanations that could have accounted for those for that correlated behaviour by saying, Oh, you overlooked the fact that something happened, you know, 10 days ago or 10 minutes ago. To do that. For arguments you say, you'd have to say something set this, this, these correlations in motion, 8 billion years ago on a galaxy far, far away. And that's still logically possible, but it's a lot different than what had been available before.
EK: Wow that’s actually really kind of cool.
JH: Yeah It’s fascinating how much quantum is really about measurement, how we can hope to measure the world and the material matter of nature.
Yeah. I really enjoyed talking to Professor Kaiser, because even if I still find it really hard to get a grip of many aspects of quantum physics, his examples and stories elucidate many parts of it. And was just kind of entertaining if I’m honest. To finish, I asked him where we can see quantum in our everyday life. Does it have many practical or applied uses?
DK: So so one way I'd say is many, many of us, meaning a significant fraction of all the people on earth, not everyone but a large fraction now, we're benefiting from this research every day, when we think about things like GPS and our cell phones and navigation. So people, these GPS system relies on basically what we call atomic clocks or atomic frequency standards. That doesn't require entanglement it requires an incredible, you know, near century of development of both physics and engineering, to understand the very subtle, basically quantum vibrations of certain atoms that lets us make some of the most precise clocks imaginable we need those that level of kind of near nanosecond or 10s of nanoseconds accuracy, which we get because we understand quantum theory and how certain atoms behave.
DK: So in some sense, it's here already, it's in our pockets, or at least many of our pockets with smartphones and GPS and all the rest. So I want to be clear that we've benefited time and time again, even frankly, just the idea of consumer electronics and transistors, I mean, some of the most important steps there were really thinking hard about the quantum theory of, of how these little little bits of matter behave.
DK: And one of you mentioned would be quantum encryption. Another that maybe is maybe not quite so close by, but maybe still, in our future will be something like quantum computation, quantum computing, with quantum encryption. Now we've gotten to pretty impressive kind of real world beta tests. It's not quite that we're all relying on that, on that in our pockets. We're doing other forms of encryption when we purchase things on the internet, or send emails that don't rely on quantum entanglement. But there have been pretty stunning demonstrations that quantum entanglement is getting closer to to, you know, to, to real world use. Including trans continental quantum encrypted video chats, you and I are chatting across continents using a video chat but not protected by quantum encryption.
JH: And so we come to the end of this little introductory forway into the weird and god damn difficult world of quantum physics, conducted in large part thanks to one such quantum encrypted video chat.
EK: We did it!
JH: Will I remember any of this down the road, in like two week’s time? Two days time? Maybe not.
EK: You can just listen back to the episodes. Just play them while you’re asleep.
JH: They can enter my dreams.
EK: Your dreams.
JH: Quantum nightmares [laughs]
JH: A very special quantum thank you to all of you for listening. Thanks also to Professor David Kaiser for the conversation and chat.
EK: This episode was written and produced by John Holten with additional writing by myself, Eva Kelley.
JH: Sound editing and design was by David Magnusson.
EK: Mundi Vondi is our executive producer and he also created the artwork for this episode, in collaboration with Midjourney.
JH: Additional research, script supervision, and factchecking was done by Savita Joshi.
EK: Follow us on social media and subscribe for more wherever it is you listen to your podcasts.
JH: And please reach out to us, we’d love to hear from you. You can also try and do so with your mind [laughs].