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Antimatter Theory
-Paul Dirac
-unified the princilples of quantum mechanics and relativity to describe the electron
-the Dirac equation and implied the existence of antimatter. -
"Missing" Energy
-Wolfgang Pauli
-during nuclear particle decay, some energy went "missing."
-theorized that this energy was carried by electrically neutral particles and that escaped, undetecable, from the decay process. -
Anti-Electrons
-Carl Anderson, a physicist at Caltech
-cloud chamber exposed to cosmic rays, causing radioactive decay
-traces of an anti-electron (positron) given off by decay
-prompted creation of more radioactive elements, confirmed that every particle has an antiparticle -
Positrons
-Frederic and Irene Joliot-Curie
-identified positrons as the antiparticles of electrons
-revealed that positrons move in the opposite direction than electrons do in a magnetic field
-collided alpha particles with certain elements, discovered that those elements emitted positrons and neutrons
-"artificial radioactivity" -
Dark Matter Theory
-Fritz Zwicky, astrophysicist at the California Institute of Technology
-first to theorize dark matter -
Antineutrino
-Enrico Fermi
-built on Wolfgang Pauli's nuclear particle decay theory
-called the neutral particles "antineutrinos"
-formulated a theory for calculating the simultaneous emission of an electron and an antineutrino -
Majorana Fermions
-Italian physicist Ettore Majorana
-built on Dirac's equation
-included the existence of antoher electrically neutral particle called a fermion
-basic particle of dark matter, equivalent of a quark -
Dark Matter Development
-Vera Rubin
-developed Zwicky's theory of the existence of dark matter
-observed that all of the planets in other galaxies moved at similar speeds, regardless of distance from the galaxies' respective centers
-this finding contradicted Newton's Laws
-Rubin concluded dark matter's gravity acted on the planets -
The Bevatron
-Ernest O. Lawrence, a member of Radiation Laboratory of the University of California at Berkeley
-commissioned the construction of a particle accelerator capable of simultaneously creating a proton and an antiproton
-called the Bevatron
-particle creation required 6 billion eV, so Lawrence commissioned the machine to produce up to 6.5 billion eV
-created a proton and an antiproton, observed their mutual annhilation -
Detecting the Antineutrino
-Fred Reines and Clyde Cowan of Los Alamos
-designed an experiment t0 detect the energy emissions of neutrinos created during a nuclear explosion
-registered gamma rays produced by the nuclear annhilation of a neutron and a positron
-their annhilation produced a proton and an a neutrino, conclusively proving its existence -
Magnetic Anapole
-Russian physicist named Yakov Zel’dovich
-hypothesized the existence of a magnetic anapole
-doughnut-shaped magnetic field, interacts with external electromagnetic forces only when in motion
-this magnetic formation makes detection of dark matter difficult -
Matter and Antimatter
-James Cronin and Val Fitch, CERN physicists
studied the decay of two different types kaons, particles that consist of one-half matter and one-half antimatter.
-two types had identical masses but different lifetimes
-did not expect to detect the decay of the short-lived kaon
-however, did register the decay of both particles
-challenged conclusions about symmetry of anti- and regular matter -
Antideuteron
-physicists at CERN and Brookhaven National Laboratory
-created antiparticle to a deuteron (the nucleus of a proton and a neutron)
-combined an antiproton and an antineutron to produce the first antideuteron -
Model of the Universe
-Princeton physicists Jeremiah Ostriker and Jim Peebles
-created Milky Way Galaxy computer simulation
-computer did not allow the simulation to function, not enough gravity
-must be much more matter -- dark matter -- in the universe than science accounted for
-O & P reformulated simulation, included dark matter, & it was successful -
Antiatom
-physicists at CERN
-combined anitprotons, antineutrons, and antielectrons to create 9 antihydrogen antiatoms
-first antiatoms in existence -
Hubble Telescope
-astrophysicists at NASA
-used the Hubble Space Telescope to observe distant supernovae
-supernovae data suggested that the rate of the universe's expansion has been accelerating since the Big Bang
-challenged accepted idea that expansion had slowed
-theorized that the gravity produced by dark matter has contributed to this increased rate of expansion -
Thousands of Antihydrogen Atoms
-CERN physicists
-created thousands of "cold" antihydrogen atoms for the first time -created them at a low enough energy to slow them, delay annhilation -
Direct Proof of Dark Matter
-team of NASA physicists observed galaxy cluster 1E0657-56 for 100 hours with Chandra telescope
-observed collision of two smaller clusters
-impact slowed by force similar to drag/air resistance
-the separation between dark matter and normal matter not possible without gravity of dark matter -
Trapping Antihydrogen
-physicists at CERN
-trapped 38 antihydrogen atoms like those they created in 1995
-created each antiatom by: creating an antiproton, decelerating it, trapping it in a magnetic Penning trap, cooling it, producing a positron from a radioactive sodium-22 isotope, cooling it, & combining the antiparticles
-Penning trap allows combining and containing of ground-state antihydrogen -
Antihydrogen Atoms 1000 Seconds
-CERN physicists trapped 300 antihydrogen atoms for 1000 seconds (over 16 minutes)
-unprecedented amount of time for antimatter particles to exist without mutually annhilating with regular-matter particles
-will allow in-depth study of antihydrogen atoms
-antihydrogen's comparison with hydrogen atoms will reveal more about the nature of antimatter
