William Phillips delivers commencement address

RIT officially kicked off its two-day commencement celebration Friday morning with Academic Convocation. William Daniel Phillips, an award-winning researcher with the National Institute of Standards and Technology who shared the 1997 Nobel Prize in physics, delivered the keynote address. The full text of his speech is below:

President Destler, platform party, members of the faculty, honored guests, and most important: graduating students of the Rochester Institute of Technology. This is a wonderful day, a joyous occasion, a time for celebration, a time for fond memories, a time to look forward to great times to come.

You are receiving degrees from one of this great country’s great universities. You deserve to be proud of your accomplishments, and I am happy and honored to congratulate you for what you have achieved.

I know that you are eager to get on with this happy ceremony, to rejoice with your fellow students, and to celebrate with family and friends. But first you have to listen to ME giving this commencement address. I know how you feel. I have listened to a lot of commencement addresses and affirm that they have been almost uniformly forgettable.

There was one exception: The renowned cellist Yo Yo Ma declared that just as each musician must find his or her “voice,” that unique interpretation a performer gives to well-known compositions…each student, indeed each one of us, must find our own unique way through the familiar life experiences. Good advice. But what made it memorable was that as part of his address, Yo Yo Ma played his cello. It was awesome.

So, when Bill Destler asked me to address you today, I wondered if I could pull the same trick—that is, could I, as an experimental physicist, do an experiment in the same spirit as Yo Yo Ma playing his cello? We shall see.

As a physicist, what I do is to make things really, really cold. Why? Because when something is cold, the atoms and molecules in it move more slowly. The molecules in the air in this room are moving at about the speed of sound—300 meters/second. It is hard to measure things that move that fast, and so we want to slow them down—that is, to cool them down.

Here, courtesy of this great university, we have some really cold stuff. Liquid nitrogen—essentially liquid air. It is so cold that compared to it, this floor is burning hot. What would happen if you poured cold water onto a burning hot stove—it would boil [here, pour out liquid nitrogen and it boils on the floor].

This stuff is really cold. In fact, unless you have been in a low-temperature physics lab, it is probably the coldest stuff you have ever seen. So, it seems reasonable that if you want to cool down a gas of atoms, you could use liquid nitrogen as a refrigerator. Here (picking up balloon) I have a traditional container for hot gas (or, as we say in Washington, “hot air”), and here (gesturing toward bait bucket) I have a container of liquid nitrogen. So, let’s fill the balloon with hot air, and put it in the bait bucket to cool it down. (Inflate balloon and put it into the nitrogen).

OK, what else can I do to show how cold this stuff is. Here is a dewar flask, just a fancy name for a thermos bottle. It has been sitting out at room temperature and compared to the liquid nitrogen, it is burning hot. Imagine if you took a metal bucket and heated it up until is was red hot, then poured cold water into it—the water would boil (here pour nitrogen into dewar, so it boils up and spills over the sides). Don’t try this at home. The nitrogen is boiling away, cooling down the inside of the dewar. While that is happening, let’s cool down some more gas (repeat inflation of balloon and stuffing it into the bait bucket).

Let’s return to the dewar—the boiling has subsided, so the inside of the dewar is down to liquid nitrogen temperature; let’s top it up (pour more nitrogen into dewar). Now, here we have a nice fresh flower (pick it up, and squeeze it in hand, tap against head…). It is at room temperature—red hot compared to liquid nitrogen. Imagine you took a fireplace poker and heated it up until it was red hot, then plunged it into a bucket of cold water (plunge flower into nitrogen); it would make the water boil, and that is what is happening here. While the nitrogen is boiling away, let’s cool down some more gas (repeat inflation of balloon and stuffing it into the bait bucket).

Let’s come back to the flower—the boiling has subsided, meaning the flower is at the temperature of liquid nitrogen. It is frozen so hard that when I take it out (remove flower with one hand, hold it up and crush it to bits with the other hand) I can crush it like it was made glass. This stuff is really cold. And if you’ve got something this cold, why not use it to cool down your gas so the atoms move more slowly. (repeat inflation of balloon and stuffing it into the bait bucket).

What else can we do to see how cold this stuff is? A rubber band, nice, stretchy, let’s put it in the liquid nitrogen (picking up rubber band with tongs, dip into liquid)—you can’t see it, but it makes the nitrogen boil, just like anything at room temperature does. Soon the boiling stops and the rubber band is frozen so hard (take rubber band out, break it with hands) I can break it as if it were a dry twig. This stuff is really cold, and if you have something that cold, why not use it to cool down your gas, to make the atoms move more slowly. (repeat inflation of balloon and stuffing it into the bait bucket).

Let’s do something else to see how cold this stuff is—a nice, bouncy rubber ball (bouncing ball on floor and on concrete block), let’s see what happened to it in the nitrogen (put it into the liquid).

How cold is this stuff? Normally we measure temperatures in degrees Fahrenheit or Celsius and on a cold day, it might be below zero Celsius outside, or on a really cold day below zero Fahrenheit. But physicists don’t care for temperatures below zero, so we use a different scale—the absolute or Kelvin scale, where zero is the coldest possible temperature. On that scale, room temperature is about 300 degrees. Ice melts at about 273 degrees. Dry ice is about 195 degrees, and the coldest air temperature ever measured on the surface of the earth, someplace in Antarctica, was about 185 degrees above absolute zero—even colder than dry ice. But this stuff, which is so cold it boils when I pour it on the ground, (here pour some more on the ground), probably the coldest stuff you’ve ever seen, is only 77 degrees above absolute zero.

