David Kirkpatrick

September 30, 2010

Metamaterials and warp drives

Filed under: et.al., Science — Tags: , , , , , — David Kirkpatrick @ 2:20 pm

It’s almost time to call metamaterials simply that science fiction stuff. Usually you hear about metamaterials around these parts in posts about actual invisibility cloaking technology, and here’s one about metamaterials and warp drives. Metamaterials — turning science fiction into science fact …

From the link:

That means physicists can use metamaterials to simulate the universe itself and all the weird phenomenon of general relativity. We’ve looked at various attempts to recreate black holes, the Big Bang and even multiverses.

But there’s another thing that general relativity appears to allow: faster than light travel. In 1994, the Mexican physicist, Michael Alcubierre, realised that while relativity prevents faster-than-light travel relative to the fabric of spacetime, it places no restriction on the speed at which regions of spacetime can move relative to each other.

That suggests a way of building a warp drive. Alcubierre imagined a small volume of flat spacetime in which a spacecraft sits, surrounded by a bubble of spacetime that shrinks in the direction of travel, bringing your destination nearer, and stretches behind you. He showed that this shrinking and stretching could enable the bubble–and the spaceship it contained–to move at superluminal speeds.

Today, Igor Smolyaninov at the University of Maryland, points out that if these kinds of bubbles are possible in spacetime, then it ought to be possible to simulate them inside a metamaterial.

August 25, 2010

Quantum entanglement and free will

A little more closely related than you might think.

From the link:

In practical terms, this means that there can be no shared information between the random number generators that determine the parameters of the experiments to be made, and the particles to be measured.

But the same also holds true for the experimenters themselves. It means there can be no information shared between them and the particles to be measured either. In other words, they must have completely free will.

In fact, if an experimenter lacks even a single bit of free will then quantum mechanics can be explained in terms of hidden variables. Conversely, if we accept the veracity of quantum mechanics, then we are able to place a bound on the nature of free will.

That’s an interesting way of stating the problem of entanglement and suggests a number of promising, related conundrums: what of systems that are partially entangled and others in which more than two particle become entangled.

Free will never looked so fascinating.

June 16, 2010

One step closer to quantum computing

Filed under: Science, Technology — Tags: , , , , — David Kirkpatrick @ 12:40 am

Alternative computing is always an fascinating topic, and the sheer processing power potential for quantum computers makes that field particularly interesting.

From the link:

Quantum computers can solve in a matter of moments problems that would take ordinary computers years to work out. But thus far, these computers exist only as state-of-the-art experimental setups in a few physics laboratories.

Now, Elena Kuznetsova, a post-doctoral researcher in UConn’s Department of Physics, has proposed a new type of quantum computer that could bring the technology one step closer to becoming a reality.

“The main excitement about quantum computers,” says Kuznetsova, “ comes from their potential ability to solve certain problems exponentially faster compared to classical computers, such as factoring a large number into its primes, which would allow us to break cryptographic codes. These problems cannot be solved using a  in the foreseeable future.”

June 9, 2010

The 2010 World Cup ball — here comes the science

Filed under: et.al., Science, Sports — Tags: , , , , , , , — David Kirkpatrick @ 2:03 am

I’m getting pretty excited about this year’s World Cup. It’s a fun tournament and a truly international sporting event. There’s already been some controversy over this year’s ball, so how did it perform in the lab? Here’s research from the University of Adelaide.

The release:

Will the new World Cup soccer ball bend?

Physics plays a role in on-ground action

Physics experts at the University of Adelaide believe the new ball created for the 2010 World Cup, called the Jabulani, will play “harder and faster”, bending more unpredictably than its predecessor.

But why? And what will it mean for the game?

“The Jabulani is textured with small ridges and ‘aero grooves’ and represents a radical departure from the ultra-smooth Teamgeist ball, which was used in the last World Cup,” says Professor Derek Leinweber, Head of the School of Chemistry & Physics at the University of Adelaide, who has previously written about and lectured on the aerodynamics of cricket balls, golf balls and the 2006 World Cup soccer ball, the Teamgeist.

Along with student Adrian Kiratidis, who is studying for his Master of Philosophy (MPhil) in Physics, Professor Leinweber has been reviewing the physics behind soccer balls and what that means for the Jabulani. Adrian is also a soccer enthusiast.

“While the governing body FIFA has strict regulations on the size and weight of the balls, they have no regulations about the outside surface of the balls,” Professor Leinweber says.

