No matter what tests we throw at Albert Einstein鈥檚 theory of gravity, it just won鈥檛 break. A collision of stars has now shown he was right, again.
The general theory of relativity predicts there are four dimensions, three of space and one of time, and that both gravity and light exist in these. But some people argue there may be extra dimensions. They think that gravity, but not light, could occupy them.
To test the idea, a team of more than 1000 researchers looked at the聽aftermath of neutron stars smashing together. The collision of these stars is so cataclysmic that it causes ripples in space and time known as gravitational waves.
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The team detected such an event using both light waves and gravitational waves. They believed that if the gravitational waves travel in more dimensions than light, the strength of the gravitational waves should be reduced in comparison to light by the time they reached Earth.
鈥淭he collision of two highly dense neutron stars is so cataclysmic that it causes ripples in space and time鈥�
But the two measurements matched up perfectly. Although this isn鈥檛 definitive proof that extra dimensions don鈥檛 exist, it is another hint that Einstein was right.
The team also measured how long the neutron stars took to spiral towards one another and how the gravitational waves stretched and squeezed space-time. These too came out in favour of general relativity.
There is one potential spoiler. All of the tests included data from LIGO, the gravitational wave detector in the US, however some physicists question if it has detected any gravitational waves.
Because general relativity isn鈥檛 compatible with quantum mechanics, the suspicion is that Einstein鈥檚 theory will have to break. 鈥淓very time we get a new result that is again perfectly consistent with general relativity, I am secretly surprised,鈥� says team member Michalis Agathos at the University of Cambridge.
This article appeared in print under the headline 鈥淣eutron star smash supports Einstein again鈥�
Reference: arxiv.org/abs/1811.00364
