Physicists believe that the fastest object on Earth may be a subatomic particle known as the neutrino.
The Earth is home to many speed marvels, such as spacecraft launching from their pads, racing cars speeding around tracks, and cheetahs chasing their prey. However, the answer to what is the fastest object on the planet depends on how we define “object” and “on Earth.”, according to Live Science.
Neutrinos are very difficult to detect on Earth. (Photo: Big Think).
The clearest answer is likely light. In a vacuum, light travels at a speed of 300,000 km/s. There is no object in the universe that we know of that can exceed that speed. But is light considered an object? Physicists do not agree on this issue. Some argue it is not because light has no mass. Others say it is because, according to quantum mechanics, light behaves as both a wave and a particle. The majority of physicists agree that particles are objects. According to John Matthews, a physicist at the University of Utah, in the vacuum of space, particles known as photons are the fastest objects.
On Earth, the situation becomes more complicated unless in a vacuum chamber. When a photon particle enters the Earth’s atmosphere, it slows down. Then, under the right conditions, it may encounter some challengers. This is because not all particles slow down in the atmosphere in the same way as photons.
Matthews is part of a research team that discovered some very fast particles originating from ultra-high-energy cosmic rays. These are subatomic particle showers falling to Earth from outer space. One of these particles, nicknamed Oh-My-God particle, was discovered by his colleagues in 1991 from the highest-energy cosmic ray ever recorded. Such particles travel at speeds extremely close to the speed of light in a vacuum chamber. However, when they collide with the Earth’s atmosphere, they continue to race forward. Therefore, they exceed the speed of light in the atmosphere, Matthews explains.
This makes the Oh-My-God particle one of the fastest massive objects on Earth, but the top position belongs to the neutrino, according to Justin Vandenbroucke, a particle physicist at the University of Wisconsin-Madison. The Oh-My-God particle could be a proton or similar to a proton; it is relatively large on the subatomic scale. The mass of a neutrino is at least 10 billion times smaller than that of a proton, thus according to fundamental physics laws, it could even move faster at the same energy level.
In a long-term experiment called IceCube in Antarctica, physicists placed detectors within a cubic kilometer of ice, hoping to find high-energy neutrinos. Inside the ice, high-energy neutrinos can move faster than light. When a high-energy neutrino collides with the nucleus of an atom in the ice, it can create charged subatomic particles that also move faster than light. These fast-moving particles emit a flash of light known as Cherenkov radiation, which helps to indirectly detect neutrinos.
In 2016, scientists in the IceCube project discovered the highest-energy neutrino. “As far as we know, this is the fastest particle ever observed”, said Bill Louis, a physicist at the Los Alamos National Laboratory.