“The Teamgeist was a big departure at the last World Cup. Because it was very smooth – much smoother than a regular soccer ball – it had a tendency to bend more than the conventional ball and drop more suddenly at the end of its trajectory.

“By comparison, the aerodynamic ridges on the Jabulani are likely to create enough turbulence around the ball to sustain its flight longer, and be a faster, harder ball in play.

“The Jabulani is expected to ‘bend’ more for the players than any ball previously encountered. Players are also discovering new opportunities to move the ball in erratic ways, alarming the world’s best goalkeepers. By the time the ball reaches the goalkeeper, the Jabulani will have swerved and dipped, arriving with more power and energy than the Teamgeist.”

University of Adelaide students have also put the new World Cup soccer ball to the test on the soccer field. Based on Professor Leinweber’s theories, they’ve attempted to “bend” the Jabulani and have also kicked the Teamgeist and a regular soccer ball for comparison.

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May 21, 2010

Quantum information sent over 16 kilometers

A major distance breakthrough in “teleporting” quantum entanglement.

From the link:

Scientists in China have succeeded in teleporting information between photons further than ever before. They transported quantum information over a free space distance of 16 km (10 miles), much further than the few hundred meters previously achieved, which brings us closer to transmitting information over long distances without the need for a traditional signal.

Quantum teleportation is not the same as the teleportation most of us know from science fiction, where an object (or person) in one place is “beamed up” to another place where a perfect copy is replicated. In quantum teleportation two photons or ions (for example) are entangled in such a way that when the  of one is changed the state of the other also changes, as if the two were still connected. This enables  to be teleported if one of the photons/ions is sent some distance away.

March 5, 2010

Multiple choice theories of everything

Filed under: Science — Tags: , , , , , , — David Kirkpatrick @ 5:30 pm

Back in January I blogged about “the most beautiful structure in mathematics,” the basis of a physics theory-of-everything proposed by Garrett Lisi, That theory is part of an article on “Knowing the mind of God” at NewScientist outlining seven different theories of everything.

From the last link, more on Lisi’s concept”

E8

In 2007 the physicist (and sometime surfer) Garrett Lisi made headlines with a possible theory of everythingMovie Camera.

The fuss was triggered by a paper discussing E8, a complex eight-dimensional mathematical pattern with 248 points. Lisi showed that the various fundamental particles and forces known to physics could be placed on the points of the E8 pattern, and that many of their interactions then emerged naturally.

Some physicists heavily criticised the paper, while others gave it a cautious welcome. In late 2008, Lisi was given a grant to continue his studies of E8.

And here’s the article’s synopsis of string theory, one of the better known ideas out there:

String theory

This is probably the best known theory of everything, and the most heavily studied. It suggests that the fundamental particles we observe are not actually particles at all, but tiny strings that only “look” like particles to scientific instruments because they are so small.

What’s more, the mathematics of string theory also rely on extra spatial dimensions, which humans could not experience directly.

These are radical suggestions, but many theorists find the string approach elegant and have proposed numerous variations on the basic theme that seem to solve assorted cosmological conundrums. However, they have two major challenges to overcome if they are to persuade the rest of the scientific community that string theory is the best candidate for a ToE.

First, string theorists have so far struggled to make new predictions that can be tested. So string theory remains just that: a theory.

Secondly, there are just too many variants of the theory, any one of which could be correct – and little to choose between them. To resolve this, some physicists have proposed a more general framework called M-theory, which unifies many string theories.

But this has its own problems. Depending how you set it up, M-theory can describe any of 10500 universes. Some physicists argue that this is evidence that there are multiple universes, but others think it just means the theory is untestable.

February 7, 2010

Another step closer to quantum computers

Here’s the release from Friday:

Princeton scientist makes a leap in quantum computing

A major hurdle in the ambitious quest to design and construct a radically new kind of quantum computer has been finding a way to manipulate the single electrons that very likely will constitute the new machines’ processing components or “qubits.”

Princeton University’s Jason Petta has discovered how to do just that — demonstrating a method that alters the properties of a lone electron without disturbing the trillions of electrons in its immediate surroundings. The feat is essential to the development of future varieties of superfast computers with near-limitless capacities for data.

Petta, an assistant professor of physics, has fashioned a new method of trapping one or two electrons in microscopic corrals created by applying voltages to minuscule electrodes. Writing in the Feb. 5 edition of Science, he describes how electrons trapped in these corrals form “spin qubits,” quantum versions of classic computer information units known as bits. Other authors on the paper include Art Gossard and Hong Lu at the University of California-Santa Barbara.

