Time crystals and nuclear clocks, explained
A time crystal is a form of matter whose particles settle into a pattern that repeats in time, ticking steadily on their own; they were first made in labs in 2016–2017. A nuclear clock keeps time with a transition inside an atom's nucleus (thorium-229); the first one was announced in Vienna in October 2026.
Key facts
| Time crystal proposed | 2012, Frank Wilczek |
|---|---|
| First made | 2016–2017 (Maryland and Harvard) |
| On a quantum computer | 2021, Google Sycamore |
| Nuclear clock isotope | Thorium-229 |
| First nuclear clock | TU Wien, announced October 2026 |
| Its accuracy (first test) | About 1 second in 30 million years |
What is a time crystal?
An ordinary crystal, like salt or diamond, is a pattern that repeats in space: atoms line up at regular distances. In 2012 the Nobel laureate Frank Wilczek asked whether matter could also form a pattern that repeats in time, ticking forever without using energy.
A perfect version, in a system at rest, turned out to be impossible. But in 2016–2017 two teams, led by Christopher Monroe (University of Maryland, with trapped ions) and Mikhail Lukin (Harvard, with diamond impurities), created discrete time crystals: systems that are pushed at one rhythm but respond at a different, steady rhythm of their own, and keep it even when disturbed. In 2021 Google built one on its Sycamore quantum processor.
Time crystals do not break the laws of physics and cannot power anything: they are a new phase of matter, like a solid or a liquid, that only exists out of equilibrium. Researchers hope they could help protect information in quantum computers.
What is a nuclear clock?
Today's atomic clocks count the vibrations of electrons jumping between energy levels in atoms such as cesium or strontium. A nuclear clock counts a transition inside the atom's nucleus instead. The nucleus is tiny and shielded by its electrons, so outside disturbances barely affect it.
Only one nucleus has a transition gentle enough to excite with a laser: thorium-229. In 2024 teams at TU Wien (Austria) and JILA (Colorado) measured it precisely for the first time. In October 2026 the TU Wien group, led by Thorsten Schumm, announced the first working thorium nuclear clock: in a 24-hour comparison with an ytterbium-ion clock, it kept time to about one second in 30 million years. The best atomic clocks are still more precise, but nuclear clocks could become smaller, sturdier and more stable, and they could detect whether the constants of nature change over time.
See also how the second is defined and the future of timekeeping.
Questions people ask
What is a time crystal in simple terms?
A group of particles that settles into a rhythm that repeats in time, the way an ordinary crystal's atoms repeat in space, and keeps that rhythm even when nudged.
Are time crystals real?
Yes. Discrete time crystals were first created in labs in 2016–2017, and Google made one on a quantum computer in 2021.
Can time crystals be used for time travel or free energy?
No. They do not let you travel in time and cannot be used to extract energy; they are a phase of matter studied mainly for quantum technology.
What is a nuclear clock?
A clock that keeps time using a transition inside an atomic nucleus, thorium-229, instead of the electrons used in atomic clocks. It is less affected by its surroundings.
Who built the first nuclear clock?
A team at TU Wien in Vienna, led by Thorsten Schumm, announced the first working thorium-229 nuclear clock in October 2026, building on 2024 measurements by TU Wien and JILA.
Last updated October 23, 2026.