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The Matter Of Antimatter: Answering The Cosmic Riddle Of Existence

World Science Festival・80 minutes read

The discovery of antimatter in the early 20th century raised questions about the composition of our universe, with Dirac's equation and subsequent experiments confirming its existence and exploring the imbalance between matter and antimatter. Physicists continue to study antimatter through experiments, seeking to understand its properties, behavior, and potential applications, while investigating theories like grand unified theories, Higgs field interactions, and matter/antimatter asymmetry.

Insights

  • The discovery of antimatter in the early 20th century through Paul Dirac's equation raised questions about the imbalance between matter and antimatter, hinting at a tiny difference in their creation that allowed matter to dominate in the universe.
  • Scientists, including Hitoshi Murayama, Janet Conrad, Michael Doser, Marcela Carena, and Neil Turok, are actively exploring antimatter through experiments to understand its fundamental role in the existence of the universe.
  • Various experiments, such as ALF and Athena, focus on creating and studying antimatter particles like anti-hydrogen atoms, while neutrino oscillations offer insights into neutrino behavior and potential differences between matter and antimatter particles.

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Recent questions

  • What is antimatter?

    Antimatter is a form of matter composed of antiparticles with properties opposite to those of normal matter particles.

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Summary

00:00

Unraveling the Mysteries of Antimatter

  • In the early 20th century, the discovery of antimatter raised questions about the existence of our matter-filled universe.
  • Paul Dirac's 1928 equation described how particles like electrons behave near the speed of light, revealing two solutions.
  • One solution represented electrons, while the other described antimatter, like the positron with opposite charge to electrons.
  • Dirac's theory extended to all particles, including quarks and anti-quarks forming anti-protons and anti-atoms.
  • In 1932, Carl Anderson's experiment confirmed Dirac's prediction by detecting the first positron, verifying antimatter's existence.
  • The annihilation of matter and antimatter poses the question of why any matter remains in the universe.
  • The imbalance between matter and antimatter after the Big Bang suggests a tiny difference in their creation, allowing matter to persist.
  • Scientists explore theories like separated antimatter or a slight imbalance to explain the universe's matter dominance.
  • Ongoing experiments aim to understand antimatter better, seeking answers to the fundamental question of our existence.
  • Physicists, including Hitoshi Murayama, Janet Conrad, Michael Doser, Marcela Carena, and Neil Turok, discuss Dirac's equation and the mysteries of antimatter.

18:08

"Antimatter Production and Challenges at CERN"

  • Energy can transform into matter and antimatter pairs, as seen in a photon converting into an electron and positron.
  • The positive and negative charges of the electron and positron spin in opposite directions due to a magnetic field.
  • Antimatter is detected in detectors through the observation of particles and antiparticles traveling in opposite directions.
  • Background interference, similar to the signal being sought, complicates the detection of antimatter.
  • Antimatter particles, like anti-electrons and antiprotons, are constantly present, with an anti-electron appearing every hour.
  • To produce antiprotons, an accelerator is required to provide the necessary energy for particle production.
  • Antiprotons interact with matter, annihilating or causing nuclear fragmentation, leaving traces in photographic emulsions.
  • CERN operates an antimatter factory, where hydrogen is accelerated to produce antiprotons through collisions with iridium.
  • Antiprotons are decelerated for study, trapped using electric and magnetic fields, and manipulated within potential landscapes.
  • Despite the ability to produce large quantities of antimatter, the cost and challenges of containment and transportation remain significant.

33:35

Creating Imbalance: Matter vs Antimatter Experiments

  • Symmetry between particles is crucial; if protons and anti-protons remain equal, there is no change in numbers.
  • To create an imbalance, two rabbits and two anti-rabbits must pass through a black box.
  • The goal is to find a mechanism to create an imbalance between matter and antimatter.
  • Experimental work focuses on finding tiny differences between matter and antimatter.
  • The ALF experiment measures light emitted by anti-hydrogen atoms.
  • Creating anti-hydrogen atoms involves combining an antiproton and an anti-electron.
  • The Athena experiment in 2002 was one of the first to create and trap anti-hydrogen atoms.
  • The Aegis experiment aims to test gravity's effect on antimatter by shooting atoms out of a cannon.
  • Neutrinos, with no electric charge, can transition between matter and antimatter, potentially saving from annihilation.
  • Neutrino oscillation, where neutrinos change flavors, is a key method to study neutrinos and their interactions with matter.