Previous experiments used a technique in which electrons in a sample were exposed to microwave radiation. However, because it affected all the electrons uniformly, the technique could not be used to manipulate single electrons in spin qubits. It also was slow. Petta’s method not only achieves control of single electrons, but it does so extremely rapidly — in one-billionth of a second.

“If you can take a small enough object like a single electron and isolate it well enough from external perturbations, then it will behave quantum mechanically for a long period of time,” said Petta. “All we want is for the electron to just sit there and do what we tell it to do. But the outside world is sort of poking at it, and that process of the outside world poking at it causes it to lose its quantum mechanical nature.”

When the electrons in Petta’s experiment are in what he calls their quantum state, they are “coherent,” following rules that are radically different from the world seen by the naked eye. Living for fractions of a second in the realm of quantum physics before they are rattled by external forces, the electrons obey a unique set of physical laws that govern the behavior of ultra-small objects.

Scientists like Petta are working in a field known as quantum control where they are learning how to manipulate materials under the influence of quantum mechanics so they can exploit those properties to power advanced technologies like quantum computing. Quantum computers will be designed to take advantage of these characteristics to enrich their capacities in many ways.

In addition to electrical charge, electrons possess rotational properties. In the quantum world, objects can turn in ways that are at odds with common experience. The Austrian theoretical physicist Wolfgang Pauli, who won the Nobel Prize in Physics in 1945, proposed that an electron in a quantum state can assume one of two states — “spin-up” or “spin-down.” It can be imagined as behaving like a tiny bar magnet with spin-up corresponding to the north pole pointing up and spin-down corresponding to the north pole pointing down.

An electron in a quantum state can simultaneously be partially in the spin-up state and partially in the spin-down state or anywhere in between, a quantum mechanical property called “superposition of states.” A qubit based on the spin of an electron could have nearly limitless potential because it can be neither strictly on nor strictly off.

New designs could take advantage of a rich set of possibilities offered by harnessing this property to enhance computing power. In the past decade, theorists and mathematicians have designed algorithms that exploit this mysterious superposition to perform intricate calculations at speeds unmatched by supercomputers today.

Petta’s work is using electron spin to advantage.

“In the quest to build a quantum computer with electron spin qubits, nuclear spins are typically a nuisance,” said Guido Burkard, a theoretical physicist at the University of Konstanz in Germany. “Petta and coworkers demonstrate a new method that utilizes the nuclear spins for performing fast quantum operations. For solid-state quantum computing, their result is a big step forward.”

Petta’s spin qubits, which he envisions as the core of future quantum logic elements, are cooled to temperatures near absolute zero and trapped in two tiny corrals known as quantum wells on the surface of a high-purity, gallium arsenide chip. The depth of each well is controlled by varying the voltage on tiny electrodes or gates. Like a juggler tossing two balls between his hands, Petta can move the electrons from one well to the other by selectively toggling the gate voltages.

Prior to this experiment, it was not clear how experimenters could manipulate the spin of one electron without disturbing the spin of another in a closely packed space, according to Phuan Ong, the Eugene Higgins Professor of Physics at Princeton and director of the Princeton Center for Complex Materials.

Other experts agree.

“They have managed to create a very exotic transient condition, in which the spin state of a pair of electrons is in that moment entangled with an almost macroscopic degree of freedom,” said David DiVencenzo, a research staff member at the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y.

Petta’s research also is part of the fledgling field of “spintronics” in which scientists are studying how to use an electron’s spin to create new types of electronic devices. Most electrical devices today operate on the basis of another key property of the electron — its charge.

There are many more challenges to face, Petta said.

“Our approach is really to look at the building blocks of the system, to think deeply about what the limitations are and what we can do to overcome them,” Petta said. “But we are still at the level of just manipulating one or two quantum bits, and you really need hundreds to do something useful.”

As excited as he is about present progress, long-term applications are still years away. “It’s a one-day-at-a-time approach,” Petta said.

###

January 13, 2010

Life in a parallel universe?

Maybe so.

The release:

Across the multiverse: FSU physicist considers the big picture

Alejandro Jenkins writes in Scientific American that life may exist — in other universes

IMAGE: Alejandro Jenkins is a researcher at Florida State University.

Click here for more information.

TALLAHASSEE, Fla. ⎯ Is there anybody out there? In Alejandro Jenkins’ case, the question refers not to whether life exists elsewhere in the universe, but whether it exists in other universes outside of our own.

