… The particles that make up light, photons, may live for at least 1 quintillion (1 billion multiplied by 1 billion) years, new research suggests.
If photons can die, they could give off particles that travel faster than light.
Many particles in nature decay over time. For instance, radioactive atoms are unstable, eventually breaking down into smaller particles and giving off energy as they do so.
Scientists generally assume photons do not break down, since they are thought to lack any mass with which to decay. However, while all measurements of photons currently suggest they have no mass, they might instead potentially have masses too small for current instruments to measure. [10 Implications of Faster-Than-Light Travel]
“How much do we actually know about photons?” asked particle physicist Julian Heeck at the Max Planck Institute for Nuclear Physics at Heidelberg, Germany. “They led to several revolutions in science, but their properties are still a puzzle.”
The current upper limit for the mass of the photon is less than two-billionths of a billionth of a billionth of a billionth of a billionth of a billionth of a kilogram. This would make it about less than a billionth of a billionth of a billionth of the mass of a proton.
Based on the Standard Model of particle physics, which governs the realm of the very tiny, Heeck calculated that photons in the visible spectrum would live for at least 1 quintillion years.
The extraordinarily long lifetime Heeck calculated is an average. “There is the possibility that some photons – very few, though – have decayed,” he said. (The universe is currently about 13.7 billion years old.) Scientific projects such as the Planck mission, aimed at measuring the afterglow of the Big Bang, could potentially detect signs of such decay, Heeck noted.
If photons do break down, the results of such decay must be even lighter particles, ones that would travel even faster than photons. Assuming photons have mass, “there is only one particle we know from the Standard Model of particle physics that might be even lighter – the lightest of the three neutrinos,” Heeck said.
Neutrinos are ghostly particles that only very rarely interact with normal matter. Countless neutrinos rush through everyone on Earth every day with no effect.
“It might well be that the neutrino is lighter than the photon,” Heeck said. In principle, each photon might decay into two of the lightest neutrinos.
“The lightest neutrino, being lighter than light, would then actually travel faster than photons,” Heeck said.
The idea of neutrinos that move faster than photons would seem to violate the notion, based on Einstein’s theory of relativity, that nothing can travel faster than light. However, this assumption is based on the idea of the photon not having any mass. Einstein’s theory of relativity “just states that no particle can travel faster than a massless particle,” Heeck said.
Intriguingly, the speed that photons travel at means their extraordinary life spans will pass by quickly from their perspective. Einstein’s theory of relativity suggests when particles travel extraordinarily quickly, the fabric of space and time warps around them, meaning they experience time as passing more slowly than objects moving relatively slowly. This means that if photons live for 1 quintillion years, from their perspective, they will only live about three years.
Archive for the ‘Physics’ Category
Posted by Xeno on July 31, 2013
Posted by Xeno on July 23, 2013
… Called upsalite in honor of the university where it was discovered, the material features a surface area of 800 square meters per gram. It’s got the highest surface area measured for a synthesized alkali metal carbonate. And in addition, upsalite is filled with empty pores all having a diameter smaller than 10 nanometers.
This means that it can absorb – or more accurately, adsorb – more water at low relative humidities than the most advanced materials currently in existence.
Unlike absorption, where fluids permeate or are dissolved by a liquid or solid, adsorption involves the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. And it does so as a consequence of surface energy (similar to surface tension)….
Once refined, upsalite could significantly reduce the amount of energy required to control environmental moisture in electronics and in drug delivery. It could also be used in hockey rinks and warehouses. Perhaps more crucially, the material could be used to suck up toxic waste, dangerous chemicals, and oil spills.
Scientists have known about natural and ordered forms of magnesium carbonate, both with and without water structure, for quite some time. But creating a water-free disordered version has proven difficult. As early as 1906, German researchers concluded that the material could not be created in the same way as other disordered carbonates, namely by bubbling C02 through an alcoholic suspension. Other studies in 1926 and 1961 came to the same conclusion.
“We started to get excited”
But on one fateful Thursday afternoon in 2011 this all changed. A research team led by Johan Goméz de la Torre made some slight changes to the synthesis parameters of an earlier unsuccessful attempt to create a water-free disordered form of magnesium carbonate – and they left it in the reaction chamber by mistake! It sat there for the entire weekend, and when the researchers returned to the lab the following Monday, a rigid gel had formed.
