2023-08-11 00:03:02
Dark matter through the prism of time: how atomic clocks reveal the unknown boundaries of space
A fresh look at ultralight particles and their potential impact on the Universe.
Observatories in astronomy indicate the presence of “dark matter”, which makes up more than 80% of all matter in the universe. It interacts with visible matter mainly through gravitational forces, and the lack of interaction with photons makes it “dark”.
One promising theoretical approach is the idea that dark matter can be made up of particles that behave more like waves than individual particles. These so-called “ultra-light” dark matter particles might lead to tiny fluctuations in the fine structure constant.
To search for ultralight dark matter, PTB researchers used a watch that is sensitive to possible changes in the fine structure constant. In the course of many months of measurements, the clock was compared with two other atomic clocks with less sensitivity.
The measurement results did not show significant fluctuations characteristic of ultralight dark matter, so dark matter remained “dark” even upon closer examination. However, the absence of a signal made it possible to determine new experimental upper limits for the possible interaction of ultralight matter with photons, improving the previous limits by more than an order of magnitude.
At the same time, the researchers studied whether the fine structure constant changes over time and found no such variation. These data indicate that the constant remains unchanged even over long time periods.
This experiment is an important step towards creating more compact and reliable optical frequency comparisons – for example, for the future search for dark matter in space.
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