John Clauser did the first experiment.
Clauser was born in California. He went to college at Caltech and then to
Columbia University for graduate school. It was while he was at Columbia
that he had read Bell’s paper announcing his discovery.
It was incredible to me. I didn’t understand it or couldn’t believe it. … I thought
“if I don’t believe it, I should be able to give counterexamples” [to prove it wrong]. … So I tried to and failed. I realized: this is the most amazing result I’ve ever seen in my life.1
He had never been happy with quantum theory’s refusal to provide a
picture of the physical world:
I am not really a very good abstract mathematician or abstract thinker. Yes, I can conceptualize [quantum theory’s mathematics]. I can work with it, I can sort of know what it is. But I can’t really get intimate with it. I am really very much of a concrete thinker, and I really kind of need a model, or some way of visualizing something in physics.2
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Figure 12.1
Clauser later in life. John Clauser performed the first pioneering experiments on Bell’s Theorem. Bell had shown that we have not one but two theories: one is quantum mechanics, and the other is some theory that would fully describe the reality underlying quantum phenomena. Clauser realized that an experiment could be done that would tell us which was correct. His result favored quantum mechanics. Photo courtesy of John Clauser.
Perhaps it was the abstractness of the theory that bothered him. As a
matter of fact, all abstractness bothered him:
I had great problems all my life understanding the square root of minus one. In high school, I learned that the square root of minus one was called this little symbol i. Well, there is no such actual number … it’s an imaginary number. If you multiply i times i you get minus one. All right. But suppose I go to the store to buy 1+i candy bars. I could buy one candy bar, or one and a half candy bars, but I couldn’t buy 1+i candy bars. But it’s useful because it makes the equations work out, and once you play with it, the equations work out better that way. So then when I get to [college
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people would say] “Well, it’s a mathematical artifact. Don’t worry about it. It just makes the equations look nicer.” … I was not very good at it; and didn’t understand, didn’t know why I was doing it. And I felt very uncomfortable with it. And once I felt uncomfortable with it, my brain kind of refused to do it.3
Clauser may have disliked abstraction— but he loved experiments. His
father had been an engineer.
As I grew up, basically as a kid, I just would come in after school to his lab. We lived in the suburbs, and so I would do homework— I was supposed to be doing homework, but mostly what I would do is just sort of wander around the lab and gawk at all of the nifty laboratory equipment. And I kept thinking, “Wow, boy do these guys have fun toys. When I grow up I want to be a scientist so that I can play with neat toys like this.”
I was an electronics whiz kid. [My dad] taught me some of the basics of electronics, and I just went off and built some of the earliest computers and the like.
I built the world’s first video games, and I actually won a whole bunch of prizes in the National Science Fair for doing this.4
Clauser is enamored of gadgets, and he loves to do experiments. He has
lots of patents. One is for a device inspired by something he read in Tom
Clancy’s thriller The Hunt for Red October. Another is for a new kind of sail (he is an accomplished yachtsman, with many trophies). Clauser’s garage
has done double duty as a laboratory. A bookshelf at home is crammed with
catalogs from scientific equipment supply houses. “Anything I need to make, if I don’t have the pieces already, I look for it here. I can make anything.”5
“I’ve gotten pretty good at dumpster diving. … If you are innovative and
clever, it’s amazing what you [can do].”6
As for quantum theory, nobody else seemed to share his misgivings
about it. “I sat in my corner and tried to understand it myself. Nobody else talked my language.”7 He was alone as he stewed over what he felt to be the theory’s deficiencies.
And the more he stewed, the more Clauser became convinced that quantum theory could not be the whole story. He decided that there had to be hidden variables. And so:
The Vietnam War dominated the political thoughts of my generation. Being a young student living in this era of revolutionary thinking, I naturally wanted to “shake the world.” Since I already believed that hidden variables may indeed exist, I figured that this was obviously the crucial experiment for finally revealing their existence. But if they do exist, then quantum mechanics must be verifiably wrong here, with its error having gone undiscovered heretofore. … To me, the
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possibility of actually experimentally discovering a flaw in quantum mechanics was mind boggling.8
So he resolved to do an experiment.
Before he did that experiment, there were a few loose ends to tie up. One
was that he needed a different version of Bell’s Theorem. Bell had concerned himself with an ideal situation in which experiments get perfect results. Real experiments, on the other hand, are imperfect. In collaboration with colleagues, Clauser produced a new version of the theorem, one appropriate to such a situation.
I submitted my thesis to Columbia, and I think there was like two weeks or so between submitting the thesis and the thesis defense, which was kind of a dead time. And so I just went up to Boston— actually it was to Wellesley and stayed in [one of my colleague’s] house with him. And [the other colleague] came over pretty much every day, and we just sat there and took two weeks to hash the whole thing out.9
The other loose end was that he had gotten a job across the country, at
the University of California at Berkeley. He needed to get from New York to California— and he needed to get his yacht out there too. So he resolved to go by sail.
