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  • richardmitnick 9:28 am on May 22, 2017 Permalink | Reply
    Tags: , , Bose–Einstein condensates simulate transformation of elusive magnetic monopoles, COSMOS, Dirac monopole, ,   

    From COSMOS: “Bose–Einstein condensates simulate transformation of elusive magnetic monopoles” 

    Cosmos Magazine bloc

    COSMOS

    22 May 2017
    Robyn Arianrhod

    For the first time physicists have experimentally simulated a long-predicted relationship between two kinds of magnetic monopole.

    1
    Left: The quantum monopole. Right: the Dirac monopole. The different colors represent the direction of the internal magnetic state of the atoms and the brightness corresponds to particle density.
    Tuomas Ollikainen

    A team of physicists led by David Hall from Amherst College, USA, and Mikko Möttömen from Aalto University, Finland, has experimentally demonstrated the relationship between two different analogues of magnetic monopoles. The results, published in Physical Review X, provide the first demonstration of quantum monopole dynamics.

    The new research builds on a decade of earlier work, by Hall and Möttömen as well as by other teams, which focused on trying to synthesize monopole analogues in the first place.

    2
    No image credit. http://io9.gizmodo.com/5620547/ask-a-physicist-what-ever-happened-to-magnetic-monopoles

    Real magnetic monopoles – the magnetic counterparts of electrons and protons, the fundamental negative and positive electric charges that make up the atoms in our universe – have yet to be observed. Magnets always have two poles, north and south, and so far no amount of metaphorical slicing and dicing has been able to isolate separate north and south poles: rather, cutting a magnet in two simply produces two magnets, each with a north and a south pole.

    This asymmetry between electricity and magnetism has long puzzled physicists. It also spoils the beauty of James Clerk Maxwell’s celebrated 1864 equations of electromagnetism. But there is no theoretical reason not to put the symmetry back into Maxwell’s equations, by adding in magnetic “charges” (monopoles) analogous to the electric charges, and in 1931, pioneering British quantum physicist Paul Dirac showed how to reinterpret the relevant quantum mechanical equations in this light. He found that the force between two opposite magnetic monopoles would be nearly 5000 times as strong as the force between an electron and a proton. No wonder, he mused, that no-one has yet been able to separate magnetic poles. Which is why physicists have recently turned to simulating monopoles.

    “My feeling is that some of the details associated with the Dirac monopole are not fully appreciated by the wider physics community,” says Hall. Experiments can help physicists to better understand this elegant theory, and ultimately, perhaps, point to ways of discovering whether or not real monopoles exist. But there are also potential practical benefits.

    Back in 2009, Jonathan Morris was part of a team from Berlin’s Helmholtz Centre that found magnetic monopole analogues in strange structures known as “spin-ice”, and he believes we could be in for a slew of new technologies using simulated monopoles. But first, he cautions, “we must get to the bottom of how monopoles behave”.

    And that means spending many hours in the lab – hours that often involve “a lot of unglamorous day-to-day problem-solving,” as Hall puts it. Working out how to remove “noise” from everyday magnetic fields created by overhead power lines, computers, and the Earth itself was a real headache in the early research, Hall laments; in these latest delicate experiments, even something as simple as a pair of steel scissors had to be banned from the lab.

    To isolate and study their monopole analogues, Hall, Möttönen and their colleagues used a cloud of extremely cold rubidium atoms.

    (This is known as a Bose–Einstein condensate, or BEC for short.

    4
    Condensed matter physics
    Phase diagram of a second order quantum phase transition
    Author DG85

    Theoretically predicted in 1924, the first BEC was not actually made until 1995; its creators received the 2001 Nobel Prize for physics. Following in their footsteps, Hall and his undergraduate students at Amherst made their own atomic refrigerator in 2002, and it is still going strong.)

    A BEC acts as a sort of magnifying glass, because the cloud of atoms, cooled to almost absolute zero, behaves in just the same way as if it were a single quantum particle. This “magnification” makes it possible to observe and photograph the way a BEC “electron” behaves in a simulated magnetic monopolar field, or the way a “monopole” forms. It’s about making a model of something that is not really electromagnetic, but which behaves just the way quantum mechanics says that an electron or a magnetic monopole should behave.

