Archive for the ‘Physics’ Category

Fusion Breakthrough

April 29, 2013

 

If we had anything like a reasonable energy policy in this country, the government would be doing its best to remove regulatory obstacles and excessive costs to building nuclear power plants. Most people think of nuclear power as being much more dangerous than other forms of producing energy and incidents at places like Chernobyl and Fukushima have not helped nuclear power’s image. Still nuclear power is cleaner than any fossil fuel in terms of pollution and waste products and safer in terms of lives lost at all stages of production. In the United States alone, over 100,000 coal miners have been killed in accidents in the past century. The worst nuclear accident in history, at Chernobyl, may have been responsible for 4000 deaths. Even some environmentalists are coming around to the idea that nuclear power is not so bad.

 

Still, nuclear power is not without its drawbacks. So far, when we have spoken of nuclear power, we have meant power obtained by nuclear fission, that is power obtained from the breakup of radioactive atoms, usually uranium. Nuclear fission reactions can yield millions of times more energy than any chemical reaction, which includes burning fossil fuels. There is another type of nuclear reaction which yields even more energy than fission and does not leave any radioactive waste. This is nuclear fusion. Nuclear fusion is the opposite of fission. Instead of a relatively large atomic nucleus breaking apart, fusion occurs when smaller nuclei smash together, forming a larger nucleus, the most common reaction would be hydrogen atoms fusing together to create helium. The actual steps involved are a little more complicated than that, but the details are not important.

 

Every star in the universe is powered by fusion power. We have managed to produce fusion reactions here on Earth in the form of hydrogen or thermonuclear bombs. While these weapons are very destructive, they are not very useful in production the power we need. For that, we need to learn how to produce a controlled fusion reaction. The trouble is that atomic nuclei, being positively charged, are mutually repelled by the electro-magnetic force. Protons and neutrons inside a nucleus are held together by the strong nuclear force, which is far stronger than the electromagnetic force but has an extremely short range.

Diagram illustrating, in a schematic way, the ...

In order for nuclei to to pushed close enough for the strong force to work, the temperature has to be very high, the core of the Sun is 15.7 million Kelvin or 28 million degrees Fahrenheit. This is a problem.

We can get temperatures that high on Earth, in a nuclear explosion.

Nuclear weapon test Mike (yield 10.4 Mt) on En...

 

We can even get temperatures that high in the lab. The problem is that the plasma heated to such a high temperature must be contained, somehow, or it will disperse before any useful reactions take place. There is no substance on Earth that would not be instantly vaporized at that temperature.

 

Which leads me at last to the article in the Independent on the latest progress in making fusion power a reality.

 

An idyllic hilltop setting in the Cadarache forest of Provence in the south of France has become the site of an ambitious attempt to harness the nuclear power of the sun and stars.

It is the place where 34 nations representing more than half the world’s population have joined forces in the biggest scientific collaboration on the planet – only the International Space Station is bigger.

The international nuclear fusion project – known as Iter, meaning “the way” in Latin – is designed to demonstrate a new kind of nuclear reactor capable of producing unlimited supplies of cheap, clean, safe and sustainable electricity from atomic fusion.

If Iter demonstrates that it is possible to build commercially-viable fusion reactors then it could become the experiment that saved the world in a century threatened by climate change and an expected three-fold increase in global energy demand.

 

Nothing is left to chance in a project that has defied potential Babel-like misunderstandings between the collaborating nations. The design, development and construction of a machine that will attempt to emulate the nuclear fusion reactions of the Sun is proving to be a triumph of diplomacy, as well as science and engineering.

“It is the largest scientific collaboration in the world. In fact, the project is so complex we even had to invent our own currency – known as the Iter Unit of Account – to decide how each country pays its share,” says Carlos Alejaldre, Iter’s deputy director responsible for safety.

“We’ve passed from the design stage to being a construction project. We will have to show it is safe. If we cannot convince the public that this is safe, I don’t think nuclear fusion will be developed anywhere in the world,” Dr Alejaldre said.

