Physics ‘Constants’ Changing
The strange case of solar flares and radioactive elements
When researchers found an unusual linkage between solar flares and the inner life of radioactive elements on Earth, it touched off a scientific detective investigation that could end up protecting the lives of space-walking astronauts and maybe rewriting some of the assumptions of physics.
It's a mystery that presented itself unexpectedly: The radioactive decay of some elements sitting quietly in laboratories on Earth seemed to be influenced by activities inside the sun, 93 million miles away.
Is this possible?
Researchers from Stanford and Purdue University believe it is. But their explanation of how it happens opens the door to yet another mystery.
There is even an outside chance that this unexpected effect is brought about by a previously unknown particle emitted by the Sun. "That would be truly remarkable," said Peter Sturrock, Stanford professor emeritus of applied physics and an expert on the inner workings of the sun.
The story begins, in a sense, in classrooms around the world, where students are taught that the rate of decay of a specific radioactive material is a constant. This concept is relied upon, for example, when anthropologists use carbon-14 to date ancient artifacts and when doctors determine the proper dose of radioactivity to treat a cancer patient.
Random numbersBut that assumption was challenged in an unexpected way by a group of researchers from Purdue University who at the time were more interested in random numbers than nuclear decay. (Scientists use long strings of random numbers for a variety of calculations, but they are difficult to produce, since the process used to produce the numbers has an influence on the outcome.)
Ephraim Fischbach, a physics professor at Purdue, was looking into the rate of radioactive decay of several isotopes as a possible source of random numbers generated without any human input. (A lump of radioactive cesium-137, for example, may decay at a steady rate overall, but individual atoms within the lump will decay in an unpredictable, random pattern. Thus the timing of the random ticks of a Geiger counter placed near the cesium might be used to generate random numbers.)
As the researchers pored through published data on specific isotopes, they found disagreement in the measured decay rates – odd for supposed physical constants.
Checking data collected at Brookhaven National Laboratory on Long Island and the Federal Physical and Technical Institute in Germany, they came across something even more surprising: long-term observation of the decay rate of silicon-32 and radium-226 seemed to show a small seasonal variation. The decay rate was ever so slightly faster in winter than in summer.
Was this fluctuation real, or was it merely a glitch in the equipment used to measure the decay, induced by the change of seasons, with the accompanying changes in temperature and humidity?
"Everyone thought it must be due to experimental mistakes, because we're all brought up to believe that decay rates are constant," Sturrock said.
Peter Sturrock, professor emeritus of applied physics
Image: L.A. Cicero
The sun speaksOn Dec 13, 2006, the sun itself provided a crucial clue, when a solar flare sent a stream of particles and radiation toward Earth. Purdue nuclear engineer Jere Jenkins, while measuring the decay rate of manganese-54, a short-lived isotope used in medical diagnostics, noticed that the rate dropped slightly during the flare, a decrease that started about a day and a half before the flare.
If this apparent relationship between flares and decay rates proves true, it could lead to a method of predicting solar flares prior to their occurrence, which could help prevent damage to satellites and electric grids, as well as save the lives of astronauts in space.
The decay-rate aberrations that Jenkins noticed occurred during the middle of the night in Indiana – meaning that something produced by the sun had traveled all the way through the Earth to reach Jenkins' detectors. What could the flare send forth that could have such an effect?
Jenkins and Fischbach guessed that the culprits in this bit of decay-rate mischief were probably solar neutrinos, the almost weightless particles famous for flying at almost the speed of light through the physical world – humans, rocks, oceans or planets – with virtually no interaction with anything.
Then, in a series of papers published in Astroparticle Physics, Nuclear Instruments and Methods in Physics Research and Space Science Reviews, Jenkins, Fischbach and their colleagues showed that the observed variations in decay rates were highly unlikely to have come from environmental influences on the detection systems.
Their findings strengthened the argument that the strange swings in decay rates were caused by neutrinos from the sun. The swings seemed to be in synch with the Earth's elliptical orbit, with the decay rates oscillating as the Earth came closer to the sun (where it would be exposed to more neutrinos) and then moving away.