    By contrast, a number of international teams have found that “spin-ice” does seem to contain a lattice of monopoles that are really magnetic, although they, too, are analogues of the free-moving real monopoles that would parallel electrons and protons. Each experimental analogue adds to physicists’ knowledge, and in the latest research, Hall, Möttönen and their colleagues have taken their model to a new level by demonstrating the relationship between analogues of Dirac monopoles and “isolated” or “topological” monopoles.

    Predicted by t’Hooft and Polyakov in 1974, an “isolated” monopole is mathematically different from Dirac’s version, but theory says that at a suitable distance it effectively becomes a Dirac monopole.

    Hall’s team began by allowing a simulated “isolated” monopole to evolve in time.

    “This is where noise can really wreak havoc,” says Hall. “The problem is compounded because to study the process over time, we don’t simply take a movie of a sample, one frame after the other, but we have to take each frame with a different sample, waiting a little longer after the creation [of the isolated monopole analogue] to take each successive frame. It’s as if you create the movie set, take a picture, and then the set is destroyed. Then you recreate the set, wait a little longer, take the picture, and it is destroyed again. It’s annoying enough to have to recreate the set every time you need another frame of the movie. Now imagine that every time the director calls ‘Action!’ the scene props are being blown randomly all over the place because it is violently windy.” The winds are the “noise” that needs to be filtered out before the data can be interpreted.

    But these laborious experiments have hit paydirt: for the first time, physicists have observed the spontaneous creation of a Dirac monopole analogue from the decay of a simulated t’Hooft–Polyakov monopole.

    5
    Artistic view of the decay of a quantum-mechanical monopole into a Dirac monopole. Credit: Heikka Valja. phys.org

    “I was jumping in the air the first time I saw it,” says Möttönen. As for Hall, “I knew to expect this from the theory, but to see it in the data – that was pretty wild. It felt like watching a sculpture take form from a block of marble.”

    See the full article here .

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  • richardmitnick 9:54 am on May 16, 2017 Permalink | Reply
    Tags: , , , , COSMOS,   

    From COSMOS: “Exoplanet’s rotation speed may hold key to life” 

    Cosmos Magazine bloc

    COSMOS

    16 May 2017
    Andrew Masterson

    1
    An artist’s impression of the surface of Proxima-B. ESO / M. Kornmesser

    How fast the exoplanet Proxima-B rotates on its axis could determine its climate and the possibility of it containing life.

    The planet, discovered in August 2016, orbits the star Proxima Centauri, 4.2 million light-years from the Sun and is thought to be the closest candidate beyond the Solar System for hosting extraterrestrial life.

    A new study published in Astronomy and Astrophysics, using the complex weather and climate modeling tools that comprise the UK Met Office’s Unified Model, indicates Proxima-B’s atmospheric stability is affected by how often it rotates compared to how often it orbits its host star.

    The research, led by Ian Boutle, found Proxima-B’s rotational speed – known as “resonance” – significantly affected the area of the planet’s surface that could sustain liquid water, considered to be a critical precursor for life to exist.

    Previous studies have picked Proxima-B as a prime life candidate because the Earth-sized planet orbits its star within the “habitable zone”, a distance far enough from Proxima Centauri to prevent water vapour boiling away but close enough to stop it turning to ice.

    Whether the planet actually has water vapour is, of course, unconfirmed – a probe would have to travel more than 50 million kilometres to get close enough to take a cloud sample.

    The researchers therefore derived their conclusions from two possible atmospheric models – one similar to Earth’s, and another comprising just nitrogen with a small amount of carbon dioxide. They then used the Unified Model to run the numbers on a range of possible orbit-to-rotation variations – known as “eccentricities”.

    One possibility considered was a “tidally locked” scenario, in which the rotational period matched the orbital period. The Moon is an excellent example here: its rotation of the Earth lasts exactly as long as its orbit, which is why we always only see one side of it.