“A Fukushima-like accident is impossible at Iter because the fusion reaction is fundamentally safe. Any disturbance from ideal conditions and the reaction will stop. A runaway nuclear reaction and a core meltdown are simply not possible,” he said.

Conventional nuclear power produces energy by atomic fission – the splitting of the heavy atoms of uranium fuel. This experimental reactor attempts to fuse together the light atoms of hydrogen isotopes and, in the process, to liberate virtually unlimited supplies of clean, safe and sustainable energy.

Nuclear fusion has been a dream since the start of the atomic age. Unlike conventional nuclear-fission power plants, fusion reactors do not produce high-level radioactive waste, cannot be used for military purposes and essentially burn non-toxic fuel derived from water.

 

The roots of the Iter project go back to 1985 when Mikhail Gorbachev, General Secretary of the former Soviet Union, offered his country’s prowess in nuclear fusion as a bargaining chip in the nuclear disarmament talks with the US, which at that time was pursuing its “Stars Wars” defence system.

Gorbachev and President Reagan, with the support of Margaret Thatcher and French President François Mitterand, signed an agreement to cooperate on nuclear fusion using the Russian “tokamak” reactor. This was a revolutionary device that could hold the super-hot fusion fuel by creating a “magnetic bottle” within the reactor’s doughnut-shaped vacuum vessel.

Several experimental tokamak reactors around the world, including one at the Culham Centre for Fusion Energy in Oxfordshire, have shown nuclear fusion is theoretically possible, but the giant tokamak at Iter will be the first to generate more power than it needs to attain the very high temperatures required for nuclear fusion.

The Iter tokamak machine, which is twice the linear size and 10 times the volume of its nearest rival at Culham, will produce temperatures of well over 100 million C – many times hotter than the centre of the Sun.

It is the first experimental fusion reactor to receive a nuclear operating licence because of its power-generating capacity. For every 50 megawatts of electricity it uses, it should generate up to 500mw of power output in the form of heat.

 

A critical phase of the project will be the injection of plasma – the superhot, electrically-charged gases of the atomic fuel – into the reactor’s vacuum chamber. This plasma, a mix of the hydrogen isotopes deuterium and tritium, will drive the nuclear-fusion reaction.

The plasma will be heated to temperatures as high as 300 million C to force the atomic nuclei close enough together to cause them to fuse into helium, a harmless and inert waste product that could be recycled as an important industrial raw material. Giant electromagnets powerful enough to trap an aircraft carrier will contain the plasma within a spinning vortex held by the magnetic bottle of the tokamak reactor.

 

There is more to read there. All I can say is hurry up, the sooner fusion power is practical for the large scale production of electricity, the better.

 

 

 

 

Advertisements

How to Teach Physics to Your Dog

February 24, 2013

Physicist Chad Orzel talks to his dog. This is not all that unusual. Many pet owners talk to their pets and dogs make particularly good listeners. What might be a little strange is that Professor Orzel talks to his German Sheppard mix Emma about quantum physics. It turns out that dogs have a good intuitive grasp of quantum physics so they are able to have long conversations on quantum physics. In How to Teach Physics to Your Dog, Chad Orzel relates these conversations in which he explains to an eager Emma the basics of quantum physics. Emma interrupts his explanations with just the sort of questions the reader might happen to have. The dog and physicist talk about such topics as the uncertainty principle, virtual particles, quantum tunneling and entanglement.

96514

It’s a fun idea and Chad Orzel does a terrific job explaining physics to the lay reader in the guise of talking to his dog. He seems to have a good feel for how a dog acts and thinks, and I have no trouble imagining that if a dog could talk about physics she would be just as excitable, and as easily distracted by squirrels, bunnies, and treats.

The most important chapter in this book must be the last one, Beware of Evil Squirrels. Here Professor Orzel warns the read of the misuses and outright scams involving quantum physics. There are any number of con artists and New Age frauds who make use of scientific sounding terminology to mislead their victims into believing that one can get free energy from “vacuum energy” or heal oneself of all diseases by imagining oneself to be perfectly healthy. As Orzel explains, despite the many weird and wonderful manifestations of quantum physics, it is not magic, and follows the same sort of rules as anything else in the universe, including the common sense rule that if it sounds too good to be true, it probably is.

