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  • richardmitnick 9:01 am on July 10, 2014 Permalink | Reply
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    From BBC: “LHC scientists to search for ‘fifth force of Nature'” 

    BBC

    10 July 2014
    Pallab Ghosh

    The next couple of years will be make or break for the next big theory in physics called supersymmetry – SUSY for short. It might make way for a rival idea which predicts the existence of a ‘fifth force’ of nature.

    Next Spring, when the Large Hadron Collider (LHC) resumes its experiments, scientists will be looking for evidence of SUSY. It explains an awful lot that the current theory of particle physics does not. But there is a growing problem, provocatively expressed by Nobel Laureate George Smoot: “supersymmetry has got symmetry and it’s super but there is no experimental data to suggest it is correct.”

    CERN LHC Grand Tunnel
    LHC tunnel

    CERN LHC New
    LHC map

    According to the simplest versions of the theory, supersymmetric particles should have been discovered at the LHC by now. One set of null results prompted Prof Chris Parkes, of the LHCb to quip: “Supersymmetry may not be dead but these latest results have certainly put it into hospital”.

    But other forms of the theory are still very much in play.

    Next year will be an important year for SUSY. The LHC will be smashing atoms together at almost twice the energy it did in its first run. Even those who are still strong advocates of SUSY, such as Cern’s revered professor of theoretical physics, John Ellis, agree that if LHC scientists do not find super particles in the LHC’s second run, it might be time for the hospital patient to be moved to the mortuary.

    “If it is not found in LHC run two then there will be relatively few corners it could hide,” he told BBC News.

    “I know that at that point the community may decide that the guys who predicted supersymmetry are dying off like flies and that young guys will be interested in different types of theories and supersymmetry may be forgotten. But I don’t think we are at that point yet.”
    LHC Tunnel Engineers have spent more than a year upgrading the LHC’s systems. The hope is that this will allow a new realm of physics to be opened up

    One of those young guys is Thibaut Mueller, a 24-year-old PhD student at Cambridge University. He is already checking out alternatives to SUSY.

    “A few years ago we thought it was a case of who will be first to find supersymmetry,” he said.

    “Now there is less and less focus on it and more people are starting to branch out into other models.”

    Mr Mueller’s PhD looks at an alternative to supersymmetry called the composite Higgs model. This idea has been around for decades but is undergoing a resurgence as some researchers raise questions over supersymmetry. Physicists will be looking for evidence for it in the next run of the LHC in 2015.

    Thibault’s colleague Dr Ben Gripaios believes that the Composite Higgs theory is now a serious alternative to supersymmetry.
    Continue reading the main story

    “SUSY was regarded by many people as the perfect theory. We have been looking really hard for it for a long time and we have not found it and so possibly there is a different explanation. For me the most compelling alternative is the Composite Higgs. It is just as plausible as supersymmetry,” he told BBC News.

    The current theory to explain the forces of nature was developed in the 1960s and is called the Standard Model. It elegantly explains how 13 particles, including the Higgs, interact to create three of the four forces of nature: electromagnetism, and the nuclear strong and weak forces.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    But the Standard Model does not explain how gravity works, nor can it account for the [dark] matter and [dark] energy that makes up 95% of the Universe – referred to by physicists as the “Dark Universe”.

    Supersymmetry is an extension of the Standard Model and is an attempt to explain some of the things the current theory can’t.
    Super particles The stage has been set for some years for the detection of super particles. But so far they have been a no show.

    It predicts the existence of so-called superparticles which account for much of the missing mass and energy of the Universe.

    Supersymmetry standard model
    Supersymmetry standard model

    Supersymmetry also neatly solves what physicists describe as the “fine tuning problem”. In very crude terms, all subatomic particles can be thought to have two values for their mass: Their mass in isolation which is called their “bare” mass, and their experimental mass, which includes interactions with other sub-atomic particles.

    For all particles the two masses are about the same, except for the Higgs, whose bare mass must be many times larger than its experimental mass.

    Going from such a relatively big number to a small number is an unlikely occurrence, rather like a skydiver landing on the head of a pin each time they jump out of a plane. It can only happen if there is an overarching force guiding the skydiver on to the pin head – something that physicists call “fine tuning”.