    Another modelled eccentricity is known as a 3:2 resonance. In this scenario Proxima-B would rotate three times during every two orbits around the star. This is similar to Mercury’s behaviour.

    The researchers also factored in the fact that light from Proxima Centauri sits much more towards the infrared end of the spectrum than light from the Sun.

    “These frequencies of light interact much more strongly with water vapour and carbon dioxide in the atmosphere,” explains co-author James Manners, “which affects the climate that emerges in our model.”

    The results of the computer simulations show very stable atmospheres produced by both the tidally locked and 3:2 models, but with the latter resulting in much larger areas of the planet being potentially habitable.

    See the full article here .

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  • richardmitnick 6:57 am on May 16, 2017 Permalink | Reply
    Tags: , COSMOS, EPR paradox, , , , , Spooky action at a distance   

    From COSMOS: “Using Einstein’s ‘spooky action at a distance’ to hear ripples in spacetime” 

    Cosmos Magazine bloc

    COSMOS

    16 May 2017
    Cathal O’Connell

    1
    The new technique will aid in the detection of gravitational waves caused by colliding black holes. Henze / NASA

    In new work that connects two of Albert Einstein’s ideas in a way he could scarcely have imagined, physicists have proposed a way to improve gravitational wave detectors, using the weirdness of quantum physics.

    The new proposal, published in Nature Physics, could double the sensitivity of future detectors listening out for ripples in spacetime caused by catastrophic collisions across the universe.

    When the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves in late 2015 it was the first direct evidence of the gravitational waves Einstein had predicted a century before.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    Now it another of Einstein’s predictions – one he regarded as a failure – could potentially double the sensitivity of LIGOs successors.

    The story starts with his distaste for quantum theory – or at least for the fundamental fuzziness of all things it seemed to demand.

    Einstein thought the universe would ultimately prove predictable and exact, a clockwork universe rather than one where God “plays dice”. In 1935 he teamed up with Boris Podolsky and Nathan Rosen to publish a paper they thought would be a sort of reductio ad absurdum. They hoped to disprove quantum mechanics by following it to its logical, ridiculous conclusion. Their ‘EPR paradox’ (named for their initials) described the instantaneous influence of one particle on another, what Einstein called “spooky action at a distance” because it seemed at first to be impossible.

    Yet this sally on the root of quantum physics failed, as the EPR effect turned out not to be a paradox after all. Quantum entanglement, as it’s now known, has been repeatedly proven to exist, and features in several proposed quantum technologies, including quantum computation and quantum cryptography.

    2
    Artistic rendering of the generation of an entangled pair of photons by spontaneous parametric down-conversion as a laser beam passes through a nonlinear crystal. Inspired by an image in Dance of the Photons by Anton Zeilinger. However, this depiction is from a different angle, to better show the “figure 8” pattern typical of this process, clearly shows that the pump beam continues across the entire image, and better represents that the photons are entangled.
    Date 31 March 2011
    Source Entirely self-generated using computer graphics applications.
    Author J-Wiki at English Wikipedia

    Now we can add gravity wave detection to the list.

    LIGO works by measuring the minute wobbling of mirrors as a gravitational wave stretches and squashes spacetime around them. It is insanely sensitive – able to detect wobbling down to 10,000th the width of a single proton.

    At this level of sensitivity the quantum nature of light becomes a problem. This means the instrument is limited by the inherent fuzziness of the photons bouncing between its mirrors — this quantum noise washes out weak signals.

    To get around this, physicists plan to use so-called squeezed light to dial down the level of quantum noise near the detector (while increasing it elsewhere).

    The new scheme aids this by adding two new, entangled laser beams to the mix. Because of the ‘spooky’ connection between the two entangled beams, their quantum noise is correlated – detecting one allows the prediction of the other.

    This way, the two beams can be used to probe the main LIGO beam, helping nudge it into a squeezed light state. This reduces the noise to a level that standard quantum theory would deem impossible.

    The authors of the new proposal write that it is “appropriate for all future gravitational-wave detectors for achieving sensitivities beyond the standard quantum limit”.