I found How to Teach Physics to Your Dog to be appealing and informative. I think that some of the explanations were a bit hard to follow but that is perhaps more my fault than the writer’s.

 

We’re All Doomed

February 20, 2013

As if the recent near miss by an asteroid and the actual impact in Russia were not enough, we have even more to worry about. Asteroids may be deflected. We could conceivably colonize other planets if something were to happen to the Earth, but what could we possibly do if the whole universe is destroyed? Yet that is a terrifying possibility, if the latest theories on the higgs boson turn out to be true. The higgs boson is believed to be the reason why matter has mass in the universe, and it would seem that the higgs boson is just the right mass to make the entire universe unstable, causing it all to destroy itself. I read the story at yahoo news.

A subatomic particle discovered last year that may be the long-sought Higgs boson might doom our universe to an unfortunate end, researchers say.

The mass of the particle, which was uncovered at the world’s largest particle accelerator — the Large Hadron Collider (LHC) in Geneva — is a key ingredient in a calculation that portends the future of space and time.

“This calculation tells you that many tens of billions of years from now there’ll be a catastrophe,” Joseph Lykken, a theoretical physicist at the Fermi National Accelerator Laboratory in Batavia, Ill., said Monday (Feb. 18) here at the annual meeting of the American Association for the Advancement of Science.

“It may be the universe we live in is inherently unstable, and at some point billions of years from now it’s all going to get wiped out,” added Lykken, a collaborator on one of the LHC’s experiments. [Gallery: Search for the Higgs Boson]

The Higgs boson particle is a manifestation of an energy field pervading the universe called the Higgs field, which is thought to explain why particles have mass. After searching for decades for proof that this field and particle existed, physicists at the LHC announced in July 2012 that they’d discovered a new particle whose properties strongly suggest it is the Higgs boson.

For example, the mass of the new particle is about 126 billion electron volts, or about 126 times the mass of the proton. If that particle really is the Higgs, its mass turns out to be just about what’s needed to make the universe fundamentally unstable, in a way that would cause it to end catastrophically in the far future.

That’s because the Higgs field is thought to be everywhere, so it affects the vacuum of empty space-time in the universe.

“The mass of the Higgs is related to how stable the vacuum is,” explained Christopher Hill, a theoretical physicist at the Fermi National Accelerator Laboratory. “It’s right along the critical line. That could either be a cosmic coincidence, or it could be that there’s some physics that’s causing that. That’s something new, which we didn’t know before.”

Strikingly, if the Higgs mass were just a few percent different, the universe wouldn’t be doomed, the scientists said.

Oh, tens of billions of years from now. Well, maybe I won’t worry too much about it after all.

 

The Disappearing Spoon

August 14, 2012
Cover of "The Disappearing Spoon: And Oth...

Cover via Amazon

Like many people who have taken a high school science class, I have seen the old, familiar periodic table of the elements hanging on a classroom wall on in the back of the chemistry textbook. I sometimes looked at that table, wondering about the strange letters and numbers on it. Obviously, H stood for hydrogen and O for oxygen, and C for carbon, but why Fe for iron, or Sn for tin and Au for gold? What was an atomic number and what was its relation to atomic weight? Little did I know that behind the periodic table were stories of mystery, adventure, and romance?

 

Sam Kean tells these stories in his wonderful book, The Disappearing Spoon. He takes the reader up and down the table with stories of elemental discoveries, their differing properties and their impact on the course of history. We learn of the invention of the table, usually attributed to Dmitri Mendeleev, though the story is a little more complicated. We learn of the hunt for elements to fill in the empty spaces and some of the deadly consequences of the discovery of the radioactive elements. How the elements changed the course of history and the results of wars. In the final chapter Kean goes above and beyond the familiar table to introduce the reader to newly discovered exotic forms of matter that might require a periodic table all their own.

 

Overall, Sam Kean does a marvelous job taking what might be considered a dry and dull table of symbols and numbers and bringing it to life.  The Disappearing Spoon was a joy to read.

 

God Particle Found?

