The Riddle of AntiMatter
Ανέβηκε στις 19 Αυγ 2011
Explore
one of the deepest mysteries about the origin of our universe.
According to standard theory, the early moments of the universe were
marked by the explosive contact between subatomic particles of opposite
charge. Featuring short interviews with Masaki Hori, Tokyo University
and Jeffrey Hangst, Aarhus University.
Scientists are now
focusing their most powerful technologies on an effort to figure out
exactly what happened. Our understanding of cosmic history hangs on the
question: how did matter as we know it survive? And what happened to its
birth twin, its opposite, a mysterious substance known as antimatter?
A
crew of astronauts is making its way to a launch pad at the Kennedy
Space Center in Florida. Little noticed in the publicity surrounding the
close of this storied program is the cargo bolted into Endeavor's hold.
It's a science instrument that some hope will become one of the most
important scientific contributions of human space flight.
It's a
kind of telescope, though it will not return dazzling images of cosmic
realms long hidden from view, the distant corners of the universe, or
the hidden structure of black holes and exploding stars.
Unlike
the great observatories that were launched aboard the shuttle, it was
not named for a famous astronomer, like Hubble, or the Chandra X-ray
observatory.
The instrument, called the Alpha Magnetic
Spectrometer, or AMS. The promise surrounding this device is that it
will enable scientists to look at the universe in a completely new way.
Most
telescopes are designed to capture photons, so-called neutral particles
reflected or emitted by objects such as stars or galaxies. AMS will
capture something different: exotic particles and atoms that are
endowed with an electrical charge. The instrument is tuned to capture
"cosmic rays" at high energy hurled out by supernova explosions or the
turbulent regions surrounding black holes. And there are high hopes that
it will capture particles of antimatter from a very early time that
remains shrouded in mystery.
The chain of events that gave rise
to the universe is described by what's known as the Standard model. It's
a theory in the scientific sense, in that it combines a body of
observations, experimental evidence, and mathematical models into a
consistent overall picture. But this picture is not necessarily
complete.
The universe began hot. After about a billionth of a
second, it had cooled down enough for fundamental particles to emerge in
pairs of opposite charge, known as quarks and antiquarks. After that
came leptons and antileptons, such as electrons and positrons. These
pairs began annihilating each other.
Most quark pairs were gone
by the time the universe was a second old, with most leptons gone a few
seconds later. When the dust settled, so to speak, a tiny amount of
matter, about one particle in a billion, managed to survive the mass
annihilation.
That tiny amount went on to form the universe we
can know - all the light emitting gas, dust, stars, galaxies, and
planets. To be sure, antimatter does exist in our universe today. The
Fermi Gamma Ray Space Telescope spotted a giant plume of antimatter
extending out from the center of our galaxy, most likely created by the
acceleration of particles around a supermassive black hole.
The
same telescope picked up signs of antimatter created by lightning
strikes in giant thunderstorms in Earth's atmosphere. Scientists have
long known how to create antimatter artificially in physics labs - in
the superhot environments created by crashing atoms together at nearly
the speed of light.
Here is one of the biggest and most enduring
mysteries in science: why do we live in a matter-dominated universe?
What process caused matter to survive and antimatter to all but
disappear? One possibility: that large amounts of antimatter have
survived down the eons alongside matter.
In 1928, a young
physicist, Paul Dirac, wrote equations that predicted the existence of
antimatter. Dirac showed that every type of particle has a twin,
exactly identical but of opposite charge. As Dirac saw it, the electron
and the positron are mirror images of each other. With all the same
properties, they would behave in exactly the same way whether in realms
of matter or antimatter. It became clear, though, that ours is a matter
universe. The Apollo astronauts went to the moon and back, never once
getting annihilated. Solar cosmic rays proved to be matter, not
antimatter.
It stands to reason that when the universe was more
tightly packed, that it would have experienced an "annihilation
catastrophe" that cleared the universe of large chunks of the stuff.
Unless antimatter somehow became separated from its twin at birth and
exists beyond our field of view, scientists are left to wonder: why do
we live in a matter-dominated universe?
one of the deepest mysteries about the origin of our universe.
