- 3152 - ANTIMATTER - is there another world? - Antimatter particles have the opposite charge of normal matter particles. When particles of matter and antimatter meet, they destroy each other. Otherwise, antimatter behaves similarly to ordinary matter.
----------------- 3145 - ANTIMATTER - is there another world?
- An antihydrogen atom, consisting of an antiproton and a positron (the antimatter counterpart of an electron), is the antimatter version of a hydrogen atom. Using the Antiproton Decelerator at CERN's ALPHA (the Antihydrogen Laser Physics Apparatus) instrument, researchers combined antiprotons with positrons to form antihydrogen atoms.
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- Researchers trapped hundreds of antihydrogen atoms in a vacuum and used laser pulses to excite the atoms, prompting them to jump into a higher energy state. Prompting or measuring this change, known as the Lyman-alpha transition, is a method used frequently in astronomy to study dark energy, that unseen, yet abundant force that makes up about 68 percent of the total energy of the universe.
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- When the antihydrogen atoms drop back down to a lower energy state, they release photons. The researchers measured these photons, which revealed that the antihydrogen emissions were the same as those one would expect from a normal hydrogen atom.
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- The researchers plan to use this approach to test how antimatter and gravity interact. This gets us just a bit closer to answering some of these big questions in physics. Over the past decades, scientists have been able to revolutionize atomic physics using optical manipulation and laser cooling, and with this result, we can begin applying the same tools to probing the mysteries of antimatter.
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- Antimatter is just like normal matter, with all the same properties and all the same abilities to make up atoms and molecules, except for one crucial difference: It has an opposite charge.
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- The electron, for example. Mass of 9.11 x 10^-31 kg. Quantum spin of 1/2. Charge of -1.6 x 10^-9 coulombs.
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- It has an antimatter evil twin, the “positron“. The positron has a mass of 9.11 x 10^-31 kg. Quantum spin of 1/2. Charge of … 1.6 x 10^-9 coulombs.
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- It is the same for every other particle. There's a dark-side twin for the top quark, the neutrino, the muon and all the fundamental particles that make up our daily lives have a partner, living just on the other side of the charge fence.
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- Our universe ought to be swimming with antimatter, existing in equal parts with normal matter. Whole planets, stars and galaxies made of antimatter.
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- When matter and antimatter meet just as the pairs are produced in perfect symmetry in fundamental interactions, they are destroyed in symmetry as well. When a particle finally gets to meet with its antiparticle all their combined matter is converted into energy, usually in the form of high-energy gamma-ray radiation.
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- The universe is filled with constantly-interacting particles. High-energy particles zipping across light-years. Fountains of material escaping from galaxies and new material drifting in. Stars colliding. In our universe, stuff mixes with stuff all the time. If some decent proportion of that was antimatter, the universe ought to be a lot more energetic than it is.
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- If the antimatter isn't here anymore, where did it go?
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- One possibility is that our universe was simply born this way, with an abundance of matter and a severe lack of antimatter. Something in the early universe caused an imbalance between matter and antimatter.
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- An imbalance. A strange process that produced more matter than antimatter. Most of the pairs would be annihilated, but a few normal particles would remain. It wouldn't have to be much: Just one particle in a billion would be enough to lay the foundations for all the stars and galaxies that we see today.
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- Whatever interaction, whatever process, led to matter's ultimate victory had to be strange indeed. It had to start with producing not just an excess quantity of regular matter, but also an excess quantity of charge to counterbalance it.
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- This process had to happen during a sharp boundary, when the infant cosmos was transforming rapidly from one state to another. It's only there that the physics would permit such a rule-breaking violation to take place; otherwise a universe in equilibrium would just end up balancing all interactions out.
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- Is there anything in all of known physics that could make the antimatter go away? There are some hints and suggestions buried in rare particle interactions involving the weak nuclear force. We understand these interactions only dimly, especially the way they would occur in the early universe, but even there our best guess for its matter-favoring ability put it far, far below the minimum needed to explain our present situation.
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- The origins of the asymmetry between matter and antimatter is an outstanding problem in physics. A problem that pushes the boundaries of current knowledge and pushes our understanding of the universe into some of its earliest moments.
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- New discoveries are needed. Innovative laser experiments at the CERN lab in Switzerland has brought physicists one step closer to understanding mysterious antimatter.
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- An antihydrogen atom, consisting of an antiproton and a positron (the antimatter counterpart of an electron), is the antimatter version of a hydrogen atom. Using the Antiproton Decelerator at CERN's ALPHA (the Antihydrogen Laser Physics Apparatus) instrument, researchers combined antiprotons with positrons to form antihydrogen atoms.
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- The researchers trapped hundreds of antihydrogen atoms in a vacuum and used laser pulses to excite the atoms, prompting them to jump into a higher energy state.
-
- Prompting or measuring this change, known as the “Lyman-alpha transition“, is a method used frequently in astronomy to study dark energy. This unseen, yet abundant force that makes up about 68 percent of the total energy of the universe.
-
- When the antihydrogen atoms drop back down to a lower energy state, they release photons. The researchers measured these photons, which revealed that the antihydrogen emissions were the same as those one would expect from a normal hydrogen atom.
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- The Lyman-alpha transition is the most basic, important transition in regular hydrogen atoms, and to capture the same phenomenon in antihydrogen opens up a new era in antimatter science.
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- The researchers plan to use this approach to test how antimatter and gravity interact.
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- More antimatter particles stream toward Earth than scientists can explain and new research from a mountaintop observatory in central Mexico deepens the mystery by crossing off one possible source.
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- The Earth is constantly showered by high-energy particles from a variety of cosmic sources. The recent finding, November 2020, concerns positrons, the antimatter complements of electrons. High-energy particles, usually protons, traveling across the galaxy can create pairs of positrons and electrons when they interact with dust and gas in space.
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- In 2008, the space-based PAMELA detector measured unexpectedly high numbers of earthbound positrons. This was about 10 times what they were expecting to see. After years of work, camps coalesced around two distinct explanations.
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- One hypothesis suggests the particles come from nearby pulsars, rapidly spinning cores of burnt-out stars, which can whip particles like electrons and positrons to incredible speeds.
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- The other group posits a more exotic origin for the excess positrons, perhaps involving dark matter, an unknown yet pervasive entity that accounts for 80 percent of the universe's mass.
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- Particles like positrons that carry an electric charge are difficult to detect on Earth since they can be deflected by the planet's magnetic field. But scientists have a workaround. The particles also interact with the cosmic microwave background, an ever-present stream of low-energy photons left over from the birth of the universe.
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- The high-energy electron, or positron, will kick the low-energy photon ... so this the photon becomes a high-energy gamma-ray. These gamma-rays, which have no electric charge, can pass right through the magnetic field and make it all the way to Earth's surface.
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- Scientists used the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, located about 4 hours east of Mexico City. HAWC comprises more than 300 tanks of extra-pure water.
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- When gamma-rays plow into the atmosphere, they create a cascade of high-energy particles. As this shower of particles passes through HAWC's tanks, it emits flashes of blue light, which scientists can use to determine the energy and origin of the original cosmic ray.
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- The data from HAWC revealed that particles are streaming away from the pulsars too slowly to account for the excess positrons.
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- The measurement do not decide the question in favor of dark matter, but any new theory that attempts to explain the excess using pulsars will need to match the new data.
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- By observing the rotations of galaxies, scientists determined that the universe contains more mass than the objects we can observe. They call this mysterious extra mass dark matter. Aside from seeing dark matter's gravitational influence from afar, no one has directly detected it otherwise.
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- However, a popular model of the substance involves weakly interacting massive particles, or WIMPS, which interact with regular matter solely through gravity. If these proposed particles were to decay, or be annihilated somehow, they could conceivably generate pairs of electrons and positrons.
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- There are other astrophysical processes to consider. Supernova remnants and micro quasars, extremely bright objects formed as matter spirals toward a blackhole, can produce positrons. And there's the possibility that the initial model of particle interactions with the cosmic microwave background is inaccurate.
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- May 9, 2021 ANTIMATTER - is there another world? 3152
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