Surprised and excited, they dried the gel and studied it further. They soon realized that they were onto something.
After a year of further experiments and refinements, upsalite was born. The new material featured an adsoprtion capacity about 50% larger than that of comparable materials at low relative humidities, and an ability to retain more than 75% of the adsorbed water when the humidity was decreased from 95% to 5% at room temperature.
“This places the new material in the exclusive class of porous, high surface area materials including mesoporous silica, zeolites, metal organic frameworks, and carbon nanotubes”, noted researcher Maria Strømme through a release. Indeed, it can adsorb more water at low humidities than the best materials available – and with less energy. “This, together with other unique properties of the discovered impossible material is expected to pave the way for new sustainable products in a number of industrial applications”, said Strømme…
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Posted by Xeno on June 30, 2013
Antimatter, created naturally above storm clouds, has now been created by device that uses magnets and tabletop lasers fired at a gold sheet through helium gas.
A team of physicists working at the University of Michigan just published a paper about their device in Physical Review Letters. But basically, it’s small enough to sit on a table and can create positrons – anti-electrons – like its big,big brother, the particle accelerator at CERN. Positrons, if you aren’t familiar, are found around black holes and pulsars.
PhysOrg explains the process in more detail:
The team fired a petawatt laser at a sample of inert helium gas. Doing so caused the creation of a stream of electrons moving at very high speed. Those electrons were directed at a very thin sheet of metal foil which caused them to smash into individual metal atoms. Those collisions resulted in a stream of electron and positron emissions – the two were then separated using magnets.
The researchers report that each blast of their gun lasts just 30 femtoseconds, but each firing results in the production of quadrillions of positrons – a density level comparable to those produced at CERN.
For scale: petawatt is one quadrillion watts, a femtosecond is a one quadrillionth of a second, and a quadrillion is 1,000,000,000,000,000.
The thought is that we can use gadgets like this to study positrons more easily than ever and learn more about those gaping black holes in space and other things like them. … [PhysOrg]
From the Wikipedia antimatter bomb page:
An antimatter weapon is a hypothetical device using antimatter as a power source, a propellant, or an explosive for a weapon. Antimatter weapons do not currently exist due to the cost of production and the limited technology available to produce and contain antimatter in sufficient quantities for it to be a useful weapon. The United States Air Force, however, has been interested in military uses — including destructive applications — of antimatter since the Cold War, when it began funding antimatter-related physics research. The primary theoretical advantage of such a weapon is that antimatter and matter collisions convert a greater fraction of the weapon’s mass into explosive energy when compared to a fusion reaction, which is only on the order of 0.7%. There is considerable skepticism within the physics community about the viability of antimatter weapons. According to CERN laboratories, which regularly produces antimatter, “There is no possibility to make antimatter bombs for the same reason you cannot use it to store energy: we can’t accumulate enough of it at high enough density. (…) If we could assemble all the antimatter we’ve ever made at CERN and annihilate it with matter, we would have enough energy to light a single electric light bulb for a few minutes.”, but this would be a considerable feat because the accumulated antimatter would weigh less than one billionth of a gram.
If those scientists at the University of Michigan made just 12 grams of antimatter they’d have enough energy to light all 12 billion lightbulbs in the world for a few minutes.
Universe Today has this to say:
Antimatter is powerful. Even a tiny amount would create a devastating explosion. Just a kilogram of antimatter would release the same amount of energy as a 20 megaton thermonuclear bomb.
But here’s the problem. Generating antimatter is an incredibly expensive process. It’s been estimated that if you took all of the antimatter ever created in all the particle colliders in the world, you would only have enough to power a lightbulb for a few minutes. To create antimatter on an industrial scale to create an antimatter bomb would require the collective resources of the entire planet. Furthermore, there’s no easy way to store antimatter once you create it, since it will explode with even the slightest touch with regular matter.
There’s no risk of an antimatter bomb ever being created. Perhaps in the distant future, hundreds of years from now, but not any time soon. …
1 kilogram is 1,000 grams so we can estimate roughly that 1 gram of antimatter has the power of a 20 kiloton nuclear bomb. That’s more powerful than the bomb dropped on Hiroshima (13 to 18 kilotons).