    Indeed, the proposal could as much as double the sensitivity of future detectors.

    Over the next 30 years, astronomers aim to improve the sensitivity of the detectors, like LIGO, by 30-fold. At that level, we’d be able to hear all black hole mergers in the observable universe.

    ESA/eLISA, the future of gravitational wave research

    However, along with improved sensitivity, the proposed system would also increase the number of photons lost in the detector. Raffaele Flaminio, a physicist at the National Astronomical Observatory of Japan, points out in a perspective piece for Nature Physics [no link], Flaminio that the team need to do more work to understand how this will affect ultimate performance.

    “But the idea of using Einstein’s most famous (mistaken) paradox to improve the sensitivity of gravitational-wave detectors, enabling new tests of his general theory of relativity, is certainly intriguing,” Flaminio writes. “Einstein’s ideas – whether wrong or right – continue to have a strong influence on physics and astronomy.”

    See the full article here .

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  • richardmitnick 5:54 am on May 16, 2017 Permalink | Reply
    Tags: , Campi Flegrei volcano, COSMOS,   

    From COSMOS: “A sleeping Italian supervolcano rumbles closer to eruption” 

    Cosmos Magazine bloc

    COSMOS

    16 May 2017
    Jessica Snir

    1
    A crate full of sulphurous rocks surrounded by steam and smoke from the Solfatara volcano, part of the Campi Flegrei. Andrea Pistolesi

    The Campi Flegrei volcano situated to the west of Naples in southern Italy has been stirring for the past 67 years. Similar stirrings were recorded for a century before its last great week-long eruption, in 1538.

    Now, new research from University College London (UDL) and the Vesuvius Observatory in Naples suggests that another eruption of the supervolcano may be more imminent than previously anticipated.

    The research, published in Nature Communications, finds that the periods of unrest occurring intermittently since the 1950s – namely small-scale, local earthquakes and ground uplifts – have led to the accumulation of energy within the volcanic crust and an increased susceptibility to eruption.

    The discovery of this cumulative effect is contrary to an earlier belief that the energy built up during each period of unrest dissipated afterwards.

    To investigate the activity of Campi Flegrei and attempt to forecast future eruptions, the researchers utilised a new model of volcano fracturing developed at UCL involving detailed physical models of how the ground is cracking and moving at the site.

    “We don’t know when or if this long-term unrest will lead to an eruption, but Campi Fleigrei is following a trend we’ve seen when testing our model on other volcanoes,” explains Dr Christopher Kilburn of UCL. “It may be approaching a critical stage where further unrest will increase the possibility of an eruption.”

    Rather than a conical mountain-like volcano, Campi Flegrei manifests as a large caldera, an enormous depression in the surface, covering a colossal 100 square kilometres.

    Episodes of unrest since 1950 have together raised the port of Pozzuoli more than three metres out of the sea and forced the evacuation of the town.

    An eruption of Campi Fleigrei now would devastatingly affect not only the 360,000 residents of the caldera region but also the nearly one million people in neighbouring Naples.

    “We must be ready for a greater amount of local seismicity,” explained Professor Giuseppe De Natale, former Director of the Vesuvius Observatory. “We must adapt our preparations for another emergency.”

    See the full article here .

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  • richardmitnick 6:32 am on May 15, 2017 Permalink | Reply
    Tags: , COSMOS, , ,   

    From COSMOS: “Physicists sketch plans for a matter-wave tractor beam” 

    Cosmos Magazine bloc

    COSMOS

    15 May 2017
    Robyn Arianrhod

    1
    UFO-style tractor beams may not be in the cards, but matter waves could provide an unprecedented ability to manipulate particles at microscopic scales.
    Aaron Foster / Getty

    A team of physicists have outlined a means of making tractor beams to push and pull objects at a distance using “matter waves”, those strange analogues of light waves that underlie quantum mechanics.

    Tractor beams, staple tools of science fiction for remotely pulling in space shuttles and yanking away incoming space debris, have been edging into reality in recent years.