While that might be a mind-blowing concept for the layperson to ponder, it’s all in a day’s work for Jenkins, a postdoctoral associate in theoretical high-energy physics at The Florida State University. In fact, his deep thoughts on the hypothetical “multiverse” — think of it as a mega-universe full of numerous smaller universes, including our own — are now receiving worldwide attention, thanks to a cover article he co-wrote for the January 2010 issue of Scientific American magazine.

In “Looking for Life in the Multiverse,” Jenkins and co-writer Gilad Perez, a theorist at the Weizmann Institute of Science in Israel, discuss a provocative hypothesis known as the anthropic principle, which states that the existence of intelligent life (capable of studying physical processes) imposes constraints on the possible form of the laws of physics.

“Our lives here on Earth — in fact, everything we see and know about the universe around us — depend on a precise set of conditions that makes us possible,” Jenkins said. “For example, if the fundamental forces that shape matter in our universe were altered even slightly, it’s conceivable that atoms never would have formed, or that the element carbon, which is considered a basic building block of life as we know it, wouldn’t exist. So how is it that such a perfect balance exists? Some would attribute it to God, but of course, that is outside the realm of physics.”

The theory of “cosmic inflation,” which was developed in the 1980s in order to solve certain puzzles about the structure of our universe, predicts that ours is just one of countless universes to emerge from the same primordial vacuum. We have no way of seeing those other universes, although many of the other predictions of cosmic inflation have recently been corroborated by astrophysical measurements.

Given some of science’s current ideas about high-energy physics, it is plausible that those other universes might each have different physical interactions. So perhaps it’s no mystery that we would happen to occupy the rare universe in which conditions are just right to make life possible. This is analogous to how, out of the many planets in our universe, we occupy the rare one where conditions are right for organic evolution.

“What theorists like Dr. Perez and I do is tweak the calculations of the fundamental forces in order to predict the resulting effects on possible, alternative universes,” Jenkins said. “Some of these results are easy to predict; for example, if there was no electromagnetic force, there would be no atoms and no chemical bonds. And without gravity, matter wouldn’t coalesce into planets, stars and galaxies.

“What is surprising about our results is that we found conditions that, while very different from those of our own universe, nevertheless might allow — again, at least hypothetically — for the existence of life. (What that life would look like is another story entirely.) This actually brings into question the usefulness of the anthropic principle when applied to particle physics, and might force us to think more carefully about what the multiverse would actually contain.”

“Looking for Life in the Multiverse” can be purchased, or accessed by Scientific American subscribers, at the magazine’s Web site. The January issue of the magazine is also on sale now throughout the United States.

“Having an article in Scientific American is a magnificent accomplishment, but being selected for the cover story is special indeed,” said Mark Riley, chairman of the Department of Physics at Florida State. “My congratulations to Dr. Jenkins and our High Energy Physics Group.”

Jenkins has degrees from Harvard University and the California Institute of Technology, and he previously conducted postgraduate research on the topic of alternative universes while at the Massachusetts Institute of Technology. Despite all of his training, however, the Scientific American article was unexpected.

“I am very proud of our research, but to be honest, I think that this had something to do with the fact that people are naturally intrigued by speculative ideas about cosmology and the ‘big picture.’

“The idea of parallel universes, in particular, is one that many people find exciting,” Jenkins said. “The current season of (the Fox-TV comedy) ‘Family Guy’ recently premiered with an episode called ‘Road to the Multiverse,’ which was premised on the idea that one can visit other universes — although that seems impossible given what we know about physics. Nevertheless, whether other universes actually exist is a question that has consequences for our understanding of physics in this world. I think our research raises important questions in that regard.”

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January 8, 2010

Get a free online education with Khan Academy

Filed under: Arts, Business, Media, Science, Technology — Tags: , , , , , , , — David Kirkpatrick @ 11:00 pm

I came across this post at Metamodern discussing a very interesting, and utile, online resource — Khan Academy. If you’re looking for short, to-the-point online lessons (more than 1000) on mathematics ranging from basic arithmetic and algebra to differential equations, physics, chemistry, biology and finance, this is a great resource.

From the first link:

I got a pointer to a free, online educational resource today.

It deserves more attention.

The eyeballs of a few million students might be a good start. Students in elementary school, grad school, rural Africa… places like that.

It consists of 1000+ brief lectures on YouTube.

It centers on math, but goes beyond.

” … perhaps the most beautiful structure in mathematics.”

