Don’t forget to turn off the lights next time you leave a room. You’ll make an 83-year-old physicist, with a passion for saving kilowatts, very happy

Do you know what the biggest energy drain is on your house? Well, if you don’t have a hot tub, it’s heating and cooling your house. My head is swimming with energy efficiency facts after producing this week’s QUEST radio piece on efficiency guru Art Rosenfeld. Rosenfeld is retiring, stepping down after two terms on the California Energy Commission. The guy has spent the past thirty five years fighting for us, California’s energy consumers. While electricity consumption has risen, sharply, in the rest of the country, California’s electricity use, per capita, has remained nearly flat since the early 1970’s. It is not that we are any less addicted to our flat screen TVs and personal computers, it’s that the state, thanks in large part to Rosenfeld’s dogged persistence, has put in place some of the strictest energy standards in the world. His passion for saving killowatts has saved billions on utility bills and improved air quality.

As it goes with people who are driven by a cause, the 83-year-old physicist is not really retiring. Rosenfeld will be returning to Lawrence Berkeley National Labs a few days a week to continue his research on low reflective white roof tops. His work has shown white roofs can cut electricity use by 15-percent by reducing the need for air conditioning and they combat climate change at the same time. White roofs are now mandatory on commercial buildings in California, thanks, in part, to Rosenfeld. Check out our radio story on cool roofs.

And by the way, don’t forget to turn off the lights next time you leave a room. You’ll make an 83-year-old physicist, with a passion for saving kilowatts, very happy.

Listen to The Godfather of Green radio report online.

The Cartesian Diver: this is a classic demo named after the17^th-century philosopher and mathematician René Descartes.

Buoyancy is the force that decides whether an object will sink or float, and has had a long and colorful history. As the story goes, the Greek thinker Archimedes was sitting in his bathtub one day when he noticed how the water around him rose when he got in. Suddenly, he realized that he could use the water level rise to measure an object’s volume. Shouting “Eureka!” he burst out of the tub and ran out into the streets stark naked.

Fascination with buoyancy continues into modern times. Astronauts have exploited buoyancy to simulate being in space. Scuba divers use it to turn the underwater world into their playground. And then of course there is David Letterman’s Will it Float?, an entire sketch dedicated to watching what happens when something is dropped into a giant pool of water. Demonstrations at home of buoyancy are easy to come by, too. Below are two of my favorites.

Cartesian Diver

This is a classic demo named after the17^th-century philosopher and mathematician René Descartes, although curiously, no one seems to know why. Build a miniature model of a submarine here and take control of an object’s depth.

What to do: You need a 2-liter plastic soda bottle, the cap to a ballpoint pen, water, and a lump of clay. Drain the soda bottle and refill with water. Attach a lump of clay to the bottom of the pen cap (enough to weigh it down but not quite to sink it). Drop the cap into the filled soda bottle and seal the bottle’s top. Squeeze! Depending on the amount of pressure you apply, you should be able to make your pen cap dive to the bottom of the bottle and resurface at will.

What’s going on? An object will float or sink depending on how its density (its mass divided by its volume) compares with that of the surrounding liquid. For example, a steel rod is heavy for its size so it sinks. However, if you increase the rod’s volume by trapping an air bubble inside or reshaping the steel into a boat, then you can make it float. In the case of the Cartesian diver there is an air bubble trapped beneath the pen cap. When you squeeze the bottle you compress the air bubble into a smaller volume, and while the diver still weighs the same it now sinks. This is exactly how the ballast tanks of a submarine work, and many fish have an organ called a swim bladder that uses the principle to control their depth.

Layered Liquids

Awesomeness ensues when you mix the effects of buoyancy with liquids that don’t mix. You may already be familiar with the fancier versions of this demo in the form of lava lamps or the oil drop toys you can buy in many trinket stores.

What to do: You need corn syrup, water, vegetable oil, a clear container, and some food coloring. Use the food coloring to dye the corn syrup, water, and oil different colors for increased effect. Pour about an inch of corn syrup into the bottom of the clear container, then gently pour about an inch of water above it, and finally pour the oil atop the water. Each liquid will float atop the one beneath it.