47:57

Neutrino Oscillations: Detecting Matter-Changing Particles

  • Homer Simpson orders a strawberry chocolate, which starts to interact and mix into strawberry and chocolate.
  • The experiment involves detecting strawberry neutrinos, distinct from chocolate, leading to a surprise when half of them turn into chocolate.
  • Neutrino oscillations allow neutrinos to shift identities while traveling through space.
  • To determine if anti-neutrinos behave differently, an experiment is conducted at Fermi National Accelerator Laboratory.
  • A beam of neutrinos is created using an accelerator, with protons surfing radio frequency waves to gain energy.
  • Neutrinos produced from proton decay are sent through the ground to a detector far away.
  • Matter and antimatter particles are separated using a magnetic field to direct decay particles towards the detector.
  • The detector, resembling an electronic bubble chamber, is a 40-kiloton state-of-the-art device.
  • An experiment in Japan hints at an asymmetry between neutrinos and anti-neutrinos, potentially explaining matter/antimatter differences.
  • The search for matter turning into antimatter or vice versa continues, with experiments like neutrino double beta decay using tellurium crystals.

01:03:26

Unraveling Neutrinos and the Higgs Boson

  • Neutrinos are enigmatic particles with unknown properties, potentially behaving differently from each other.
  • The United States is collaborating on a significant neutrino experiment in the next decade.
  • Theories like grand unified theories suggest forces like electromagnetic, strong, and weak may have unified in the early universe.
  • The convergence of non-gravitational forces at high energies hints at grand unified theories.
  • Proton decay experiments, like those at Fermilab and Super-K, aim to test these theories.
  • The Higgs field gives mass to particles, turning on 1/10 of a billionth of a second after the Big Bang.
  • The Higgs field's role in matter/antimatter asymmetry is being explored, potentially linked to exotic configurations.
  • Experiments at CERN and future colliders aim to study the Higgs field's role in asymmetry.
  • Supersymmetry or additional dark forces may be needed to explain the matter/antimatter asymmetry.
  • The Higgs boson's mass may impact the rapid turning off of the asymmetry process, suggesting the need for additional particles or forces.

01:20:31

"Exploring Theoretical Particle Physics and Multiverse"

  • The field of theoretical particle physics has been exploring various avenues over the last 30 to 35 years, primarily by adding more particles, fields, symmetries, and dimensions.
  • Despite the initial success of discovering new particles through experiments, the last 35 years have not yielded any successful predictions of natural phenomena.
  • The concept of a multiverse, arising from particle physics, string theory, and supersymmetry, introduces numerous theories and possibilities, leading to a vast array of potential universes.
  • Observations of the universe have consistently shown a remarkable simplicity in its large-scale structure, characterized by a single number representing the level of fluctuation from the Big Bang.
  • Dark energy plays a significant role in making the observable universe finite, suggesting that the universe may be simpler and self-contained.
  • Quantum mechanics implies that while multiple possibilities exist, one dominant probability typically prevails, potentially indicating that the current universe is the most likely.
  • Matter and antimatter creation, exemplified by an electric field generating particle-antiparticle pairs, showcases the fundamental principle of particles existing in both forward and backward time directions.
  • The creation of a particle-antiparticle pair can be viewed as a single particle moving backward and forward in time, akin to the formation of the universe.
  • The proposed scenario suggests that the Big Bang event could be a unified occurrence where the universe and anti-universe emerge as a single entity, challenging the concept of a definite beginning.
  • Antimatter applications, such as positron emission tomography utilizing positrons emitted by bananas or injected radioisotopes for medical imaging, demonstrate practical uses of antimatter technology.

01:38:07

Unveiling the Theory Behind Future Phenomena

  • Future puzzles will explain other phenomena as side effects of a larger theory.
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