Reason for suspicion
Reason for suspicion
So there was good reason to suspect the sun, but could it be proved?
Enter Peter Sturrock, Stanford professor emeritus of applied physics and an expert on the inner workings of the sun. While on a visit to the National Solar Observatory in Arizona, Sturrock was handed copies of the scientific journal articles written by the Purdue researchers.
Sturrock knew from long experience that the intensity of the barrage of neutrinos the sun continuously sends racing toward Earth varies on a regular basis as the sun itself revolves and shows a different face, like a slower version of the revolving light on a police car. His advice to Purdue: Look for evidence that the changes in radioactive decay on Earth vary with the rotation of the sun. "That's what I suggested. And that's what we have done."
Going back to take another look at the decay data from the Brookhaven lab, the researchers found a recurring pattern of 33 days. It was a bit of a surprise, given that most solar observations show a pattern of about 28 days – the rotation rate of the surface of the Sun.
The explanation? The core of the sun – where nuclear reactions produce neutrinos – apparently spins more slowly than the surface we see. "It may seem counter-intuitive, but it looks as if the core rotates more slowly than the rest of the sun," Sturrock said [there are more plausible explanations, but these invalidate the nuclear furnace theory of solar energy generation and are unlikely to be accepted by the current generation of physicists – New Illuminati Ed].
All of the evidence points toward a conclusion that the Sun is "communicating" with radioactive isotopes on Earth, said Fischbach.
But there's one rather large question left unanswered. No one knows how neutrinos could interact with radioactive materials to change their rate of decay.
"It doesn't make sense according to conventional ideas," Fischbach said. Jenkins whimsically added, "What we're suggesting is that something that doesn't really interact with anything is changing something that can't be changed."
"It's an effect that no one yet understands," agreed Sturrock. "Theorists are starting to say, 'What's going on?' But that's what the evidence points to. It's a challenge for the physicists and a challenge for the solar people too."
If the mystery particle is not a neutrino, "It would have to be something we don't know about, an unknown particle that is also emitted by the sun and has this effect, and that would be even more remarkable," Sturrock said.
BY DAN STOBER
Chantal Jolagh, a science-writing intern at the Stanford News Service, contributed to this story.From http://news.stanford.edu/news/2010/august/sun-082310.html
Proton Smaller Than Thought—May Rewrite Laws of Physics
Scientists "totally surprised" by "significant shake-up."
Protons and neutrons are shown as red and blue spheres at the center of this diagram of an atom.
Image courtesy Dorling Kindersley, Getty Images
Protons, among the building blocks of atoms, are even smaller than we thought—and the unexpected discovery may alter some of the most trusted laws of physics.
All atoms are made up of nuclei orbited by electrons. The nuclei, in turn, are made of neutrons and protons, which are themselves made of particles called quarks. (Related: "'God Particle' May Be Five Distinct Particles, New Evidence Shows.")
For years the accepted value for the radius of a proton has been 0.8768 femtometers, where a femtometer equals one quadrillionth of a meter.
The size of a proton is an essential value in equations that make up the 60-year-old theory of quantum electrodynamics, a cornerstone of the Standard Model of particle physics. The Standard Model describes how all forces, except gravity, affect subatomic particles. (See "Einstein's Gravity Confirmed on a Cosmic Scale.")
But the proton's current value is accurate only by plus or minus one percent—which isn't accurate enough for quantum electrodynamics, or QED, theory to work perfectly. So physicists have been searching for ways to refine the number.
Smaller Proton Size Revealed by LasersIn a ten-year experiment, a team led by Randolf Pohl of the Max-Planck Institute of Quantum Optics in Garching, Germany, used a specialized particle accelerator to alter hydrogen atoms, which are each made of a single proton orbited by an electron.
(Related: "Large Hadron Collider Smashes Protons, Sets Record.")
For each hydrogen atom, the team replaced the atom's electron with a particle called a muon, which is 200 times more massive than an electron.