    The existence of superparticles interacting with their normal counterparts fine tunes the Higgs’s two masses perfectly. The drawback though is that there is no evidence of SUSY, at least not yet.

    The composite Higgs theory also solves the fine tuning problem, albeit less elegantly and, just as with SUSY, there is no experimental evidence for it. It supposes that the Higgs is not a fundamental particle, but is instead made up of other fundamental particles bound together by a hitherto unseen fifth force of nature. This is similar to what is already known to happen with the strong nuclear force, which binds quarks together to produce nuclear particles like protons and neutrons.

    Scientists at the LHC hope to detect evidence for one or other theory when they resume their experiments in April. In effect, the starting gun goes off in an invisible two-horse race where the winner emerges only at the finish line. Supersymmetry is still the favourite in the minds of most particle physicists, but Thibaut Mueller thinks that the likelihood of finding evidence for composite Higgs theory is not far behind.

    Why then is this promising youngster gambling his still early career on the outsider?

    High risk

    “This is a high risk, high gain game,” he explained. “If we find either (SUSY or the composite Higgs) this would be the biggest revolution in particle physics and possibly the whole of physics since quantum mechanics in the the 1940s.

    “Even if we do not find evidence for SUSY or composite Higgs, we will still have learned important facts about the Standard Model, which will guide us to new theories”.

    Of course, the researchers may see neither, which raises the possibility that no fine tuning is needed to turn the big Higgs into the little Higgs.

    That would mean that we live in a Universe where the dice are loaded to ensure that the Higgs experimental mass will always improbably land neatly on its bare mass each and every time.

    In the absence of evidence for either theory, this anthropic principle might seem like a tempting option. But it’s one that those on the front line of research vehemently resist.

    According to Thibault Mueller that view is a “conversation stopper”.

    “It says that ‘we are special because we as humans are here to observe it and so we exist’. If we accept that then we might as well give up science altogether.

    “We (have established) that we as a species are not special, the Earth is not special, our Solar System is not special. Now we are saying: ‘Ah! Our Universe is not that special either’.”

    Prof Rolf Dieter Heuer, the director-general of the European Centre for Nuclear Research (Cern) recently told researchers at the International Conference on High Energy Physics (ICHEP) in Valencia, that there was “a lot at stake” for the LHC’s second run starting next year.

    Indeed there is: careers, reputations and deeply cherished ideas.

    But whatever the outcome, physicists are preparing themselves for the ride of their lives. As Prof Heuer told the physics community: “There’s much more to be discovered in the Dark Universe”.

    See the full article here.


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  • richardmitnick 4:53 am on April 12, 2014 Permalink | Reply
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    From BBC: “Dark matter hunt: LUX experiment reaches critical phase” 

    BBC

    8 April 2014
    Rebecca Morelle

    The quest to find the most mysterious particles in the Universe is entering a critical phase, scientists say.

    An experiment located in the bottom of a gold mine in South Dakota, US, could offer the best chance yet of detecting dark matter.

    Scientists believe this substance makes up more than a quarter of the cosmos, yet no-one has ever seen it directly.

    Early results from this detector, which is called LUX, confirmed it was the most powerful experiment of its kind.

    LUX Dark matter

    In the coming weeks, it will begin a 300-day-long run that could provide the first direct evidence of these enigmatic particles.

    Spotting WIMPs

    Beneath the snow-covered Black Hills of South Dakota, a cage rattles and creaks as it begins to descend into the darkness.

    For more than 100 years, this was the daily commute for the Homestake miners searching for gold buried deep in the rocks.

    Today, the subterranean caverns and tunnels have been transformed into a high-tech physics laboratory.

    Scientists now make the 1.5km (1-mile) journey underground in an attempt to solve one of the biggest mysteries in science.

    “We’ve moved into the 21st Century, and we still do not know what most of the matter in the Universe is made of,” says Prof Rick Gaitskell, from Brown University in Rhode Island, one of the principle investigators on Large Underground Xenon (LUX) experiment.

    lux
    The LUX detector is located 3km underground – and could be our best hope yet of finding dark matter

    Scientists believe all of the matter we can see – planets, stars, dust and so on – only makes up a tiny fraction of what is actually out there.