July 2, 2012
Large Hadron Collider quadrupole magnets for d...

Large Hadron Collider quadrupole magnets for directing proton beams to interact. These superconducting quadrupole electromagnetas were made in Fermilab. (Photo credit: Wikipedia)

Well, maybe. According to the AP, physicists working at the Large Hadron Collider are expected to announce that they have found convincing evidence for the existence of the Higgs Boson, or the “God Particle”. If their observations are confirmed, than this could be the biggest discovery in physics in decades. Here is part of the story.

Scientists believe the “God particle” that might explain the underpinnings of the universe is real, and they are about to present their evidence to the world.

Physicists at the world’s biggest atom smasher plan to announce Wednesday that they have nearly confirmed the primary plank of a theory that could shape the scientific understanding of all matter.

The idea is much like gravity and Isaac Newton’s discovery: It was there all the time before Newton explained it. But now scientists know what it is and can put that knowledge to further use.

The focus of the excitement is the Higgs boson, a subatomic particle that, if confirmed, could help explain why matter has mass, which combines with gravity to give an object weight.

Researchers at the European Organization for Nuclear Research, or CERN, say that they have compiled vast amounts of data that show the footprint and shadow of the particle – all but proving it exists, even though it has never actually been glimpsed.

But two independent teams of physicists are cautious after decades of work and billions of dollars spent. They don’t plan to use the word “discovery.” They say they will come as close as possible to a “eureka” announcement without uttering a pronouncement as if from the scientific mountaintop.

“I agree that any reasonable outside observer would say, `It looks like a discovery,'” said British theoretical physicist John Ellis, a professor at King’s College London who has worked at CERN since the 1970s. “We’ve discovered something which is consistent with being a Higgs.”

CERN’s atom smasher, the $10 billion Large Hadron Collider on the Swiss-French border, has been creating high-energy collisions of protons to investigate dark matter, antimatter and the creation of the universe, which many theorize occurred in a massive explosion known as the Big Bang.

The phrase “God particle,” coined by Nobel Prize-winning physicist Leon Lederman, is used by laymen, not physicists, more as an explanation for how the subatomic universe works than how it all started.

I really wish that they wouldn’t refer to the Higgs Boson as the God particle. Unless someone is planning to start a new religion that worships sub-atomic particles, it is neither an accurate nor appropriate term. Also, the writers of this article really should know better than to refer to the Large Hadron Collider as an “atom smasher”. The LHC is a particle accelerator. Writing atom smasher sounds as if they don’t know much about the subject they are writing about.

One possible way the Higgs boson might be prod...

One possible way the Higgs boson might be produced at the Large Hadron Collider. Similar images at: http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/Conferences/2003/aspen-03_dam.ppt (Photo credit: Wikipedia)

You can find up to date and accurate information from  physicist Matt Strassler at Of Particular Significance.

Shape Shifting Neutrinos

June 11, 2012

I’ll follow that last post with some real science. Last year ,the whole scientific community was excited over the possibility that neutrinos could possibly travel faster than light. Unfortunately, that doesn’t seem to be the case. This was finally confirmed by studies by the OPERA team at CERN, as I read in this article in New Scientist.

The faster-than-light neutrino saga is officially over. Today, at the Neutrino 2012 conference in Kyoto, Japan, the OPERA collaboration announced that according to their latest measurements, neutrinos travel at almost exactly the speed of light.

“Although this result isn’t as exciting as some would have liked, it is what we all expected deep down,” said CERN research director Sergio Bertolucci in a statement.

Even though they do not travel faster than light, neutrinos are still interesting little particles. There are three different types, each associated with a lepton particle; electron neutrinos, muon neutrinos, and tau neutrinos. But the odd thing is that a neutrino can actually change its type or oscillates between the three types. Confirming this oscillation, is in fact, the real job of the OPERA team.

With the dust settling, OPERA is getting back to its real job: finding tau neutrinos. This week the team also announced that they have found the second-ever instance of a muon neutrino morphing into a tau neutrino, strengthening the case that neutrinos have mass.

