Stephen Hawking, the master of time, space, and black holes, steps back into the spotlight to secure his scientific legacy—and to explain the greatest mystery in physics: the origin of the universe.
Two decades after rocketing to scientific stardom with his book A Brief History of Time, Stephen Hawking still knows how to make an entrance. On a mild March evening in Pasadena, California, 4,500 people fill the convention center to hear him give a talk called “Why We Should Go Into Space.” Shortly after 8 p.m. the lights dim, a few thousand conversations stop, and the soaring trumpet fanfare from Richard Strauss’s Also Sprach Zarathustra (better known as the theme from 2001: A Space Odyssey) fills the room. Hawking is in the house. The crowd turns to watch the frail physicist being wheeled at a good clip down the center aisle. He is wearing a charcoal gray suit and an open-neck white shirt; his head slumps toward his right shoulder; his hands are folded neatly in his lap. The music segues to The Blue Danube Waltz as he rolls up a ramp to the stage.
Hawking sits silently for a few moments, alone at center stage, before a member of his Cambridge, England, posse appears. Sam Blackburn, a graduate student who manages the beeping, bulky communications complex that is Hawking’s wheelchair, runs over and makes a few adjustments to his boss’s Lenovo ThinkPad X61 laptop. The iconic synthesized voice kicks in. “Can you hear me?” Hawking asks. The crowd cheers.
Physicists at UC Santa Barbara have made an important advance in quantum mechanics using a superconducting electrical circuit. The finding is reported in this week’s issue of the journal Nature.
The researchers showed that they could detect the quantum correlations in the results of measurements of entangled quantum bits, using a superconducting electrical circuit. The correlations are stronger than can be obtained using classical (non-quantum mechanical) physics, and according to the physicists, this illustrates that the oddities of quantum mechanics clearly extend to macroscopic systems. The work is part of an ongoing collaboration between the UCSB laboratories of John Martinis and Andrew Cleland.
The results of measurements in quantum mechanics are intrinsically unpredictable, according to the theory of quantum mechanics, and yet still contain very strong correlations, in contradiction with classical physics. In particular, measurements of “entangled states,” such as a pair of particles with opposite spins, allow stringent tests of the predicted discrepancy between quantum and classical physics, as described by the “Bell inequalities.” Measuring such a discrepancy is known as a “Bell violation.”
According to quantum theory, Bell violations should be detectable using “qubits,” superconducting quantum bits, but measuring these violations is technologically challenging. Martinis, Cleland, and their colleagues have overcome these challenges, and report a clear violation of Bell’s inequality with two entangled superconducting qubits. Thus, they have demonstrated that this macroscopic electrical circuit is a quantum system.
Physicists at the Physikalisch-Technische Bundesanstalt (Germany) have succeeded in producing a Bose-Einstein condensate from the alkaline earth element calcium. The use of alkaline earth atoms creates new potential for precision measurements, for example for the determination of gravitational fields.
The physicist and Nobel Prize winner Wolfgang Ketterle once described it as an “identity crisis” of the atoms: If atoms are caught in a trap and cooled to a temperature close to the absolute zero point, they condense - similar to vapour to water - and take on an all new condition: They become indistinguishable. This collective condition is called - named for its intellectual fathers - Bose-Einstein condensate.
Physicists at the Physikalisch-Technische Bundesanstalt (PTB) have now succeeded for the first time worldwide in producing a Bose-Einstein condensate from the alkaline earth element calcium. The use of alkaline earth atoms creates new potential for precision measurements, for example for the determination of gravitational fields. Because as opposed to previous Bose-Einstein condensates from alkali atoms, alkaline earth metals react one million times more responsively to the wavelength at optical excitations - a fact which can be used for super exact measurements.
With little fanfare, last week the Tevatron at Fermilab, and the two experiments CDF and D0, emerged from an 11-week shutdown for what will likely be the final run of the collider, which is over 20 years old. In the past year, the machine has regularly set new records for luminosity (essentially the number of collisions per second) and delivered over 2 fb-1 (inverse femtobarns) of proton-antiproton collisions at a center of mass energy of 1.96 TeV to the experiments, still the highest in the world. The startup has gone very smoothly, and the Tevatron delivered a solid load of data to the experiments last week.
