What are gravitational waves

questions and answers - What are gravitational waves actually?

What are gravitational waves?

So far, gravitational waves were among the last unproven building blocks of Albert Einstein's general theory of relativity, which was published a hundred years ago. The tiny waves are distortions of space-time and, according to Einstein, arise during particularly high-energy events in the universe - for example, violent star explosions or black holes that crash into one another. However, the existence of the gravitational waves emitted during such cosmic catastrophes could only be inferred indirectly - for example when observing extremely massive neutron stars and pulsars.

If Einstein predicted the existence of gravitational waves a hundred years ago, why weren't they discovered for decades?

Because they are incredibly tiny. Direct detection of gravitational waves is extremely difficult because they compress and expand space on a very small scale: According to the European Space Agency ESA, gravitational waves, which are generated, for example, by two black holes orbiting one another, do not exceed a ruler one million kilometers long once the size of an atom. Even Einstein did not believe that the tiny changes in length caused by gravitational waves could ever be measured.

How did the researchers find them out anyway?

In their search for gravitational waves, the scientists have been using enormous systems for years that would have been hard to imagine in Einstein's time. These include the two four-kilometer Ligo detectors in the USA. The plants in Hanford (Washington state) and Livingstone (Louisiana) have been working with a new generation of instruments since last autumn, which are much more sensitive than their predecessors. The gravitational waves were recorded on September 14, 2015 with the laser detectors of the Ligo observatories, 3000 kilometers apart.

What cosmic event do these gravitational waves come from?

From the merging of two black holes 1.3 billion years ago, as the researchers announced. These black holes, remnants of the explosion death of giant stars, were 29 times and 36 times more massive than our sun.

Were German scientists involved in the discovery?

Yes. The Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hanover and Potsdam, which works closely with the Institute for Gravitational Physics at Leibniz University Hanover, made decisive contributions to the new generation of Ligo observatories. The Max Planck Institute for Gravitational Physics near Hanover also operates the GEO600 gravitational wave detector together with partners from Great Britain. It is part of a worldwide network of detectors, which includes Ligo in the USA as well as systems in Italy and Japan.

Gravitational wave research is also carried out at the Albert Einstein Institute in Hanover at Leibniz University. It cooperates with the Max Planck Institute for Gravitational Physics. An insight into the institute in Ruthe.

What does the detection of gravitational waves mean for future science?

The discovery opens a new window to the “dark” side of the cosmos - it marks the beginning of gravitational wave astronomy, which should complete our picture of the universe and its development since the Big Bang. Scientists even compare the detection of gravitational waves with the moment when Galileo Galilei first pointed his telescope at the sky more than 400 years ago.

What new findings can the researchers now hope for?

By directly measuring gravitational waves, scientists can investigate the structure of our galaxy, explore the formation, growth and merging processes of black holes and explore the processes in the core areas of galaxies. With the possibility of detecting gravitational waves, "fundamental phenomena of the cosmos" could be explored, explained the NASA astrophysicist Tuck Stebbins. Even a look at the first millisecond of the Big Bang 13.8 billion years ago is conceivable.

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