I had the job out [in California], and I had a boat [in New York City]. And originally, we were just going to sail the boat all the way to Galveston and put it on a truck there, and truck it across to LA and sail it up the coast to Berkeley.
It turns out we ran into Hurricane Camille, so we got kind of stopped at Fort Lauderdale. We didn’t save any extra mileage by doing this, but we had a lot of fun sailing down the coast. So every time we put into a port, I would get on the phone and [one of my colleagues] knew my schedule. And so basically he would send off his re drafts to all of the various marinas in the next city where we put in, some of which I picked up, and some of which are probably still sitting there for all I know. While I was sailing, I would be writing furiously away and editing various things. And we’d get on the phone and chatter about various versions, and we’d keep swapping drafts. This continued all the way until I got to Berkeley, writing the paper, and then we finally submitted it, pretty much right as I arrived in Berkeley.10
If you want to do quantum theory, you need to think about things like the
square root of minus one. If you want to do an experiment testing quantum
theory, you need to think about things like sandwiches and cardboard.
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I had a friend who worked with a particle accelerator. Every time they
fired up the machine they needed to pump out all the air within it (you
don’t want any air molecules flying around: the particles you are trying to accelerate would bump into them). One day they turned on the vacuum
pump and it just couldn’t clear out all the air. It would pump and pump, but the pressure gauge always showed a faint residual pressure. Finally they got tired of waiting. They turned off the pump and opened up the accelerator.
Inside they found a half eaten ham sandwich
. Someone had inadvertently left the thing inside. It had been outgassing, the emitted volatiles spoiling the accelerator’s vacuum. “It was pretty desiccated by the time we got to it,” my friend allowed. “As if it had been freeze dried.”
Another friend once clapped a sheet of cardboard over the front end of a
cutting edge experiment he was doing— just to keep out the dust. As I recall he also used cardboard to fashion a small, meandering dam around the base
of the experiment, to keep out any puddles of water that might form on his laboratory’s floor.
The famous Cosmic Background Radiation, the faint glow left over from
the Big Bang, was discovered by two scientists using a gigantic radio telescope. When they got ready to start up the telescope their first project was to get rid of a “milky white dielectric substance” they found coating its surface. The substance turned out to be bird droppings. Another radio astronomer I know used to deal with bird droppings by driving his car right up to his antenna and gently bumping it, to shake the stuff loose.
Clauser built his experiment with the help of a graduate student, Stuart
Freedman. The device they built stood maybe waist high and it was about
10 feet long. Inside, an oven heated a chunk of calcium to the vaporization point. Individual atoms streamed out at several thousand miles per hour.
They entered a chamber, where they were illuminated by light at a set of
precisely calibrated wavelengths. The light induced the atoms to emit a
pair of entangled photons (the experiment used photons rather than electrons). These were sent off in opposite directions. Plates of glass formed polarizers— the photon analog of the direction an electron spin detector
would point. The photon detectors were immersed in an ultracold slush to
improve their performance. Every so often motors would rotate the polarizers to a new configuration, as required by Bell’s Theorem: At the end of each hundred second counting cycle, the machine automatically paused and a sequencer (an old telephone relay that Clauser had rescued) would
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order one or the other polarizer to turn 22.5 degrees in an orchestrated cacophony of domino like noise and action, vivid in Clauser’s mind thirty years later. “These big mama two horsepower motors would crank over the “coffins” [holding the polarizers] and the teletype would clatter away,” the paper tape pummeling, accordion
style, into a peach basket, spraying its chads across the floor, to the ka- chunk of the serial printer monitoring the quartz crystal that monitored the calcium beam.11
Two years to build the experiment. Two years of seemingly endless checking and re checking, of improvising and fiddling and fussing over the details.
An experimenter has to fuss about all sorts of things. You can’t take anything for granted. You have to understand every facet of your experiment.
Students often don’t understand this: they want to charge ahead, throw the apparatus together, turn it on and get a result. Their instructors can have a hard time of it slowing them down.
Clauser:
People always think you don’t have the time to test everything. … The truth is you don’t not have the time. It’s actually the time saving way of doing it. It’s hard, when you’re eager to know what Nature’s doing: you almost have to train yourself to be anti curious while you’re building your hardware. People always want to slap it all together, turn it on, and see what happens. But for the first run, you can almost guarantee it’s not going to work right.12
If you don’t like this sort of thing, you don’t want to become an experimentalist. Many people don’t— me, for instance. Others do. I was chatting with a friend recently about the whole business of getting an experiment
up and running. He was talking about how careful he had to be, how many
errors there were to be chased down, and how slow was the progress. At one point he leaned back, gazed at the ceiling, and mused. “There are so many
things in an experiment to worry over,” he said. “So much to get under
control. It is really— ”
Before my friend finished speaking, I thought I knew what he was going
to say. In my mind I finished his sentence for him. In my mind I had him
saying something like “a royal pain in the ass.” But, as it turned out, that was not what he said.
