Ever since gravitational waves were first directly detected in 2015, scientists have gained a completely new tool for studying the universe.
Instead of relying solely on the light emitted by stars, galaxies, and other celestial objects, researchers have begun to monitor tiny disturbances in the very fabric of spacetime.
These waves are created during some of the most dramatic events in the cosmos, such as the collision of black holes and neutron stars, carrying information from parts of the universe that are often inaccessible by traditional astronomical methods, according to SciTech Daily.
Although the study of gravitational waves has seen tremendous progress in recent years, one important question remains without a clear answer. How to precisely measure gravitational waves in an ever-expanding universe?
Researchers from the Leibniz University in Hanover dealt with this very problem, presenting a new theoretical framework for understanding and measuring gravitational waves on a cosmological scale.
Their work does not bring a new telescope or a new type of detector, but it does offer something that could be equally significant in the long run – a different way of interpreting the signals that scientists register as they study the universe.
Gravitational waves are space-time disturbances that propagate at the speed of light. More than a century ago, they were predicted by Albert Einstein within his General Theory of Relativity.
However, only the development of extremely sensitive instruments enabled their direct registration.
Since then, gravitational waves have become one of the most important sources of information about extreme cosmic events.
The problem arises when the observation extends from local cosmic events to the entire universe.
Unlike the stable environment often used in theoretical models, the real universe is not static.
It has been expanding since the Big Bang, and that expansion affects everything that moves through it, including gravitational waves.
For this reason, physicists have been debating for a long time how to properly define the energy of gravitational waves in such an environment. At first glance, the question may seem very abstract, but it has direct consequences on the way data collected during space observation is interpreted.
When a gravitational wave travels through space that is changing, it is not always easy to determine which part of the signal belongs to the wave itself, and which part is the result of the expansion of the universe.
This is precisely why existing methods have certain limitations when applied to cosmological scales.
The researchers therefore proposed a different approach.
Instead of trying to define the energy of gravitational waves on a global scale throughout the universe, they focused on what could be directly measured.
In other words, the starting point of their model is not an abstract mathematical definition, but the actual response of the detector to the passage of a gravitational wave.
Such an approach connects theory with concrete measurements and enables a clearer understanding of what the instruments actually register. According to the authors of the study, this is precisely where the greatest advantage of the new framework lies. Instead of describing the energy of gravitational waves in a way that may depend on the choice of a mathematical model, the new method emphasizes physically measurable effects.
This is especially important because the next generations of gravity observatories promise much more data than we have today. Future instruments will be able to register weaker and more distant signals, enabling the study of events that took place very early in the history of the universe.
As the amount of available data increases, so does the need for theoretical models that can reliably explain what is observed. Even the smallest ambiguities in the definition of gravitational waves can become significant when analyzing signals from vast cosmic distances.
For this reason, the authors of the research believe that their work represents an important step towards a more precise connection between gravitational astronomy and cosmology. If the new approach proves to be successful, it could help scientists study the development of the universe, its expansion and the processes that shaped today’s cosmos with greater certainty.
It is particularly significant that gravitational waves provide information that cannot be obtained by observing light. While electromagnetic radiation can be absorbed, scattered or blocked, gravitational waves travel through space almost unhindered. That is why they represent a unique source of data on remote and extreme events.
This is precisely why any progress in their understanding has the potential to advance our knowledge of the universe.
Although the new research at first glance deals with a very specific theoretical question, its significance far exceeds the boundaries of mathematical physics, reports Telegraf.rs.
It refers to one of the most important questions of modern science – how to correctly interpret the information that the universe sends us.