Filed under: Science — Tags: , , , , , , — David Kirkpatrick @ 9:34 pm

Via KurzweilAI.net — Do hit the “Read Original Article” link for this entire interesting intersection of mathematics, string theory and practical physics.

Most beautiful math structure appears in lab for first time
New Scientist Physics & Math, Jan. 7, 2010

A complex form of mathematical symmetry linked to string theory has been glimpsed in the real world for the firsttime, in laboratory experiments on exotic crystals.

The structure is also the basis for another proposed theory of everything advanced in 2007 by surfer-physicist Garrett Lisi, who refers to E8 as “perhaps the most beautiful structure in mathematics“.
Read Original Article>>

From the New Scientist link:

Radu Coldea of the University of Oxford and his colleagues chilled a crystal made of cobalt and niobium to 0.04 °C above absolute zero. Atoms in the crystal are arranged in long, parallel chains. Because of a quantum property called spin, electrons attached to the atom chains act like tiny bar magnets, each of which can only point up or down.

Strange things occurred when the experimenters applied a powerful 5.5-Tesla magnetic field perpendicular to the direction of these electron “magnets”. Patterns appeared spontaneously in the electron spins in the chains – in a simplified example with three electrons, the spins could read up-up-down or down-up-down, among other possibilities. Each distinct pattern has a different energy associated with it.

The ratio of these different energy levels showed that the electron spins were ordering themselves according to mathematical relationships in E8 symmetry.

October 9, 2009

CERN, LHC hit new PR speedbump

This announcement doesn’t seem to have any relevance of the science going on at CERN or the Large Hadron Collider, and sounds like one scientist’s life took a change in a bad direction. Of course the LHC doesn’t need any additional bad news.

From the link:

The French authorities have arrested a physicist who worked for years at CERN, the huge nuclear research center in Switzerland, on suspicion of links to Al Qaeda’s affiliate in North Africa, the center said Friday.

James Gillies, a CERN spokesman, said the physicist was still registered as a member of the research team but had not been seen for some time. In a statement, the center said that he was arrested Thursday and had worked as an analyst on projects involving itsLarge Hadron Collider, the world’s largest particle accelerator, since 2003, but that he was not an employee and his project would not have been of any use to terrorists.

“His work did not bring him into contact with anything that could be used for terrorism,” said the statement from the center, whose formal name is the European Organization for Nuclear Research. “None of our research has potential for military application, and all our results are published openly in the public domain.”

A person with knowledge of the investigation said that the physicist was arrested along with a younger brother, but that the physicist was the focus of the investigation. Both are French citizens of Algerian origin.

August 6, 2009

Large Hadron Collider to initially run at lower power

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 9:24 pm

As an update to this post, here’s the latest news out of CERN regarding the troubled LHC:

LHC to run at 3.5 TeV for early part of 2009-2010 run rising later

Geneva, 6 August 2009. CERN’s1 Large Hadron Collider will initially run at an energy of 3.5 TeV per beam when it starts up in November this year. This news comes after all tests on the machine’s high-current electrical connections were completed last week, indicating that no further repairs are necessary for safe running.

“We’ve selected 3.5 TeV to start,” said CERN’s Director General, Rolf Heuer, “because it allows the LHC operators to gain experience of running the machine safely while opening up a new discovery region for the experiments.”

Following the incident of 19 September 2008 that brought the LHC to a standstill, testing has focused on the 10,000 high-current superconducting electrical connections like the one that led to the fault. These consist of two parts: the superconductor itself, and a copper stabilizer that carries the current in case the superconductor warms up and stops superconducting, a so-called quench. In their normal superconducting state, there is negligible electrical resistance across these connections, but in a small number of cases abnormally high resistances have been found in the superconductor. These have been repaired. However, there remain a number of cases where the resistance in the copper stabilizer connections is higher than it should be for running at full energy.

The latest tests looked at the resistance of the copper stabilizer. Many copper connections showing anomalously high resistance have been repaired already, and the tests on the final two sectors, which concluded last week, have revealed no more outliers. This means that no more repairs are necessary for safe running this year and next.

“The LHC is a much better understood machine than it was a year ago,” said Heuer. “We can look forward with confidence and excitement to a good run through the winter and into next year.”

The procedure for the 2009 start-up will be to inject and capture beams in each direction, take collision data for a few shifts at the injection energy, and then commission the ramp to higher energy. The first high-energy data should be collected a few weeks after the first beam of 2009 is injected. The LHC will run at 3.5 TeV per beam until a significant data sample has been collected and the operations team has gained experience in running the machine. Thereafter, with the benefit of that experience, the energy will be taken towards 5 TeV per beam. At the end of 2010, the LHC will be run with lead ions for the first time. After that, the LHC will shut down and work will begin on moving the machine towards 7 TeV per beam.

