The so far unique laboratory is located around 2,400 light years away in the constellation Puppis, the aft deck of the ship: There, two neutron stars orbit each other in just 147 minutes. They also rotate around themselves, and one neutron star only needs 44 milliseconds to rotate around its own axis. His companion is a bit more leisurely with 2.8 seconds. Researchers on earth notice something of this because both neutron stars act as pulsars that emit radio waves towards the earth. With the help of the radio signals from this double pulsar called PSR J0737-3039, an international team was able to thoroughly check Albert Einstein’s general theory of relativity. your results put it in the journal »Physical Review X« before.
The short summary is: Einstein is right again. Unfortunately.
The double pulsar PSR J0737-3039 as a test bench for Einstein’s general theory of relativity
For more than 16 years, Michael Kramer’s team from the Max Planck Institute for Radio Astronomy in Bonn had examined the PSR J0737-3039 double pulsar, discovered in 2003, with seven radio telescopes distributed around the world. Double systems, which consist of at least one pulsar, are valued by scientists because of their extreme properties. Because the neutron stars may only have a little more mass than the sun, but with a diameter of only about 20 kilometers they are quite small. Therefore effects of the theory of relativity should become noticeable in them, which cannot be produced with earthly means.
According to a prediction of the general theory of relativity, such a double system should emit gravitational waves, for example. Since nothing is free in the universe, the system loses energy as a result, with the result that the two neutron stars get closer and closer – until they eventually merge. The team has now proven this approach, and thus indirectly also the gravitational waves: “Every year, the neutron stars need 39 microseconds less to orbit,” says Paulo Freire from the Max Planck Institute for Radio Astronomy. “That means that the neutron stars will merge with each other in around 86 million years.” Such a measurement on the Hulse-Taylor pulsar was already worth a Nobel Prize in Physics in 1993. But the current measurements are 25 times more accurate – mainly because the team succeeded in estimating the distance from PSR J0737-3039 more precisely than was and is possible with the Nobel Prize-winning Hulse-Taylor pulsar.