Scaled up and put to good use this invention might solve world energy problems… unless it takes more energy to generate, separate and store the antimatter than could be recovered using it as a fuel.
Storage is tricky:
“Trapping antihydrogen proved to be much more difficult than creating antihydrogen,” says ALPHA team member Joel Fajans, a scientist in Berkeley Lab’s Accelerator and Fusion Research Division (AFRD) and a professor of physics at UC Berkeley. “ALPHA routinely makes thousands of antihydrogen atoms in a single second, but most are too ‘hot’”—too energetic—“to be held in the trap. We have to be lucky to catch one.”
The ALPHA collaboration succeeded by using a specially designed magnetic bottle called a Minimum Magnetic Field Trap. The main component is an octupole (eight-magnetic-pole) magnet whose fields keep anti-atoms away from the walls of the trap and thus prevent them from annihilating. Fajans and his colleagues in AFRD and at UC proposed, designed, and tested the octupole magnet, which was fabricated at Brookhaven. ALPHA team member Jonathan Wurtele of AFRD, also a professor of physics at UC Berkeley, led a team of Berkeley Lab staff members and visiting scientists who used computer simulations to verify the advantages of the octupole trap….
Posted by Xeno on June 25, 2013
… Nerval’s Lobster writes “The powerful, reliable combination of transistors and semiconductors in computer processors could give way to systems built on the way electrons misbehave, all of it contained in circuits that warp even the most basic rules of physics. Rather than relying on a predictable flow of electrons that appear to know whether they are particles or waves, the new approach depends on quantum tunneling, in which electrons given the right incentive can travel faster than light, appear to arrive at a new location before having left the old one, and pass straight through barriers that should be able to hold them back. Quantum tunneling is one of a series of quantum-mechanics-related techniques being developed as possible replacements for transistors embedded in semiconducting materials such as silicon. Unlike traditional transistors, circuits built by creating pathways for electrons to travel across a bed of nanotubes are not limited by any size restriction relevant to current manufacturing methods, require far less power than even the tiniest transistors, and do not give off heat or leak electricity as waste products, according to Yoke Khin Yap of Michigan Technological University, lead author of a paper describing the technique, which was published in the journal Advanced Materials last week.” …
Does this mean future computers will have an answer for us before we even know we are going to ask? Imagine that world!
Posted by Xeno on June 24, 2013
Just before the weekend I read about a new technique which can be used to shoehorn around 1,000TB of data onto a “DVD disc”. This is quite a feat and it was achieved by circumnavigating some laws of physics with a technique which uses two different coloured light beams to selectively cancel each other out and produce a much finer beam – required for such a huge increase in data density.
Optical discs have their positive aspects, such as being cheap to produce as well as longevity and robustness but they are falling out of favour compared to other ways to back up or share data. Once thought of as an essential computer component, many people are now buying laptops that don’t include an optical disc reader or writer.
The storage capacity of a standard 12cm optical disc is limited by how small the pits burnt into its surface by a laser can be, itself limited by the diameter of the light beam doing the “burning” and the reading. The upgrade from DVD to Blu-ray was down to a finer laser beam and new media which could be “burnt” by that light beam.
In Physics, Abbe’s Law states that the width of light beams which can be“obtained by focussing the light through a lens, cannot be smaller than half its wavelength”. This means a visible light beam cannot be smaller than 500nm reports Phys.org. Using an optical two beam system comprised of a “writing beam” and an “inhibitor beam” it is possible to circumvent Abbe’s Law to create a practical laser beam that is less than 100nm in diameter, as shown in the diagram below. Phys.org says the scientists managed to achieve a laser of diameter significantly below 100nm; “This new technique produces an effective focal spot of nine nanometres – or one ten thousandth the diameter of a human hair”.
The diagram shows that the two beams are of different shapes and their overlaps cancel out to leave a much smaller focussed central light beam. Recording on the optical disc is “tightly confined to the centre” of this resulting light beam. Using this very fine laser to record on a 12cm optical disc should be able to yield capacities in the region of 1,000TB of data. This is equivalent to “10.6 years of compressed high-definition video or 50,000 full high-definition movies”.
