A neutron star is the remains of a star after it has exploded and collapsed in on itself.
"The theory of general relativity has fixed parameters that can't be changed, whereas other theories of gravity have parameters whose values can change to keep them consistent with this result, ' Dr Deller says". Even the Earth and the moon fall in the same way toward the sun.
Like all scientific theories, general relativity makes testable predictions. It sounds obvious put that way, of course, but the idea that heavier objects should fall at the same rate as lighter objects (discounting air resistance) still surprises people. It is a principle that has been tested over and over on Earth, even Galileo is believed to have tested this by dropping things of different densities from the Leaning Tower of Pisa. The strong equivalence principle states that even these objects would fall at the same rates as others, too.
So, for example, a hammer and a feather dropped from the same height in a vacuum will hit the ground at the same time; astronaut Dave Scott famously demonstrated this on the Moon in 1971.
The researchers were able to come to this conclusion by studying the movements of the neutron star.
The researchers tested this principle by analyzing a system called PSR J0337+1715, consisting of 2 "superdense stellar corpses" called white dwarfs along with a much denser "neutron star" called pulsar.
In the three-star system, the neutron star is in a 1.6-day orbit with one white dwarf, and the second white dwarf orbits this pair with a period of 327 days.
"This remarkable system turns out to be the most precise laboratory to carry out these tests", said Lorimer, who carried out some of the Green Bank Telescope and Arecibo observations. "That makes it a one-of-a-kind laboratory for putting Einstein's theories to the test". Luckily, advancements in radio telescopes promise more chances at finding the "perfect" triple system to test. Over 400 hours have been spent observing this system, taking data and measuring how the objects move in relation to each other.
The neutron star is a fast-spinning type star and known as a pulsar. "It spins in a very predictable way and each time it sweeps past the Earth we see a little blip of radio emission, which we can treat like the ticks of a clock". "As one of the most sensitive radio telescopes in the world, the GBT is primed to pick up these faint pulses of radio waves to study extreme physics", Lynch said.
"We can account for every single pulse of the neutron star since we began our observations", said principle author Anne Archibald of the University of Amsterdam and the Netherlands Institute for Radio Astronomy.
"We can tell its location to within a few hundred metres". These radio pulses were used to track the position of the neutron star.
Small and dense, the white dwarf is, well, dwarfed in substantiality by the neutron star-the smallest and densest of the celestial bodies. This enabled the scientists to determine how the pulsar and inner white dwarf were affected by the gravity of the outer white dwarf.
"If there is a difference, it is no more than three parts in a million", co-author Nina Gusinskaia, a doctoral student at the University of Amsterdam, said in the same statement.
Researchers said the result is ten times more precise that the previous best test of gravity, making the evidence for Einstein's Strong Equivalence Principle that much stronger.
Now, scientists have, for the first time, proved the validity of Einstein's theory in a distant galaxy, confirming their understanding of how gravity works.
This is because Einstein's principle of gravity has just been proven right by yet another major science experiment, making it increasingly hard for alternative gravity theories to demonstrate their case.
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