CERN is publishing regular updates on the LHC in its internal Bulletin, available at cern.ch/bulletin, as well as via twitter and YouTube at twitter.com/cern and youtube.com/cern1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

You can find the rest of my posts on the Large Hadron Collider here.

August 3, 2009

Large Hadron Collider facing more problems

Filed under: Science, Technology — Tags: , , , , , — David Kirkpatrick @ 11:22 pm

This New York Times article on the Large Hadron Collider is disturbing for anyone who’s been looking forward to major scientific advancement coming out of Geneva anytime soon. I’ve done plenty of blogging on the LHC and was looking forward to it finally being up and running after the initial misfire. Looks like major problems are going to be a part of this project for a while to come.

From the first link:

The biggest, most expensive physics machine in the world is riddled with thousands of bad electrical connections.

Many of the magnets meant to whiz high-energy subatomic particles around a 17-mile underground racetrack have mysteriously lost their ability to operate at high energies.

Some physicists are deserting the European project, at least temporarily, to work at a smaller, rival machine across the ocean.

After 15 years and $9 billion, and a showy “switch-on” ceremony last September, the Large Hadron Collider, the giant particle accelerator outside Geneva, has to yet collide any particles at all.

But soon?

This week, scientists and engineers at the European Center for Nuclear Research, or CERN, are to announce how and when their machine will start running this winter.

That will be a Champagne moment. But scientists say it could be years, if ever, before the collider runs at full strength, stretching out the time it should take to achieve the collider’s main goals, like producing a particle known as the Higgs boson thought to be responsible for imbuing other elementary particles with mass, or identifying the dark matter that astronomers say makes up 25 percent of the cosmos.

The energy shortfall could also limit the collider’s ability to test more exotic ideas, like the existence of extra dimensions beyond the three of space and one of time that characterize life.

“The fact is, it’s likely to take a while to get the results we really want,” said Lisa Randall, a Harvard physicist who is an architect of the extra-dimension theory.

March 14, 2009

Stalking the Higgs boson

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 2:49 pm

News from Fermilab:

Fermilab experiments constrain Higgs mass

CDF, DZero experiments exclude significant fraction of Higgs territory

Batavia, Ill.—The territory where the Higgs boson may be found continues to shrink. The latest analysis of data from the CDF and DZero collider experiments at the U.S. Department of Energy’s Fermilab now excludes a significant fraction of the allowed Higgs mass range established by earlier measurements. Those experiments predict that the Higgs particle should have a mass between 114 and 185 GeV/c2. Now the CDF and DZero results carve out a section in the middle of this range and establish that it cannot have a mass in between 160 and 170 GeV/c2.

“ The outstanding performance of the Tevatron and CDF and DZero together have produced this important result,” said Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. “We’re looking forward to further Tevatron constraints on the Higgs mass.”

The Higgs particle is a keystone in the theoretical framework known as the Standard Model of particles and their interactions. According to the Standard Model, the Higgs boson explains why some elementary particles have mass and others do not.

So far, the Higgs particle has eluded direct detection. Searches at the Large Electron Positron collider at the European laboratory CERN established that the Higgs boson must weigh more than 114 GeV/c2. Calculations of quantum effects involving the Higgs boson require its mass to be less than 185 GeV/c2.

“A cornerstone of NSF’s support of particle physics is the search for the origin of mass, and this result takes us one step closer,” said Physics Division Director Joe Dehmer, of the National Science Foundation.

The observation of the Higgs particle is also one of the goals of the Large Hadron Collider experiments at CERN, which plans to record its first collision data before the end of this year.

The success of probing the Higgs territory at the Tevatron has been possible thanks to the excellent performance of the accelerator and the continuing improvements that the experimenters incorporate into the analysis of the collider data.

“Fermilab’s Tevatron collider typically produces about ten million collisions per second,” said DZero co-spokesperson Darien Wood, of Northeastern University. “The Standard Model predicts how many times a year we should expect to see the Higgs boson in our detector, and how often we should see particle signals that can mimic a Higgs. By refining our analysis techniques and by collecting more and more data, the true Higgs signal, if it exists, will sooner or later emerge.”

To increase their chances of finding the Higgs boson, the CDF and DZero scientists combine the results from their separate analyses, effectively doubling the data available.

