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Sunday, July 22, 2012

Exploring the Quantum World

Researchers at JPL and Caltech have developed an instrument for exploring the cosmos and the quantum world.

This new type of amplifier boosts electrical signals and can be used for everything from studying stars, galaxies and black holes to exploring the quantum world and developing quantum computers. An amplifier is a device that increases the strength of a weak signal.

One of the key features of the new amplifier is that it incorporates superconductors--materials that allow an electric current to flow with zero resistance when lowered to certain temperatures. For their amplifier, the researchers are using titanium nitride and niobium titanium nitride, which have just the right properties to allow the pump signal to amplify the weak signal.

Although the amplifier has a host of potential applications, the reason the researchers built the device was to help them study the universe. The team built the instrument to boost microwave signals, but the new design can be used to build amplifiers that help astronomers observe in a wide range of wavelengths, from radio waves to X-rays.

Monday, July 9, 2012

The Higgs boson made simple

So what's the Higgs boson, and why are people spending billions of dollars to find that god-danged subatomic particle? I've rounded up a variety of resources aimed at showing you why the hunt for the Higgs is a big deal.
First, a little context: The Higgs particle, and its associated field, were hypothesized back in the 1960s by British physicist Peter Higgs and others to fill a weird gap in the Standard Model, one of physics' most successful theories. The model as it stood had no mechanism to explain why some particles are massless (such as the photon, which is the quantum bit for light and other types of electromagnetic radiation), while other particles have varying degrees of mass (such as the W and Z bosons, which play a part in the weak nuclear force). By rights, all particles should be without mass and zipping around freely.
The Higgs mechanism sets up a field that interacts with particles to endow them with mass, and the Higgs boson is the particle associated with that field — just as photons are associated with an electromagnetic field. For more than four decades, physicists have assumed that the Higgs field existed, but found no experimental evidence for it. It requires a super-powerful particle smasher such as the Large Hadron Collider to produce energies high enough to knock a Higgs boson into existence under controlled conditions.
But the heavy particles created in a collider exist for just an instant before they decay into lighter particles. The LHC's physicists have been looking for particular patterns in the spray of particles that match what they'd expect to see from the decay of the Higgs boson. They've collected data for roughly a quadrillion proton-on-proton collisions, and on Wednesday they'll announce the status of the Higgs search based on those conclusions.

The teams at the LHC's ATLAS and CMS detectors are likely to say they're pretty sure they see a new type of particle with Higgs-like characteristics, but will need more time to nail down those characteristics completely. If that's the case, physicists can then go on to find out if the Higgs mechanism works exactly the way they expected it to, or whether there are unexpected twists. Some of the theories about how the universe is put together are pretty far-out — for example, suggesting that there are several dimensions in space that we can't perceive directly, or that there are huge troops of subatomic particles that we haven't yet discovered. Following the tracks left behind by the Higgs could reveal whether there's any truth to those theories.
Analogies, please!
For decades, experts have been trying to come up with analogies to illustrate how the Higgs mechanism works. One of the best-known was proposed in 1993 by David Miller, a physicist at University College London. Imagine looking down from a balcony in a ballroom, watching a cocktail party below. When just plain folks try to go from one end of the room to the other, they can walk through easily, with no resistance from the party crowd. But when a celebrity like Justin Bieber shows up, other partygoers press around him so tightly that he can hardly move ... and once he moves, the crowd moves with him in such a way that the whole group is harder to stop.
The partygoers are like Higgs bosons, the just plain folks are like massless particles, and Bieber is like a massive Z boson.
The Guardian's Ian Sample demonstrates a variant of this analogy in a 4.5-minute video: Imagine a tray with ping-pong balls scattered on it. The balls roll freely around the empty tray. But then, if you spread a layer of sugar over the tray, the balls sitting on the piled-up sugar don't roll so easily. The grains of sugar introduce a kind of inertial "drag," and that's the kind of effect that the Higgs field supposedly has on particles with mass.
In a 60-second shot of science written for Symmetry magazine, Howard Haber of the University of California at Santa Cruz uses a livelier comparison to a high-speed bullet plowing through a vat of molasses.
What good is it?
Particle physicists try to avoid forecasting the applications of an experimental advance before the actual advance is confirmed, but in the past, advances on a par with the discovery of the Higgs boson have had lots of beneficial applications, and some that are more questionable. The rise of nuclear power and nuclear weaponry is a prime example of that double-edged sword.
The discovery of antimatter is what made medical PET scanning possible, and antimatter propulsion could eventually play a part in interstellar travel, just like on "Star Trek." Particle accelerators have opened the way to medical treatments such as proton eye therapy — as well as advances in materials science, thanks to neutron scattering.
It's conceivable that the discoveries made at the Large Hadron Collider will eventually point to new sources of energy, Michio Kaku, a physicist at City College of New York, told me during a discussion of the LHC's promise and peril. And if the discovery of the Higgs leads to fresh insights into the fabric of the universe, it's conceivable that we could take advantage of the as-yet-unknown weave of that fabric for communication or transportation. Who knows? Maybe this is how "Star Trek" gets its start.

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Thursday, July 5, 2012

Dirac's Poser

While a student at Cambridge, Paul Dirac attended a mathematical congress that posed the following problem:

After a big day’s catch, three fisherman go to sleep next to their pile of fish. During the night, one fisherman decides to go home. He divides the fish in three and finds that this leaves one extra fish. He throws this into the water, takes one third of the remaining fish, and departs.

The second fisherman awakes. Not knowing that the first has left, he too divides the fish into three piles, finds one fish left over, discards it, and takes a third of the remainder. The third fisherman does the same. What is the least number of fish that the fishermen could have started with?

Dirac proposed that they had begun with -2 fish. The first fisherman threw one into the water, leaving -3, and took a third of this, leaving -2. The second and third fisherman followed suit.

This story was recalled by “a well-meaning experimenter” in the Russian miscellany Physicists Continue to Laugh (1968). “I could tell many other stories about theoreticians and their work,” he wrote, “but they have told me that one theoretician is writing a story under the title ‘How Experimental Physicists Work.’ That, of course, will be presented upside down.”

Of the integers from 1 to 1,000,000, which are more numerous: the numbers that contain a 1 or those that don’t?

To list the numbers that don’t contain a 1, imagine six spaces and fill each with the digits 0, 2, 3, 4, 5, 6, 7, 8, or 9. The number of ways of doing this is 96. There’s one exception: 000000 doesn’t fall between 1 and 1,000,000. So the number of integers without 1 is 96 – 1 = 531,440, and the number with 1 is 468,560.