The scientists say this new laser technique is “cost-effective and portable, as only conventional optical and laser elements are used, and allows for the development of optical data storage with long life and low energy consumption”. I’m looking forward to seeing this technology used in the first real-world devices which should be in “Big Data centres”according to the researchers. …
Posted by Xeno on June 14, 2013
Warning: Turn your volume way down during this entire video. The sound that produces the patterns is loud enough to cause permanent hearing damage.
… This demonstration is by a prolific YouTube user who goes by the handle brusspup. I’ve been enjoying his amazing visual illusions for a few years – and I’m not the only one! His videos have wracked up tens of millions of views.
But this one isn’t an illusion. Rather, it’s a clever way to reveal patterns not normally visible to our senses. And it traces back to the 18th – and even the 17th – century and a somewhat obscure scientist.
Ernst Chladni was a German-born Hungarian physicist and musician who did pioneering work in acoustics and also in the study of meteorites.
In fact, in 1794, he was the first to publish the outlandish idea that meteorites were extraterrestrial in origin, a proposal for which he was ridiculed. At the time they were thought to be of volcanic origin. But we all know who got the last laugh on that one. He was vindicated within ten years – within his lifetime – when a dramatic meteor shower left hard-to-dispute meteoritic evidence all over a French town.
But the phenomenon seen in the video is the one for which Chladni is perhaps best known. It is a technique to reveal the complex patterns of vibration in a rigid surface.
A plate or membrane vibrating at resonance is divided into regions vibrating in opposite directions, bounded by lines of zero vibration called nodal lines… Chladni’s technique… consisted of drawing a bow over a piece of metal whose surface was lightly covered with sand. The plate was bowed until it reached resonance, when the vibration causes the sand to move and concentrate along the nodal lines where the surface is still, outlining the nodal lines.
Modern versions of the demonstration tend to use modern equipment such as loudspeakers and signal generators with adjustable frequency. In the video, as the frequency is altered we are able to see how the patterns in the plate assume various intricate shapes. The sand is pushed away from the areas of vibration and gathers in the places where the surface remains motionless (the nodal lines).
The beautiful patterns that emerge are now called Chladni figures, although Chladni was actually building on earlier experiments performed by Robert Hooke, who, in 1680, observed these nodal patterns in vibrating glass plates….
Is this effect seen in 2D here also a 3D phenomena? Since cells seem form, then break and reform new different cells, shuffling the cell contents non-biologically in the presence of vibration, this effect offers one way life may start to form. I’m visualizing vibration from an undersea volcano having this effect in 3D on surrounding suspended lipid and other molecules, forming hollow spheres (cells), jump starting life as we know it.
Posted by Xeno on June 6, 2013
The ultimate dream of nanotechnology is to be able to manipulate matter atom by atom. To do that, we first need to know what they look like. In what could be a major step in that direction, researchers have developed a method that can determine the shape of a single molecule and identify its constituent atoms.
The laws of nature limit what can be seen with the help of light alone. Only objects separated by less than half the wavelength of the light that illuminates it can be observed. To overcome this limit, in 1928, Edward Hutchinson Synge came up with an idea of imaging things too small for the naked eye. The idea was to shine light on a small particle and study the scattering when reflected back, making the wavelength of incident light irrelevant.
The realisation of Synge’s idea had to wait till the 1980s, when Heinrich Rohrer, the father of nanotechnology, developed scanning tunnelling microscopy (STM). This method uses a special property of electric current called quantum tunnelling to achieve this.
Since the development of STM, techniques for imaging smaller and smaller objects have been improving incrementally. Today it is possible to identify the shapes of molecules and where the atoms reside. But none of these techniques can identify the atoms those molecules are made of.
Now researchers from China, Spain and Sweden have combined STM with another method called Raman spectroscopy to determine not just the shape, but also the constituent atoms of a single molecule. …
When some form of energy, like heat or light, hits molecules it makes them vibrate and rotate, even in solid structures. This process is called “excitation”. The movement emits some of the energy back, which is called “emmission”. Raman spectroscopy works by detecting this tiny amount of emitted energy, which tells us things about the molecule that’s doing the emitting.
One of the many uses for Raman spectroscopy is analysing old ruined paintings. It can detect the presence of certain elements at very specific locations. The salts of these elements have specific colours and thus they can reveal what a particular part of the painting might have looked like originally.
