Big Think Interview With William Phillips
William \r\nPhillips: Laser cooling means shining light on stuff and making it \r\ncold. Now, that in itself sounds like it’s completely backwards because,\r\n after all, you typically think that if you shine light on something, \r\nit’s going to get warm. So how is it even possible to shine light on \r\nsomething and make it cold?
To cool the air down means to make \r\nthose molecules, atoms in the air, move more slowly. That’s the \r\ndifference between hot and cold. So, how do you make something cold with\r\n a laser? Well, lasers, all light, pushes on stuff. There’s a thing \r\ncalled radiation pressure... light pushes on things. But what we’ve \r\nfigured out what to do over the years is how to push on atoms in such as\r\n way as to make them slow down.
Question: What did \r\nyour team discover about laser cooling?
William Phillips:\r\n The thing that was perhaps the crowning achievement of the early days \r\nof laser cooling was the discovery that we made in our laboratory that \r\nit was possible to get these atoms colder than everyone had thought was \r\nthe limit to how cold you could get something.
The prediction \r\nsaid that we could get down to temperatures of 240 millionths of a \r\ndegree. In other words, one-quarter of one-thousandth of a degree above \r\nabsolutely zero. Pretty cold, right? Well, in fact, we got a whole lot \r\ncolder than that. And that was the big breakthrough discovery that made a\r\n whole lot of other things possible.
Question: How has\r\n laser cooling contributed to the development of atomic clocks?
William\r\n Phillips: Well, all clocks have tickers. All of these tickers have \r\nimperfections. Every quartz crystal is made a little bit differently, \r\nthe length of the pendulum can change a little bit and that changes how \r\nfast it will swing back and forth. So, all these clocks have \r\nimperfections.
And so one has throughout history been trying to \r\nmake these clocks better by making the tickers be more reliable. That is\r\n always had the same ticking frequency. Well, it turns out that atoms \r\nare the best choice for making tickers that always tick at the same \r\nfrequency. Even atoms have their imperfections. Temperature means that \r\nthe atoms are moving with a certain velocity having a certain kinetic \r\nenergy. The hotter the gas is, the faster the atoms are moving. It’s not\r\n so easy to measure the ticking frequency of something that whizzing \r\naround at the speed of sound. And that’s the problem that everybody was \r\nfacing with atomic clocks was that atoms were moving at approximately \r\nthe speed of sound and it wasn’t so easy to measure the ticking \r\nfrequency.
So, we said, "let’s cool them down using lasers so \r\nthey’re going more slowly and that’ll make it easier to measure the \r\nticking frequency and you can make better clocks.”
When I \r\nstarted doing laser cooling, the very best clocks were accurate to a \r\npart in ten to the 13, so that’s one part divided by 1, with 13 zeroes \r\nafter it. That’s the fractional error in how good that clock was. Sounds\r\n incredible right? But today, those clocks are a couple and ten to the \r\n16th. Almost three orders of magnitude better and that has been made \r\npossible because of laser cooling.
Question: How did \r\nyou first get interested in science?
William Phillips:\r\n I suppose that young children are curious about everything and very \r\nearly my curiosity tended toward a curiosity about science. My parents \r\ngot me a microscope when I was very young, maybe six years old, and I \r\nremember looking at all kids of things around the house with this \r\nmicroscope. I remember collecting various household chemicals and fluids\r\n to mix together, which was my homemade chemistry set. And in addition, I\r\n was doing all the other things that kids do, climb trees and scurry up \r\nand down cliffs and collect huckleberries in the woods. But there was \r\nalways a lot of physical activity and a lot of that physical activity \r\nfor me involved doing things that related to science; looking at stuff, \r\nbeing curious about the natural world.
Question: Will it ever be possible to get a temperature down to absolute zero?
William Phillips: Well, that’s an interesting question. And sadly, the answer isn’t simple. The simple answer is, no. But now I’ve got to explain why I’m saying that the answer is no. And answer is that every process for cooling either also introduces the possibility that you can introduce some extra energy into the system. You see, cooling means taking energy out, and heating means putting energy in. But in order to take energy out, then it turns out that you open the door for energy to go in.
Take laser cooling. Laser cooling takes energy out by having an atom coming along and then a photon hits the atoms and slows the atom down, but then that photon has to go someplace. And when that photon is shot out by the atom, the atom recoils and more energy goes in. so, there’s a balance between the cooling and the heating and you can try to make that balance work more and more in your favor, but you can never make it work 100% cooling and no heating.
So that’s one of the reasons why you don’t expect to ever get to absolute zero. On the other hand, what does it mean to be at absolute zero? It means that all of the thermal motion stops. Well, I can take one atom and I can take as much energy out of it as possible so that it’s in what would call the ground state, the lowest possible state of energy. Is it absolute zero? Not really because in order to be at absolutely zero, I really have to have a whole bundle of things. I can’t really talk easily about the temperature of a single object. I should really talk about a whole ensemble. And if I do that with a whole bunch of atoms, what’s going to happen is, maybe if I’m lucky, maybe 99 percent of them are going to be in the ground state and then one percent isn’t. So, it’s not absolute zero.
I can’t come up with any procedure that is going to say 100 percent of the time this atom’s going to end up in the ground state. And that’s what I would need to be able to claim that I really had gotten down to absolute zero. But on the other hand, I can get so close to absolute zero that for many experiments, it’s basically absolute zero for all practical purposes. But not for all experiments and we are constantly working on making things colder because for some experiments, it really matters that were not quite there.
Question: What was your reaction when you learned you won the Nobel Prize?
