Physicists check whether neutrinos really can travel faster than light | Science According to Einstein's theory of special relativity nothing – not even neutrinos – can travel faster than the speed of light in a vacuum. Photograph: Cine Text/Allstar The scientists who last month appeared to have found that certain subatomic particles can travel faster than light have fine-tuned their experiment to check whether the remarkable discovery is correct. Their modified experiments – which are the result of suggestions from other physicists about potential flaws in their research – should be completed before the end of the year. The original experiment, reported last month, involved firing beams of neutrinos through the ground from Cern near Geneva to the Gran Sasso lab in Italy 720 kilometres (450 miles) away. The finding sent the physics world into a frenzy because it appeared to go against Albert Einstein's theory of special relativity. First time around, the Cern scientists fired pulses of neutrinos lasting around 10 microseconds each through the rock to Gran Sasso.
Finding a direction of time in exotic particle transformations Unlike our daily experience, the world of elementary particle physics is mostly symmetrical in time. Run the clock backward on your day and it won't work; run the clock backward on a process in particle physics and things are just fine. However, to preserve certain fundamental aspects of space-time the Standard Model predicts that certain reversible events nevertheless have different probabilities, depending on which way they go. This time-reversal asymmetry is remarkably hard to observe in practice since it involves measurements of highly unstable particles. New results from the BaBar detector at the Stanford Linear Accelerator Center (SLAC) have uncovered this asymmetry in time. Researchers measured transformations of entangled pairs of particles, including the rates at which these transformations occurred. A direct consequence of relativity in particle physics is the presence of three related symmetries, known as CPT: charge, parity, and time.
Bullet Cluster Two colliding clusters of galaxies in constellation Carina The object is of a particular note for astrophysicists, because gravitational lensing studies of the Bullet Cluster are claimed to provide the best evidence to date for the existence of dark matter.[3][4] Observations of other galaxy cluster collisions, such as MACS J0025.4-1222, similarly support the existence of dark matter. Overview[edit] The major components of the cluster pair—stars, gas and the putative dark matter—behave differently during collision, allowing them to be studied separately. The third component, the dark matter, was detected indirectly by the gravitational lensing of background objects. The Bullet Cluster is one of the hottest-known clusters of galaxies. Significance to dark matter[edit] According to Greg Madejski: Particularly compelling results were inferred from the Chandra observations of the 'bullet cluster' (1E0657-56; Fig. 2) by Markevitch et al. (2004) and Clowe et al. (2004). According to Eric Hayashi:
Leading Light: What Would Faster-Than-Light Neutrinos Mean for Physics? The stunning recent announcement of neutrinos apparently exceeding the speed of light was greeted with startled wonderment followed by widespread disbelief. Although virtually every scientist on record expects this discovery to vanish once more detailed analysis takes place, dozens of researchers are exploring the question whose answer could shake the foundations of physics: What if this anomaly is real? Neutrinos are ghostly particles that only weakly interact with normal matter; trillions of neutrinos stream through our bodies every second. Last month researchers from the European OPERA (Oscillation Project with Emulsion-tRacking Apparatus) collaboration reported clocking pulses of neutrinos moving at speeds that appeared to be a smidgen faster than light-speed. The credibility of the OPERA scientists who made the supposed discovery of superluminal neutrinos is not in doubt.
7 Superpowered Animal Senses You Won't Believe Are Possible The human imagination is pretty limited when it comes to animal senses. We call people with good vision "eagle eye," and believe that toucan's can smell cereal because they have big noses. It turns out the animal kingdom has plenty of creatures whose senses go beyond what we can conceive without our head exploding. Silvertip Grizzlies Can Smell You From 18 Miles Away (And Across Time) Humans use smell to get us excited about pie before we actually put it in our mouths, and not much else. His nose is a time-traveler. It knows who walked down the street last night at 11PM, what the soles of their shoes were made of, the brand of cigarette they were smoking. ... and tell you Ingrid had a secret admirer last spring when they fixed the sidewalk. Fortunately for the sake of this article, and unfortunately for the sake of everyone who's afraid of bears, the silvertip grizzly's sense of smell is seven times stronger than that of the bloodhound. Jumping Spiders Can See Four Primary Colors Wrong.
Einasto profile From Wikipedia, the free encyclopedia The Einasto profile (or Einasto model) is a mathematical function that describes how the density of a spherical stellar system varies with distance from its center. Jaan Einasto introduced his model at a 1963 conference in Alma-Ata, Kazakhstan.[1] The Einasto profile possesses a power law logarithmic slope of the form: which can be rearranged to give The parameter controls the degree of curvature of the profile. The larger , the more rapidly the slope varies with radius (see figure). , which has a constant slope on a log-log plot. Einasto's model has the same mathematical form as Sersic's law, which is used to describe the surface brightness (i.e. projected density) profile of galaxies. Einasto's model has been used to describe many types of system, including galaxies,[2] and dark matter halos.[3] See also[edit] NFW profile References[edit] External links[edit] Spherical galaxy models with power-law logarithmic slope.
