The movements of the Sun, Moon and stars have long been used to keep track of time, and now engineers from the University of Tokyo have proposed a new way to use the cosmos to precisely track time, using showers of particles from cosmic rays.
For most of us, everyday timekeeping can be out by a few seconds without causing any major dramas. But in more scientific, industrial and technological scenarios, differences on the scale of nanoseconds can be crucial. Keeping time this precisely requires networks of GPS and atomic clocks, but these systems are expensive and don’t work everywhere – particularly underground or underwater.
The new technology outlined by the U Tokyo researchers is designed to solve both of those problems. They call it cosmic time synchronization (CTS), and it works by tracking cosmic ray events in the sky.
Cosmic rays are constantly pouring in from deep space, and when they reach Earth they interact with particles in the atmosphere, converting them into a shower of other particles. One of the resulting particles are muons, which have a high energy that allows them to pass through most matter, so they penetrate a few kilometers into the Earth’s surface and oceans.
A CTS system would use muon detectors to synchronize a series of clocks extremely precisely, even if some of the clocks were underground or underwater. The process starts at an altitude of around 15 km (9 miles), where cosmic rays first interact with the atmosphere and produce a shower of particles, including muons. These muons, which all have a specific signature based on the particular cosmic ray event that generated them, can spread out over an area of a few square kilometers, and any CTS devices in that range can be synced up to the same shower with a precision of under 100 nanoseconds.
It might sound like this technique is relying on a lot of chance, like trying to sync up lightning strikes, but the team says that these cosmic ray strikes occur extremely frequently, all over the planet – around 100 times per hour for every square kilometer of Earth. That means a network of CTS systems could service most of the world, including places that GPS can’t reach.
The team says there are other advantages too. CTS is far cheaper than GPS, with muon detectors costing as little as US$100 each, instead of hundreds of thousands for atomic clocks. And since comic rays can’t be produced artificially, CTS systems should be far more secure against hacking than GPS.
“The principle is robust, and the technology, detectors and timing electronics already exist. So we could implement this idea relatively quickly,” said Hiroyuki Tanaka, lead author of the study. “Satellite-based time synchronization has so many blind spots at the poles, in mountainous regions or underwater, for example, and CTS could fill these gaps and more.”
The team does acknowledge that widespread adoption of the technology could be a major hurdle, but it could perhaps start in areas where GPS can’t service.
The research was published in the journal Scientific Reports.
Source: University of Tokyo