"Because the muon is so much heavier, it orbits very close to the proton, so it is sensitive to the proton's size," said team member Aldo Antognini, of the Paul-Scherrer Institute in Switzerland.
Muons are unstable, and they decay into other particles in just 2.2 microseconds. The team knew that firing a laser at the atom before the muon decays should excite the muon, causing it to move to a higher energy level — a higher orbit around the proton. The muon should then release the extra energy as x-rays and move to a lower energy level.
The distance between these energy levels is determined by the size of the proton, which in turn dictates the frequency of the emitted x-rays.
But based on the accepted proton radius, the experiment failed to produce x-rays at the anticipated frequency.
In the summer of 2009 the team decided to widen their search to include other possible proton sizes. To their astonishment, the scientists detected x-rays at an assumed proton radius of 0.8418 femtometers—4 percent smaller than expected.
"We were totally surprised and don't have any explanation for it currently," Antognini said.
Smaller Proton a "Significant Shake-up"The proton finding won't impact most people's daily lives. But if it proves correct, it means something fundamental is wrong in particle physics.
It's possible the smaller proton means the Rydberg constant hasn't been correctly measured. This value describes the way light gets emitted from various elements—a key component of spectroscopy, which is used, for instance, to tell which kinds of elements exist in galaxies and the vast interstellar gas-and-dust clouds called nebulae.
(Related: "Particles Larger Than Galaxies Fill the Universe?")
Or, if the Rydberg constant is correct, the smaller size of a proton could mean the equations in QED theory will fail to work.
"It is a significant shakeup and could mean a complete rethink of QED, potentially opening the door to a new theory," said Jeff Flowers, a scientist with the National Physical Laboratory in the U.K., who wasn’t involved with the experiment.
Over the coming weeks physicists all over the world will be scrutinizing the experimental setup and complex calculations, making sure that there are no mistakes.
Assuming no errors are found, the scientists may have to get to work rebuilding the Standard Model.
Findings appear in this week's issue of the journal Nature. - Published July 7, 2010
by Kate RaviliousFrom http://news.nationalgeographic.com/news/2010/07/100707-science-proton-smaller-standard-model-quantum-physics/
Laws of Physics Vary Throughout the Universe, New Study Suggests
A team of astrophysicists based in Australia and England has uncovered evidence that the laws of physics are different in different parts of the universe.
The team -- from the University of New South Wales, Swinburne University of Technology and the University of Cambridge -- has submitted a report of the discovery for publication in the journal Physical Review Letters. A preliminary version of the paper is currently under peer review.
The report describes how one of the supposed fundamental constants of Nature appears not to be constant after all. Instead, this 'magic number' known as the fine-structure constant -- 'alpha' for short -- appears to vary throughout the universe.
"After measuring alpha in around 300 distant galaxies, a consistency emerged: this magic number, which tells us the strength of electromagnetism, is not the same everywhere as it is here on Earth, and seems to vary continuously along a preferred axis through the universe," Professor John Webb from the University of New South Wales said.
"The implications for our current understanding of science are profound. If the laws of physics turn out to be merely 'local by-laws', it might be that whilst our observable part of the universe favours the existence of life and human beings, other far more distant regions may exist where different laws preclude the formation of life, at least as we know it."
"If our results are correct, clearly we shall need new physical theories to satisfactorily describe them."
The researchers' conclusions are based on new measurements taken with the Very Large Telescope (VLT) in Chile, along with their previous measurements from the world's largest optical telescopes at the Keck Observatory in Hawaii.
Mr Julian King from the University of New South Wales explained how, after combining the two sets of measurements, the new result 'struck' them. "The Keck telescopes and the VLT are in different hemispheres -- they look in different directions through the universe. Looking to the north with Keck we see, on average, a smaller alpha in distant galaxies, but when looking south with the VLT we see a larger alpha."
"It varies by only a tiny amount -- about one part in 100,000 -- over most of the observable universe, but it's possible that much larger variations could occur beyond our observable horizon," Mr King said.
