Scientists compared the falling speeds of a fluff and a neutron star, the densest object in the Universe, and did not find a difference between them, which once again confirmed Einstein's theory of relativity. Their findings were published in the journal Nature.
“If there is a difference between them, then it is no more than three parts per million. Now supporters of alternative theories of gravity will have to drive themselves into an even narrower corridor of values in order for their calculations to coincide with what we observe,”says Nina Gusinskaya from the University of Amsterdam (Netherlands).
Gusinskaya and her colleagues carried out the most rigorous and distant test of the so-called equivalence principle - one of the foundations of Einstein's general theory of relativity.
This principle, in its most general and simplified form, states that particles of light with different wavelengths must arrive at the Earth at the same time, even if they have passed through powerful gravitational fields on the way from a distant star or other object. Other things should behave in a similar way, starting with balls and fluffs from the famous experiments of Galileo and ending with lumps of energy.
The principle of equivalence has already been repeatedly verified using the Gravity Probe A probes, the Russian Radioastron, and a pair of European Galileo vehicles. On the other hand, scientists are not yet completely sure whether it is observed in the most extreme corners of space - in the "families" of neutron stars or in the vicinity of black holes.
The first such tests were carried out, as the Gusinskaya team reported back in January of this year, as part of observations of the unique star system J0337 + 1715 in the constellation Taurus. It consists of three "dead stars" - one pulsar and two white dwarfs, 4200 light years distant from us.
One of the white dwarfs and the pulsar revolve around each other at such a small distance that they generate yet invisible to us, but powerful enough gravitational waves. The situation is further complicated by a second white dwarf moving around the first two stars at a great distance.
A similar arrangement of this star system allowed scientists to check whether Einstein was right, using the pulsar as a heavy "weight", and one of the white dwarfs as a kind of "fluff". The second dwarf served as a source of attraction, which simultaneously attracted both the "weight" and the "fluff".
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If the principle of equivalence is not observed and objects with a more powerful gravitational field "fall" faster than their neighbors, then the pulsar's orbit will bend in a certain way, stretching towards a more distant white dwarf and moving in a circle with it. As a result, it will change when and from what point its radio signal will come.
The relatively small distance between Earth and J0337 + 1715 helped scientists measure very accurately how far these impulses were delayed and where the pulsar was at that time. As scientists joke, after six years of observations, they have learned by heart all the points where such outbreaks occurred.
As the analysis of the data showed, the "migrations" of the second white dwarf did not in any way affect the frequency of pulses of the pulsar and its orbit, and, therefore, the speed of falling of the "fluff" and "weight". This once again speaks of the correctness of Einstein and the absence of worthy alternatives to general relativity, scientists conclude.