Neutrinos: faster than the speed of light? By Frank Close To readers of Neutrino, rest assured: there is no need yet for a rewrite based on news that neutrinos might travel faster than light. I have already advertised my caution in The Observer, and a month later nothing has changed. If anything, concerns about the result have increased. The response to my article created some waves. I already mentioned some of the problems with the experiment – how it measures the time and the distance involved at huge accuracy, and then takes the ratio to get a speed. This aspect of my personal mystery typifies the problems that the actual experimenters have. A neutrino is detected in Italy, 500 miles from CERN, and the time is recorded. More theoretical perhaps, but from a Nobel Laureate, Sheldon Glashow, comes evidence of an inconsistency in the evidence for super-luminal neutrinos. Ultimately though, as I said in The Observer article, it is experiment that decides and it doesn’t matter how many theorists say nay.
10 Creepy Plants That Shouldn't Exist We spend a lot of time here at Cracked pointing out horrors of nature that slither on the land and lurch through the sea. But staying under the radar in nature's landscape of nightmares is the twisted carnival of things that grow out of the ground. Like ... Bleeding Tooth Fungus The bleeding tooth fungus looks kind of like a wad of chewing gum that leaks blood like a rejected prop from The Shining. They're also called the strawberries and cream, the red-juice tooth, and the devil's tooth. Oh, and they are listed as "inedible," which implies that someone attempted to eat one at some point. Chinese Black Batflowers There's a good reason that Batman uses bat imagery to strike terror into the hearts of Gotham's criminals, rather than, say, some kind of shrew. It is kept as an ornamental plant by gardeners who prefer to cultivate nightmares, and have the balls to live in the presence of a plant that looks like it crawled out of a Bosch painting and wants to plant its young in their head.
Dark-energy star Hypothetical object that potentially explains accelerating universal expansion A dark-energy star is a hypothetical compact astrophysical object, which a minority of physicists think might constitute an alternative explanation for observations of astronomical black hole candidates. The concept was proposed by physicist George Chapline. The theory states that infalling matter is converted into vacuum energy or dark energy, as the matter falls through the event horizon. The space within the event horizon would end up with a large value for the cosmological constant and have negative pressure to exert against gravity. There would be no information-destroying singularity.[1] Theory[edit] In March 2005, physicist George Chapline claimed that quantum mechanics makes it a "near certainty" that black holes do not exist and are instead dark-energy stars. In the dark-energy star hypothesis, infalling matter approaching the event horizon decays into successively lighter particles. See also[edit]
Baryon A baryon is a composite subatomic particle made up of three quarks (as distinct from mesons, which comprise one quark and one antiquark). Baryons and mesons belong to the hadron family, which are the quark-based particles. The name "baryon" comes from the Greek word for "heavy" (βαρύς, barys), because, at the time of their naming, most known elementary particles had lower masses than the baryons. As quark-based particles, baryons participate in the strong interaction, whereas leptons, which are not quark-based, do not. The most familiar baryons are the protons and neutrons that make up most of the mass of the visible matter in the universe. Background[edit] Baryons are strongly interacting fermions — that is, they experience the strong nuclear force and are described by Fermi−Dirac statistics, which apply to all particles obeying the Pauli exclusion principle. Baryons, along with mesons, are hadrons, meaning they are particles composed of quarks. Baryonic matter[edit] Baryogenesis[edit]
Mészáros effect From Wikipedia, the free encyclopedia Evolution of Cold Dark Matter perturbations The Mészáros effect "is the main physical process that alters the shape of the initial power spectrum of fluctuations in the cold dark matter theory of cosmological structure formation".[1] It was introduced in 1974 by Péter Mészáros[2] considering the behavior of dark matter perturbations in the range around the radiation-matter equilibrium redshift and up to the radiation decoupling redshift . an additional distinct growth period which alters the initial fluctuation power spectrum, and allows sufficient time for the fluctuations to grow into galaxies and galaxy clusters by the present epoch. in which , the variable , and is the length scale parametrizing the expansion of the Universe. .
Trapping flying qubits in a crystal (and getting them back out) Quantum computers come in many different shapes and forms, but the granddaddy of them all is based on light. This is because it is very easy to create the basic computational unit, called a qubit, from light. The big problem is the memory unit. Light has a pesky habit of traveling quite fast, so by the time you are ready to use your carefully prepared qubit, it is halfway to the Moon, never to return. A pair of research groups, working independently, showed an effective and reliable memory for light-based qubits. There are three key elements that make a quantum computer special: superposition, coherence, and entanglement. If we limit ourselves to light, there are still many possible ways to encode a qubit on a photon. Why was memory so difficult? But memory is a problem. Unfortunately, it's not as simple as sticking a bit of material in the path of the photon and hoping that the photon will be absorbed. No, to store the quantum state, one needs to carefully prepare the material.