This funny unit, inverse femtobarns, allows us to calculate how many collision events of a certain type to expect. Take top quark pair production, for example. For protons colliding with antiprotons at Tevatron energies, we can calculate (or measure) what we call the production cross section. This cross-section is in fact expressed as an area, a very small area, since protons and antiprotons are so small. One “barn” is 10-28 m2, and the cross section for top pair production is about 7 x 10-12 barns, or 7 pb. By multiplying the cross-section times the integrated luminosity we can get the number of top quark pairs events produced. To get the number we actually observe in the detector, we need to take into account the efficiency for reconstructing them.
For the first time, MIT scientists have observed ferromagnetic behavior in an atomic gas, addressing a decades-old question of whether it is possible for a gas to show properties similar to a magnet made of iron or nickel… (more @ ScienceDaily)
1736: German physicist and instrument maker Gabriel Daniel Fahrenheit dies in the Netherlands. His pioneering work on thermometers means he will live on, to a degree.
Fahrenheit, however, wanted to standardize the thermometer. First, he produced two thermometers in 1714 that gave identical readings, a major accomplishment for the time. He went on to substitute mercury for alcohol as the measuring medium that would expand and contract. And he introduced the cylindrical shape, replacing the spherical bulbs that had been used previously.
He introduced the scale that bears his name and that’s still used to measure temperature — if only in the metric-averse United States. Folklorically, zero was the coldest day of the winter he created the scale, and 32 degrees the freezing point of water, which resulted in 212 degrees for the boiling point of water at sea level (which, you will recall, is overhead in much of Holland).
But that’s not the way of a methodical scientist who wanted to standardize things. Zero was as cold as he could make a concentrated solution of ice, water and salt, and 96 was supposed to be human body temperature.
He was a little low on that, but he was striving for mathematical convenience: 96 = 3 x 32. In any event, water’s boiling point at 212 is 180 degrees opposite to its freezing point at 32.
How do we discover new things? For scientists, observation and measurement are the main ways to extract information from Nature. Based on observations, scientists build models that, in turn, are used to make predictions about the future or the past. To the extent that the predictions are successful, scientists conclude that their models capture Nature’s organization. However, Nature does not reveal secrets easily - there is no way for observers to learn everything about a process, so some information always remains hidden from view; other kinds of information are present, but difficult to extract. In a recent study, researchers have investigated how to measure the degree of hidden information in a process (its “crypticity”) and, along the way, solved several puzzles involved in extracting, storing, and communicating information.
In their study, James Crutchfield, Physics Professor at the University of California at Davis, and graduate students Christopher Ellison and John Mahoney, have developed the analogy of scientists as cryptologists who are trying to glean hidden information from Nature. As they explain, “Nature speaks for herself only through the data she willingly gives up.” To build good models, scientists must use the correct “codebook” in order to decrypt the information hidden in observations and so decode the structure embedded in Nature’s processes.
In their recent work, the researchers adopt a thorough-going informational view: All of Nature is a communication channel that transmits the past to the future by storing information in the present. The information that the past and future share can be quantified using the “excess entropy” - the mutual information between the past and the future.
Generally, scientists prefer to avoid the concept of perpetual motion. The idea of a machine that could produce movement that goes on forever, and using that movement to generate an endless stream of energy, is usually considered more science fiction than science. But recently, physicist Pavel Ivanov has investigated previous speculation that an exotic fluid with unusual properties could cause energy to flow continuously between different regions of space, resulting in a runaway transfer of energy. If an advanced civilization were able to construct a device to capture this energy, it might finally possess its own “perpetuum mobile” — or perpetual motion.
With the Large Hadron Collider set to start up in November, a new book takes you inside the world’s largest and most powerful particle accelerator.
Physicist Paul Halpern explores the past, present and intriguing future of high-energy particle physics in Collider. He explains what all the hubbub surrounding the LHC is about and why physicists are pretty much beside themselves with anticipation.
Wired.com spoke with Halpern about what the LHC may find and how the United States failed in its quest for its own giant collider.
Among the most astounding, unexpected, and important achievements of the past century (or even more) have been the discoveries of dark matter and dark energy, collectively dubbed the “dark sector.”
A whopping 96% of the essence of our universe lies in the dark sector, where essence refers to everything that controls evolution and large-scale properties of the cosmos. Dark matter is unseen matter — unseen in the sense that it emits no detected electromagnetic radiation (light, radio waves, etc) — but it has been definitively spotted nonetheless because its gravity has measurable effects on stars, things that we can see. Of all of the matter in the universe, an incredible 90% is dark matter, with galaxies and stars being only minor constituents. We do not know what dark matter is, only that it is almost surely made of kinds of elementary particles unlike those that comprise normal atoms.