What’s going on? Density can affect whether or not a liquid will float in exactly the same way that it can determine whether a solid object floats. In this example water is less dense than corn syrup, so it floats on top. Oil is less dense than both corn syrup and water, so it floats highest of all. Such layering of liquids can also happen between salt water and fresh water in underwater caves, sometimes dangerously tricking divers into believing there is an air bubble over their heads when in fact there is just a different kind of water.

Perhaps no single development of the last century has been more influential or more important than the laser.

The concept of discovery is a powerful sentiment in science. Television’s Discovery Channel and print journalism’s Discover Magazine have folded the word into their identities, and as a child that my iconic scientist was a paleontologist, literally unearthing discoveries of the prehistoric wilderness. Just as motivating, however, is the concept of invention, and perhaps no single development of the last century has been more influential or more important than the laser. In 2010 the laser turns 50, and to celebrate, a group of organizations including the American Physical Society, the Optical Society, SPIE and IEEE Photonics Society have organized a year-long series of events this year dubbed LaserFest.

UC Berkeley has been celebrating LaserFest this past week with special exhibits and events over the weekend at the Lawrence Hall of Science, and a special lecture on Monday the 25th by Roger Falcone, Bob Byer, and Nobel laureate Charles Townes, also at the Lawrence Hall of Science.

Theodore Maiman built the first laser out of a rod of pink ruby in 1960. However, the laser’s precursor and underlying principle belongs to Townes. In 1954, he and colleagues constructed the ammonia maser, a stunning proof-of-principle device demonstrating that intense beams of light within a narrow color range could be produced. A flurry of excitement and research efforts followed aimed primarily at developing masers that could work at higher and higher frequencies of light.

As maser research matured the name changed as well. A high-frequency MASER (the acronym stands for microwave amplification by stimulated emission of radiation) became the optical MASER. Then at a conference in 1959, Gordon Gould coined it as the LASER. (The L stands for light.) One of the conference’s organizers, Arthur Schawlow, rebutted that these new devices would be more important as oscillators rather than amplifiers, so perhaps they should really be calling it the LOSER (see the recent article in Physics Today). Curiously, substituting the O never caught on.

The laser’s influence in science and society, however, has been dramatic. We use lasers to read our hard drives and play DVDs. We use them to improve our vision. Lasers play an integral role in security systems. They are a crucial component of our ability to keep time accurately. The world’s biggest laser in Livermore could be on the verge of igniting fusion reactions. We even shot a laser at the moon, waited for it to bounce back, and used the information to calculate the moon’s distance to the Earth with unprecedented accuracy.

Time will tell what the laser’s future applications might be. Personally, I am rooting for a sign of extraterrestrial life from the SETI optical telescope. The research collaboration’s website says that “A tightly focused light beam, such as a laser, can be 10 times as bright as the Sun and be easily observed from enormous distances.” Then again, if the aliens do decide to shoot a message our way via laser, let’s just hope that that they don’t decide to crank up the power so high that we all get vaporized.

The first evidence for dark matter came from Fritz Zwicky’s observation of the Coma Galaxy Cluster. Image Credit: NASA, JPL-Caltech, SDSS, Leigh Jenkins, Ann Hornschemeier (Goddard Space Flight Center), et al.

Dark matter (think of matter as a fancy word for stuff) is one of the most exciting but also potentially frustrating phenomena in cosmology today. It plays no detectable role on Earth in deciding how far we can throw a baseball, or determining the characteristics of the complicated materials we use to build computers. In fact the only reason we know that it exists at all is by looking through telescopes at objects so distant that it would take hundreds of millions of years to get to them even traveling at the speed of light. And yet we believe there is almost six times as much dark matter in the universe as the regular matter that we can see and feel and touch. Recent results of the Cryogenic Dark Matter Search (CDMS) may have brought us a step closer to understanding this elusive material.