“Fascinating” was what he said. And he smiled again.
Clauser kept slogging. Throughout it all, he had finally found other
people interested in his favorite topic, the mysteries of quantum mechanics. This was a wild and woolly group of physicist hippies— it was, after all, the age of the counterculture and the antiwar movement— that called
itself the Fundamental Fysiks Group. Its members would meet every Friday
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afternoon around a table at the University of California at Berkeley. There they engaged in a wide ranging, free form discussion of a breathtakingly wide variety of subjects. Topics ranged from the significance of Bell’s Theorem to faster than light communication, from ESP to LSD.
Clauser joined the group— sort of: “Those guys were a bunch of nuts,
really. … But we kind of used that as a forum. The real physicists were over here in one corner, and all the kooks are in the other corner.”13 There were meetings at the Esalen Institute in Big Sur:
The guy who was running this decided that quantum mechanics was related to this consciousness expansion, and would bring us down there. It was free for us, and there were hot sulfur baths that were there, and the rocks, and you’d go into these hot baths, all communal, with everybody naked, which I guess was part of the grand excitement. And then the hot water would sort of overflow the tubs and go cascading down the cliff into the Pacific Ocean. And so part of the highlight of every evening was a trip to the baths. And then during the day, we would sit around and talk about new aspects of quantum mechanics and the like, and how it was related to the great cosmic cockroach, or whatever. None of which I thought very much of, but what the heck?14
Eventually, Clauser and Freedman got their machine up and running.
Once built, it ran for a total of two hundred hours spaced over several
months. They got a result.
Their result disagreed with the local hidden variables hypothesis, and it supported quantum mechanics.
Clauser’s pioneering experiment had been conducted in the face of the
scorn and antipathy of which I wrote in the previous chapter. And Clauser
paid a price. Many colleagues felt little interest in his work, showed little interest in its results, and felt free to advise others of their opinion. He never got a position at a university or college— this in spite of glowing
recommendations from prestigious senior colleagues. “I believe he shows
promise of becoming one of the most important experimentalists of the
next decade,” wrote one. But it was to no avail: over the decades following on his experiment Clauser was forced to work in a research laboratory or on his own as an entrepreneur.
In 2002 Clauser wrote about his early experiences. His article rings with
irritation at the reception his work had received:
Most of the [subject] represented forbidden thinking for practicing physicists.
Indeed, any open inquiry into the wonders and peculiarities of quantum
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mechanics … was then virtually prohibited by the existence of various religious stigmas and social pressures, that taken together, amounted to an evangelical crusade against such thinking.15
Later on in his article Clauser writes of McCarthyism and relates it to
a very powerful secondary stigma [that] began to develop within the physics community towards anybody who sacrilegiously was critical of quantum theory’s fundamentals. … The net
impact of this stigma was that any physicist who openly criticized or even seriously questioned these foundations (or predictions) was immediately branded as a “quack.”16
In the long run, Clauser’s work has been widely recognized as a pioneering triumph— he received a prestigious award for it in 2010. But the long run was far off in the future while he was doing his experiment.
A quick aside.
It was when he was a graduate student at Columbia University in New
York (working on a PhD thesis involving astrophysics) that Clauser became
captivated by Bell’s Theorem. It turns out that he and I are pretty much
the same age— and I was working at a research institute just a few blocks
down the street from Columbia. I remember meeting him. We did not get
to know each other well. It was a matter of just a few encounters. But even now, decades after these encounters, memories stand out in my mind.
One was that Clauser lived, not in an apartment like everybody else in
New York, but on a yacht— a yacht of his own, which he moored in some
marina nearby. (Recall that, on finishing up at Columbia he had set out to sail all the way to California. He is a serious yachtsman.) Unusual enough.
Another was that all he wanted to talk about was Bell’s Theorem.
And there’s one other memory. I recall what I said to him. “Bell’s Theorem?
Never heard of it. What is it?”
There’s that stigma again. I was infected too.
Clauser’s experiment had shot down the hidden variable idea … nearly.
Quantum theory was vindicated … nearly. Unfortunately, however, there
was a loophole— a loophole through which the hidden variable concept
might just possibly manage to squeeze.
An analogy to Clauser’s experiment is a variation of my angry couple,
intent on disagreeing with one another. To make it vivid, imagine that they live in Kansas. One day, furious and irritable, they separate. The wife heads
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off to Oregon. When she arrives she encounters an individual (named
Alice) who for some reason is full of questions. The questions keep changing. “Do you like steak?” Alice might ask. Or alternatively “do you like fish?” or “do you like exercise?” Meanwhile, the husband has just arrived in Florida, where he is bombarded with questions by Bob— questions that are
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