But all of that was a sidebar to the experiment’s real goal: catching shape-shifting neutrinos in the act. Neutrinos come in three flavours: electron, muon and tau. Several experiments had seen evidence for neutrinos spontaneously switching, or oscillating, from one type to another. Those oscillations proved, to many physicists’ surprise, that the supposed massless particles must have some infinitesimal mass, and offered a route to explaining why there is more matter than anti-matter in the universe.

Before OPERA, all the evidence for neutrino oscillations came from disappearances: detectors would end up with less of a certain type of neutrino than they started with, suggesting some had morphed into other flavours. Then in 2010, OPERA found the first tau neutrino in a beam of billions of muon neutrinos streaming to the Gran Sasso detectors from CERN. The discovery was a big deal at the time, but the team said they needed more tau neutrinos to make it statistically significant.

Now, a second tau neutrino has shown up in the detectors, they report.

“This result shows that the collaboration is definitely and effectively back to its original goal of discovering neutrino oscillations in appearance mode,” De Lellis says.

OPERA will need at least six tau neutrinos to definitively claim they’re seeing the oscillation effect, so they’re not there yet. And when they do, they may find they’ve been scooped: in another experiment, the team behind the T2K detector in Japan announced this week that they have seen 10 muon neutrinos shifting into electron neutrinos.

The idea of neutrino oscillation is not a new one. Scientists first suspected this might be the case when only about one third the expected number of electron neutrinos were detected from the sun. It seemed as though something was badly wrong about our understanding of solar physics. But, if neutrinos have mass, they were believe to be massless at the time, and they could oscillate between the three types, than we would only detect about one third of the expected number from the sun. Detecting the oscillation would also confirm that neutrinos have mass and would be an important step in confirming the standard model of particle physics.

Scientists on Track of the Elusive God Particle

December 17, 2011

Here is some exciting news from the world of particle physics. I wrote about this once before and it seems that they have made some progress.

Physicists are closer than ever to hunting down the elusive Higgs boson particle, the missing piece of the governing theory of the universe’s tiniest building blocks.

Scientists at the world’s largest particle accelerator, the Large Hadron Collider at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, announced today (Dec. 13) that they’d narrowed down the list of possible hiding spots for the Higgs, (also called the God particle) and even see some indications that they’re hot on its trail.

“I think we are getting very close,” said Vivek Sharma, a physicist at the University of California, San Diego, and the leader of the Higgs search at LHC’s CMS experiment. “We may be getting the first tantalizing hints, but it’s a whiff, it’s a smell, it’s not quite the whole thing.”

Is it just me, or does the beginning of the article sound like they are on the trail of some obscure species of squirrel? Kind of like a hunting magazine?

Tally-ho!! We've got that higgs boson cornered!!!

Or maybe like something from Croc Hunter.

“Crikey!! Today mate, we are on the trail of the elusive higgs boson! It’s hard to find because nobody knows exactly what its mass is!?

Large Hadron Collider Physicist tackles Higgs boson

I really miss that show. Okay, I’m being silly. Here is a bit more from that article.

The Higgs boson is thought to be tied to a field (the Higgs field) that is responsible for giving all other particles their mass. Ironically, physicists don’t have a specific prediction for the mass of the Higgs boson itself, so they must search a wide range of possible masses for signs of the particle.

Based on data collected at LHC’s CMS and ATLAS experiments, researchers said they are now able to narrow down the Higgs’ mass to a small range, and exclude a wide swath of possibilities.

“With the data from this year we’ve ruled out a lot of masses, and now we’re just left with this tiny window, in this region that is probably the most interesting,” said Jonas Strandberg, a researcher at CERN working on the ATLAS experiment.

The researchers have now cornered the Higgs mass in the range between 114.4 and 131 gigaelectronvolts (GeV).For comparison, a proton weighs 1 GeV. Outside that range, the scientists are more than 95 percent confident that the Higgs cannot exist.

Within that range, the ATLAS findings show some indications of a possible signal from the Higgs boson at 126 GeV, though the data are not strong enough for scientists to claim a finding with the level of confidence they require for a true discovery.