Dark matter’s discovery belongs to Fritz Zwicky. Known for a bullying personality and a fondness for doing one-armed pushups in the Caltech dining hall, Zwicky also measured the Coma Galaxy Cluster in 1933, and noticed that galaxies seemed to be moving far more quickly than gravitational theory would predict. Either the theory of gravity had to be wrong, or some other hidden form of matter–dark matter–must be playing a role here. (Careful! This is not to be confused with antimatter, which stars in Dan Brown’s Angels and Demons, or with dark energy, an even more bizarre cosmological idea.)

Subsequent measurements have corroborated Zwicky’s conclusions, and today we can say with a fair degree of confidence that dark matter must exist. Still, we don’t have any idea why this is so or what dark matter might actually be.

Enter CDMS, a whopper of an experiment buried deep within the Soudan mine of northern Minnesota and consisting of a collaboration of no fewer than 18 experimental research groups scattered across the world. Some of the most promising theories predict that dark matter consists of a deluge of particles constantly washing through the distant galaxies we see, but also through our own Milky Way Galaxy and in particular through the Earth. Such particles, coined sometime in the 1980s as Weakly Interacting Massive Particles (or WIMPs), should be detectable on extraordinarily rare occasions if you can put your detector in a pristine enough location.

On December 17^th, CDMS disclosed the final results of their most recent experiment, and they have reported two events that seem likely to have been caused by WIMPS. Statistically, they find that these events have only a 23 percent chance of being a coincidence. If they are real events, this will certainly be a landmark moment in the history of physics.

However, the search for dark matter has been marred by controversy before. Another large experiment called DAMA in Italy has insisted for years that they have irrefutable evidence for dark matter particles at their own detector. Unfortunately, many other experiments are in direct conflict with DAMAs claims, and consequently nobody seems to take that group seriously. Consequently, CDMS researchers are being careful not to overstate their case.

In the end the hunt goes on, perhaps rightly so. After all, there is a 23 percent chance of dark matter being something else entirely, and if the odds of winning the lottery were 23 percent I would be running off to buy a ticket right now.

Electron microscope image of a hole embedded within a sheet of graphene. The corners of the green hexagons are carbon atoms which form graphene’s crystal structure. Image courtesy of the Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley.

Acquiring a sample of graphene is almost comically easy. Start with an ordinary piece of graphite, which is basically the same material that is used in pencil lead. Squeeze it between two pieces of Scotch tape and tear them apart. Repeat several times until pieces of the graphite have been cleaved into sheets no more than a single atom thick. Voila – graphene! Total cost of 1 pencil plus a roll of Scotch tape: about $3.

Simple as this process is, scientists did not even know that single sheets of graphene could exist until 2004. Now that we know that we can make graphene, it turns out that it has some amazing electrical properties and someday might even replace silicon as the most important component in computer circuitry. To that end, researchers in Alex Zettl’s group at Berkeley have endeavored recently to isolate suspended membranes of graphene for study and image them at Lawrence Berkeley Lab’s TEAM 0.5, the world’s most powerful transmission electron microscope (TEM). Results were published last spring by Çaglar Ö. Girit and others in the Science.

Two aspects of the Zettl group’s recent work have been particularly interesting. First, the TEAM 0.5 microscope not only has the ability to see individual atoms of graphene, but can also take pictures in close to real time. This means that Girit was able to see dynamics of graphene as they actually happened. Other types of microscopy (scanning tunneling microscopes, for example) can take several minutes to get a single picture.

Second, Girit and others centered their images at a hole within the graphene sheet. This allowed them to observe the dynamics that occur at the material’s edge. Such edges can have a notable effect on a graphene sheet’s electrical properties and thus understanding them and controlling them would be crucial in the design of any future technology.

Aside from technological applications, graphene is a theoretical physicist’s dream system because it beautifully combines the dynamics of relativistic particles from space such as neutrinos with the experimental accessibility of an easy system to make and manipulate here on Earth. Girit thinks that this is perhaps the single most exciting aspect of the system.

