Einstein's dream came true

For 100 hundred years the astrophysical phenomenon of gravitational waves has been a believable prediction made by Einstein. Today, scientist are able to detect the faint waves using a giant interferometer called the LIGO-detector. // By Teresa Herrera and Sarah Marie Lange

5.02.2017 // This year the Nobel Prize in physics went to the US-Scientists Rainer Weiss, Barry Barish and Kip Thorne for their involvement in creating a system called the "Ligo-Detector." This new technology recently enabled scientists to record and prove the existence of gravitational waves.

Albert Einstein was right

In 1915, Albert Einstein speculated about the existence of gravitational waves, an idea conceived from his general relativity theory. In fact, his calculations proved them indirectly. He believed, that gravitation arises from mass curving space and time. This curvature would not take place infinitely fast, but rather at the speed of light. Furthermore, Einstein believed that gravitational waves emerge from incredibly energetic occurrences within the universe. For example, two very large masses that attract and orbit each other – like two black holes, or intense star explosions. The released energy radiates into space and deforms spacetime, and thus forms a gravitational wave.

So, how did scientist today manage to do it? Why did it take so long to discover gravitational waves, although the theory existed for nearly a hundred years?
"The technique needed to detect those, could not be developed until very recently.“ Eduardo Ros, Scientific Coordinator of the Radio Astronomy/VLBI Department at Max-Planck-Institut for Radio Astronomy in Bonn, Germany states. „Years and years of discoveries and fine adjustment of detectors, as developed by our colleagues of the Max-Planck-Institute of Gravitational Physics in Hannover, made possible the construction of LIGO in the USA and the proper calibration of the instruments, so that they are capable of detecting variations much smaller than the size of an atom, which is the size of the effect of gravitational lenses. Already Einstein said 100 years ago that he could hardly imagine that these waves would be discovered one day, but present techniques have made it possible."

Present techniques have made it possible

LIGO was built in 1999 and the search for the gravitational waves began around 2002. After the lack of success, scientist redesigned the instruments between 2010 and 2014, leading to an improvement that made LIGO’s interferometers 10 times more sensitive. This enabled LIGO to listen for gravitational waves that are 10 times farther away than the old construction.

This evolution ultimately led to the point in 2015, LIGO recorded gravitational waves, coming from a collision of two black holes that occurred 1.3 billion years ago. Currently, far more accurate frequencies are registered. On August 17th, 2017, a signal of 90 seconds was recorded, that emerged from a big collision of two neutron stars – something that has been foreshadowed for decades, but never before recorded.

Some scientists celebrate this advancement as the biggest discovery of the century.

So what does this mean for the future of astrophysics and space travel?
"With the detection of gravitational waves, the physical conditions in extreme objects can be studied in further detail, which opens a new branch in multi-band astrophysics", says Thomas Kirchbaum, Astronomer in the Very Long Baseline Interferometry Group at Bonn's Max-Planck-Institut. Eduardo Ros adds:

"The discovery of gravitational waves opens a new window to the universe and to the phenomenon of merging of very compact and massive objects. These compact objects are either neutron stars or black holes. The largest gravitational waves are originated by the merging of black holes, detectable by LIGO if having stellar origin, or eventually detectable with radio telescopes by a technique called "pulsar timing" if the black holes are super massive objects of millions of solar masses. For the merging of neutron stars a flash of light at different wavelengths was expected, as this was recently discovered immediately after a gravitational wave detection, as gamma rays and radio waves, detected by the Fermi and Integral satellites, and by the Very Large Array, respectively. Concerning astronautics, namely, space travel, a new impulse will come to put forward astronomical space missions such as LISA, with the objective of exploring gravitational waves from space," Ros continues, „Nothing changes for the manned missions, these efforts are carried in parallel by the space agencies, and I don’t think the discovery of gravitational waves has an impact in this effort."

The authors

Teresa Herrera

Sarah Marie Lange

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