    They say about 85% of the matter in the Universe is actually dark matter, so called because it cannot be seen directly and nobody really knows what it is.

    This has not stopped physicists coming up with ideas though. And the most widely supported theory is that dark matter takes the form of Weakly Interacting Massive Particles, or WIMPs.

    Prof Gaitskell explains: “If one considers the Big Bang, 14bn years ago, the Universe was very much hotter than it is today and created an enormous number of particles.

    “The hypothesis we are working with at the moment is that a WIMP was the relic left-over from the Big Bang, and in fact dominates over the regular material you and I are made of.”

    hills
    The Homestake gold mine, which has now been converted into a lab, is in the Black Hills of South Dakota

    The presence of dark matter was first inferred because of its effect on galaxies like our own.

    As these celestial systems rotate around their dense centre, all of the regular matter that they contain does not have enough mass to account for the gravity needed to hold everything together. Really, a spinning galaxy should fly apart.

    Instead, scientists believe that dark matter provides the extra mass, and therefore gravity, needed to hold a galaxy together.

    It is so pervasive throughout the Universe that researchers believe a vast number of WIMPs are streaming through the Earth every single second. Almost all pass through without a trace.

    However, on very rare occasions, it is thought that dark matter particles do bump into regular matter – and it is this weak interaction that scientists are hoping to see.

    The LUX detector is one of a number of physics experiments based in the Sanford Underground Research Facility that require a “cosmic quietness”.

    Prof Gaitskell says: “The purpose of the mile of rock above is to deal with cosmic rays. These are high-energy particles generated from outside our Solar System and also by the Sun itself, and these are very penetrating.

    “If we don’t put a mile of rock between us and space, we wouldn’t be able to do this experiment.”

    Inside a cavern in the mine, the detector is situated inside a stainless steel tank that is two storeys high.

    tank
    The detector is in housed in a tank that is filled with purified water

    This is filled with about 300,000 litres (70,000 gallons) of ultra-purified water, which means it is free from traces of naturally occurring radioactive elements that could also interfere with the results.

    “With LUX, we’ve worked extremely hard to make this the quietest verified place in the world,” says Prof Gaitskell.

    At the detector’s heart is 370kg (815lb) of liquid xenon. This element has the unusual, but very useful, property of throwing out a flash of light when particles bump into it.

    And detecting a series of these bright sparks could mean that dark matter has been found.

    The LUX detector was first turned on last year for a 90-day test run. No dark matter was seen, but the results concluded that it was the most sensitive experiment of its kind.

    Now, when the experiment is run for 300 days, Prof Gaitskell says these interactions might be detected once a month or every few months.

    The team would have to see a significant number of interactions – between five and 10 – to suggest that dark matter has really been glimpsed. The more that are seen, the more statistical confidence there will be.
    detect
    LUX uses light detectors called photomultiplier tubes to record any flashes of light

    However, LUX is not the only experiment setting its sights on dark matter.

    With the Large Hadron Collider, scientists are attempting to create dark matter as they smash particles together, and in space, telescopes are searching for the debris left behind as dark matter particles crash into each other.

    CERN LHC New
    LHC at CERN

    Mike Headley, director of the South Dakota Science and Technology Authority, which runs the Sanford laboratory, says a Nobel prize will very probably be in store for the scientists who first detect dark matter.

    He says: “There are a handful of experiments located at different underground laboratories around the world that want to be the first ones to stand up and say ‘we have discovered it’, and so it is very competitive.”

    Finding dark matter would transform our understanding of the Universe, and usher in a new era in fundamental physics.

    However, there is also a chance that it might not be spotted – and the theory of dark matter is wrong.

    Dr Jim Dobson, based at the UK’s University of Edinburgh and affiliated with University College London, says: “We are going into unknown territory. We really don’t know what we’re going to find.

    “If we search with this experiment and then the next experiment, LUX Zeppelin, which is this much, much bigger version of LUX – if we didn’t find anything then there would be a good chance it didn’t exist.

    He adds: “In some ways, showing that there was no dark matter would be a more interesting result than if there was. But, personally, I would rather we found some.”