Only time will tell if graphene will have a long-term impact on society, but this would not be the first time a new discovery has transformed the Bay Area. In 1955 William Shockley moved to Mountain View, CA to found a new startup developing the silicon transistor. His company’s success was ultimately marred by Shockley’s own belligerent personality (“He understood everything except people,” Charles Townes once remarked), but the invention and the industry that grew up around it have revolutionized the region. The Santa Clara Valley’s old nickname, “the Valley of Heart’s Delight,” has long since been whisked away into a memory of a distant time and setting. Today most of us know it only as Silicon Valley. Our children may know the region as something entirely different.

Lawrence Berkeley Lab's TEAM 0.5 is capable of resolving individual carbon atoms in the honeycomb crystal structure of graphene. See QUEST's video The World's Most Powerful Microscope for more information. Image source: Nano Letters

Fifty years later, a new field of nanotechnology has exploded. At the cutting edge, researchers are successfully manufacturing everything from corporate logos to radios that are all small enough to be stacked end-to-end perhaps a million items long across the proverbial head of a pin. The advent of personal computers and smart phones has brought the power of such miniaturization into sharp focus for the general public. In a very real sense, we have all become bottom feeders. Below is a brief progress report on the state of the field.

Microscopes: The old adage “seeing is believing” was not lost on Feynman back in the late fifties. He noted that many of the most fundamental questions in biology could be readily solved if we only had the ability to see the molecules directly. Today, new inventions such as the scanning tunneling microscope (STM), the atomic force microscope (AFM), and the transmission electron microscope (TEM) have all achieved resolution at the scale where individual atoms can actually be seen and manipulated.

Miniature Motors: Perhaps the speech’s most imaginative scenario, due to Feynman’s friend (and graduate student) Albert Hibbs, was the concept of being able to “swallow the surgeon.” Feynman imagined that we might some day be able to construct robots capable of repairing or investigating the inner reaches of an ailing patient’s body. Mixing engineering and biology like this can run quickly into thorny ethical questions. Nevertheless, interesting progress has been made. Researchers in Alex Zettl’s group at UC Berkeley have recently constructed a nano motor, for example.

Information Storage: Using order-of-magnitude arguments, Feynman argued that the Encyclopedia Britannica could be squeezed into a pin’s area if the text were reduced by a factor of 25,000. He offered a $1,000 prize to the first person capable of printing one page of any book at this scale. Tom Newman, a graduate student at Stanford, first accomplished this in 1986 with an impressive reprinting of the first page of Dickens’ classic A Tale of Two Cities. Today, you can buy the book in its entirety for only 1.9 megabytes. For a high-end smart phone with 30 gigabytes of memory, you could perhaps hold 15,000 books within the palm of your hand. Not bad.

Then again, at the extreme limit, Feynman also reasoned that you ought to be able to squeeze the text of every book that has ever been written (now more than 32 million titles according the Library of Congress) within the confines of a single speck of dust. We still have a long way to go.

The Sloan Telescope used to conduct BOSS

One of those is BOSS, the Baryon Oscillation Spectroscopic Survey, is a new project to create a 3-D map of over 2 million galaxies and quasars representing the best data ever obtained on the large-scale structure of the universe. Baryon oscillations began as pressure waves through the hot plasma of the early universe. Those waves left an imprint on the matter that makes up the universe, including the dark matter. The survey will essentially act as a ruler, in order to measure how the universe has been expanding.

Next Monday, you’ll be able to meet David Schlegel, the principal investigator of BOSS. He’ll be part of a panel of Lawrence Berkeley Laboratory scientists discussing their search for dark energy. As a primer, check out QUEST’s story on Dark Energy from last year. The piece features astrophysicist Saul Perlmutter, who will also be speaking at the event.

See QUEST's Video on Dark Energy below:

QUEST on KQED Public Media.


