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We're on the Threshold of Unraveling the Biggest Mystery in Modern Physics

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  • derhexerus
    Interesting post about dark matter and dark energy from The Daily Galaxy. Chris ____________________________________ From: vlandi@yahoo.com To:
    Message 1 of 1 , Jan 21, 2013
      Interesting post about dark matter and dark energy from The Daily Galaxy.


      From: vlandi@...
      To: derhexer@...
      Sent: 1/21/2013 6:48:42 P.M. Eastern Standard Time
      Subj: The Daily Galaxy: News from Planet Earth & Beyond

      _The Daily Galaxy: News from Planet Earth & Beyond_


      _"We're on the Threshold of Unraveling the Biggest Mystery in Modern
      Physics" (Weekend Feature)_
      Posted: 21 Jan 2013 08:11 AM PST

      Dark matter makes up about 23 percent of the mass-energy content of the
      universe, even though we don’t know what it is or have yet to directly see it
      (which is why it’s called “dark”). So how can we detect it and when we
      do, what will it reveal about the universe? In mid-October, more than 100
      cosmologists, particle physicists and astrophysicists gathered for a meeting
      called "_Dark Matter_ (http://en.wikipedia.org/wiki/Dark_matter) Universe:
      On the Threshold of Discovery" at the National Academy of Sciences’ Beckman
      Center in Irvine, CA. Their goal: to take stock of the latest theories and
      findings about dark matter, assess just how close we are to detecting it
      and spark cross-disciplinary discussions and collaborations aimed at
      resolving the dark matter puzzle.

      The image above is one of the most detailed maps of dark matter in our
      universe ever created. The location of the dark matter (tinted blue) was
      inferred through observations of magnified and distorted distant galaxies seen
      in this picture.

      "Figuring out what is dark matter has become a problem that
      astrophysicists, cosmologists and particle physicists all want to solve, because dark
      matter is central to our understanding of the universe," says _Michael S.
      Turner_ (http://en.wikipedia.org/wiki/Michael_Turner_(cosmologist)) – Rauner
      Distinguished Service Professor and Director of the Kavli Institute for
      Cosmological Physics at the University of Chicago. "We now have a compelling
      hypothesis, namely that dark matter is comprised of WIMPs (_Weakly Interacting
      Massive Particle_
      (http://en.wikipedia.org/wiki/Weakly_interacting_massive_particles) ), particles that don’t radiate light and interact rarely with
      ordinary matter. After decades of trying to figure out how to test the idea
      that dark matter is made up of WIMPs, we have three ways to test this
      hypothesis. Best of all, all three methods are closing in on being able to
      either confirm or falsify the WIMP. So the stars have truly aligned."
      A theoretical cosmologist trained in both particle physics and
      astrophysics, Michael Turner coined the term “dark energy” and helped establish the
      interdisciplinary field that combines cosmology and elementary particle
      physics. "Ten years ago," Turner says, "I don't think you would've found
      astronomers, cosmologists, and particle physicists all agreeing that dark matter
      was really important. And now, they do. And all of them believe we can
      solve the problem soon. It's wonderful listening to particle physicists explain
      the evidence for dark matter, and vice versa –astronomers explaining WIMPs
      as dark matter. At this meeting nobody said, “Oh, I don't really believe
      in the evidence. Nor did anyone say, “Yikes – a new form of matter. That’s
      _Maria Spiropulu_ (http://en.wikipedia.org/wiki/Maria_Spiropulu) –
      Professor of Physics at _California Institute of Technology_
      (California%20Institute%20of%20Technology)&t=h) who also works on experiments at
      the _Large Hadron Collider_
      (http://maps.google.com/maps?ll=46.2333333333,6.05&spn=0.01,0.01&q=46.2333333333,6.05%20(Large%20Hadron%20Collider)&t=h) ,
      and a former fellow at the _Enrico Fermi Institute_
      6666667 (Enrico%20Fermi%20Institute)&t=h) , observed that "One important
      thing we’ve seen at this meeting is a crossing of professional boundaries
      that have separated researchers in many different fields in the past. These
      boundaries have been strict. Cosmologists, astrophysicists and particle
      physicists, however, have now really started talking to one another about dark
      matter. We’re only beginning and our language – the way speak to each
      other – is not yet settled so that we completely understand each other; but we
      are on the threshold of discovering something very important for all of us.
      This is critical because cosmologists and particle physicists have talked
      for a long time about how the very big and very small might be linked. And
      while the particle physicists study the very small with colliders,
      cosmologists study the galaxies and billions and billions of stars that make up
      the large-scale structure we see in the universe."
      "The convergence of inner space and outer space really started in the
      1980s, said Turner."Back then it began with the origin of the baryon asymmetry,
      the monopole problem and dark matter to a lesser extent. Particle
      physicists agreed that dark matter was a real problem but said, “The solution could
      be astrophysics – faint stars, ‘Jupiters’, black holes and the like.” It’
      s been a long road to get to where we are now, namely where we all agree
      that the most compelling solution is particle dark matter. And even today,
      the different fields are still, in a sense, getting to know one another."
      "As cosmologists," said _Rocky Kolb_
      (http://en.wikipedia.org/wiki/Edward_Kolb) , who studies the application of elementary-particle physics to the
      _very early Universe_ (http://en.wikipedia.org/wiki/Timeline_of_the_Big_Bang)
      , and is the co-author with Michael Turner of The Early Universe, the
      standard textbook on particle physics and cosmology, "one of our jobs is to
      understand what the universe is made of. To a good approximation, the galaxies
      and other structures we see in the universe are made predominantly of dark
      matter. We have concluded this from a tremendous body of evidence, and now
      we need to discover what exactly is dark matter. The excitement now is
      that we are closing in on an answer, and only once in the history of humans
      will someone discover it. There will be some student or postdoc or
      experimentalist someplace who is going to look in the next 10 years at their data,
      and of the seven or so billion people in the world that person will discover
      what galaxies are mostly made of. It's only going to happen once."
      "The dark matter story started with fragmentary evidence discovered by
      Fritz Zwicky, a Swiss American," Turner pointed out."He found that there were
      not enough stars in the galaxy clusters he observed to hold them together.
      Slowly, more was understood and finally dark matter became a centerpiece of
      cosmology. And now, we have established that dark matter is about 23
      percent of the universe; ordinary matter is only 4½ percent; and dark energy is
      that other 73 percent – which is an even bigger puzzle. Nothing in
      cosmology makes sense without dark matter. We needed it to form galaxies, stars and
      other structures in the Universe. And so it's absolutely central to
      cosmology. We also know that none of the particles known to exist can be the dark
      matter particle. So it has to be a new particle of nature. Remarkably, our
      most conservative hypothesis right now is that the dark matter is a new
      form of matter – out there to be discovered and to teach us about particle
      physics. An experimental particle physicist, Maria Spiropulu is interested
      in the search for dark matter at the Large Hadron Collider at CERN (The
      _European Organization for Nuclear Research_
      )&t=h) ), and questions about dark matter that cut across particle
      physics, astrophysics and cosmology."
      Maria Spiropulu added that "The phenomenon of dark matter was discovered
      from astronomical observations. We know that galaxies hang together and they
      don't fly apart, and it’s the same with clusters of galaxies. So we know
      that we have structure in the universe. Whatever it is that keeps it there,
      in whatever form it is, we call that dark matter. This is the way I teach
      it to undergraduates. It’s a fantastical story. It's still a mystery and so
      it’s “dark,” but the universe and its structures – galaxies and
      everything else we observe in the macroscopic world – are being held together
      because of it."
      "Dark matter is absolutely central to cosmology, said Turner, "and the
      evidence for it comes from many different measurements: the amount of
      deuterium produced in the big bang, the cosmic microwave background, the formation
      of structure in the Universe, galaxy rotation curves, gravitational
      lensing, and on and on."
      What is dark matter? We don’t know, but cosmologists, astrophysicists and
      experimental particle physicists say they are closing in on an
      answer.Knowing exactly what dark matter is is less important than the work done already
      – measuring its gravitational influence on ordinary matter, estimating how
      much of the universe is made from it, and affirming that what we do know
      about it fits with the standard model of cosmology.
      "There is five times more dark matter than ordinary matter, and its
      existence allows us to understand the history of the universe beginning from a
      formless particle soup until where we are today," said Turner. "If you said,
      'You no longer have dark matter,' our current cosmological model would
      collapse. We would be back to square one."
      "The hypothesis that dark matter is made up of WIMPs – and that it was
      produced by normal particles, say quarks, in the early universe – is an
      amazing achievement all by itself, observed Kolb. "Independent of a lot of the
      details of what goes on there and exactly how that happens, we expect that
      you should be able to reverse things and produce WIMPs in particle
      accelerators. We also expect they should be annihilating today in the galaxy, which
      we should be able to detect indirectly. Now, it's another issue who will be
      the first to find WIMPs. It's possible that it will be another 30 years
      before we do that, but we should be able to make a detection – whether it’s
      direct or indirect."
      Marion Spiropulu answered that "With the Large Hadron Collider, and before
      that the Tevatron collider, we have been chasing and targeting the dark
      matter candidate. For us, the optimism is because the LHC is working and we’
      re collecting a lot of data. In the standard model of particle physics, when
      we enlarge it to help explain how the universe began and evolved, we have
      a story that is a mathematical story. It’s very good at describing how we
      can have dark matter. And if the mathematics accurately describes reality,
      then the LHC is now achieving the energies that are needed to produce dark
      matter particles. Getting to these high energies is critical, and we are
      even going to higher energies. When we were building the standard model of
      particle physics, we kept saying that the next particle discovery that we
      predicted was 'right around the corner.'In other words, we were not, and we are
      not, flying in the dark. We are guided by a huge amount of data and
      knowledge, and while you might think there are infinite possibilities of what
      can happen, the data actually points you to something that is more probable.
      For example, we have found the Higgs-like particle, but that was predicted.
      So the next big step for this edifice of knowledge is to find something
      that will look like supersymmetry – a hypothesis that, if true, offers a
      perfect candidate for dark matter. We call it a miracle, because the
      mathematics works. But the way nature works, in the end, is what you see in the data.
      So if we find it, there is no miracle."
      "Dark matter particles, or WIMPs," said Turner, "don’t interact with
      ordinary matter often. It's taken 25 years to improve the sensitivity of our
      detectors by a factor of a million, and now they have a good shot at detecting
      the dark matter particles. Because of the technological developments, we
      think we are on the cusp of a direct detection. Likewise for indirect
      detection. We now have instruments like the Fermi satellite (the Fermi Gamma-ray
      Space Telescope) and the IceCube detector (the IceCube Neutrino Observatory
      at the South Pole) that can detect the ordinary particles (positrons,
      gamma rays or neutrinos) that are produced when dark matter particles
      annihilate, indirectly allowing dark matter to be detected. IceCube is big enough to
      detect neutrinos that are produced by dark matter annihilations in the
      Answering the observation that the dark matter particle might not be
      detectable, Turner said that for 20 to 30 years, this idea that dark matter is
      part of a unified theory has been our Holy Grail and has led to the WIMP
      hypothesis and the belief that the dark matter particle is detectable. "But
      there’s a new generation of physicists that is saying, 'Well, there's an
      alternative view. Dark matter is actually just the tip of an iceberg of another
      world that is unrelated to our world. And I cannot even tell you about
      that world. There are no rules for that other world, at least that we know of
      yet.' Sadly, this point of view could be correct and might mean the
      solution to the dark matter problem is still very far away, that discovering what
      dark matter actually is could be 100 years away.
      Michael Witherell, Professor of Physics at the University of California,
      Santa Barbara, said that nature doesn't guarantee an observation, which
      Turner said is ture. But that we have the WIMP hypothesis and it is
      falsifiable. And there's a good chance it's true. A “good chance” in this business
      means 10 percent or 20 percent. *"It's easy to say that wimps will be
      discovered in “A decade.” said Kolb. "LHC is turning on now. It'll be another
      year or so before they are at full energy, and they may run a couple of years
      to accumulate data. Meanwhile, the Fermi satellite is in space making
      observations. And then we have experiments underground: a detection may come
      with Xenon100, one dark matter experiment now underway in central Italy, or
      some successor to Xenon100. In ten years, if there is no indication of
      supersymmetry or a WIMP – either from direct detection or indirect detection
      searches – then there is going to be a sea change. Now, there is not going to
      be one experiment announcement that says, 'OK, let's look at something
      else.' But if ten years from now there is no evidence, then we are going to
      other possibilities. You could not have said that ten years ago, or even five
      years ago. Today, I think you can say that."
      "I think it's fair to say the discovery is 'around the corner,” said
      Spiropulu. "If we continue with exclusions, then we have to come up with better
      ideas. We are doing all this because we want to characterize dark matter.
      We are not just saying, “It is dark matter.” We don't want to just say, “
      The universe is.” We want to know exactly what it is made of. We want to know
      the dynamics and what it involves. A lot of work is ahead of us. Somebody
      said that it's not going to be as easy as finding the Higgs. Well, finding
      the Higgs was extremely nontrivial. Of course, once we find it, it goes in
      the pool of knowledge and then you say, “Well, it was easy.”
      "Ee need to discover what exactly is dark matter. The excitement now is
      that we are closing in on an answer, and only once in the history of humans
      will someone discover it." said Rocky Kolb.
      The Daily Galaxy via _http://www.kavlifoundation.org_
      Image Credit: NASA/JPL-Caltech/ESA/Institute of Astrophysics of Andalusia,
      University of Basque Country/JHU

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      _NASA Spacecraft finds Evidence of an Ancient Lake on Mars' Crater Floor_
      Posted: 21 Jan 2013 09:46 AM PST

      NASA's Mars Reconnaissance Orbiter is providing spectrometer data that
      shows a wet underground environment on Mars on the floor of McLaughlin Crater
      that adds to an increasingly complex picture of the Red Planet's early
      evolution. The Martian crater is 57 miles (92 kilometers) in diameter and 1.4
      miles (2.2 kilometers) deep. McLaughlin's depth apparently once allowed
      underground water, which otherwise would have stayed hidden, to flow into the
      crater's interior. Layered, flat rocks at the bottom of the crater contain
      carbonate and clay minerals that form in the presence of water. McLaughlin
      lacks large inflow channels, and small channels originating within the
      crater wall end near a level that could have marked the surface of a lake. The
      crater sits at the low end of a regional slope several hundreds of miles,
      or kilometers, long on the western side of the _Arabia Terra_
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      region of Mars. As on Earth, groundwater-fed lakes are expected to occur
      at low regional elevations. Therefore, this site would be a good candidate
      for such a process.Together, these new observations suggest the formation
      of the carbonates and clay in a groundwater-fed lake within the closed
      basin of the crater. Some researchers propose the crater interior catching the
      water and the underground zone contributing the water could have been wet
      environments and potential habitats. The findings are published in Sunday's
      online edition of _Nature Geoscience_ (http://www.nature.com/ngeo/) .
      "Taken together, the observations in McLaughlin Crater provide the best
      evidence for carbonate forming within a lake environment instead of being
      washed into a crater from outside," said Joseph Michalski, lead author of the
      paper, which has five co-authors. Michalski also is affiliated with the
      _Planetary Science Institute_ (http://www.psi.edu/) in Tucson, Ariz., and
      London's _Natural History Museum_
      (http://maps.google.com/maps?ll=51.495983,-0.176372&spn=0.01,0.01&q=51.495983,-0.176372 (Natural%20History%20Museum)&t=h)
      . Michalski and his co-authors used the _Compact Reconnaissance Imaging
      Spectrometer for Mars_ (http://en.wikipedia.org/wiki/CRISM) (CRISM) on the
      Mars Reconnaissance Orbiter (MRO) to check for minerals such as carbonates,
      which are best preserved under non-acidic conditions.
      " Launched in 2005, the Mars Reconnaissance Orbiter and its six
      instruments have provided more high-resolution data about the Red Planet than all
      other Mars orbiters combined. Data are made available for scientists worldwide
      to research, analyze and report their findings.
      "A number of studies using CRISM data have shown rocks exhumed from the
      subsurface by meteor impact were altered early in Martian history, most
      likely by hydrothermal fluids," Michalski said. "These fluids trapped in the
      subsurface could have periodically breached the surface in deep basins such as
      McLaughlin Crater, possibly carrying clues to subsurface habitability."
      "This new report and others are continuing to reveal a more complex Mars
      than previously appreciated, with at least some areas more likely to reveal
      signs of ancient life than others," said Mars Reconnaissance Orbiter
      Project Scientist Rich Zurek of NASA's _Jet Propulsion Laboratory_
      118.171666667 (Jet%20Propulsion%20Laboratory)&t=h) .
      The Daily Galaxy via NASA
      Image credit: This view of layered rocks on the floor of McLaughlin Crater
      shows sedimentary rocks that contain spectroscopic evidence for minerals
      formed through interaction with water. Image credit: NASA/JPL-Caltech/Univ.
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