    The first real-life tractor beams were made of photons. It is easy to imagine a stream of photons carrying a particle of matter along like a river picking up a leaf and carrying it downstream. What is astounding about tractor beams is that by skilfully manipulating the transfer of momentum from the beam, physicists do not have to rely only on pushing particles, but can make light pull particles of matter, like a tractor. Beams made of sound waves have also been demonstrated in the lab.

    In a paper published last week in Physical Review Letters, Alexey Gorlach from Belarusian State University and colleagues from St Petersburg’s ITMO University and the Technical University of Denmark make the case for using a more exotic, less tangible kind of wave.

    The new research is purely theoretical, but the result is still surprising: “The completely different (probabilistic) interpretation of quantum mechanics does not harm the pulling force phenomenon,” the authors write.

    It’s surprising because matter waves are essentially waves of probability – they point the way to predicting where a particle is most likely to be at any point in time. Yet Gorlach’s team’s calculations suggest that these waves of chance can still be harnessed to pull physical nanoparticles as if they were magnets drawing tiny iron filings.

    “It is the wave nature that is the uniting principle,” the researchers point out: light, sound, and matter waves all behave in similar ways. All have different wavelengths, however, and wavelength determines the size of the particles that can be towed by the tractor beam. (The particle must be smaller than the wavelength of the beam.)

    The wavelength of visible light ranges from about 1000 nanometres to 10 nanometres. In 2014, a team from ANU set the optical record [Nature Photonics] by towing microscopic glass beads for a distance of 20 centimetres. The wavelength of sound is longer than that of light, and in 2015, a team from Bristol [Nature Communications]used these longer waves to pull larger objects (up to a millimetre in diameter).

    At the nanoscale is where matter waves could have an edge. Their wavelengths are much smaller than those of light, and Gorlach’s team are looking at wavelengths of one hundredth of a nanometre.

    Optical and acoustic beams are still in the testing phase, and matter-wave tractor beams are yet to make it into the lab, but the possibilities are huge. Gorlach’s team member Andrey Novitsky outlines one such application: “Matter-wave tractor beams could be used in an electron microscope that enables us not only to see atomic-scale objects with unprecedented precision, but also to manipulate them.”

    See the full article here .

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  • richardmitnick 9:08 am on May 10, 2017 Permalink | Reply
    Tags: A laser-guided path to diamond superconductors?, , COSMOS, , Raman spectroscopy,   

    From COSMOS: “A laser-guided path to diamond superconductors?” 

    Cosmos Magazine bloc

    COSMOS

    10 May 2017
    Andrew Stapleton

    1
    A diamond, recently. Mina De La O / Getty

    Besides glittering beautifully in the sun, diamonds have another attractive property: they can become superconductive. Superconductivity occurs when a material has zero electrical resistance and is normally only seen when the material is chilled to temperatures very close to absolute zero (around –273 °C), which severely limits the use of superconductors in commercial applications.

    Scientists from India and Israel conducted the first systematic study to understand how doping diamond with boron effects its ability to become superconducting. They reported their findings in Applied Physics Letters.

    The scientists fabricated a series of thin diamond films doped with increasing levels of boron and monitored the samples with a technique called Raman spectroscopy. This technique uses pulses of laser light at specific wavelengths to measure the unique energy states in materials. Raman spectroscopy can be used for analysing the makeup of material or, as in this study, to watch how the energy states are affected by impurities.

    Associate Professor Rongkun Zheng of the University of Sydney, a physicist not involved with the study, said: “Raman scattering probes the vibration and rotation of atoms or molecules in a sample, which is related to the superconductivity of the material.”

    The team noticed a remarkable change in the energy states of the doped diamond. They concluded that their study provided a new understanding of how impurities effect the energy levels in diamonds and, perhaps more tenuously, that this could lead to a superconductive material that doesn’t have to be chilled to absolute zero.

    The results, they believe, could inform the fabrication of materials for future applications such as high-performance electrical grids and high-speed transport.

    Zheng, however, is less convinced. “The paper emphasised superconductivity but did not explore the effect on superconductivity. The significance and quality of this paper is very limited.”

