Physicists have measured the shortest span of time ever. It’s 0.000000000000000000247 second, also known as 247 zeptoseconds. And this period is how it takes a single particle of light to pass through a molecule of hydrogen.
Not familiar with zeptoseconds? Take all the seconds that have passed since the beginning of the universe. (The universe is about 13.8 billion years old.) Multiply that number by 2,500. That’s about how many zeptoseconds fit into just one second.
Researchers reported their new measuring feat in the October 16 Science. It should allow physicists to now study interactions between light and matter at a whole new level of detail.
To begin, the scientists shined X-ray light on hydrogen gas. Every hydrogen molecule contains two hydrogen atoms. Light particles are known as photons. Each is considered a quantum of light. When a photon crossed each molecule, it booted an electron — first from one hydrogen atom, then the other.
Those kicked-out electrons stirred up waves. That’s because electrons sometimes act like waves. These “electron waves” were similar to ripples that form by a stone skipped twice over a pond. As those electron waves spread out, they interfered with each other. In some places they made each other stronger. In other places, they cancelled each other out. The researchers were able to observe the ripple pattern using a special type of microscope.
If the electron waves had formed at the same time, the interference would have been perfectly centered around the hydrogen molecule. But one electron wave formed slightly before the other. This gave the first wave more time to spread out. And that shifted the interference toward the source of the second wave, explains Sven Grundmann. He’s a physicist at Goethe University in Frankfurt, Germany.
This shift let the researchers calculate the time delay between the creation of the two electron waves. That delay: 247 zeptoseconds. It matches what the team had expected, based on the speed of light and the known diameter of a hydrogen molecule.
Past experiments have observed particle interactions as short as attoseconds. One attosecond is 1,000 times as long as a zeptosecond.
Power Words
More About Power Wordsatom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
diameter: The length of a straight line that runs through the center of a circle or spherical object, starting at the edge on one side and ending at the edge on the far side.
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues.It’s made of a single proton (which serves as its nucleus) orbited by a single electron.
microscope: An instrument used to view objects, like bacteria, or the single cells of plants or animals, that are too small to be visible to the unaided eye.
molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).
particle: A minute amount of something.
photon: A particle representing the smallest possible amount of light or other type of electromagnetic radiation.
physicist: A scientist who studies the nature and properties of matter and energy.
quantum:(pl. quanta) A term that refers to the smallest amount of anything, especially of energy (light) or subatomic mass.
speed of light: A constant often used in physics, corresponding to 1.08 billion kilometers (671 millionmiles) per hour.
universe: The entire cosmos: All things that exist throughout space and time. It has been expanding since its formation during an event known as the Big Bang, some 13.8 billion years ago (give or take a few hundred million years).
wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.
X-ray: A type of radiation analogous to gamma rays, but having somewhat lower energy.
Citations
Journal: S. Grundmann et al.Zeptosecond birth time delay in molecular photoionization.Science. Vol. 370, October 16, 2020, p. 339. doi: 10.1126/science.abb9318.
About Maria Temming
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Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.