    Prof Carlos Frenk, a cosmologist from Durham University, says that many scientists have gambled decades of research on finding dark matter.

    He adds: “If I was a betting man, I think LUX is the frontrunner. It has the sensitivity we need. Now, we just need the data.

    “If they don’t [find it], it means the dark matter is not what we think it is. It would mean I have wasted my whole scientific career – everything I have done is based on the hypothesis that the Universe is made of dark matter. It would mean we had better look for something else.”

    See the full article here.


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  • richardmitnick 5:51 pm on March 10, 2013 Permalink | Reply
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    Brian Cox, BBC Wonders of Life 

    It is no secret in these pages that I believe that Brian Cox, Sir Brian Cox, physicist, teacher, TV darling, is the best thing to happen for Basic Science Research ever.

    Brian was the host of The Big Bang Machine about the LHC at CERN, which was featured here.

    Brian also did the BBC produced Wonders of the Solar System, Wonders of the Universe and so far two series of Stargazing.

    Now comes also from the BBC Wonders of Life, Brian’s latest bit of programming. The program is truly a wonder in itself. Pretty much all of the above you can find on YouTube with some searching.

    Here is the first video in Wonders of Life to get you started.

     
  • richardmitnick 2:58 pm on February 27, 2013 Permalink | Reply
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    From BBC: “First glimpse of a black hole’s spin” 

    BBC News

    Astronomers have measured the rate of spin of a supermassive black hole for the first time – and it is big.

    spin

    Measurements undertaken with two space-based X-ray telescopes imaged the black hole at the centre of galaxy NGC 1365

    1365
    NGC 1635 Credit:ESO

    The spin measurement, published in Nature, gives precious clues as to how the black hole grew and achieved supermassive status.

    Now Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics and colleagues have looked at markedly higher energies – less subject to absorption in those gas layers – using Europe’s XMM-Newton telescope and the recently launched Nu-Star telescope.

    ESA XMM Newton
    ESA XMM Newton

    NASA NuSTAR
    NASA Nu-Star

    Nustar is unprecedented in its ability to focus in on distant parts of the cosmos in these high-energy X-rays. The results suggest a black hole more than 3 million km across, whose outermost edge is moving at a speed near that of light.”

    Expansion from Lawrence Livermore Lab

    ‘We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole,’ said Fiona Harrison, NuSTAR principal investigator at the California Institute of Technology, Pasadena, and coauthor of a new study appearing in the Feb. 28 edition of Nature. ‘The radiation we see is warped and distorted by the motions of particles, and by the black hole’s incredibly strong gravity.’

    The formation of supermassive black holes is thought to mirror the formation of the galaxy itself, since a fraction of all the matter drawn into the galaxy finds its way into the black hole. Because of this, astronomers are interested in measuring the spin rates of black holes in the hearts of galaxies.

    The observations also are a powerful test of Einstein’s theory of general relativity, which holds that gravity can bend light and space-time. The X-ray telescopes detected these warping effects in the most extreme of environments, where the immense gravity field of a black hole is severely altering space-time.

    NuSTAR and XMM-Newton simultaneously observed the two-million-solar-mass supermassive black hole lying at the dust and gas-filled heart of a galaxy called NGC 1365. The results showed that the black hole is spinning close to the maximal rate allowed by Einstein’s theory of gravity.”

    See the full article here.

     
  • richardmitnick 2:43 pm on February 20, 2013 Permalink | Reply
    Tags: , , , BBC,   

    From BBC: “Exoplanet Kepler 37b is tiniest yet – smaller than Mercury” 

    BBC News

    20 February 2013
    Jason Palmer

    Astronomers have smashed the record for the smallest planet beyond our Solar System – finding one only slightly larger than our Moon.

    chart

    To spot the tiny, probably rocky planet, they first needed to precisely measure the size of its host star. They did so using astroseismology – effectively, turning tiny variations in the star’s light into sounds. A report in Nature describes the blistering, probably rocky planet, which orbits its star in just 13 days.

    It is joined in this far-flung solar system by two other planets, one three-quarters Earth’s size and one twice as large as Earth. The record for smallest exoplanet is routinely being broken, as astronomers get better and better at finding them.