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  • richardmitnick 1:03 pm on May 9, 2017 Permalink | Reply
    Tags: , , , , COSMOS, RAISE (Rapid Acquisition Imaging Spectrograph Experiment),   

    From COSMOS: “A simple rocket for staring at the sun” 

    Cosmos Magazine bloc

    COSMOS

    09 May 2017
    Jana Howden

    1
    The RAISE rocket being prepared for take-off. Amir Caspi, Southwest Research Institute

    Capable of snapping 1,500 images in just five minutes, NASA’s newly launched rocket is raising the bar on studies of the sun. RAISE (Rapid Acquisition Imaging Spectrograph Experiment) is a type of sounding rocket, a relatively simple and cost-effective rocket that goes up 300 kilometres and spends 15–20 minutes making observations from above the atmosphere before returning to the ground.

    Although NASA runs several missions geared towards continuous study of the sun, this new sounding rocket, RAISE will allow researchers to study the fast processes and split-second changes occurring near the sun’s active regions.

    These active regions are areas of complex and intense magnetic activity that can cause solar flares, which spew energy and solar material into space.

    “With RAISE, we’ll read out an image every two-tenths of a second, so we can study very fast processes and changes on the sun,” explains Don Hassler, principal investigator for the RAISE mission.

    The data collected by RAISE can be used to create what’s called a spectrogram – a visual representation of the light emitted by the sun at different wavelengths. Looking at the intensity of light at these different wavelengths allows scientists to study the ways in which energy and solar material moves around the sun, and how this can evolve into solar eruptions.

    RAISE was launched on 5 May from a missile range in the US state of New Mexico, soaring to an altitude of around 296 kilometres before parachuting gently down to Earth, where the machine is to be recovered and reused.

    Read more at NASA.

    Related Links

    More about NASA’s sounding rocket program

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  • richardmitnick 9:07 am on May 8, 2017 Permalink | Reply
    Tags: A neutron-to-proton mass ratio of 1.00137841887 makes them weapons of mass creation, , COSMOS,   

    From COSMOS: “A neutron-to-proton mass ratio of 1.00137841887 makes them weapons of mass creation” 

    Cosmos Magazine bloc

    COSMOS

    04 May 2017
    Paul Davies

    1
    Did the Great Cosmic Designer initially intend the proton and neutron to have same mass but then threw in a bit more for the neutron as an afterthought? Jeffrey Phillips

    Galileo famously wrote that the book of nature is “written in mathematical language”. It’s true that numbers crop up everywhere in the lives of scientists and engineers. But not all numbers are equal: some numbers are much more significant than others. The number of kookaburras in New South Wales on Christmas Day may be of interest to ornithologists, but is hardly of cosmic importance.

    A few numbers do seem to be fundamental to the workings of the universe, however, because they describe the most basic processes of nature. High on this list are the masses of subatomic particles. Dozens of particles are known to physicists, but the most familiar are the constituents of atoms: electrons, protons and neutrons. The proton is about 1,836 times as heavy as the electron; nobody knows why nature picked that particular number. The neutron is very slightly heavier than the proton, by about 0.1%, or 1.00137841887 according to the best measurements. Why is this? Did the Great Cosmic Designer initially intend the proton and neutron to have same mass but then threw in a bit more for the neutron as an afterthought?

    The neutron-proton mass difference may seem trivial but it has momentous consequences, because mass is a form of energy (remember E = mc2). The neutron, as it happens, has a little more mass (and thus energy) than a proton and an electron combined. There is a general principle in nature that physical systems, when left alone, seek out their lowest energy state. Sure enough, an isolated neutron will soon, within about 15 minutes on average, spontaneously turn into an electron and a proton, a process known as beta decay. (Another particle, called an antineutrino, is also involved, but that need not concern us here because it is almost massless.) The only reason that any neutrons still exist is because, within a few minutes after the hot big bang that made the universe, some neutrons stuck themselves to protons. The strong neutron-proton binding force changes the energy balance – not by much, but enough to stabilise the neutrons.

