University of Siegen Develops Key Technology for the Einstein Telescope

Every day, massive collisions occur throughout the universe: black holes and neutron stars orbit each other and merge—generating gravitational waves that travel through space at the speed of light. As early as 1916, Albert Einstein predicted that gravitational waves would cause a minimal distortion of space itself: distances are stretched and then compressed again for a tiny moment. About 100 years later, scientists succeeded for the first time in actually measuring such an event. With the planned European “Einstein Telescope,” scientists aim to measure gravitational waves much more precisely in the future in order to peer deep into the cosmic past. Physicists at the University of Siegen are directly involved in preparing this major international project. The Federal Ministry of Research, Technology, and Space has now awarded initial funding of more than 400,000 euros for this purpose.

“Thanks to our expertise in state-of-the-art data electronics, we have been invited to participate in the Einstein Telescope. We are, of course, very pleased about this—it’s wonderful to be part of this highly exciting, large-scale European project, which is planned to span decades,” says project leader Prof. Dr. Markus Cristinziani.

The planned Einstein Telescope is expected to be able to detect up to a thousand times more gravitational waves than today’s observatories: completely hidden beneath the Earth’s surface, it will take measurements using three arms, each ten kilometers long. The length of the detector arms is constantly monitored using sensitive lasers and mirrors that have been meticulously isolated against vibrations. If the length changes in a specific pattern, this indicates a passing gravitational wave. By precisely measuring these waves, the telescope will one day offer a glimpse into the early universe: It is designed to detect gravitational waves from a time when the universe was still very young—and thus provide insights into, among other things, the formation of the first black holes.

“By taking measurements in the low-frequency range, we can even use the Einstein Telescope to detect in advance when an exciting event is about to occur,” says Cristinziani’s colleague, Prof. Dr. Markus Risse. Telescopes around the world could then be aligned in time to observe the event as effectively as possible.

For such an early-warning system to work, even the smallest disturbances must be filtered out. One of these is so-called “Newtonian noise”: Seismic waves displace and compress the rock surrounding the detector. This creates tiny fluctuations in the local gravitational field, which directly affect the sensitive mirrors and can interfere with the measurement signal.

This is precisely where the funded project by the Siegen-based researchers comes in: The physicists are developing particularly fast and flexibly programmable electronics; chips are configured so that they can execute AI algorithms to actively suppress unwanted interference signals. “With the help of artificial intelligence and specialized electronics, we aim to detect and compensate for these disturbances with an extremely short time delay. This allows a correction signal to be fed into the detector’s control system almost in real time,” explains Prof. Cristinziani.

The research being conducted in Siegen is intended to help ensure that the enormous amounts of data the Einstein Telescope will record in the future can be analyzed quickly and accurately. The project demonstrates how closely modern basic research is linked to technological development, says Prof. Risse: “The Einstein Telescope will investigate fundamental questions about the universe. At the same time, we are developing methods that push the boundaries of what is technically possible. It is precisely this connection that makes our research so exciting.”