Dark Secrets: What Science Tells Us About the Hidden Universe

Where: Berkeley Repertory Theater, 2025 Addison Street, Berkeley

When: Monday, October 26th 7-830 PM

Cost: FREE

Details: No mystery is bigger than dark energy — the elusive force that makes up three-quarters of the Universe and is causing it to expand at an accelerating rate. KTVU Channel 2 health and science editor John Fowler will moderate a panel of Lawrence Berkeley National Laboratory scientists who use phenomena such as exploding stars and gravitational lenses to explore the dark cosmos.

The Large Hadron Collider, if located in the Bay Area, would encompass a sizable piece of San Francisco. Image Credit: NASA.

She’s Electric: To power a standard light bulb you need 60 Watts (or 15 watts for an equivalent CFL). To power a small house you need an average of about a thousand watts. To run the LHC at full power researchers will need 120 million watts. Alternatively, you could run the LHC, supply electricity to a population the size of Berkeley, or simultaneously bake 60,000 Thanksgiving turkeys. You could only fly three 747 airplanes, though.

Life in the Fast Lane: A fundamental axiom of physics states that no information can travel faster than the speed of light. The LHC’s proton beams are no exception, but their speeds do approach light speed to within a fraction of a millionth of 1 percent. Such velocities defy comprehension. Suffice it to say that if we ever managed to accelerate a person to this velocity, time would warp so much that we could expect her to live for half a million years.

The Long and Winding Road: The LHC’s 17-mile circumference could make it a nice racetrack for a half-marathon, but don’t try racing the beam. When operational, protons will shoot around the LHC more than 11,000 times per second. Even more mind-boggling is the length of wire used in the construction of the LHC’s thousands of superconducting magnets. CERN claims there is enough wire wrapped up in these magnets to trace out more than six trips to the Sun and back.

OK Computer: When operational, the LHC is expected to generate 15 petabytes of data and simulations per year, which amounts to the hard drive space of about 30,000 high-end personal computers. At CERN in 1989, Tim Berners-Lee and Robert Cailliau revolutionized the world with their development of key pieces in the framework of the World Wide Web. The networks being developed to manage the LHC’s expected data have inspired talk of a similar revolution to come.

A Whole New World?: All of these wonders of physics and engineering have been developed for the purpose of one thing: to create a particle smasher with the capability of knocking two protons together with an energy of 14 TeV (trillions of electron volts). This is about the same energy that it takes to pick a grain of salt up off the floor. Compressed into such an acute space, however, it just might lend us insight into the most fundamental properties of our universe.

Now, if they can only get those wires hooked up correctly…

Bumps and ripples in the otherwise flat ring system of Saturn cast long shadows at equinox. Image credit: NASA/Cassini

Hard to imagine what it would be like to float just above the rings of Saturn, but what a sight it must be! As a kid, one of my favorite astronomical pass-times was imagining the view from other places in the Solar System.

Now imagine a towering bulge of frosty mist rising up out of this super-flat plane of ice chunks, literally the size of a mountain. Such is what was beheld by NASA's Cassini spacecraft last month–albeit, from a distance–when it turned its cameras to Saturn's vast rings during the few days surrounding Saturn's equinox (August 29, 2009), giving us a view never before seen.

Equinox on Earth, when the Sun is positioned directly over our equator, happens twice a year. Due to Earth's tilted rotational axis, as we orbit the Sun the latitude over which the Sun shines directly cycles north and south between the latitudes of the Tropics. On its way north to warm our (Northern Hemisphere) summers or south to leave us in the chill, the Sun crosses the equator on the equinoxes (Fall and Spring).

The same thing happens on Saturn, with two differences. First, Saturn takes nearly 30 years to orbit the Sun, so equinox comes only about every 14 years. Second, Saturn has its system of rings that encircle the planet directly above its equator, serving as a visible extension of the equator. At Saturn's equinox, the Sun is not only directly over the equator, but sunlight strikes the rings edge-on, like a flashlight shining on a flat piece of paper from the edge, the light just grazing over the surfaces on either side.

