The so far unique laboratory is located about 2400 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, for a rotation around its own axis, the one neutron star needs only 44 milliseconds. His companion is a little more leisurely on the road with 2.8 seconds. Researchers on Earth are aware of this because both neutron stars act as pulsars that emit radio waves to Earth. With the help of the radio signals of this double pulsar called PSR J0737-3039, an international team has now been able to thoroughly verify Albert Einstein's general theory of relativity. They present their results in the journal "Physical Review X".
The short summary is: Einstein is right again. Unfortunately.
Using the double pulsar PSR J0737-3039 as a general theory of relativity test bed
For over 16 years, the team around Michael Kramer from the Max Planck Institute for Radio Astronomy in Bonn had examined the 2003 double pulsar PSR J0737-3039 with seven radio-released radio staple around the world.
Double systems that consist of at least one pulsar are estimated by scientists due to their extreme characteristics.
Because the neutron stars may only have a little more mass than the sun has, but with a diameter of only about 20 kilometers, they are quite small.
Therefore, they should be noticeable effects of relativity theory that cannot be generated by earthly means.
According to a prediction of the general theory of relativity, such a double system should, for example, emit gravitational waves. Since nothing is in vain in the universe, the system loses energy as a result, with the result that the two neutron stars are getting closer and closer – until at some point they merge with each other. The team has now demonstrated exactly this approximation, and thus also the gravitational waves indirectly: "After each year, the neutron stars need 39 microseconds less for an orbit," says Paulo Freire from the Max Planck Institute for Radio Astronomy. "This means that the neutron stars will merge with each other in about 86 million years." It is true that such a measurement at 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 managed to estimate the distance of PSR J0737-3039 more accurately than was and is possible with the Nobel Prize-worthy Hulse-Taylor pulsar.
The general relativity can only be explained by the general theory of relativity, in which the planetary orbit changes over time. »We can also observe this effect very closely with the double pulsaries. However, the effect here is just as large as with Mercury in around 400 years, «says Paulo Freire. In addition, the researchers had to observe another relativistic effect in order to be able to explain this rotary rotation at all: the lens-thirring effect. To put it simply, this effect describes the phenomenon that the rotating neutron star pulls the space -time around the entire double system with it. This effect had previously only been measurable in our own solar system.
Using the double pulsar PSR J0737-3039, the research team, in which Paulo Freire was also involved, was able to verify and confirm a total of seven predictions and effects of general relativity. What sounds like a complete success for Albert Einstein and his general theory of relativity is actually a small disappointment for the researchers: "We would find nothing better than uncovering evidence of something that points to a deviation from the general theory of relativity," says Paulo Freire. "But I have to say that it's an excellent theory. All the effects we observe follow their predictions exactly."