“Based on the predicted size of the signal, the experiments may have their first glimpse of a positive signal,” University of Chicago physicist Jim Pilcher wrote in an email to LiveScience. “It is especially important to compare the results of two independent experiments to help reduce statistical fluctuations and experimental biases.”

But it shouldn’t be much longer before scientists can be sure if the Higgs exists, and if so, how much mass it has.

“We know we must be getting close,” Strandberg told LiveScience. “All we need is a little bit more data. I think the data we take in 2012 should be able to really give a definitive answer if the Higgs boson exists.”

I hope they will have a definite answer soon and they win the Nobel Prize.

For more information, here is a blog by a real scientist. I believe that he has just attended a conference where they discussed their latest results.

 

Three New Elements

November 5, 2011

Three new elements have been added to the periodic table by the International Union of Pure and Applied Physics. Well, they aren’t exactly new, having all been created some years ago but the IUPAP has given them their official names. The new elements are: Darmstadtium with an atomic number of 110, Roentgenium with an atomic number of 111 and Copernicium with an atomic number of 112. All three of these elements are radioactive and have half-lives of less than a minute so they are not found in nature nor is it likely that they will ever be created in large enough amounts to be visible.

 

Scientists Try to Explain the Fast-than-light Nutrinos

October 18, 2011

Since the apparent discovery of neutrinos that are moving at superluminal speeds, scientists have been trying to come up with explanations for these findings. The most obvious and likely explanation is measurement error.

Among the most recent ideas is a paper invoking Einstein’s supposedly challenged theory of relativity. The OPERA team used GPS satellites to accurately measure the 730-km distance between their detector and the CERN beam where the neutrinos were produced. Yet, according to special relativity, calculations will be slightly different when two observers are moving relative to one another.

Since the satellites were zipping around the Earth, the positions of the neutrino source and the detector changed. According to the paper, the movement would account for a 64 nanoseconds discrepancy, nearly exactly what the OPERA team observes.

A less likely explanation is that Einstein’s Theory of Relativity is wrong. In fact, both the theories of Special and General Relativity have been amply proved by experiments and observations. There is at least one good reason to suspect that neutrinos do not regularly travel faster than light.

One of the earliest objections to the faster-than-light interpretation came from an astrophysical observation. In 1987, a powerful supernova showered Earth with light and neutrinos. While neutrino detectors observed neutrinos arriving about three hours before the light, this was due to the lightweight particles getting a head start. Neutrinos, which hardly interact with matter, escaped the exploding stellar core with relative ease while photons, absorbed and re-emitted by the various elements, took longer to flee. If the effect from OPERA were as large as observed, scientists have calculated that the neutrinos should have arrived more than four years in advance of the light.

And we know that electrons do not travel faster than light.

Theoretical physicist Matt Strassler also noted on his blog that the Standard Model’s properties suggest that making neutrinos go faster than light requires electrons to do the same. But if electron neutrinos moved at the speed suggested by the OPERA experiment, then electrons should also travel faster than the speed of light by at least one part in 1,000,000,000, or one billionth. Experiments have established theoretical limits that electrons remain subluminal at a precision down to more than 5 part in a thousand trillion, effectively ruling this scenario out.

So, what is going on? We don’t know, yet. My opinion, which really isn’t worth much, is that if the observations are verified, than superluminal travel will be due to some unique property of the nutrinos, which are odd little particles anyway.

I suppose the consensus is measurement error. Too bad. No warp drive yet.

Everthing You Always Wanted to Know About Quantum Physics

October 17, 2011

But were afraid you wouldn’t understand the answers if you asked.

If you have questions about quantum physics but have been looking for a book that will actually explain the subject, than look  no farther. Kenneth W. Ford answers 101 questions about questions about the strange world of the very small. As a former director of the American Institute of Physics and one who has worked with many of the giants of twentieth and twenty-first physics, Ford has the knowledge and ability to explain the often difficult to understand and even seemingly nonsensical aspects of quantum physics.

The only fault with this book is that in the kindle edition, several of the illustrations are missing. These are largely photographs of scientists and for the most part, illustrations necessary for explanations. Other than this lack, 101 Quantum Questions is worth reading.


%d bloggers like this: