• 2/25/1997 - 1987 supernova still a bright spot for modern-day scientists.
      Supernova 1987A (a star known as Sanduleak -69 202) that died 166,000 years ago in a nearby galaxy, but the first of its kind in modern astronomy, as of 4:35 a.m. Chilean time on Feb. 23, 1987 was detected by the tiny particles known as neutrinos.    This proved the theory that exploding stars emit a burst of neutrinos as they collapse.
      Could this mean that neutrinos is what makes a unified field of space-time?
  

• electron neutrinos, known to have a mass at least 50,000 times smaller than the mass of the electron, and neutrinos are often assumed to be massless, which means zero rest mass.
• muon neutrinos.
• tau neutrinos.

• The energy spectrum of the observable electrons in a radioactive beta decay is modified if the electron neutrino has a non-zero mass.    The unseen neutrinos are emitted uniformly in momentum, but for a massive neutrino the change in energy for momenta up to about 0.5*m*c is small, so a relatively large number of electrons are emitted at close to the maximum energy.    This leads to a large number of electrons being emitted at just below the maximum possible energy, and thus an abrupt decline to zero at the maximum possible energy.    For zero rest mass, the number of electrons per unit energy declines at a constant slope to zero at the maximum energy.    What is actually seen is a smooth transition from zero to a constant slope instead of the "cliff" expected for non-zero mass, so only an upper limit of several eV is obtained for the mass of the electron neutrino.    Radioactive decays producing muon and tau neutrinos are very hard to observe, so this method gives very weak limits on their masses.
• Time-of-flight data can be used to detect the fact that massive neutrinos travel slightly slower than the speed of light.    The speed is given by
  v/c = sqrt[1-(mc²/E)²] = 1 - 0.5 *(mc²/E)² + ...
  which leads to an arrival time difference of
  Dt = (L/c)*0.5*(mc²/E)²
  Since Dt<10 seconds with (L/c)=5*10¹² seconds for 10 MeV neutrinos from SN1987A in the LMC, the mass is less than 20 eV.    All the detected neutrinos from SN1987A were electron neutrinos, so this limit only applies to one of the three types.    The Sudbury Neutrino Observatory (SNO) will be able to detect all three types of neutrinos, and if we are lucky enough to have a nearby supernova SNO may be able to improve the limits on the muon and tau neutrinos.
• Neutrino oscillations: quantum mechanics says that the wavefunction for any particle oscillates at a frequency of mc²/h cycles per second, in the rest frame of the particle.    Relativity says that a particle see a time interval in its rest frame that is smaller by the factor (mc²/E) than the lab frame time interval due to time dilation.    Thus the effective lab frame oscillation frequency of a particle is [mc²]²/[Eh] and the beat frequency between two particles of different masses is
  Df = [c⁴/Eh]*[m₂²-m₁²]
  which is 2.7 kHz for m₁ = 0, m₂c² = 0.1 eV, and E = 1 GeV.    Since it takes 40 msec for neutrinos to travel through the Earth, many cycles of the beat frequency can occur and the neutrinos become a mixture of types when traveling through the Earth.

• If neutrinos are massless then we can compute their equivalent mass density using
  rho = [Q/a³]/c² = N_n (2\sigma/c) (7/8)g_f T_n⁴
  where N_n is the number of neutrinos species: N_n=6 for 3 types of neutrinos and 3 types of anti-neutrinos.
      This density works out to be very small compared to the critical density.
      It is 0.5*[N_n*7/8](4/11)^4/3=0.68 times the equivalent mass density of the photons and only 3*10 grams per cubic centimeter.
      Even though this density is negligible now, it was significant during the time that helium was formed during Big Bang Nucleosynthesis.    The increased density due to the neutrino background during helium synthesis caused the universe to expand faster, and this reduced the time required for the temperature to fall to the point where deuterium could survive.    As a result the helium abundance is a few percent larger than it would have been without the neutrino background.
  
  
• If the neutrinos are not massless, then they could have a larger mass density now consisting of their number density times their rest mass.
      Each neutrino species has a number density of
  n = (3/4) (4\pi)\Gamma(3)\zeta(3) (kT_n/hc)³
  where \Gamma is the gamma function (\Gamma(n=1)=n! so \Gamma(3)=2),
  \zeta is the zeta function \zeta(s) = 1 + 1/2^s = 1/3^s = ... and \zeta(3) = 1/202...
      With T_n=1.947 K now the number density of each neutrino species is 56 per cubic cm.    This is just (3/22) times the number desity of photons at T_p.
      With N_n=6 species the total number density of neutrinos is 336 per cc.
      The mass density for massive neutrnos is then rho = 112*(m_n-e + m_n-mu + m_n-tau) gm/cc
  compared to the critical density of 8*10^-30 gm/cc for H_o=65.
  
  
• Thus a neutrino rest mass of 40 eV for one type would give the critical density in neutrinos, and a rest mass of 10 eV for one type or a sum of test masses of 10 eV would be a significant factor in the formation of large scale structures in the Universe such as clusters and super clusters of galaxies.
      For these masses the neutrinos are traveling slowly now but their thermal velocities were large in the past.    The typical momentum of a relativistic particle in a thermal distribution is p=3kT/c, and the product of the scaled factor and the momentum, ap, is a constant.
      Thus neutrinos with rest mass m will be moving at redshift z with a typical velocity
  v = pc/sqrt[p² + (mc)²] = 3(1+z)k(1.947 K)/mc - ...
  and the distance traveled, measured now (the comoving distance), is
  D = \int (1+z) v dt = 2(c/H_o) sqrt(3*k*(1.947 K))/mc² + ...
  which gives D=100 Mpc for mc²=5 eV in a critical density model H_o=65.
      Thus neutrinos can free stream out of the perturbations that make galaxies and cluster of galaxies, but it will remain in the perturbations that make superclusters.    Because this behavior is caused by the thermal velocity of the neutrinos, this form of dark matter is called Hot Dark Matter.

• 7/20/2000 - Scientists break speed of light - Doctored vapor in tube helped achieve landmark - by Curt Suplee, The Washington Post.
      In a landmark experiment, scientists have broken the cosmic speed limit, causing a light pulse to travel at many times the speed of light -- so fast that the peak of the pulse exited a specially prepared test chamber before it even finished entering it.
      That seems to contradict not only common sense but a bedrock principle of Albert Einstein's theory of relativity, which sets the speed of light in a vacuum, about 186,000 miles per second, as the fastest that anything can go.
      But the findings -- the long-awaited first clear evidence of faster-than-light motion -- are "not at odds with Einstein," said Lijun Wang, who with colleagues at the NEC Research Institute in Princeton reported.    "However," Wang said, "our experiment does show that the generally held misconception that ' nothing can move faster than the speed of light' is wrong."    Nothing with mass can exceed the light-speed limit.    But physicists now believe that a pulse of light -- which is a group of massless, individual waves -- can.
      To demonstrate that, the researchers created a carefully doctored vapor of laser-irradiated atoms that twist, squeeze and ultimately boost the speed of light waves in such abnormal ways that a pulse shoots through the vapor in about 1/300^th the time it would take the pulse to go the same distance in a vacuum.
      As a general rule, light travels more slowly in any medium more dense than a vacuum.    In water, light travels at about three-fourths its vacuum speed; in glass, it's around two-thirds.
      The ratio between the speed of light in a vacuum and its speed in a material is called the refractive index.    The index can be changed slightly by altering the chemical or physical structure of the medium.    Ordinary glass has a refractive index around 1.5, and if lead is added it rises to 1.6.    The NEC researchers did the opposite by creating a gaseous medium which, when manipulated with lasers, exhibits a sudden and precipitous drop in refractive index, Wang said, speeding up passage of a pulse of light.    The team used a 2.5-inch-long chamber filled with a vapor of cesium, a metallic element with a goldish color.    The laser beams on the atoms, put them in a stable but highly unnatural state.
      A pulse of light is drastically reconfigured as it passes through the vapor, with some of the component waves are stretched out, others compressed.    Yet at the end of the chamber, they recombine and reinforce one another to form exactly the same shape as the original pulse, Wang said.    "It's called re-phasing."
      The key issue is that the reconstitued pulse re-forms before the original intact pulse could have gotten there by simply traveling through empty space.
      That is, the peak of the pulse is, in effect, extended forward in time.    Thus the detectors attached to the beginning and end of the vapor chamber show that the peak of the exiting pulse leaves the chamber about 62 billionths of a second before the peak of the initial pulse finishes going in.
      When sunlight, a combination of many different frequencies - passes through a glass prism, the prism disperses, or spreads out, the white light's components.    This happens because each frequency moves at different speed in glass, smearing out the original light beam.    Blue is slowed the most, and thus deflected the farthest; red travels fastest and is bent the least.    That phenomenon produces the familiar rainbow spectrum.
      The NEC laser zapped cesium vapor producing the opposite outcome, by bending red more than blue in a process called "anomalous dispersion," causing a reshuffling of the components of light waves, causing the accelerated re-formation of the pulse, hence the speed-up.
      This is the opposite of an experiment last year by Lene Hau, Harvard University and Stanford physicist S.E. Harris who created ultracold gas of sodium atoms that slowed the speed of light pulse to an amazing 38 mph.
      The NEC results do not violate the fundamental law of causality; namely, that an effect cannot occur before its cause.
      It still leaves in tact that no meaningful signal or energy can exceed light speed.
  
  
• 4/2/2001 - Antarctic telescope detects neutrinos by The Washington Post.
      A telescope 164 stories tall and 400 feet across, buried a mile deep in Antarctic ice, has detected some of the most exotic particles known.    Neutrinos are invisible particles that have no electrical charge or mass.    They are devilishly difficult to catch, but considered worth the bother, because they carry information about the most distant and violent events in the universe.    The telescope has for the first time observed high-energy neutrinos, according to a team of scientists reporting in a recent issue of Nature.    The ability to find high-energy neutrinos promises new insights into such phenomena as colliding black holes, gamma-ray bursters and the wreckage of exploded stars, the researchers said.
• 4/2/2001 - Dark Matter detected by its influences by Gannett News Service.
      Scientists from the United States and the United Kingdom have for the first time detected the presence of dark matter in our galaxy.    Scientists say that to account for the galaxy's rotation, unseen dark matter must exist.    They can detect its presence by its influence on the motion of stars and other galaxies.
      The researchers, who published their work in the journal Science, studied ancient white dwarf stars -- dense, cool, faded stars that no longer produce energy through nuclear fusion.    They found a population of dwarf stars that may account for at least 3 percent of the halo dark matter.    Since these degenerated stars are also very ancient, they could give astronomers a glimpse of the earliest history of our galaxy as well.
  
  
• 12/26/2009 - Will dark matter neutralinos top trump the god particle?    Supersymmetry is SO 2010 By Patrick Goss, World of tech News.
  Found at http://www.techradar.com/news/world-of-tech/will-dark-matter-neutralinos-top-trump-the-god-particle--660224
      All talk (at least around the physics lab water-cooler) may have been about the Higgs Boson – or the God Particle to give it its more dramatic moniker – but the humble neutralino could potentially steal its thunder in the coming year, according to scientists.
      With the Large Hadron Collider now active and continuing on its path to enlighten/destroy humanity, the Higgs Boson could now potentially be spotted for the first time in the twenties/teenies.
      However, according to New Scientist, the as-yet unseen neutralino could be ready to steal in from stage left and elbow its way onto the front pages.
  
  Supersymmetry
  
      For those that aren't sure what the neutralino is (tssk), we can inform you that it is a key part of the theory of supersymmetry – where every elementary particle has a super-partner.
      Perhaps more headline grabbing is the suggestion that neutralino could well be what is generally known as dark matter, and that it could be properly discovered outside of theory in the coming 12 months.
      We wait with baited breath.
  
  
• February 2010 At the Heart of All Matter - The hunt for the God particle by Joel Achenbach, National Geographic.
  Found at http://ngm.nationalgeographic.com/2008/03/god-particle/achenbach-text
      If you were to dig a hole 300 feet straight down from the center of the charming French village of Crozet, you'd pop into a setting that calls to mind the subterranean lair of one of those James Bond villains.    A garishly lit tunnel ten feet in diameter curves away into the distance, interrupted every few miles by lofty chambers crammed with heavy steel structures, cables, pipes, wires, magnets, tubes, shafts, catwalks, and enigmatic gizmos.
      This technological netherworld is one very big scientific instrument, specifically, a particle accelerator-an atomic peashooter more powerful than any ever built.    It's called the Large Hadron Collider, and its purpose is simple but ambitious: to crack the code of the physical world; to figure out what the universe is made of; in other words, to get to the very bottom of things.
      Starting sometime in the coming months, two beams of particles will race in opposite directions around the tunnel, which forms an underground ring 17 miles in circumference.    The particles will be guided by more than a thousand cylindrical, supercooled magnets, linked like sausages.    At four locations the beams will converge, sending the particles crashing into each other at nearly the speed of light.    If all goes right, matter will be transformed by the violent collisions into wads of energy, which will in turn condense back into various intriguing types of particles, some of them never seen before.    That's the essence of experimental particle physics: You smash stuff together and see what other stuff comes out.
  
• Found at http://www.eurekalert.org/pub_releases/2010-01/smu-ndt010810.php
      Contact: Kim Cobb, cobbk@mail.smu.edu, 214-768-7654, Southern Methodist University
  Neutrino data to flow in 2010; NOvA scientists tune design, International collaboration hunting oscillation of muon to electron     Physicists may see data as soon as late summer from the prototype for a $278 million science experiment in northern Minnesota that is being designed to find clues to some fundamental mysteries of the universe.
      But it could take years before the nation's largest "neutrino" detector answers the profound questions that matter to scientists.
      Construction is underway now on a 220-ton detector that is the "integration prototype" for a much larger 14,000-ton detector.    Both are part of NOvA, a cooperative project of the Department of Energy's Fermi National Accelerator Laboratory near Chicago and the University of Minnesota's school of physics and astronomy.    The project may ultimately aid understanding of matter and dark matter, how the universe formed and evolved, and current astrophysical events.
      DOE gave approval Oct. 29, 2009 for "full construction start" as part of the American Recovery and Reinvestment Act.    There are 180 scientists and engineers from 28 institutions around the world collaborating on NOvA.
      About 40 scientists from the international collaboration are meeting Jan. 8-10 at Southern Methodist University in Dallas.    The meeting is the first for the collaboration since DOE's approval, said John Cooper, NOvA project manager at Fermilab.    For more information see www.smuresearch.com.    Collaboration scientists will hear technical presentations from one another during the three-day SMU meeting, where they'll refine NOvA's design, including the technical details of software, hardware and calibration, said Thomas Coan, associate professor of physics at SMU and a scientist on the collaboration team.
      The integration prototype, known as the Near Detector because it's at Fermilab, and the larger detector, known as the Far Detector because it's farther from Fermilab — are essentially hundreds of thousands of plastic tubes enclosing a massive amount of highly purified mineral oil.    The purpose is to detect the highly significant fundamental subatomic particle called the "neutrino" and better understand its nature.    NOvA, when construction is completed, will be the largest neutrino experiment in the United States.    "The 'detector prototype' has two purposes," said Cooper.    "First it serves as an 'integration prototype' forcing us to find all the problems on a real device, and second it will become the 'Near Detector' at Fermilab."    The integration prototype will operate on the surface at Fermilab for about a year starting in late summer 2010, Cooper said.    Then in 2012 it will move 300 feet underground to become the Near Detector, he said.    Construction on the Far Detector project began in June near Ash River, Minn. The detector should be fully operational by September 2013, according to Fermilab.
      A hard-to-observe fundamental particle that travels alone, the neutrino has little or no mass, so rarely interacts with other particles.    Neutrinos are ubiquitous throughout our universe.    They were produced during the Big Bang, and many of those are still around.    New ones are constantly being created too, through natural occurrences like solar fusion in the sun's core, or radioactive elements decaying in the Earth's mantle, as well as when the particle accelerator at Fermilab purposely smashes protons into carbon foils.
      Our sun produces so many that hundreds of billions are zinging through our bodies every second, Coan said.    It's hoped the new detector can resolve questions surrounding three different kinds of neutrinos — electron, tau and muon — and their "oscillation" from one type to another as they travel, he said.    Scientists at the new detectors will analyze data from Fermilab's neutrino beam to observe evidence of neutrinos when the speedy, lightweight particles occasionally smash into the carbon nuclei in the scintillating oil of the detector, causing a burst of light flashes, Coan said.
      NOvA is looking for the most elusive oscillation of the muon type of neutrino to the electron type, Cooper said.
      SMU is a private university in Dallas where nearly 11,000 students benefit from the national opportunities and international reach of SMU's seven degree-granting schools.    For more information see www.smuresearch.com.
  
• 2/16/2010 - New results confirm standard neutrino theory Provided by Fermi National Accelerator Laboratory.
      Found at http://www.physorg.com/news185555541.html
      The MINOS detector a half mile underground in Soudan, Minn.
      (PhysOrg.com) -- In its search for a better understanding of the mysterious neutrinos, a group of experimenters at DOE’s Fermi National Accelerator Laboratory has announced results that confirm the theory of neutrino oscillations and help rule out two alternative scenarios: neutrino decay and the existence of sterile neutrinos.
      The Main Injector Neutrino Oscillation Search experiment, or MINOS, explores the properties of muon neutrinos produced at Fermilab.    When sending a beam of neutrinos 735 kilometers through the earth to a neutrino detector in the Soudan Underground Laboratory in Soudan, Minn., scientists find that a significant fraction of the muon neutrinos disappears along the journey.    The standard explanation is that the missing muon neutrinos morph into two other known types of neutrinos: electron neutrinos and tau neutrinos.    This process is known as neutrino oscillations or neutrino mixing.
      But could there be another explanation? Scientists are exploring alternatives such as the decay of muon neutrinos into yet-to-be discovered particles or the transformation of muon neutrinos into a fourth type of neutrino, which is often called a sterile neutrino since it would not interact with ordinary matter like the other three known types of neutrinos.
      MINOS scientists found that neutrino decay is an unlikely option.    They looked at two scenarios: First, the possibility that no neutrino oscillations take place and hence all muon neutrinos decay.    Second, they considered the possibility that some muon neutrinos transform into other neutrinos and some decay during their trip from Fermilab to Soudan, which takes about four hundredths of a second.    In both analyses, the MINOS results provide strong evidence against the existence of neutrino decay.
      The MINOS results also disfavor the existence of a fourth, sterile neutrino.    Past analyses have shown that if muon neutrinos are oscillating into sterile neutrinos, only 68 percent of the disappearing neutrinos can do so.    The new MINOS analysis shrinks that percentage to 50 percent, and future MINOS data are expected to reduce it further.    The MINOS collaboration submitted its results to Physical Review D.
      More information: http://www-numi.fnal.gov/PublicInfo/index.html
  

• 1/17/1996 New theory on universe’s missing mass presented.
      San Antonio, Texas - Up to half of the so-called missing matter in the universe may be burned out and invisible stars, according to astronomers who used bent light from distant stars to probe for objects called MACHOs (Massive Compact Halo Objects).    This mysterious and invisible matter that shapes galaxies and keeps them from flying apart.    Lawrence Livermore National Laboratory is searching the Milky Way galaxy for events that suddenly cause light from stars in another galaxy, the Large Magellanic Cloud to appear to brighten, a phenomena known as “microlensing.”    The gravity of a passing object causes light from a star to bend and the star’s image becomes brighter, as if magnified by a lens.    So far seven instances were detected each lasting an average of 2.5 months.    Assumed to be white dwarves, the burned remnants of ordinary stars.    The analysis over two years suggests that these objects make up to 50 percent of the unseen, or dark, matter in the halo surrounding the Milky Way galaxy.    This search was prompted by the theory that only about 10 percent of the matter in the universe emits light or radiation that can be detected by telescopes.    How much matter would be needed for the gravitational effects observed in the universe?    Since the unseen matter issues no light or heat, it is called cold dark matter.    The search for this material is one of the major quests of modern astronomy.    Other theories that dark matter comprises exotic types of subatomic particles, yet to be identified.    Some researchers have proposed brown dwarfs, failed stars.    Also, cold dark matter may reside in black holes.
  
• 1/7/2003 - Ring of stars could be leftovers from gobbling galaxy by Dan Vergano, USA Today.
      Seattle -- Long hidden by gas and dust, a band of stars encircles our Milky Way Galaxy, astronomers say.
      Galaxies are huge collectors of stars that fill space like islands of light.    In seeking to discover how they are formed, scientists have in recent years discovered more signs that big ones, like our own, grow by swallowing stars ripped from their smaller brethren.
      Orbiting our galaxy more than twice as far from the center as our sun, the distant band of perhaps 500 million stars look like the remains of one of those meals, says Heidi Newberg of Rensseaer Polytechnic University.    Her Sloan Digital Sky Survey team presented the discovery at the American Astronomical Society meeting.
      About 120,000 light-years in diameter (one light-year equals about 5.9 trillion miles), the doughnut-shaped ring was observed by Newberg's team members, who digitally examined hundred of images for a peek at a wedge of space most astronomers saw as blocked by closer stars in the flat disk of our galaxy.
      Tens of thousands of stars orbiting our galaxy in an organized fashion told the astronomers that they were looking at a large, unknown structure, Newberg says.    Their mission is to completely map one-quarter of the sky, determining the distances of about 1 million distant galaxies.
      Also a Dutch, English and Australian scientists presented evidence of the size of the ring.    Looking at a separate portion of the sky, they also detected signs of the star ring in the direction of the constellation Andromeda.
      The very large ring is "unmistakable" evidence that the Milky Way consumes smaller galaxies, say astonomer Bruce Margon of the Space Telescope Science Institute.    Adding to the evidence, two University of California astronomers announced they had found signs of debris trail stars, leftovers from a consumed small galaxy, in the nearby Andromeda Galaxy.    Andromeda is a large spiral galaxy like our Milky Way.
      The astonomers hope the band of stars will tell them more about the mysterious "dark matter" that encircles our galaxy.

• 2/9/2001 - Scientists pose questions about theory of how universe works by Matt Crenson, The Associated Press.
      New York -- Physicists may have poked a hole in their current theory of how the universe operates.
      Researchers at the Brookhaven National Laboratory on Long Island reported experiments that showed a subatomic particle deviating slightly from its expected behavior.
      That tiny discrepancy could provide support for exotic theories such as supersymmetry, which hypothesizes that every particle has a much heavier, yet-to-be-observed counterpart.
      "I would say it's a glimpse or a suggestion that there's supersymmetry out there," said James Miller, a physicist at Boston University and a member of the team that conducted the Brookhaven research.
      But team members and physicists not involved with the experiment cautioned that the case is not yet proven.
      "These people are doing beautiful work," said Charles Prescott of the Stanford Linear Accelerator Center.    "But it is too early to say thery're seeing supersymmetry."
      Much of physics today is based on the Standard Model, a complex set of equations that describes how all the fundamental forces except gravity interact with known particles.
      For decades, physicists have designed experiments to challenge the model.    The Brookhaven experiment may be the first time physicists have contradicted the Standard Model in more than three decades of trying.    "If you find an experiment that disagrees with it then that's fairly significant," Miller said.
      The experiment examined the behavior of muons, heavier relatives of electrons, as they floated in a powerful magnetic field.    In a magnetic field, a muon modifies its spin, a subatomic property similar to the rotation of a toy top.
      Earlier experiments had found a spin modification fairly close to that predicted by the Standard Model.    But the Brookhaven experiment called g - 2 (gee minus two), was several times more precise than previous measurements.
      It concluded that the actual change in the muon's spin differed from predictions by just a few parts in a million.
      That samll discrepency suggests there is something lacking in the Standard Model, though there is still a chance that further results could bring theory and experiment back into line.
      The most likely explanation for the anomalous result is supersymmetry, a theory that goes beyond the Standard Model.
      In Supersymmetry, every known particle has a much heavier counterpart paired with it.    Unlike the Standard Model, the theory has a place for gravity and explains why the various particles have the masses they do.
• 3/18/2002 - Researchers report antimatter success by The Washington Post.
      Physicists think they may have, for the first time, created the antimatter equivalent of hydrogen atoms -- a long sought accomplishment researchers hope will help them better understand the fundamental nature of matter.
      A team of scientists working at the CERN physics laboratory outside of Geneva used electirc and magnetic fields to bring together antiprotons and positrons.    The researchers believe they have succeeded, and that it's likely they combined to form antihydrogen atoms.    But more research will be needed to confirm that, the researchers said.
      The eventual goal of the work is to determine whether the fundamental laws of physics, such as gravity, apply to anti-atoms.

 

• 1/17/2000 - Galaxy's Black Hole Weaker Than Thought by Curt Suplee, The Washington Post.
      The supermassive black hole at the center of our Milky Way galaxy appears to be sort of a wimp, surprised astronomers announced recently.    With a mass of 2.6 million suns, its perimeter should be ablaze with X-rays created as trillions of tons of ultra-hot compressed gas vanish into its bottomless maw.    Instead, eagerly awaited first findings from the Chandra observatory show that the output "is really puny," said Gordon Garmire of Pennsylvania State University.    A hole that hefty should be "a million or even a billion times brighter than what we're seeing.    That's a real puzzle."
      Discovery of this spectacular galactic underachievement was only one of many unprecedented observations from Chandra -- a 45-foot-long X-ray observatory placed in orbit last year -- reported at a meeting of the American Astronomical Society.
      Chandra scientists also revealed several heretofore unknown features of both the local and distant cosmos, including the richest field fo X-ray star sources ever seen (in the sword of Orion, which contains the nearest massive star-forming region), the innards of a violently expolding "starburst" galaxy, an eerie supernova remnant containing enough oxygen to supply 1,000 solar systems, and an oddball aspect of the Andromeda galaxy, the closet one that resembles ours in size and shape.
      Astronomers have long believed that our galaxy, like so many others, has a supermassive, super-hungry black hole at its core.    The radiation generated from gas, dust and stellar material falling into a black hole should create electriaclly charged particles called a plasma, which should revolve in a spiral fashion, in effect creating a giant antenna that "broadcast" in long wavelengths that can be detected by radio telescopes.    Previous observations had spotted the apparent location of our galaxy's central black hole toward the constellation Sagittarius.
      Another way to detect a hole is to measure the X-ray output from the compressed plasma.    But Earth is about 26,000 light-years from the center of the Milky Way, and X-rays originating there have to penetrate an enormous amount of matter on the way here.    So the X-ray signal from the presumptive black hole has been too faint to observe.
      Now Chandra finally has detected an X-ray source very close to the radio-wave source.    But if it is our central black hole, it is pathetically weak.    There are several possible explanations, most involving the environment around the galactic center.    Infalling gas might pile up, becoming so heated and pressurized that it pushes away from the hole, limiting the amount of gas available to produce X-rays.
      Something similar seems to be happening in the Andromeda galaxy which is weaker than ours, said Chandra scientist Stephen Murray of the Harvard-Smithsonian Center for Astrophysics.
• 2/14/2000 - Black Hole in a Lab by James Glanz, The New York Times.
      Astronomers believe that nothing, not even light, can escape after it has been captured by the gravity of a black hole in space and goes, so to speak, down the cosmic drain.
      Two physicists, Dr. Ulf Leonhardt and Paul Piwnicki of the Royal Institute of Technology in Stockholm, Sweden and University of Saint Andrews in Scotland, have now theorized that the same strange effects might be produced in laboratories on Earth, though not with gravity.    Instead, they suggest, light itself could be gobbled up by swirling gases and fluids, called an optical black hole, a creation relying on the recent discovery that in certain sustances, light can be slowed from its usual 186,000 miles a second to 40 mph.    In that sort of fluid medium, according to the physicists, a very fast vortex would also have a point of no return for light rays that came too close to its center.
      Experiments performed last year by Dr. Lene Vestergaard Hau of Harvard University, Dr. Stephen E. Harris of Stanford University using an ultracold cluster of sodium atoms called a Bose-Einstein condensate to slow light to about 40 mph.    Related experiments have been done in a vapor of rubidium atoms, Leonhardt said.
      In fact, Leonhardt and Piwnicki suggest that experimenters create vortexes in those substances while shining laser light through them.    They calculate that the black hole effect could take over in small vortexes moving at the outer edge of the effective black hole with speeds of from hundreds of yards per second to just a few feet per second, depending on how much further progress is made on the slow-light substances.
  
  
• 5/14/2001 - Finding Sheds Light On Spinning Black Holes by Kathy Sawyer, The Washington Post.
      For the first time, astronomers have evidence that a black hole can spin like a top.    In this case, a black hole 10,000 light-years from Earth appears to be whipping matter around itself at 27,000 revolutions per minute, flashing X-rays in unsteady spasms and twisting the fabric of space-time.    "We can see the light emitted from matter plunging into the black hole, said Todd Strohmayer, of NASA's Goddard Space Flight Center in Greenbelt, Md.    This material "whips frantically around the black hole before it is lost forever."    The study of black holes is suppose to move science closer to a theory that explains how all the forces of nature work together, so called "theory of everything."    This would represent the workings of gravity to fit harmoniously with the other forces of nature, said Virginia Trimble, of the University of Maryland and the University of California, Irvine.    Albert Einstein's theory of gravity has passed a series of observational tests, but nobody has figured out how to make it compatible with the laws of quantum physics that govern the subatomic world.    Black holes, where all these forces reach extremes, make ideal -- if difficult -- laboratories.    What Strohmayer found were unique patterns in the X-ray radiation emitted around the black hole as it pulls material at almost the speed of light from a companion star orbiting around it.    At the same time, the maelstrom around the hole ejects particles in jets from its north and south poles, also at incredibly high velocities.    "Black holes are one of the greatest energy sources in the universe," Strohmayer noted.    They surmised that the black hole inherited the rotation properties, or angular momentum, of the star that formed it.
  
  
• 1/10/2002 - Astronomers get X-ray pictures with clear view of galaxy's center by Paul Recer, The Associated Press.
      Washington -- The sharpest picture ever taken of the center of the Milky Way galaxy, home of the solar system, shows bizarre stellar characters -- neutron stars, dwarf stars and small black holes -- clustered around a supermassive black hole.    The galactic center is bathed in a fog of superheated gas and extremely active with stars being born, old stars blowing up into supernovae and black holes sucking in clouds of matter, said Q. Daniel Wang of the University of Massachusetts at the American Astronomical Society.    Our solar system is in the suburbs of the Milky Way, about halfway out one of the galaxy's spiral arms and about 25,000 light years from the center, resulting in astronomers unable to get a clear picture of the center using ordinary telescopes.
      But X-rays generated by the churning energy at the center penetrate the dust.    The Chandra X-Ray Observatory, launched in 1999, has been able to take a series of 30 pictures that are combined.    Wang said the portrait captures more than a thousnad X-ray sources.    Earlier X-ray telescopes detected only about a dozen, he said.    By analyzing the spectra of the X-rays, his team was able to determine that the galactic center has hundreds of white dwarfs stars, also neutron stars, and stellar black holes    And at the very center, said Wang, is a supermassive black hole.
  
  
• 1/7/2003 - Bad-tempered black hole burps up blast of X-rays by Dan Vergano, USA Today.
      Seattle -- Like most fabled monsters that are big and hard to look at, the supermassive black hole lurking in the center of our Milky Way Galaxy has a few untidy personal habits.
      In research results unveiled by NASA's Chandra X-Ray Observatory probe at the American Astronomical Society meeting, astronomers describe the black hole, called Sagittarius A^* in scientific parlance, as a messy eater that spits up near-daily X-ray blasts.    Each blast could hold 12 to 45 times the daily energy output of our sun, packed into a 10-minute tantrum.
      The X-rays are thought to be from gas accelerated to near the speed of light and heated to millions of degrees by a close encounter with the black hole.    Anything not eaten by the giant as the object passes is shot away by the strength of the black hole's gravity.

• 3/21/1993 - Spacecraft to search for faint echoes thought part of Big Bang.
      Pasadena, Calif. - Three spacecraft designed to study Mars, Jupiter and the sun will start searching today for gravitational waves, faint echoes believed to have been left by the creation of the universe and other cataclysmic events.
      Albert Einstein’s general theory of relativity predicted that gravitational waves should ripple through space and time after they are generated by the most violent events in the universe.
      So scientists from the National Aeronautics and Space Administration and the European Space Agency will conduct one of the most sensitive searches till April 11th.    During the experiment, radio signals from Mars Observer, the Jupiter-bound Galileo and the Ulysses solar explorer spacecraft will be tracked continuously by big antenna dishes near Madrid, Spain; Canberra, Australia; and Goldstone, Calif.
      If strong enough gravitational waves move through the solar system during the experiment, they should warp the fabric of space between Earth and the three spaceships, causing slight changes in the frequency of the radio signals.
      Finding gravitational waves would verify Einstein’s prediction.    Moving at the speed of light, gravitational waves are traveling distortions of space time, possibly events that created the universe roughly 15 billion years ago.    This experiment could detect very long gravitational waves, such as those produced by the “big bang,” supermassive black holes (believed to occupy the centers of galaxies) or the collision of two such objects.    The experiment won’t detect shorter gravitational waves generated by exploding stars or supernovas, ordinary black holes or the motion of two dense neutron stars orbiting each other.
  
  
• 10/27/1994 - Hubble closes in on answers.
      Scientists say the Hubble Space Telescope has brought new evidence to astronomy’s biggest questions: How fast is the universe expanding?    The result renewed a long-standing paradox in which the universe appears to be younger than some of its stars.    Will there be a revision of the theories of the cosmos.    The success came easily while looking at a galaxy called M100, hoping to get a sharp image of a particular kind of star used to estimate distance.    In this case M100 was 56 million light-years away (light year = 5.9 trillion miles).    With this accurate distance scale the rate of expansion of the universe could be determined.    The long-debated number called the Hubble constant can be combined with assumptions to estimate the age of the universe.
      Their estimate was 80 kilometers per second per megaparsec.    A megaparsec is about 3.3 million light-years, and it is needed in the Hubble constant to reflect the fact that more distant objects are flying away faster than those closer ones.    The M100 galaxy is moving fast enough to cross the continental United States in about three seconds.
      The new estimate of the expansion rate implies that the universe is a relatively young 8 billion years old, given the standard theory.
      The age becomes 12 billion years old if one assumes the universe contains far less matter than many theorists believe.
      Prior estimates have ranged up to 16 billion years.    Scientists have estimated the age for the oldest stars at 14 billion.    A dilemma to whether we assume that the star ages are correct and revise the standard theory about the universe.    Will scientist resurrect the concept that the vacuum of space somehow exerts a repulsive force that opposes gravity making an older age to the universe.
  
• 12/18/1994 Primal universe viewed.
      Fourteen billion years ago, the universe was a chaotic collection of stellar fragments amid neat galactic clusters according to Hubble Space Telescope photos released by NASA.    These views are from objects 14 billion light years from Earth, and adds to the debate about the age of the universe previously measured in October at a rate of expansion, at 8 to 12 billion years.    Still astronomers are confronting the impossible dilemma of finding stars that are older than the universe.    These objects at 14 billion light years are fuzzy points of light on ground based telescopes.    Hubble is getting sharp enough vies to determine the shapes and character of such distant objects.    At 9 billion light years away there were many ellipticals and few spirals that were asymmetrical and distorted.    At 12 billion light years away they found very old elliptical galaxies, but no spiral galaxies, instead there were a collection of “ragged objects” with no definite shape.    At 14 billion years ago the universe was chaotic, messy and different.
  
  
• 7/16/1995 - Chilly tests confirm Einstein right about state of matter.
      Seventy years after Albert Einstein predicted it, scientists have proved it: existence of a new state of matter.    In a tabletop experiment atoms of gas were chilled to the lowest temperature ever achieved to create a “superatom.”    Using a laser and an exotic evaporation to plunge the temperature of rubidium gas to within 20 billionths of a degree of absolute zero, or minus 459.67 degrees F.    Carl Wieman, a physicists has found a new state of matter with completely different properties from any other kind of matter.
      The matter is called Bose-Einstein condensate from an idea by Satyendra Nath Bose, and Indian physicist in 1925.
  
• 9/6/1995 - Space telescope study renews debate on universe.
      The standard theory of the universe may have to be revised because the age it implies for the cosmos is too young, new observations from the Hubble Space Telescope suggest.    This universe in the standard theory is estimated about 9.5 billion years old.    This clashes with solid evidence that some stars are older, at least 12 billion to 17 billion years old.    Hubble studies were suppose to find the most sought after so-called Hubble constant, which is the rate at which the universe is expanding.    It shows that the standard assumptions about the cosmos might be wrong.    Assumption upon assumptions.    If the universe contains less matter than the standard theory assumes, which would mean the universe will continue to expand without slowing.
• 11/3/1995 - Hubble photos show the birth of stars.
      Astronomers hail a photograph of stars forming inside a 6-trillion-mile-long cloud of gas as “perhaps the most spectacular picture we’ve seen from the Hubble Space Telescope.”    This will become strong operational evidence that this process works and actually happens.
  
  
• 2/18/1999 - Danish physicists finds way to slow the speed of light - Scientists says her achievement has many potential uses - by Malcolm W. Browne, The New York Times.
      A Danish pysicist Dr. Lene Vestergaard Hau of Rowland Institute for Science in Cambridge, Mass., and at Harvard University and her colleague Dr. Steve Harris of Stanford University have found a way to slow light down to about 38 miles an hour, and expect to slow the pace of light still further, to 120 feet an hour.
      Both commented that it has many potential uses, not only as a tool for studying a very peculiar state of matter but also in optical computers, high-speed switches, communications systems, television displays and night-vision devices.
      One of the most desirable features of the apparatus it does not transfer heat energy from the laser light it uses to the ultracold medium on which the light shines.    This could have a stabilizing effect on the functioning of optical computers, which use photons of light instead of conventional electrons.    A switch using the system could be made so sensitive that it could be turned on or off by a single photon, Hau said.
      The medium used in slowing light by a factor of 20 million was a cluster of atoms called a "Bose-Einstein condensate" chilled to a temperature of only fifty-billionths of a degree above absolute zero.    Absolute zero is the temperature at which nothing can be colder.    It is minus 273.15 degrees on the Celsius scale, minus 459.67 on ehe Fahrenheit scale and zero on the Kelvin scale.
      Hau's group reached an ultralow temperature in stages, using lasers to slow the atoms in a confined gas and then evaporating way the warmest remaining atoms.
      Bose-Einstein condensates, named for the theorists who predicted their existence, Satyendra Nath Bose and Albert Einstein, were first prepared in a laboratory four years ago and became the objects of research in the United States and Europe.    They owe their existence to some of the rules of quantum mechanics.    One of these is Werner Heisenberg's uncertainty principle, which states that the more accurately a particle's position is known the less accurately its momentum can be determined, and vice versa.    In the case of a Bose-Einstein condensate, atoms chilled nearly to absolute zero can barely move at all, and their momentum therefore approaches zero.    But because zero is a precise measure of momentum, the uncertainty principle makes the positions of these atoms uncertain.    In a condensate, as a result, such atoms are forced to overlap and merge into super atoms sharing the same quantum mechanical "wave function," or collection of properties.
      It was such a super atom, made of a gas of superpositioned sodium atoms, that provided Hau and her associates with the optical molasses they needed to slow light down.
      The group tuned a "coupling" laser to the resonance of the atoms in their condensate, shot the laser into the cold cluster of atoms and therby created a quantum mechanical system of which both the laser light and the condensate of atoms were components.    At this stage, the system was no more transparent than a block of lead, Hau said.    They then sent a brief pulse of tuned laser light from a probe into the condensate, at a right angle to the coupling laser, in such a way that the laser-condensate system interacted with the probe laser.    Under these conditions about 25 percent of the probe laser light passed through the "laser-dressed condensate," but at an astonishingly low speed.    The light that emerged from the apparatus, not visible to the naked eye, was only 25 percent as strong as the light that entered, but detectors found that it had roughly the same color.
  
  
• 2/12/2003 - NASA photo reveals previously unknown details of universe by The Associated Press.
      Washington -- NASA's Wilkinson Microwave Anistropy Probe, a satellite orbiting 1 million miles from Earth for 12 months, allowed a release of what it called the most vivid snapshot of the infant universe ever taken, giving evidence that answers of longstanding questions about the age, composition and evolution of the universe has been gathered.
      Charles Bennet, WMAP principal investigator at the Goddard Space Flight Center in Greenbelt, Md., said after NASA released the picture "The patterns in the picture tell us all kinds of things about the universe."    One key finding in the data is that the first generation of stars to shine in the universe ignited much earlier than previously thought -- only 200 million years after the Big Bang, the theoretical explanation for the explosion that gave birth to the universe.
      The image shows the "afterglow" of the Big Bang, called the cosmic microwave background.    Thus this portrait pegs the age of the universe at 13.7 billion years old, with a small 1 percent margin of error.    Patterns in the afterglow of the Big Bang are frozen in place only 380,000 years after the Big Bang, NASA said.
• 4/27/2003 - Earth is not, but universe really flat by Matthew Fordahl, The Associated Press.
      Pasedena, Calif. -- The first detailed images of the embryonic universe suggest the cosmos will expand forever and not someday collapse upon itself, according to new research on the Big Bang.
      U.S. team leader Andrew Lange of the California Institute of Technology for a $4 million international project dubbed "Boomerang," a sensitive telescope carried aloft for nearly 11 days in late 1998 measured minute variations in the cosmic microwave background radiation.    This faint glow is believed to be the fading remnants of the Big Bang 12 billion to 15 billion years ago.flat" universe in which parallel lines never cross, thus ruling out the possibility that the fabric of space time is curved onto itself like a sphere or bent outward like a saddle.    It also means that the universe will not collapse in a big crunch, said Italian team leader Paolo deBernardis of the University of Rome, La Sapienza.
      The flat universe also fits the so-called inflationary theory that the universe underwent a rapid expansion in a fraction of a second after its birth.
      Measurements of the small ripples indicate the large-scale geometry of the universe, which the general theory of relativity says is determined by the total amount of matter and energy in the cosmos.
      The Boomerang data also reveal hundreds of complex structures that represent the effects of the density variations in the early universe.    They are the seeds in which clusters of galaxies would form, said Boomerang scientist John Ruhl, a physicist at the University of California, Santa Barbara.
      Scientists hope to further refine the data to better quantify the nature of the matter that makes up the cosmos.    "What we will get is a census of the universe but without knowing what kind of things make up the population," said Edward Wright, an astronomer at the University of California, Los Angeles.    He also promotes that neutrinos may be the missing matter in the universe "dark matter."

• 5/1/1994 - Scientists find first evidence of top quark.
      Batavia, Ill. - The big-bang theory is intact, along with the universe as physicists know it.    A 17-year search has yielded evidence of the existence of the top quark, a basic building block of nature without which the big-bang theory and our understanding of time and matter would fall apart.    Using the world’s most powerful particle accelerator at a U.S. Energy Department’s Fermi National Laboratory outside of Chicago, 440 researchers have been trying to find the top quark.    This is only the first direct evidence of the top quark, and with 12 to 18 more months of experiments they might actually prove its existence.    As you have seen above the top quark is one of the six kinds of quarks believed to make up protons and neutrons inside atoms.    Over the years, five quarks have been discovered.
      Scientists used an electronic field to accelerate larger particles to nearly the speed of light, then made them collide.    The collisions produced miniature energy bursts like the big bang.    The bursts appeared to yield a quark that was heavier than the colliding particles.    It is as if two tennis balls collided and a bowling ball flew out.
  
  
• 2/11/2000 - Scientists create 'new state of matter' - Studies are said to verify parts of Big Bang theory - by Curt Suplee, The Washington Post.
      Luciano Maianim, general director of the CERN laboratory in Geneva and scientists at Europe's premier high-energy physics facility announced that they have created a "new state of matter" that has not existed since a few millionths of a second after the Big Bang that generated the cosmos.    The CERN team smashed lead atoms together so hard that they achieved densities 20 times greater than an ordinary atomic nucleus and temperatures 100,000 times as hot as the center of the sun.
      In the new state, which scientists have inferred from seven experiments over the past six years, tiny sub-nuclear particles called quarks and gluons are squeezed together and heated to such an extreme that they can move freely.
      This never happens under ordinary conditions.    In all but extreme circumstances, quarks are tightly bound into groups of three to form neutrons and protons, or into pairs to form particles called mesons.    There is no such thing as a free quark.
      Although theory indicates that quarks might become unbound in an ultra-high-energy environment, free moving quarks would last have been seen in the ferocious energy torrent just after the Big Bang, before the quark-and-gluon soup cooled and congealed into conventional protons and neutrons, so this new matter verifies important predictions of the present theory.
      Experts in the United States called the claim as premature at best, since no one knows exactly what a free-quark condition is supposed to look like.    The CERN achievement is promising for the next stage of research, slated to begin this summer at Brookhaven National Laboratory's new Relativistic Heavy Ion Collider on Long Island.
      The collisons produced at CERN disintregrated the lead into their constituent quarks and gluons, making them behave in weird ways.    The more familiar forces of nature, such as gravity or magnetism, get weaker over distance.    But the so-called "strong force" that binds quarks together works in reverse: the closer the particles are, the more freely they can move about.
      Theory has long predicted that if quarks and gluons could be crammed close enough together and brought to sufficiently high energies, they would create a "quark-gluon plasma" in which particles would be unconfined.    It is this plasma that is thought to have filled the universe microseconds after the Big Bang.
      As that plasma cools, the quarks would recombine into new forms including numerous mesons.    Mesons are unstable and break up almost immediately.    But CERN's detectors are able to identify the particular types of mesons emitted during the experiment.    The distinctive types of mesons emitted were exactly what theory predicted would result from the plasma condition, the scientists said.
      CERN officials stopped short, however, of saying that they had achieved the long-sought quark-gluon plasma, declaring only that they had shown quark deconfinement.
      The following articles are also shown in the
  Dark Matter for 2002-2003:
  
• 7/21/2000 - Scientists find first direct evidence of subatomic particle tau neutrino - Discovery supports standard model theorized in 1978 - by Joseph B. Verrengia, The Associated Press.
      After a two-decade search, scientists have found the first direct evidence of one of the most elusive subatomic particles in nature -- the tau neutrino.    The discovery announced by the scientists from the United States, Japan, Korea and Greece at the Fermi National Accelerator Laboratory outside of Chicago after searching since 1997.    The tau is one of the fundamental building blocks of all matter.    It is the last of the tiny particles described in the Standard Model of Particle Physics to be confirmed in experiments.
      The standard model seeks to encapsulate all elementary particles and forces in a single explanation.    Now the bits have been identified, though the many forces that guide their interplay remain a mystery.
      "It's a tremendous milestone," said Stanford University physicist and Nobel Prize winner Martin perl, who theorized the existence of the tau neutrino in 1978.    "Now it has been seen and it behaves in the way we expected."
      Neutrinos are hurtling everywhere at the speed of light.    Trillions pass through each of us every second.    Yet they are among the hardest to detect of all subatomic particles, carrying no electrical charge and virtually no mass -- perhaps one-millionth that of an electron.
      The tau neutrino is the third and perhaps final type of neutrino to be found.    The first two types -- electron neutrinos and muon neutrinos -- were discovered in 1956 and 1962.    In 1978, tests by Perl and others at Stanford discovered the existence of another class of subatomic particle, the tau lepton.    This suggested there would be a tau neutrino, too, because neutrinos are precursors to leptons.
      In 1997, scientists using the ring-shaped particle accelerator at Fermilab fired an intense neutrino beam into a 50-foot detector composed of iron plates coated with an emulsion.    Then they analyzed the 6 million impressions left on the coating, and with computer assisted video camera to create 3-D images of the particle tracks.    After narrowing it down they found four clear tracks of a tau lepton that were caused by tau neutrino collisions.    They can never be detected directly, since they have no charge, only their signature is detected.
  
  
• 1/22/2001 - Densest Matter by James Glanz, The New York Times.
      Scientists at Brookhaven National Laboratory in New York have used the particle accelerator called the Relativistic Heavy Ion Collider, to smash the nuclei of gold atoms together at nearly the speed of light to make the highest density of matter ever created in an experiment, they announced at a conference.    The debris speeding away from the collisions, made them conclude that they had produced densities more than 20 times higher than those that exist within the nuclei of ordinary matter.    Temperatures in the compressed matter reached more than a trillion degrees, similar to the large amounts of matter at those densities and temperature lasted a few millionths of a second after the start of the Big Bang.
      These experiments are hoped to shed light on the compressed matter at the cores of exploding stars called supernovas, the stellar cinders called neutron stars.
      The figure between 1.5 to 2 times, broke the record density announced last year at CERN, a European particle physics laboratory. in Geneva.
      Both still have the ultimate goal to produce a state of matter never before recorded on Earth and known as a quark-gluon plasma.
• 3/19/2001 - Unusual States of Matter by Earl Lane, Times-Post News Service.
      Reinhard Stock remembers the days in the late 1970s when a small band of physicists speculated that ordinary matter, if compressed enough, might transform into a new state that would mimic some of the conditions at the birth of the cosmos.    Theorists argued that the protons and neutrons at the core of the atom, under extreme conditions, would "melt."    That could allow the constituent building blocks, called quarks, to briefly roam free (along with particles called gluons that bind the quarks tightly together) in a state called the quark-gluon plasma.    Physicists figured they might get a glimpse of it by accelerating heavy ions -- atoms stripped of their outer electrons -- to nearly the speed of light.    The ions would then be sent crashing into each other or against stationary targets.
      Last year, officials at CERN, the European physics research center near Geneva, Switzerland, announced that heavy ion experiments at that lab had produced circumstantial evidence for a new state of matter in which quarks had been briefly "deconfined."    Many physicists were skeptical, since the current heavy ion program at CERN winds down, for the researchers to make their best case for having found a hint of the quark-gluon plasma.    Evidence from other colliders may take two or three years.    The goal is to explain why the universe turned out the way it looks today, physicists say.    Quarks combine in trios or pairs to form the bulk of the matter we see today in the cosmos, and they are tightly bound through the strong nuclear force transmitted by uncharged particles called gluons.    The experiment suggest that force gets only stronger as efforts are made to separate pairs of quarks.
  

• Electromagnetic interactions, which cause all phenomena associated with electric and magnetic fields and the spectrum of electromagnetic radiation.    This was the most familiar force to be understood, and its influence extends to infinite distances, because it describes particles interacting with the massless photons, the most basic units of the electromagnetic field.
• strong interactions, which bind atomic nuclei.
• weak nuclear force, which governs beta decay - a form or natural radioactivity - and hydrogen fusion, the source of the sun's energy.    The influence of the weak interaction is confined to subnuclear dimensions, less than about 10^-15 centimeters, and has particles W and Z which has 100 times the mass of the proton.    The Higgs particle is connected with the weak force.

• A simulated event in the CMS detector, featuring the appearance of the Higgs boson.
• Physicists hope that the LHC will help answer the most fundamental questions in physics, questions concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, especially regarding the intersection of quantum mechanics and general relativity, where current theories and knowledge are unclear or break down altogether.
      These issues include, at least:
  
  • Is the Higgs mechanism for generating elementary particle masses via electroweak symmetry breaking indeed realized in nature?    It is anticipated that the collider will either demonstrate (or rule out) the existence of the elusive Higgs boson(s), completing (or refuting) the Standard Model.    The Higgs Boson is the only particle in the Standard Model which has not been detected, a prime target for the LHC, if the Tevatron doesn’t find it first.    And it’s a boson, which improves CERN’s chances, and almost a guarantee that the Higgs exists, or a Higgs-like particle; there is an electroweak symmetry, and it is broken by something, and that something should be associated with particle-like excitations.    There’s no guarantee that the LHC will find it.    If the LHC doesn’t find the Higgs in five years, it will place very strong constraints on model building, but the Superconducting Super Collider, on the other hand, almost certainly would have found the Higgs by now.
  • Is supersymmetry, an extension of the Standard Model and Poincare symmetry, realized in nature, implying that all known particles have supersymmetric partners?
        These may clear up the mystery of dark matter.    Supersymmetry is the most popular, and the most likely to show up at the LHC.    We’ve been theorizing about it for so long that people act like it’s already been discovered — but it hasn’t.    On the contrary, the allowed parameter space has been considerably whittled down by a variety of experiments.    String theory predicts it, but why it shouldn’t be hidden up at the Planck scale, which is 10¹⁵ times higher in energy than what the LHC will reach.    On the other hand, it can help explain why the Higgs scale is so much lower than the Planck scale — the hierarchy problem — if and only if it is broken at a low enough scale to be detectable at the LHC.
  • Are there extra dimensions, as predicted by various models inspired by string theory, and can we detect them?    Large Extra Dimensions the idea of extra dimensions of space was re-invigorated in the 1990’s by the discovery by Arkani-Hamed, Dimopolous and Dvali that hidden dimensions could be as large as a millimeter across, if the ordinary particles we know were confined to a three-dimensional brane.    We could be making gravitons at the LHC, which would escape into the extra dimensions.    The models are already quite constrained, and seem to require a good amount of fine-tuning to hold together.    Warped Extra Dimensions soon after branes became popular, Randall and Sundrum put a crucial new spin on the idea: by letting the extra dimensions have a substantial spatial curvature, you could actually explain fine-tunings rather than simply converting them into different fine-tunings.    This model has intriguing connections with string theory, and its own set of experimental predictions.    So will some version of the Randall-Sundrum proposal turn out to be relevant at the LHC?
      Other questions are:
  
• Are electromagnetism, the strong nuclear force and the weak nuclear force just different manifestations of a single unified force, as predicted by various Grand Unification Theories?
• Why is gravity so many orders of magnitude weaker than the other three fundamental forces?
• Are there additional sources of quark flavors, beyond those already predicted within the Standard Model?
• Why are there apparent violations of the symmetry between matter and antimatter?    See also CP violation.
      We detected antimatter in 1932, to be precise, so it is no longer a mystery.
• What was the nature of the quark-gluon plasma in the early universe?    This will be investigated by ion collisions in ALICE.

• Dark Matter is that you can relate the strength of its interactions to the abundance it has today — and to get the right abundance, the interaction strength should be right there at the electroweak scale, where the LHC will be looking.    It might not be easy to find since dark matter is electrically neutral and doesn’t interact very much.
• Dark Energy will depend on supersymmetry or extra dimensions finds lead to our understanding of dark energy.
• Strong Dynamics or Quantum Chromodynamics (QCD), the theory that explains the strong nuclear force as arising from strongly-interacting gluons coupled to quarks, is a crucial part of the Standard Model.    An underappreciated feature of QCD is that the dynamics of quarks breaks the electroweak symmetry even without the Higgs boson — unfortunately, the numbers don’t work out for it to be the primary mechanism.    However, an interesting alternative to the standard idea of a Higgs boson is to imagine a new “QCD-like” force that operates at even higher energies; one venerable idea along these lines is known as technicolor, which are theories that have been struggling to remain compatible with various experimental bounds.
• New Massive Gauge Bosons another Standard-Model-like thing that could show up from a spontaneously broken symmetry (or more than one), similar to the W and Z bosons of the weak interactions — you will hear about searches for Z-prime bosons or W-prime bosons.
• New Quarks or Leptons the final Standard-Model-like thing we could find is a new “generation” of fermions (matter particles) — strongly-interacting quarks and non-strongly-interacting leptons.    This is not expected since each generation includes a neutrino, and neutrinos tend to be fairly light, and the existence of new light fermions is strongly constrained both by particle physics experiments and by Big Bang Nucleosynthesis.    If there are more light particles, the energy density of the universe is just a bit larger at any fixed temperature, and the universe therefore expands faster, and you therefore make a bit more Helium.
• Preons at high energies we may find even smaller particles.    The possibility that quarks and leptons are made of smaller constituents.
• Mysterious Missing Energy, which are particles that are long-lived, neutral, and weakly interacting — including dark matter particles and gravitons — can only be found indirectly at a collider like the LHC.    You are smashing things together, and if the total energy of the resulting particles you detect is less than that of the initial particles you smashed, you know that some invisible particles must have escaped as “missing energy.”    But what?    If you have a specific theory, you can match carefully to the expected dependence on the initial energy, the angle of scattering, and so forth.    But if you don’t … it will be hard to figure out what is going on.
• Baryon-Number Violation, where there are more baryons than anti-baryons in the universe, and most of us think that the asymmetry must have been dynamically generated somehow.    Therefore, some process must be able to change the number of baryons — but we’ve never observed such a process.    And we probably won’t; in most models, violation of baryon number is far too rare to be visible at the LHC.    But there is certainly no consensus about how baryogenesis happened, so we should keep an eye out.

Last updated August 16, 2003, February 26, 2010, March 17, 2010, June 10, 2010, December 31, 2011, and January 12, 2012.