Uncertainty reigns over Heisenberg's measurement analogy A row has broken out among physicists over an analogy used by Werner Heisenberg in 1927 to make sense of his famous uncertainty principle. The analogy was largely forgotten as quantum theory became more sophisticated but has enjoyed a revival over the past decade. While several recent experiments suggest that the analogy is flawed, a team of physicists in the UK, Finland and Germany is now arguing that these experiments are not faithful to Heisenberg's original formulation. Heisenberg's uncertainty principle states that we cannot measure certain pairs of variables for a quantum object – position and momentum, say – both with arbitrary accuracy. The better we know one, the fuzzier the other becomes. When Heisenberg proposed the principle in 1927, he offered a simple physical picture to help it make intuitive sense. Not necessarily wrong Optical conformations Now, Paul Busch at the University of York and colleagues have published calculations that defend Heisenberg's position.
A Critical Test of Quantum Criticality +Enlarge image APS/Martin Klanjšek Every physicist knows how a ferromagnet like iron behaves as the temperature is increased [Fig. 1(a)]. At low temperatures, the constituent spins are spontaneously aligned as a result of the local magnetic fields from neighboring spins. Thermal fluctuations act against such local fields, inducing random reorientation of the spins. Fluctuations driving quantum phase transitions are of a different nature, however. Research on quantum criticality in the past two decades has focused on heavy-fermion metals [2, 3]. To better understand the experiments focused on quantum criticality, a smaller number of relevant degrees of freedom should be involved, which brings us to magnetic insulators. A nice example is [6] where spins are ferromagnetically coupled into Ising chains. The researchers at McMaster University have now studied the nature of the quantum fluctuations across the entire phase diagram of . References S. About the Author: Martin Klanjšek
Scientists Found a Genetic Switch to Reverse Aging in Neurons Another day, another step towards that elusive fountain of youth—thanks, this time, to a new study that claims scientists have effectively reversed the effects of aging in neurons. Just last week, a study out of Italy revealed that neurons—specifically mouse neurons—could live much longer than usual when transplanted into a longer-living organism. Or, as we put it here at Motherboard, that “Brain Cells May Live Longer When Not Tied to Their Weakling, Mortal Flesh.” But what good is a brain that lives forever if that brain is an old fuddy duddy? According to a study published this week in the journal, Neuron, researchers at the Yale School of Medicine isolated a gene in mice that allowed them to reverse that change. “It suggests we can turn back the clock in the adult brain and recover from trauma the way kids recover,” said neurologist, Stephen Strittmatter, the paper’s senior author, in a Yale news release. The Nogo Receptor also impairs memory loss. Lead image via MeZu
Higgs boson: Call to rename particle to acknowledge other scientists 22 April 2013Last updated at 13:00 ET By Pallab Ghosh Science correspondent, BBC News "Fathers" of the Higgs, L-R: Francois Englert, Peter Higgs, Carl Hagen and Gerald Guralnik One of the scientists who helped develop the theory of the Higgs boson says the particle should be renamed. Carl Hagen believes the name should acknowledge the work of others - not just UK physicist Peter Higgs. The long-running debate has been rekindled following speculation that this year's Nobel Prize for Physics will be awarded for the Higgs theory. The detection of a particle thought to be the Higgs was announced at the Large Hadron Collider in July last year. American Prof Hagen told BBC News: "I have always thought that the name was not a proper one. Continue reading the main story “Start Quote Peter Higgs was treated as something of a rock star and the rest of us were barely recognised. End QuoteProf Carl HagenRochester University, New York Peter Higgs is open to a name change to "H Boson" Nobel Prize
Quantum bounce could make black holes explode A. Corichi/J.P. Ruiz The collapse of a star into a black hole could be a temporary effect that leads to the formation of a 'white hole', suggests a new model based on a theory known as loop quantum gravity. Black holes might end their lives by transforming into their exact opposite — 'white holes' that explosively pour all the material they ever swallowed into space, say two physicists. The theory suggests that the transition from black hole to white hole would take place right after the initial formation of the black hole, but because gravity dilates time, outside observers would see the black hole lasting billions or trillions of years or more, depending on its size. Albert Einstein’s general theory of relativity predicts that when a dying star collapses under its own weight, it can reach a stage at which the collapse is irreversible and no known force of nature can stop it. In a loop Information paradox All in the timing
Perovskite Perovskite (pronunciation: pe'ɹovskaɪt) is a calcium titanium oxide mineral species composed of calcium titanate, with the chemical formula CaTiO3. The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856).[1] Occurrence[edit] Perovskite is found in contact carbonate skarns at Magnet Cove, Arkansas. Special characteristics[edit] The stability of perovskite in igneous rocks is limited by its reaction relation with sphene. Physical properties[edit] Perovskites have a cubic structure with general formula of ABO3. t=(RA+RO)/(√2 (RB+RO)) where RA, RB and RO are the ionic radii of A and B site elements and oxygen, respectively. Layered perovskites[edit] Perovskites may be structured in layers, with the above ABO3 structure separated by thin sheets of intrusive material. Geologic occurrence[edit] Discovery and name[edit] See also[edit] References[edit] ^ Jump up to: a b Perovskite.