    Had the Great Designer done it the other way round, with protons about 0.1% heavier than neutrons, disaster would ensue. Under these circumstances, isolated protons would turn into neutrons rather than the other way around. Some protons would be saved by attaching to neutrons. But hydrogen, the simplest chemical element, does not contain a stabilising neutron; hydrogen atoms consist of just a proton and an electron. In this backward universe, hydrogen could not exist. Nor could there be any stable long-lived stars, which use hydrogen as nuclear fuel. Heavier elements such as carbon and oxygen, made in large stars, might never form either. Without stable protons there could be no water and probably no biology. The universe would be very different.

    The fact that the universe we know, including our own existence within it, hinges so delicately on the precise value of the neutron-to-proton mass ratio has led to heated debate among scientists. Was it just a lucky fluke that the laws of physics turned out this way? Or does it suggest something more profound?

    Scientists are disinclined to believe in luck, so there has been a surge of interest in the multiverse theory, according to which our universe, with its neutron-to-proton mass ratio of 1.00137841887, is but one among many. Other universes will have different ratios and possibly only a tiny fraction will contain water and stars that go on to form atoms like carbon, from which life may arise. Only in that fraction could there be observers to ponder the fact. It is then no surprise that we find ourselves in a universe where the neutron mass is so judiciously poised to permit complex chemistry and our presence as thinking, observing beings.

    The foregoing argument hinges on the possibility that the masses of the neutron and proton are “free parameters” – that is, they could have been different. That seemed to be the case back in the 1950s when the critical value of the mass ratio was first discussed. However, we now know that neutrons and protons are not in fact elementary particles (unlike the electron, which seems to be). Rather, they are composite bodies with smaller particles inside them. Known as quarks, these subnuclear constituents have their own masses. There is also an enormous quantity of energy inside neutrons and protons due to the immensely strong force that glues the quarks together, and this contributes to the overall mass too (E = mc2 again!). This structural complexity makes it nigh on impossible to work out accurate values for the masses of the proton and neutron by analysis of their constituents – let alone figure out what it would take for the mass contribution of this quark or that quark to shift enough to upset that crucial neutron-to-proton mass ratio.

    So for now, 1.00137841887 is just “one of those numbers” that nature has settled on for no reason humans can fathom. If the value were off just a tad, there would be no humans – Galileo or otherwise – to even attempt the fathoming.

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  • richardmitnick 8:46 am on May 1, 2017 Permalink | Reply
    Tags: , , , COSMOS, , Martian landscape created by two distinct asteroid epochs   

    From COSMOS: “Martian landscape created by two distinct asteroid epochs” 

    Cosmos Magazine bloc

    COSMOS

    01 May 2017
    Tim Wallace

    1
    Major impacts on the Martian surface include the ancient giant Borealis basin (top of globe), Hellas (bottom right), and Argyre (bottom left).There appears to have been a 400-million-year lull in impacts between the formation of Borealis and the younger basins. University of Arizona/LPL/Southwest Research Institute

    It’s magnitude, and infrequency that counts in explaining how asteroid impacts shaped Mars, with new research dramatically revising down the number of giant asteroids that crashed into the Red Planet to just one-tenth of some previous estimates.

    The analysis by planetary scientists Wiilliam Bottke, of the Southwest Research Institute, in Colorado, and Jeff Andrews-Hanna, of the University of Arizona’s Lunar and Planetary Laboration, suggests a lull of 400 million years between two periods of intense asteroid numbers and collisions. The first led to the most significant asteroid impact on Mars 4.5 million years ago, while the second to four more giant impacts between 4.1 and 3.8 million years ago.

    In their paper published in Nature Geoscience, Bottke and Andrews-Hanna argue on the basis of topographical, gravitational and geochemical analyses against there being any gradual decline in impact events.

    Rather, the surface of Mars bears the signature of two distinct periods of intense asteroid activity within the inner Solar System; the earlier period of asteroid impacts associated with the formation of the inner planets; and the later period with the Late Heavy Bombardment, the cause of which a number of explanations have been proposed including the migration of the giant planets.