According to standard theory, the early moments of the universe were
marked by the explosive contact between subatomic particles of opposite
charge. Featuring short interviews with Masaki Hori, Tokyo University
and Jeffrey Hangst, Aarhus University.
Scientists are now
focusing their most powerful technologies on an effort to figure out
exactly what happened. Our understanding of cosmic history hangs on the
question: how did matter as we know it survive? And what happened to its
birth twin, its opposite, a mysterious substance known as antimatter?
A
crew of astronauts is making its way to a launch pad at the Kennedy
Space Center in Florida. Little noticed in the publicity surrounding the
close of this storied program is the cargo bolted into Endeavor's hold.
It's a science instrument that some hope will become one of the most
important scientific contributions of human space flight.
It's a
kind of telescope, though it will not return dazzling images of cosmic
realms long hidden from view, the distant corners of the universe, or
the hidden structure of black holes and exploding stars.
Unlike
the great observatories that were launched aboard the shuttle, it was
not named for a famous astronomer, like Hubble, or the Chandra X-ray
observatory.
The instrument, called the Alpha Magnetic
Spectrometer, or AMS. The promise surrounding this device is that it
will enable scientists to look at the universe in a completely new way.
Most
telescopes are designed to capture photons, so-called neutral particles
reflected or emitted by objects such as stars or galaxies. AMS will
capture something different: exotic particles and atoms that are
endowed with an electrical charge. The instrument is tuned to capture
"cosmic rays" at high energy hurled out by supernova explosions or the
turbulent regions surrounding black holes. And there are high hopes that
it will capture particles of antimatter from a very early time that
remains shrouded in mystery.
The chain of events that gave rise
to the universe is described by what's known as the Standard model. It's
a theory in the scientific sense, in that it combines a body of
observations, experimental evidence, and mathematical models into a
consistent overall picture. But this picture is not necessarily
complete.
The universe began hot. After about a billionth of a
second, it had cooled down enough for fundamental particles to emerge in
pairs of opposite charge, known as quarks and antiquarks. After that
came leptons and antileptons, such as electrons and positrons. These
pairs began annihilating each other.
Most quark pairs were gone
by the time the universe was a second old, with most leptons gone a few
seconds later. When the dust settled, so to speak, a tiny amount of
matter, about one particle in a billion, managed to survive the mass
annihilation.
That tiny amount went on to form the universe we
can know - all the light emitting gas, dust, stars, galaxies, and
planets. To be sure, antimatter does exist in our universe today. The
Fermi Gamma Ray Space Telescope spotted a giant plume of antimatter
extending out from the center of our galaxy, most likely created by the
acceleration of particles around a supermassive black hole.
The
same telescope picked up signs of antimatter created by lightning
strikes in giant thunderstorms in Earth's atmosphere. Scientists have
long known how to create antimatter artificially in physics labs - in
the superhot environments created by crashing atoms together at nearly
the speed of light.
Here is one of the biggest and most enduring
mysteries in science: why do we live in a matter-dominated universe?
What process caused matter to survive and antimatter to all but
disappear? One possibility: that large amounts of antimatter have
survived down the eons alongside matter.
In 1928, a young
physicist, Paul Dirac, wrote equations that predicted the existence of
antimatter. Dirac showed that every type of particle has a twin,
exactly identical but of opposite charge. As Dirac saw it, the electron
and the positron are mirror images of each other. With all the same
properties, they would behave in exactly the same way whether in realms
of matter or antimatter. It became clear, though, that ours is a matter
universe. The Apollo astronauts went to the moon and back, never once
getting annihilated. Solar cosmic rays proved to be matter, not
antimatter.
It stands to reason that when the universe was more
tightly packed, that it would have experienced an "annihilation
catastrophe" that cleared the universe of large chunks of the stuff.
Unless antimatter somehow became separated from its twin at birth and
exists beyond our field of view, scientists are left to wonder: why do
we live in a matter-dominated universe?
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Ημερομηνία κυκλοφορίας
- 21/8/11
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