Planck constant Plaque at the Humboldt University of Berlin: "Max Planck, discoverer of the elementary quantum of action h, taught in this building from 1889 to 1928." In 1905 the value (E), the energy of a charged atomic oscillator, was theoretically associated with the energy of the electromagnetic wave itself, representing the minimum amount of energy required to form an electromagnetic field (a "quantum"). Further investigation of quanta revealed behaviour associated with an independent unit ("particle") as opposed to an electromagnetic wave and was eventually given the term photon. The Planck relation now describes the energy of each photon in terms of the photon's frequency. Since the frequency , wavelength λ, and speed of light c are related by λν = c, the Planck relation for a photon can also be expressed as The above equation leads to another relationship involving the Planck constant. The energy of a photon with angular frequency ω, where ω = 2πν, is given by Value[edit] Origins[edit]
Quantum "spooky action at a distance" travels at least 10,000 times faster than light Quantum entanglement, one of the odder aspects of quantum theory, links the properties of particles even when they are separated by large distances. When a property of one of a pair of entangled particles is measured, the other "immediately" settles down into a state compatible with that measurement. So how fast is "immediately"? Despite playing a vital role in the development of quantum theory, Einstein felt philosophically at odds with its description of how the universe works. Niels Bohr and Albert Einstein debating quantum theory in the mid 1920s In 1935 Einstein and his coworkers discovered quantum entanglement lurking in the equations of quantum mechanics, and realized its utter strangeness. Einstein, as the primary prophet of relativity theory, was revolted by the notion of nonlocality, and hence regarded the EPR result as a demonstration that underlying quantum mechanics was a deterministic hidden-variable theory. Space-time diagram of Prof.
Limb regeneration: do salamanders hold the key? Salamander (credit: UCL) The secret of how salamanders successfully regrow body parts is being unravelled by University College London (UCL) researchers in a bid to apply it to humans. For the first time, researchers have found that the “ERK pathway” must be constantly active for salamander cells to be reprogrammed, and hence able to contribute to the regeneration of different body parts. The team identified a key difference between the activity of this pathway in salamanders and mammals, which helps us to understand why humans can’t regrow limbs and sheds light on how regeneration of human cells can be improved. The study published in Stem Cell Reports (open access) demonstrates that the ERK pathway is not fully active in mammalian cells, but when forced to be constantly active, it gives the cells more potential for reprogramming and regeneration. Salamander cells being reprogrammed, and hence re-entering the cell cycle to divide. Abstract of Stem Cell Reports paper
Quantum spacetime In mathematical physics, the concept of quantum spacetime is a generalization of the usual concept of spacetime in which some variables that ordinarily commute are assumed not to commute and form a different Lie algebra. The choice of that algebra still varies from theory to theory. As a result of this change some variables that are usually continuous may become discrete. Often only such discrete variables are called "quantized"; usage varies. The idea of quantum spacetime was proposed in the early days of quantum theory by Heisenberg and Ivanenko as a way to eliminate infinities from quantum field theory. Physical reasons have been given to believe that physical spacetime is a quantum spacetime. are already noncommutative, obey the Heisenberg uncertainty principle, and are continuous. Again, physical spacetime is expected to be quantum because physical coordinates are already slightly noncommutative. The Lie algebra should be semisimple (Yang, I. Bicrossproduct model spacetime[edit] .
Golden Ratio Discovered in the Quantum World | Science By Rakefet TavorEpoch Times Staff Created: January 19, 2010 Last Updated: June 17, 2012 PICTURING THE GOLDEN RATIO: Scientists fired neutrons at cobalt niobate particles, finding resonant notes with the golden ratio. (Tennant/HZB) The “golden ratio,” which is equal to approximately 1.618, can be found in various aspects of our life, including biology, architecture, and the arts. But only recently was it discovered that this special ratio is also reflected in nanoscale, thanks to researchers from the U.K.’s Oxford University, University of Bristol, and Rutherford Appleton Laboratory, and Germany’s Helmholtz-Zentrum Berlin for Materials and Energy (HZB). Their research, published in the journal Science on Jan. 8, examined chains of linked magnetic cobalt niobate (CoNb2O6) particles only one particle wide to investigate the Heisenberg Uncertainty Principle. Neutrons were fired at the cobalt niobate particles to detect the resonant notes. Dr.
The ERK Signal Transduction Pathway Its Role in Growth Factor Signaling and Cancer Contents Growth factors, through receptor tyrosine kinases, recruit a large network of signaling proteins to execute their cellular programs. The first of these networks to be discovered was the Ras-Raf-ERK signal transduction cascade, defined by Extracellular Signal-regulated Kinase-1 (ERK1) and ERK2.1 One of four Mitogen-Activated Protein Kinase (MAPK) signaling pathways, the ERK phosphorylation cascade's importance in intracellular signaling has been compared to the role of the Krebs cycle in energy metabolism.2 The ERK cascade functions in cellular proliferation, differentiation, and survival, and its inappropriate activation is a common occurrence in human cancers. Upstream from ERK During growth factor stimulation, the ERK phosphorylation cascade is linked to cell surface receptor tyrosine kinases (RTKs) and other upstream signaling proteins with known oncogenic potential (Figure 1).3 RTKs Adaptors Ras The Core Module Raf Assess Enzyme Activity
Bohr and beyond: a century of quantum physics › Opinion (ABC Science) In Depth › Analysis and Opinion Our understanding of the quantum world began with Niels Bohr's discovery of the quantum atom in 1913. Bohr would be astounded by where his theory has since led, says Professor David Jamieson. Bohr's discovery of the quantum nature of the atom, published when he was a young man of 28, was an important pioneering contribution to the earliest days of quantum physics. This field emerged to explain the common sense-defying behaviour of atoms, molecules and light at the smallest scales, forming the foundations on which we have built one of the greatest and most successful theories of all time — quantum mechanics. What is quite remarkable to modern eyes was that Bohr had very little to go on. The true nature of the atom as an incredibly tiny nucleus surrounded by a cloud of orbiting electrons had only been discovered a few years earlier, in the separate work of physicists Thomson and Rutherford. ^ to top Bohr's quantum atom: nature is digital From theory to evidence