Analyzing trillions of molecules is easy, because molecules of the same type will combine to produce a more intense signal, since they all experience the same vibrations and rotations. Where things become tricky is when single molecules need to be excited and their weak energy emission measured. Researchers led by Jianguo Hou, at the University of Science and Technology of China, have found a way to do that. The results of their work are published in the journal Nature today.
They use a modified STM technique that produces just enough light to excite only a few atoms of a molecule at a time. A laser is focused in a metal cavity which contains the molecule to be analysed. The laser’s energy creates an excited cloud of electrons called plamsons, which creates the local energy needed to excite different parts of a single molecule….
Posted by Xeno on May 31, 2013
When Felix Fischer of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) set out to develop nanostructures made of graphene using a new, controlled approach to chemical reactions, the first result was a surprise: spectacular images of individual carbon atoms and the bonds between them.
“We weren’t thinking about making beautiful images; the reactions themselves were the goal,” says Fischer, a staff scientist in Berkeley Lab’s Materials Sciences Division (MSD) and a professor of chemistry at the University of California, Berkeley. “But to really see what was happening at the single-atom level we had to use a uniquely sensitive atomic force microscope in Michael Crommie’s laboratory.” Crommie is an MSD scientist and a professor of physics at UC Berkeley.
What the microscope showed the researchers, says Fischer, “was amazing.” The specific outcomes of the reaction were themselves unexpected, but the visual evidence was even more so. “Nobody has ever taken direct, single-bond-resolved images of individual molecules, right before and immediately after a complex organic reaction,” Fischer says.
Posted by Xeno on May 28, 2013
It’s not the same as turning lead into gold, but scientists at the Illinois-based Argonne National Laboratory and the Japan Synchrotron Radiation Research Institute/SPring-8 have developed a method for turning cement into a liquid metal semiconductor.
The process sounds like a mad scientist’s invention. It involves equipment like an aerodynamic levitator and a carbon dioxide laser beam. The levitator uses gas pressure to keep the material out of contact with any container surfaces. The carbon dioxide laser beam can heat the material to 3,632 degrees Fahrenheit.
The material in question is mayenite, a calcium aluminum oxide material that is part of alimuna cement. It was placed in the aerodynamic levitator and thoroughly cooked until it melted. It was then allowed to cool down into a glassy state. This method resulted in a material that traps electrons and allows for conduction, effectively turning cement into a semiconductor that behaves much like metal does.
“This new material has lots of applications, including as thin-film resistors used in liquid-crystal displays, basically the flat panel computer monitor that you are probably reading this from at the moment,” Argonne physicist Chris Benmore said Monday in a statement.
The results is being published under the title “Network topology for the formation of solvated electrons in binary CaO-Al2O3 composition glasses” in the Proceedings of the National Academy of Sciences journal.
Score one for modern alchemy.
Posted by Xeno on May 24, 2013
The first direct observation of the orbital structure of an excited hydrogen atom has been made by an international team of researchers. The observation was made using a newly developed “quantum microscope”, which uses photoionization microscopy to visualize the structure directly. The team’s demonstration proves that “photoionization microscopy”, which was first proposed more than 30 years ago, can be experimentally realized and can serve as a tool to explore the subtleties of quantum mechanics….
The wavefunction is a central tenet of quantum theory – put simply, it contains the maximum knowledge that is available about the state of a quantum system. More specifically, the wavefunction is the solution to the Schrödinger equation. The square of the wavefunction describes the probability of where exactly a particle might be located at a given time. Although it features prominently in quantum theory, directly measuring or observing the wavefunction is no easy task, as any direct observation destroys the wavefunction before it can be fully observed.
In the past, “Rydberg wavepacket” experiments have tried to observe the wavefunction using ultrafast laser pulses. In these experiments, the atoms are in a superposition of their highly excited “Rydberg states”. These experiments show that the periodic electron orbitals around nuclei are described by coherent superpositions of quantum-mechanical stationary states. The wavefunction of each of these states is a standing wave with a nodal pattern (a “node” is where there is zero probability of finding an electron) that reflects the quantum numbers of the state. While previous experiments have attempted to capture the elusive wavefunction or the nodal patterns, the methods used were not successful. Direct observation of the nodal structure of a single atom being most difficult to achieve…