Key Points
- Antimatter and regular matter were both banged into existence at the same time.
- Negatively charged particles in matter have an opposite twin in antimatter.
- Humans first created antimatter particles in labs after they were hypothesized and found in nature.
- These discoveries were made at CERN.
Antimatter and regular matter were both banged into existence at the same time during the Big Bang. They’re two sides of the same coin. They represent a common configuration of particles, but with opposing motions or charges.
The opposing particles are virtually identical to one another, complete with the same properties, differing only by charge. Negatively charged particles in matter, or electrons, for instance, have an opposite twin in antimatter, the positron with the same mass and spin but a positive charge. Neutral particles like neutrons in the matter also have their antimatter counterparts. And when opposing particles collide, they explode violently, releasing a burst of energy.
But we can’t call it a perfect symmetry yet, as scientists are still trying to match up all the partners in both configurations. Particles like neutrinos in the matter, for example, are still singletons. Also, the matter has come to dominate the pair significantly, and the disproportionate difference in their availability still puzzles scientists to date.
During the 20th Century, antimatter dominated scientific discourse, much like dark matter in the 21st Century. It also inspired a new wave of art and literature, including fiction novels and movies that became icons of popular culture. But all the pomp and publicity made antimatter sound more fictitious, with spurious claims from movies eclipsing the real-life applications gradually being discovered from research.
One of those real-life applications is the construction of the Standard Model of physics, which leads to a better understanding of the universe and how it works.
How is Antimatter Made, and How Was It Discovered?
Humans first created antimatter particles in labs after they were hypothesized and found in nature. And since then, they’ve been chasing them down with countless ultra-high-speed collisions at massive particle accelerators like CERN’s Large Hadron Collider. So far, the most complex antimatter element produced is antihelium, the opposite twin of helium. Most of the experiments have focused on creating antihydrogen, the opposite of hydrogen.
Antimatter was first proposed by British physicist Paul Dirac in the late 20s. In trying to tie in two emerging fields of modern physics, relativity – which deals with the disposition of particles in time and space, and quantum mechanics – which revolves around the subatomic qualities of matter, he showed how the energy of particles was affected by their speed.
His proposition that energy could be negative when particles with the same spin have an opposite charge befuddled scientists of the age.
Dirac first stumbled on the idea when trying to solve an equation describing the movement of electrons at the near speed of light. His equations yielded dual results – they could either be positive or negative. His idea startled him at first, and he was hesitant to share it.
Just like any emerging theory, Dirac’s proposition met with stiff resistance when he finally brought it to light. It wasn’t until about a decade later that tangible proof emerged.
In a research led by technology physicist Carl Anderson at American California Institute, cosmic ray particles were found to leave tracks inside a cloud chamber that bore a striking semblance to Dirac’s anti-electrons. Both Dirac and Anderson won the Nobel prize in Physics in 1933 and 1936 respectively for their work.
To Dirac, his equations revealed a dimension of lower energies that were far below the radar of regular science at the time. He declared that the ‘normal’ energy range recorded in labs was all a product of just the ‘normal’ particles. However, a ‘hole’ is left behind when a particle is excited from a lower energy state to a recognizable higher state, creating a strange mirror image that we can observe – or antimatter.
Over the decades more particle and antiparticle pairs have been revealed. They’ve been detected from the interactions of cosmic rays with the earth’s atmosphere. They’re also found to be produced from high-energy thunderstorms.
Antimatter occurs throughout the universe through many natural processes. However, the collision between antimatter and matter destroys both with the result being a spark of energy. In a universe dominated by matter, that means antimatter doesn’t exist for too long before it’s gone.
The universe was a huge ball of energy moments after the Big Bang, and as it cooled and expanded, produced particles and anti-particles. Antimatter can help us unravel the mysteries of the universe.
How Does Matter Interact with Antimatter?
When matter and antimatter collide, we see a spark of light, but to scientists, the particles decay into gamma radiation, a high-level form of energy. Gamma decay is a regular feature of many different radiating materials like potassium. In science fiction, the release of high energy from antiparticle-particle collision has been used to power everything from rocket engines to weapons of mass destruction.
The reality on the ground, though, is that antimatter is quite difficult to produce. With the current capacities at CERN’s Large Hadron Collider, it would take nearly 100 billion years to generate a gram of antimatter. It’s even more difficult to store antimatter in tangible quantities for any practical use. Any container used is made of matter, which instantly annihilates antimatter.
However, scientific inquiries show that antiparticles and particles have completely identical properties, and particles can be interchanged with their antiparticle – a concept known as CP symmetry. It’s also been proposed that the same laws of physics apply to both.
And according to the laws of physics, they should be available in equal quantities. But then if they were both created in equal quantities during the Big Bang, they should have canceled each other out instantly on contact, wiping out everything.
However, it seems the universe has bent the rules in matter’s favor. It’s so far managed to retain disproportionate amounts of matter to support the physical world. The relative scarcity of antimatter in the universe is still a major mystery to scientists today.
Why is Antimatter so Scarce?
Some propositions eliminate the conundrum from the onset, claiming there was originally more matter than antimatter from the Big Bang. The theory holds that only a minute amount of antimatter was created, and after the initial annihilation, a huge amount of matter was still left behind to form stars and galaxies. The disproportion was about one to one billion, according to the theory.
Another take has been the neutrino, a particle yet without its antiparticle match. Neutrinos have a neutral charge and barely interact with any other particle. In theory, neutrinos could be their anti-particle.
A few neutrinos may drop down to the low energy, antiparticle states now and then, but the rest mostly remain in their high-energy states. On the universal level, this could explain the dominance of high-energy states. But so far, experiments have been inconclusive.
As of yet, nothing in physics endows matter with qualities that would explain its dominance. And since particle pairs are identical in every dimension, it begs the question of why the two should exist separately instead of just one or nothing at all. And why would the charge become so much of a deal as to transform both into an energy soup on contact?
We could gain more clues from radioactive experiments producing unequal amounts of particles and antiparticles. But the discrepancy in these experiments is no match for that on the universal level. Large colliders are buzzing with antiparticle activities and scientists are discovering more about the mirror qualities every day.
For instance, a research group at CERN’s colliders have shown a slightly significant difference in the quantity of charge in positron particles of antihydrogen compared to their electron counterpart. Other researchers are investigating the effects of forces like gravity and electromagnetism on opposing particles. These experiments are also expected to lead us to ground-breaking revelations in fields like quantum mechanics and relativity.
What Are Some Real-Life Applications of Antimatter?
Antimatter is at the heart of the radioactive decay processes used in Positron Emission Tomography (PET) scanners in hospitals. This scanner allows for high-precision imaging of internal body parts.
The spark of energy from the antimatter-matter collision could have space travel applications. Engineers have proposed antimatter fuel as a more energy-efficient way to power a spacecraft.
The idea was seriously considered by NASA for Mars travel and for sending probes to the nearest star system, the Alpha Centauri. The energy from the matter-antimatter collision can send a spacecraft shuttling at near-light speeds, but also slow enough to capture observable images.
A small ounce of fuel could power a spacecraft at near-light speeds for decades. However, the idea is prohibitively expensive with current technologies. As earlier noted, it takes an incredible amount of resources to produce an ounce of antimatter.
According to Positronics Research LLC’s Gerald Smith, “A rough estimate to produce the 10 milligrams of positrons needed for a human Mars mission is about 250 million dollars using technology that is currently under development.” That seems quite expensive, but it’s not far off the mark of current expenses. With current technologies, it costs $10,000 to lift a pound into space. A human traveling to Mars would rack up eight or nine-figure expenses.