    The most striking aspect of the topography of Mars is the contrast between the remarkably flat lowlands of it northern hemisphere known as the Borealis basin, covering about 40% of the planet’s surface, and the hilly highlands of the southern hemisphere. The calculations by Bottke and Andrews-Hanna concur with previous estimates the northern polar basin – was formed by the impact of an asteroid between 1,100 and 2,300 kilometres wide.

    Only one subsequent major asteroid impact, creating the basin known as the Isidis Planitia, has impinged upon the Borealis crater, the researchers argue.

    “This sets strong statistical limits on the number of giant basins that could have formed on Mars after Borealis”, says Bottke, who is also a principal investigator with NASA’s Solar System Exploration Research Virtual Institute (SSERVI). “The number and timing of such giant impacts on early Mars has been debated, with estimates ranging from four to 30 giant basins formed in the time since Borealis. Our work shows that the lower values are more likely.”

    The similar preservation states of the between most visible impact structures on Mars – the Borealis basin and the Hellas, Isidis and Argyre craters formed more than 400,000 years later, also points to the lull which Bottke and Andrew-Hanna call “the doldrums”, as any impact basins formed in the interim should have been similarly preserved.

    See the full article here .

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  • richardmitnick 9:26 am on April 27, 2017 Permalink | Reply
    Tags: , COSMOS, Human settlement of North America, Paleo-anthropological evidence, Radiometric dating of butchered mastodon bones   

    From COSMOS: “New evidence places humans in America 130,000 years ago” 

    Cosmos Magazine bloc

    COSMOS

    27 April 2017
    Andrew Masterson

    Radiometric dating of butchered mastodon bones shows humans living in California 115,000 years earlier than any previously known settlement.

    1
    A 19th-century engraving of a mastodon skeleton. THEPALMER

    Human settlement of North America may have occurred at least 115,000 years earlier than thought, if intriguing evidence unearthed in California is correct.

    In a letter published in the journal Nature, a team of researchers led by Steven Holen from the Centre for American Paleolithic Research in South Dakota, USA, reports on the discovery and dating of broken bones found near San Diego 20 years ago.

    The bones belonged to a mastodon (Mammut americanum) – an extinct mammal that looked somewhat like an elephant, or a mammoth – and showed clear marks of human butchery. The site where they were found also contained unambiguous human artifacts, namely hammerstones and anvils.

    The artifacts, together with cut marks on the bones indicating they had been butchered while still fresh, led scientists to conclude that the massive animal had been sliced up to be eaten. However, at the time of the discovery dating methods were insufficiently precise to indicate the age of the remains.

    Revisiting the finds, Holen and his team used a type of radiometric dating that relies on gauging the ratio of uranium to thorium in calcium carbonate material. The method is particularly accurate up to 500,000 years.

    When applied to the mastodon bones, the results were unexpected, establishing that the animal died 130,000 years ago (give or take 10,000). This, in light of the strong evidence suggesting that the beast had met its demise – or at least been dismembered soon after death – by human hands, was stunning.

    All other paleo-anthropological evidence available dates human arrival in the Americas to around 14,500 years ago, at the end of the Pleistocene period. If accurate, the new finding extends the time of settlement by an order of magnitude.

    The evidence, however, does not establish that the ancient mastodon eaters were Homo sapiens. Indeed, it would be very unlikely that they were, given that our species is generally held to have migrated out of Africa only around 60,000 years ago.

    Holen and colleagues state that their “findings confirm the presence of an unidentified species of Homo”.

    The San Diego site, they add “is, to our knowledge, the oldest in situ, well-documented archaeological site in North America and, as such, substantially revises the timing of the arrival of Homo into the Americas”.


    Depiction of Homo breaking up animal

    In an accompanying editorial in Nature, archaeologist Erella Hovers of the Hebrew University of Jerusalem in Israel says the evidence presented by Holen and colleagues has been rigorously researched.

    However, she adds, “the proposed hominin narrative derived from these data has some gaping holes that need filling”.

    She concludes: “Time will tell whether this evidence will bring a paradigm change in our understanding of processes of hominin dispersal and colonisation throughout the world, including in what now seems to be a not-so-new New World.”

    See the full article here .

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