Let’s see what happened to the racquetball. (taking ball out of nitrogen) You remember how nice and bouncy it was; now it is frozen so hard (throw ball onto concrete block) that it breaks as if it were made of porcelain. This stuff is really really cold.

And if you have something this cold, it seems reasonable to use IT to cool down a gas to make the atoms go more slowly. And that is what we have been doing with the balloons. But some of you have noticed (if the audience is paying attention, after the second balloon, some people will be laughing because there is not enough room in the bait bucket to fit all the balloons. If this happens, I will gesture with my hands as if to say “what are you laughing about” and say “what?!”) that the volume of the balloon I put into the bait bucket is larger than the volume of the bucket. That is because these balloons have turned into pancakes (take a balloon out and set it aside to re-inflate, take another out and throw it like a Frisbee). These are like Frisbees. How many balloons did I put in? What colors? Right, your school colors. How many? balloons did I put in? How many? (pulling out balloons of different colors that never when into the bucket). I put all these other balloons in before we started—I could have put any number of balloons in because they all collapsed into pancakes. Not because the air went out of the balloons, but because it condensed—it turned into a liquid or a solid; it stuck to the inside of the balloon, and it was not a gas anymore. And we cannot have that, because we want our atoms in a gas—so we can study them individually, not stuck to other atoms or to a container.

So we had to find another way to cool the atoms. I wish I had time to tell you about how we did that, but the trick was to push on the atoms with laser light, and make them slow down, which is the same as cooling them. And it worked so well that we got our atoms down to less than a millionth of a degree about absolute zero—the coldest thing that had ever been made—the atoms are moving slower than an ant crawls, not faster than a speeding bullet. Our atoms were 100 million times colder than liquid nitrogen—this stuff that boils when you pour it out on the floor, that is colder than anything else you have seen—we got 100 million times colder than that.

And with those atoms, we have been able to make such good measurements that atomic clocks made with these atoms will only lose or gain a few seconds in the entire age of the universe.

But where do you keep the coldest stuff that has ever been? You can’t keep it in any ordinary bottle, because a hot bottle will heat it up, and a cold bottle, if you could find one, will make it condense, like the air in our balloons. What we do is use a magnetic bottle, where there is no material to enclose the atoms, just a magnetic field. (here I go to the table to do the levitation experiment).

When you were children and playing with magnets you found that if you held two magnets the right way, they would push apart without touching each other. We will use that push on our atoms to hold them in place, because it turns out that our atoms are little tiny magnets.

What I have here on the table is big magnet, arranged so it is pushing up on this little magnet that represents our atom. If I hold the little magnet right here, which you can see on the video screen, I can feel it being pushed up. If I let go of the little magnet at just the right place, it should float. (release the little magnet) but it doesn’t float, because it flips over and is attracted down to the big magnet. But you learned something else playing with toys as a kid—you learned that if you spin a top it doesn’t fall over. And our atoms are like tiny spinning magnets, so we will spin the small magnet and lift it to the place where the big magnet just pushes enough to counter gravity, and the spinning magnet floats. And that is how we hold onto our atoms—the coldest stuff in the universe.

What great fun. And useful too. But why did I do it? I mean, what point do all these wonderful, fun tricks have in this commencement ceremony, where I am supposed to send you off to the rest of your lives with some message, some profound words of wisdom. In that long-ago graduation where Yo Yo Ma played the cello, his message was “find your voice.” A great message. But what is MY message? Simply this: I am having a lot of fun, and I hope that you will, too.

Perhaps you were expecting something more profound. Something along the lines of how your status as RIT graduates gives you a special responsibility to make a positive difference in your communities near and far, and in the lives of those you touch. Of course that is true. But I think you are both smart enough and good enough to have figured that out already.

What you might have forgotten is that you can do all that while having fun.

Doing science, as I do, is a lot of fun. In fact doing anything that you love to do is a lot of fun. And one of the most important things you have learned in your time at RIT is how to have fun by exercising your mind. You have learned how to learn. I hope that you are going to use what you have learned here at RIT to make the world a little better. And to do that, you will need to keep on learning. One of my favorite sayings is that a good day is a day when I learn something new and interesting. And with what you have learned at RIT, you can make nearly every day a good day. As graduates of RIT, you have that wonderful, inexpressibly exciting opportunity to take part in the life of the mind. No matter what you studied in your years here, no matter whether your career takes you in the path of those studies or not, you have opened the door to learning, and that door can never be closed. It is an old proverb, repeated by many, people can take many things from you, but no one can take away your education. In his modern retelling of the Arthurian legend, T. H. White has Merlin tell Arthur: “The best thing for being sad is to learn something. That's the only thing that never fails.”

So my message to you today is “have fun.” Have fun with your mind. Read, learn, do. You have what it takes. Your education may or may not be the ticket to a financially successful career connected to your field of study. That will depend on chance and circumstance as well as on your own desires, hard work and ability. But your education is surely the ticket to a life of fun in learning and of using that learning to make a difference. I hope that you will use that ticket to travel far and wide and deep in the world of the intellect.

Today is a day for celebration. I’m sure that today you will easily follow my advice to have fun. And you should. But what about tomorrow, and the rest of your lives? The days to come may be filled with uncertainty. For what it’s worth, that uncertainty is part of the human condition, and you are in good company. But as graduates of RIT, you are in even better company. You are in the company of those who have learned how to learn, who have access to the great adventures of the mind. You will celebrate and have fun today, but the real fun will be in what you continue to learn for the rest of your lives. Good luck.