William Phillips: Well, my reaction to hearing about the Nobel Prize was one of shock and disbelief. In fact, I can remember very, very well when this happened. I was attending a meeting in California; a meeting of the American Physical Society and Optical Society of America meeting jointly out in California, Long Beach, California. And the day before the prizes were announced, a number of us were sitting around after the scientific sessions were over speculating about who was going to get the Nobel Prize that year. And believe me, nobody brought up my name. So, later that night... well it was the middle of the night that I got a call I my hotel room to the effect that I had shared the Nobel Prize with Claude Cohen-Tannoudji and Steve Chu, came as a complete shock.
Question: How did your life change after that?
William Phillips: My life changed dramatically. It’s very difficult for me to keep up with all of the invitations that I get to speak about my work, the size of my research group has grown and that’s made it possible for me to be involved in more and more new kinds of physics, but it’s made it harder and harder for me to be in intimately familiar with all the things that are going on. So, there’s a kind of a tension between the joy of doing lots of new things and the desire to understand them better and better.
Another thing that I never would have imagined would have been one of the results of become a Nobel Laureate is that I ended up meeting people who are actually famous. So, you know, people say, you’re a Nobel Laureate, you must be famous. No, nobody remembers you know, outside of the field in which you’re working, nobody remember who won the Nobel Prize even a couple of years ago. But as a result of being a Nobel Laureate, I get invited to things where I’ve met people who are actually famous.
One of the people that I have met who has been most charming is Dr. Ruth Westheimer. She lives in New York City, and I see her, probably about once a year, and she’s just a wonderfully warm and genuine person. Just a joy to know as a friend.
Question: Does science make faith in God obsolete?
William Phillips: Yeah. Well first of all, I should say that I’m not particularly comfortable with being described as a religious person because somehow I have this image in my mind of somebody who’s very proper and prim and follows all sorts of rituals and stuff. And I like rather to describe myself as a person of faith. And clearly I don’t believe that science has made belief in god obsolete, or else I wouldn’t describe myself as a person of faith.
I believe that certain ways of interpreting certain scriptures have been made obsolete by science, but that in no way makes religious faith or belief in God obsolete, it just requires what I would consider to be a different outlook, a maturation of religious faith. But if we look at the history of religious faith as told in the scriptures and as seen through history, I think the entire history of faith has been one of a maturation of that faith.
I see it as not so much as people becoming more mature in their faith, but God challenging people to become more mature, to get a clearer understanding of what god wants for human-kind and I think God is always pushing us to be better than what we are.
Question: Have your religious beliefs contributed to your work as a scientist?
William Phillips: Well, okay, so there’s two ways of answering that question. By and large, science and religion deal with different kinds of questions. Science deals with questions about how do things come to be the way they are, how should I think about the way things are? How shall I organize my understanding of the way things behave?
Whereas, religion deals with questions like, how should I behave toward my fellow human creatures? What should my relationship be to God? How should I understand the ultimate origins of this world and this universe in which we live? These are different kinds of questions. But sometimes the areas that science addresses and the areas that religion address can overlap. So, I don’t ascribe to the idea of science and religion as being non-overlapping magisterial, as they’ve sometimes been described. But I also will say that, by and large, they deal with different kinds of questions. But they are ethical questions that might involve things like medial ethics, or environmental questions where you have to understand the science in order to be able to make good ethical decisions that are guided by your religious principles.
So, there’s always going to be places where science and religion are gonna come to bear on the same kinds of problems.
Question: Have you ever been completely surprised by an outcome of your research?
William Phillips: All the time. In fact, it’s one of the greatest things about being a scientist is that you’re continually surprised. Nature is so much more clever than we are that we never understand the secrets that nature has to offer, but little by little we learn more and more. But every time we got into the laboratory, we’re surprised.
I work in an area of physics, atomic physics, where the basic principles as far as we know, the basic principles were pretty much understood in the 1930’s. Maybe some details were worked out in the 40’s and 50’s, but we are still surprised every day by the results of these things. So, in spite of the fact that some people might say, well, there’s nothing new, we’re surprised every day and the things we learned were the things that nobody imagined that things would work this way.
So for example, let’s go back to this example about laser cooling. Everybody thought they understood how cold you could get things using laser cooling. And the problem was a simple enough problem, you can write down the proof in a few minutes as to how cold it is possible to get something. And we got it eventually 200 times colder for one particular atom then the theory said it was possible. Why? Well, because the situation was a little bit more complicated.
Remember I said that physicists liked to make a problem really simple. That’s the physicist’s way of looking at a problem. Well, Einstein once said, “A problem should be made a simple as possible, but no simpler.” And sometimes you make a mistake, and you’ll leave out some really important stuff, usually when you do that it makes things worse. This was a case where putting in the complications made things work better. Nobody would have guessed that that was going to happen. I can’t imagine anybody sitting down and thinking. “Okay, we’re going to figure out how laser cooling works and coming up with what actually happens.” We had to do the experiments first. Nature showed us what was going to happen, and then clever people figured out what was really going on. These kinds of surprises happen to us all the time.
Recorded on June 4, 2010
Interviewed by Jessica Liebman
A conversation with the physicist at the National Institute of Standards and Technology.
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- Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
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The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?
But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.
What's dead may never die, it seems
The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.
BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.
The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.
As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.
The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.
"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.
An ethical gray matter
Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.
The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.
Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.
Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?
"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."
One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.
The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.
"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.
It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.
Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?
The dilemma is unprecedented.
Setting new boundaries
Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."
She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.
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