For the past two weeks, Bram Conjaerts, a Belgian filmmaker, has been touring the CERN sites and surrounding countryside conducting research for his new documentary. The film will follow the entire 27 km length of the LHC ring, but unlike most documentaries about the LHC, it will take place mostly above ground!
While working towards his film degree in 2008, Bram Conjaerts won an award at the International Documentary Festival for his documentary “Henri and the Islands”, an anthropological documentary about the smallest village in Belgium. In an unlikely change of subject matter he decided to use the prize money to make a film about the LHC.
“With the money granted by the Flemish government, I wanted to create a documentary about something adventurous and something that I did not know about, ” explains Conjaerts. “I started doing research about the LHC and CERN and I came across the fantasy of black holes and all the conspiracies revolving around CERN.”
However, the proposed documentary will not focus on black holes. Conjaerts plans on taking a tour of the countryside under which the LHC ring is laid, in order to gain perspectives from those who inhabit the local surroundings. “We will follow the path of the ring above ground. So we’ll interview scientists, but also meet locals who have formed their own opinions about what is going on at CERN,” says Conjaerts. “We might also meet the priests of churches on the route, who have special ideas about religion and science. And also the Chateau Voltaire is near the top of the ring, so there are ideas about incorporating philosophical perspectives of science and the history of the chateau.”
Conjaerts, who is only beginning his career as a filmmaker, will be conducting research for three weeks before starting preliminary filming in September. The rest of the filming will be completed before December 2010.
There’s nothing like a movie with great physics, if you can manage to understand the subject. For all the physics geeks out there, here is a great list of movies with good and very bad examples of the many different laws of physics.
The likes of Frank Sinatra, The Beatles, Janis Joplin, and Mick Jagger may have forever sealed the popular notion that musicians are the hallmark of cool. On the flip side is the popular notion of a physicist as uncool. Einstein may have been beloved, but in terms of cool, he did physicists in. No matter how much the scientific community may resist, it’s hard to associate physics with the hip crowd.
The only way around this might be a direct tip of the hat from those music icons themselves. Perhaps surprisingly, this may already be happening. With a quick look through iTunes you might notice that a lot of popular musicians have taken a cue from physics.
This year, besides seeing the CERN Rap top the YouTube charts, physics got a big break on a big scale when legendary musician Beck released a single called “Gamma Ray.” High-energy electromagnetic waves have never sounded so good.
Using one of the greatest sources of radiation energy created by man, University of Nevada, Reno researcher and faculty member Roberto Mancini is studying ultra-high temperature and non-equilibrium plasmas to mimic what happens to matter in accretion disks around black holes.
Physics department professor and chair Mancini has received a $690,000 grant from the U.S. Department of Energy to continue his research in high energy density plasma; plasmas are considered to be the fourth state of matter. He will serve as principal investigator for a project titled “Experiments and Modeling of Photo-ionized Plasmas at Z.”
Mancini has been studying the atomic and radiation properties of high-energy density plasmas for more than 15 years, and this new grant will allow him to further explore what happens to matter when it is subjected to extreme conditions of temperature and radiation - similar to what happens to many astrophysical objects in the universe.
The research will enable astrophysicists to better understand what happens around black holes and in active galactic nuclei. Scientists will also better understand the application of high-energy density plasmas to energy production, such as controlled nuclear fusion (produced in the laboratory), and production of X-ray sources for a variety of applications.
Physics teachers are fortunate (I am among friends, so I can speak frankly): ours is a subject the relevance and importance of which are beyond question, and which is intrinsically fascinating to anyone whose mind has not been corrupted by bad teaching or poisoned by dogma and superstition. I have never felt the need to “sell” physics, and efforts to do so under the banner “physics is fun” seem to me demeaning. Lay out our wares attractively in the marketplace of ideas and eager buyers will flock to us.
What we have on offer is nothing less than an explanation of how matter behaves on the most fundamental level. It is a story that is magnificent (by good fortune or divine benevolence), coherent (at least that is the goal), plausible (though far from obvious) and true (that is the most remarkable thing about it). It is imperfect and unfinished (of course), but always improving. It is, moreover, amazingly powerful and extraordinarily useful. Our job is to tell this story – even, if we are lucky, to add a sentence or a paragraph to it. And why not tell it with style and grace?
I realized once I got to the end of the article that the author was none other than David Griffiths—known to pretty much every undergraduate physics student as one of the best textbook authors on the market. Now you can see why.