“A particle collision at the Tevatron collider can produce a Higgs boson in many different ways, and the Higgs particle can then decay into various particles,” said CDF co-spokesperson Rob Roser, of Fermilab. “Each experiment examines more and more possibilities. Combining all of them, we hope to see a first hint of the Higgs particle.”

So far, CDF and DZero each have analyzed about three inverse femtobarns of collision data—the scientific unit that scientists use to count the number of collisions. Each experiment expects to receive a total of about 10 inverse femtobarns by the end of 2010, thanks to the superb performance of the Tevatron. The collider continues to set numerous performance records, increasing the number of proton-antiproton collisions it produces.

The Higgs search result is among approximately 70 results that the CDF and DZero collaborations presented at the annual conference on Electroweak Physics and Unified Theories known as the Rencontres de Moriond, held March 7-14. In the past year, the two experiments have produced nearly 100 publications and about 50 Ph.D.s that have advanced particle physics at the energy frontier.

Notes for editors:

Fermilab, the U.S. Department of Energy’s Fermi National Accelerator Laboratory located near Chicago, operates the Tevatron, the world’s highest-energy particle collider. The Fermi Research Alliance LLC operates Fermilab under a contract with DOE.

CDF is an international experiment of 602 physicists from 63 institutions in 15 countries. DZero is an international experiment conducted by 550 physicists from 90 institutions in 18 countries. Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the National Science Foundation, and a number of international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Graphics, photos and videos are available at:
http://www.fnal.gov/pub/presspass/press_releases/Higgs-mass-constraints-20090313-images.html

March 9, 2009

Fermilab finds single top quark

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 11:03 pm

Big physics news!

The release:

Graphics and photos are available at:
http://www.fnal.gov/pub/presspass/images/Single-Top-Quark-2009.html

 

Fermilab collider experiments discover rare single top quark

Batavia, Ill.—Scientists of the CDF and DZero collaborations at the Department of Energy’s Fermi National Accelerator Laboratory have observed particle collisions that produce single top quarks. The discovery of the single top confirms important parameters of particle physics, including the total number of quarks, and has significance for the ongoing search for the Higgs particle at Fermilab’s Tevatron, currently the world’s most powerful operating particle accelerator.

Previously, top quarks had only been observed when produced by the strong nuclear force. That interaction leads to the production of pairs of top quarks. The production of single top quarks, which involves the weak nuclear force and is harder to identify experimentally, has now been observed, almost 14 years to the day of the top quark discovery in 1995.

Searching for single-top production makes finding a needle in a haystack look easy. Only one in every 20 billion proton-antiproton collisions produces a single top quark. Even worse, the signal of these rare occurrences is easily mimicked by other “background” processes that occur at much higher rates.

“Observation of the single top quark production is an important milestone for the Tevatron program,” said Dr. Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. “Furthermore, the highly sensitive and successful analysis is an important step in the search for the Higgs.”

Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large background. Advanced analysis techniques pioneered for the single top discovery are now in use for the Higgs boson search. In addition, the single top and the Higgs signals have backgrounds in common, and the single top is itself a background for the Higgs particle.

To make the single-top discovery, physicists of the CDF and DZero collaborations spent years combing independently through the results of proton-antiproton collisions recorded by their experiments, respectively. Each team identified several thousand collision events that looked the way experimenters expect single top events to appear. Sophisticated statistical analysis and detailed background modeling showed that a few hundred collision events produced the real thing. On March 4, the two teams submitted their independent results to Physical Review Letters.

The two collaborations earlier had reported preliminary results on the search for the single top. Since then, experimenters have more than doubled the amount of data analyzed and sharpened selection and analysis techniques, making the discovery possible. For each experiment, the probability that background events have faked the signal is now only one in nearly four million, allowing both collaborations to claim a bona fide discovery that paves the way to more discoveries.

“I am thrilled that CDF and DZero achieved this goal,” said Fermilab Director Pier Oddone. “The two collaborations have been searching for this rare process for the last fifteen years, starting before the discovery of the top quark in 1995. Investigating these subatomic processes in more detail may open a window onto physics phenomena beyond the Standard Model.”

Notes for Editors:

Fermilab, the U.S. Department of Energy’s Fermi National Accelerator Laboratory located near Chicago, operates the Tevatron, the world’s highest-energy particle collider. The Fermi Research Alliance LLC operates Fermilab under a contract with DOE.