The discovery will force scientists to rethink their understanding of Nature's laws. "The fine structure constant, and other fundamental constants, are absolutely central to our current theory of physics. If they really do vary, we'll need a better, deeper theory," Dr Michael Murphy from Swinburne University said.
"While a 'varying constant' would shake our understanding of the world around us extraordinary claims require extraordinary evidence. What we're finding is extraordinary, no doubt about that."
"It's one of the biggest questions of modern science -- are the laws of physics the same everywhere in the universe and throughout its entire history? We're determined to answer this burning question one way or the other."
Other researchers involved in the research are Professor Victor Flambaum and PhD student Matthew Bainbridge from the University of New South Wales, and Professor Bob Carswell at the University of Cambridge (UK).
From ScienceDaily (Sep. 9, 2010) @ http://www.sciencedaily.com/releases/2010/09/100909004112.htm
Particles Larger Than Galaxies Fill the Universe?
The oldest of the subatomic particles called neutrinos might each encompass a space larger than thousands of galaxies, new simulations suggest.Neutrinos as we know them today are created by nuclear reactions or radioactive decay.
According to quantum mechanics, the "size" of a particle such as a neutrino is defined by a fuzzy range of possible locations. We can only detect these particles when they interact with something such as an atom, which collapses that range into a single point in space and time.
For neutrinos created recently, the ranges they can exist in are very, very small.
But over the roughly 13.7-billion-year lifetime of the cosmos, "relic" neutrinos have been stretched out by the expansion of the universe, enlarging the range in which each neutrino can exist.
"We're talking maybe up to roughly ten billion light-years" for each neutrino, said study co-author George Fuller of the University of California, San Diego.
"That's nearly on the order of the size of the observable universe."
"Small" Physics, Writ LargeNeutrinos have no charge, and their masses are so tiny they have yet to be accurately measured.
This means that neutrinos, which zip around at nearly the speed of light, can pass through normal matter largely undisturbed.
Most neutrinos that affect Earth come from the Sun. Billions of solar neutrinos pass through the average human every second.
While trying to calculate masses for neutrinos, Fuller and his student Chad Kishimoto found that, as the universe has expanded, the fabric of space-time has been tugging at ancient neutrinos, stretching the particles' ranges over vast distances.
Such large ranges can remain intact, the scientists suggest in the May 22 issue of Physical Review Letters, since neutrinos pass right through most of the universe's matter.An open question is whether gravity — say, the pull from an entire galaxy—can force a meganeutrino to collapse down to a single location.
"Quantum mechanics was intended to describe the universe on the smallest of scales, and now here we're talking about how it works on the largest scales in the universe," Kishimoto said.
"We're talking about physics that hasn't been explored before."
According to physicist Adrian Lee at the University of California, Berkeley, who was not part of the study team, "gravity is a real frontier these days that we don't really understand.
"These neutrinos could be a path to something deeper in our understanding with gravity."
(Related: "At Ten, Dark Energy 'Most Profound Problem' in Physics.")
Follow the Gravity?But answers to such questions depend on eventually detecting these predicted meganeutrinos.
Although they should be extraordinarily common in the universe, the relic neutrinos now have only about one ten-billionth of the energy of neutrinos generated by the sun.
"This makes relic neutrinos near impossible to detect directly, at least with anything one could build on Earth," study co-author Fuller said.
Still, the fact that there are so many relic neutrinos means that together they likely exert a significant gravitational pull—"enough to be important for how the universe as a whole behaves," Fuller added.
Dark matter, for example, has never been directly observed. But astrophysicists have found proof that dark matter exists based on its effect on colliding galaxies [no – they have proved that a gravitational effect ascribed to dark matter exists. Neutrinos don't exist either. – N.I. Ed].
"So by looking at the growth of structures in the universe," Fuller said, "you might be able to detect relic neutrinos indirectly by their gravity."
by Charles Q. ChoiFrom http://news.nationalgeographic.com/news/2009/06/090602-particles-larger-than-galaxies.html
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