The Grand Hall of the Main Building was filled to capacity with people of all ages on February 7th, 2008, as Drexel hosted its 13th annual Kaczmarczik Lecture. In addition to Drexel students and staff, high school students from Pennsylvania, New Jersey and Delaware were invited to attend the lecture, and 700 of them did. As promised, the topic of the coolest lecture in the University was "Time and Einstein in the 21st Century," presented by Dr. William D. Phillips, a Nobel Laureate and NIST Fellow who is also a professor of physics at the University of Maryland.
The University Provost, Dr. Stephen W. Director, greeted the excited crowd, and introduced the Dean of the College of Arts and Sciences, Dr. Donna Murasko. Murasko spoke of the tradition of the Kaczmarczik Lectures, and of Kaczmarczik himself; she said it was his goal to try to get "everyone to appreciate physics" and was proud to honor that goal today.
CoAS Dean Donna Murasko, University Provost Dr. Stephen Director, Dr. Michel Vallières, and Dr. William Phillips have a discussion prior to the start of the 2008 K Lecture.
Phillips, full of energy and eager to discuss about all things physics, opened by talking about World Year of Physics 2005, an event that was a worldwide celebration of physics that also marked the 100-year anniversary of the "Miraculous Year" of 1905, when Einstein published papers on three ideas that have since changed modern physics irrevocably: photoelectric effect, Brownian motion, and Special Relativity.
The last topic, specifically, dealt with time and clocks. A clock tells time by using an internal quartz crystal or spring, whose vibrations are measured in increments called seconds. Many factors, from the rotation of the earth, to whether the clock is moving or stationary, affect this time. From clocks, all sorts of things can be computed, such as longitude and latitude and GPS systems.
Another theory of Einstein's, the Theory of General Relativity, was said to be so complicated and esoteric that only three people in the world understood it. However, today, without an understanding of general relativity, GPS systems would be off by kilometers and wouldn't be nearly as accurate. All these calculations, like clocks, need to be precise. "I always know the time to the second," Phillips said. "That's what geeks do."
An atomic clock, the most precise way to measure time, does so by measuring the oscillation frequencies of atoms. However, atomic clocks are subject to problems such as the Doppler Shift, which can throw off the time of the clock by as much as a millionth of a second. A clock can be more accurate, or be less affected by the Doppler Shift, if its atoms move slower. Thus the issue of slowing down atoms became a forefront topic in the field of physics research.
Phillips suggested that the atoms could be put in something very cold to slow them down – liquid nitrogen, for example. And he just so happened to have a whole jug of it with him on stage, which he then pulled out and, to the shock, horror and amusement of the audience, proceeded to pour all over the floor of the stage. "This stuff is really cold!" he said. As the liquid nitrogen hit the floor, it boiled, producing an impressive amount of steam, which wafted over the audience. People screamed and jumped out of their seats, trying to see. Phillips walked up and down the aisles, pouring the liquid nitrogen on the floor in front of the awe-struck audience.
Phillips obviously liked playing with liquid nitrogen as much as the audience liked watching him play with it. It's "just so cool," he said as he blew up a blue balloon. He asked the audience if they thought he could fit a fully-inflated balloon into a container filled with liquid nitrogen; the container did not appear large enough to have held a fully-expanded balloon. But when Phillips put the balloon into the container, its air condensed, and it fit inside with the lid closed without a problem. Over the course of the lecture, Phillip stuffed four blue balloons into the container.
Liquid nitrogen, he explained, is 77K, or Kelvin. Absolute zero, 0K, is a theoretical concept scientists are working toward reaching. But 77K is really cold – room temperature, about 68°F, in Kelvin is about 293. He dipped a red carnation into a jar of liquid nitrogen too, and let it freeze. When he pulled it out, it was frozen. He clapped his hand over it, and it shattered. This stuff, he reiterated, is really cold.
So the solution to slowing down atoms, it seems then, is to stick them in a jar of liquid nitrogen. But, Phillips explained, sending atoms through an atomic clock when they are frozen causes them, sadly, to shatter when they reached the end of the tunnel through which they travel.
Physicists then came up with the idea of laser heating and cooling from watching the trail of a comet. The trail of a comet always points away from the sun, because the light from the sun is so strong that it pushes the trail of the comet away. This idea of cooling and trapping atoms with laser light is what won Phillips the Nobel Prize in Physics in 1997. Physicists were then able to reach temperatures as low as 240 uK, or 240 x 10-6K. But something was strange when scientists conducted this experiment. They discovered they had made an error, and the temperature they really reached was much colder than they had thought – 700nK, or 700 x 10-9K. That's 100 million times colder than liquid nitrogen. But this temperature was, once again, too cold for atoms to go through a tube, so scientists now shoot them up in the air vertically to measure the oscillation. Atomic clocks since this development are accurate to 5x10-16 of a second every 60 million years.
Another prediction of Einstein's was that if it was cold enough, atoms would stop moving. But even Einstein dismissed his own theory as impossible-sounding. However, today, scientists know that Einstein's theory is true, even if it hasn't been reproduced in a lab. If atoms could be slowed down so that they are not moving, the applications are endless. Results would include better clocks, answering some fundamental questions about nature, quantum computers and more.
Phillips then reached into the container of balloons, asking the audience how many they thought could fit in the jar. As he pulled the balloons out of the container, they were flat, like Frisbees. He pulled out all four blue balloons, and then let the audience in on a secret: he had put numerous yellow balloons in the container also. He pulled out those and flung them into the audience like Frisbees too. The point was clear: the liquid nitrogen condensed the atoms so that 10 or so fully-blown balloons could fit in a small container. "This stuff," he said, holding up a balloon that started to re-inflate in his hands, "is really cold."
Cold environments, liquid nitrogen, and condensing atoms, Phillips proved, can do more than just amaze audiences; these ideas have the potential to change the future in amazing ways, and are a very hot topic in physics research right now.
Ali Cahill is a senior at Drexel majoring in English. She is also the Managing Editor of ASK.