When this happens, any deviations from the flatness of the ring system—bumps and ripples–cast long shadows across the rings, making the features much easier to see. The same thing is seen on that piece of paper with shadows from creases and bumps leaping across the page.

As seen from Earth, equinox on Saturn means the rings appear to vanish as we look at them edge-on. This behavior puzzled astronomers long ago before they understood the rings for what they are. During the August 2009 Saturn equinox, however, for the first time in history we had a bird's-eye view of the rings during equinox, from Cassini. Cassini has been in orbit around Saturn for five years now.

Cassini spotted a number of prominent shadows trailing bright spots and ridges—bumps and ripples of different sorts rising above the ring plane.

Some of the bumps–icy ring material kicked up by the gravitational disturbance of a small moonlet inside the rings–were measured at over two miles high, the height of the Rocky Mountains. Other rippling features, such as long ridges running along the direction the rings encircle Saturn, are waves created by the gravity of moons orbiting outside the ring system. Still other types of disturbances observed are possibly caused by the impact of meteoroids or chunks of ice with the rings.

Saturn's rings are tens of thousands of miles across, but are extremely thin—perhaps no thicker than the height of a four-story building! So a bump or ripple as high as a mountain is a big deal!

Ah, to be on Saturn, now that equinox is here…

Water and cornstarch make a non-Newtonian fluid when mixed: messy but great fun!

Fast-forward fifteen years to the beginning of the present school year and the Internet has given us all a huge leg-up in finding hands-on ways to learn science. These are demonstrations rather than experiments–an important difference for those entering a fair. Nevertheless, I have included two of my favorites below.

Homemade Oobleck:

Pay tribute to Dr. Seuss's book Bartholomew and the Oobleck by whipping up this mixture that is both solid and liquid at the same time! The simplest version is listed below, but adding a few more bells and whistles can increase the demonstration's awe-factor a bunch.

What to do: You need a mixing bowl, water, and cornstarch. Fill the mixing bowl with about 1 cup of cornstarch, and add roughly an equal volume of water. Mix, incrementally adding cornstarch or water until the mixture attains an appropriate blend of goopiness and firmness. Enjoy the fluid's bizarre properties by squishing and kneading it with your hands.

What's going on? Nearly all fluids have some intrinsic flow resistance. This property, called viscosity, is the reason water flows more easily than honey and at least partly why Usain Bolt can run 100 meters in under 10 seconds while it takes Michael Phelps well over a minute to swim the same distance. Our water/cornstarch mixture has a very special viscosity, making it easy to dip your hand into the mixture slowly, but quite hard to push it in quickly. (Technically, this is an example of a non-Newtonian fluid.) Science class will teach you that almost all matter can be classified into either a solid, liquid, or gas, but this is at least one example where the distinctions blur.

Bernoulli's Hair Dryer:

In 1738 the mathematician Daniel Bernoulli (pronounced Ber-NEW-lee) published a theory of fluids that has influenced the designs of airplane wings and sailboats ever since. Exploit this concept to suspend a balloon or ping-pong ball precariously in mid-air with a hair dryer.

What to do: You need a hair dryer and a small round balloon (or a ping-pong ball, depending on the hair dryer's strength). Turn the hair dryer on, point it upward, and place the balloon in the vertical column of air. If the ceiling is not too high, you should be able to balance the balloon in mid-air this way. Now begin to tilt the hair dryer and watch the balloon stay suspended almost magically.

What's going on? Everyday experience helps us understand why the balloon or ball stays suspended when the hair dryer is pointed vertically: air blowing upward pushes on the balloon, and this in turn counteracts gravity. But why doesn't the balloon fall off to the side when we begin to tilt the hair dryer? The answer lies in Bernoulli's principle, which states that, all other things being equal, a fluid loses pressure as it picks up speed. The air coming out of the hair dryer is moving faster than the room's air so its pressure is lower. This pressure difference helps keep the balloon suspended, even when you tilt the hair dryer.

Water and cornstarch make a non-Newtonian fluid when mixed: messy but great fun!