    The best tool in the planet-hunters’ toolbox is the Kepler space telescope, which stares at a fixed part of the sky, trying to detect the tiny dips in stars’ light that happens when planets pass in front of them: what is called a transit event.

    NASA Kepler Telescope
    NASA Kepler

    In its earliest days, the Kepler team tended to find large planets – Jupiter- and Neptune-sized behemoths. In more recent years, the catalogue of exoplanet has seen an increasing number of so-called super-Earths, up to about twice the radius of our planet. Only recently has something definitively Earth-sized been found. But the new find is a planet just a third the size of that recent record-holder, smaller even than our Solar System’s smallest planet, Mercury.

    ‘I think it’s an amazing technological achievement to be able to be able to detect small rocks like this,’ said Francois Fressin, a co-author of the paper based at the Harvard-Smithsonian Center for Astrophysics.’It means we’re really in the arena where it’s possible to detect all the planets of our Solar System, but around other stars,’ he told BBC News.”

    See the full article here.

     
  • richardmitnick 12:31 pm on February 18, 2013 Permalink | Reply
    Tags: , , , , BBC, ,   

    From BBC: “Alpha Magnetic Spectrometer to release first results” 

    BBC News

    18 February 2013
    Jonathan Amos

    The scientist leading one of the most expensive experiments ever put into space says the project is ready to come forward with its first results.
    The Alpha Magnetic Spectrometer (AMS) was put on the International Space Station to survey the skies for high-energy particles, or cosmic rays. Nobel Laureate Sam Ting said the scholarly paper to be published in a few weeks would concern dark matter.

    Alpha Magnetic Spectrometer
    AMS

    This is the unseen material whose gravity holds galaxies together. Researchers do not know what form this mysterious cosmic component takes, but one theory points to it being some very weakly interacting massive particle (or Wimp for short).

    The Massachusetts Institute of Technology professor said the project he first proposed back in the mid-1990s had now reached an important milestone. ‘We’ve waited 18 years to write this paper, and we’re now making the final check,’ he told reporters.’I would imagine in two or three weeks, we should be able to make an announcement.’

    Although telescopes cannot detect the Wimp, there are high hopes that AMS can confirm its existence and describe some of its properties from indirect measures.

    Alpha Magnetic Spectrometer (AMS-02) is a state-of-the-art particle physics detector constructed, tested and operated by an international team composed of 60 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. The AMS-02 will use the unique environment of space to advance knowledge of the universe and lead to the understanding of the universe’s origin by searching for antimatter, dark matter and measuring cosmic rays.

    See the full BBC article here.

     
  • richardmitnick 8:59 pm on January 16, 2013 Permalink | Reply
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    From BBC: “The Hunt for the Higgs: A Horizon Special” 

    I was hunting around the BBC looking for something else when I came upon an excellent video originally broadcast in January 2012. While it is one year old, and while the question of the Higgs boson is probably very close to being answered*, still this video presents a valuable lesson.

    Our host is Prof JIM AL-KHALILI, OBE, Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey.

    JA
    Prof Jim Al-Khalili

    The video is especially valuable because it ventures into the LHCb Collaboration at CERN’s incredible LHC.

    lhcb

    In this section on the LHCb experiment, the subjects of Broken Symmetry and the theory, to date untested, of Supersymmetry are explored. These subjects were not at all present in the PBS Frontline piece The Atom Smashers (2008), nor the BBC video The Big Bang Machine(2008).

    If you use either the Opera browser or Firefox, there are excellent video download utilities for saving an .mp4 in at least 720p HD.

    I hope that you will enjoy the video and might add it to your collection.

    The BBC page for the video is here.

    *On July 4, 2012 The General Director of CERN, Rolf-Dieter Heuer, announced that both the ATLAS and CMS collaborations had discovered a new particle with a degree of certainty [beyond five Σ (sigma)] which placed the find beyond doubt. The particle was a boson. But, there was not then and there is still not now certainty that the find was the Higgs boson. That has yet to be confirmed. This confirmation might wait until the completion of the International Linear Collider.

     
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