CDF is an international experiment of 635 physicists from 63 institutions in 15 countries. DZero is an international experiment conducted by 600 physicists from 90 institutions in 18 countries. Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the National Science Foundation, and a number of international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Copies of the two scientific papers submitted to Physical Review Letters are available at:

March 3, 2009

Quantum paradox observed

Big, big news in physics.

The release:

Quantum paradox directly observed — a milestone in quantum mechanics

In quantum mechanics, a vanguard of physics where science often merges into philosophy, much of our understanding is based on conjecture and probabilities, but a group of researchers in Japan has moved one of the fundamental paradoxes in quantum mechanics into the lab for experimentation and observed some of the ‘spooky action of quantum mechanics’ directly.

Hardy’s Paradox, the axiom that we cannot make inferences about past events that haven’t been directly observed while also acknowledging that the very act of observation affects the reality we seek to unearth, poses a conundrum that quantum physicists have sought to overcome for decades. How do you observe quantum mechanics, atomic and sub-atomic systems that are so small-scale they cannot be described in classical terms, when the act of looking at them changes them permanently?

In a journal paper published in the New Journal of Physics, ‘Direct observation of Hardy’s paradox by joint weak measurement with an entangled photon pair’, today, Wednesday, 4 March, authored by Kazuhiro Yokota, Takashi Yamamoto, Masato Koashi and Nobuyuki Imoto from the Graduate School of Engineering Science at Osaka University and the CREST Photonic Quantum Information Project in Kawaguchi City, the research group explains how they used a measurement technique that has an almost imperceptible impact on the experiment which allows the researchers to compile objectively provable results at sub-atomic scales.

The experiment, based on Lucien Hardy’s thought experiment, which follows the paths of two photons using interferometers, instruments that can be used to interfere photons together, is believed to throw up contradictory results that do not conform to our classical understanding of reality. Although Hardy’s Paradox is rarely refuted, it was only a thought experiment until recently.

Using an entangled pair of photons and an original but complicated method of weak measurement that does not interfere with the path of the photons, a significant step towards harnessing the reality of quantum mechanics has been taken by these researchers in Japan.

As the researchers write, “Unlike Hardy’s original argument, our demonstration reveals the paradox by observation, rather than inference. We believe the demonstrated joint weak measurement is useful not only for exploiting fundamental quantum physics, but also for various applications such as quantum metrology and quantum information technology.”

 

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September 21, 2008

American Physical Society announces new online pub

Filed under: Media, Science — Tags: , , , , , — David Kirkpatrick @ 2:21 pm

The e-zine is called Physics, it’s free and will find the gems and provide commentary on papers from Physical Review Letters and Physical Review .

From the link:

The authoritative but brief reports in Physics on exciting and important new research will help keep researchers abreast of developments within and outside of their own fields and can catalyze interdisciplinary work. With the combined output of the APS peer-reviewed publications at about 18,000 papers a year, there is clearly a need to pull the truly exceptional papers out from among the merely excellent works, and place them in context.

“Our readers don’t want to miss significant developments in other subfields of physics,” says Gene Sprouse, APS Editor in Chief, “and our authors need and deserve more attention for their best papers.” Physics aims to meet those needs by means of three features, all with original content. “Viewpoints” discuss and explain a particular paper’s findings in a manner accessible to all physicists, especially to those outside its subspecialty. “Trends” are longer pieces that cover a recent body of work in a specific field, but also look ahead to the challenges and questions that fascinate that field’s top researchers. “Synopses” are staff-written summaries of papers that merit wider attention among physicists in all fields.

“The selection process will be rigorous but not rigid,” says David Voss, Physics’ Editor. “We’ll highlight papers that change the rules of the game, afford cross-disciplinary potential, or report a substantial breakthrough in a particular field.” Feedback and suggestions by email to physics_at_aps.org are welcome.

May 31, 2008

Absolute hot

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 6:43 pm

Is there an opposite to absolute zero?

From the link:

Seems like an innocent enough question, right? Absolute zero is 0 on the Kelvin scale, or about minus 460 F. You can’t get colder than that; it would be like trying to go south from the South Pole. Is there a corresponding maximum possible temperature?

Well, the answer, depending on which theoretical physicist you ask, is yes, no, or maybe. Huh? you ask. Yeah, that’s how I felt. And the question doesn’t just mess with the minds of physics dummies like me. Several physicists begged off of trying to answer it, referring me to colleagues. Even ones who did talk about it said things like “It’s a little bit out of my comfort zone” and “I think I’d like to ruminate over it.” After I posed it to one cosmologist, there was dead silence on the other end of the line for long enough that I wondered if we had a dropped call.