From Wormholes to the Fifth Force: 2021’s Biggest Breakthroughs In Space and Physics

 

Neutron Star – Black Hole merger

Whenever two massive objects collide, they send out ripples in the fabric of spacetime. These ripples are called the gravitational waves, and they serve as the signature of the merger that has occurred. Over the years, researchers have observed dozens of mergers of pairs of black holes and a couple of mergers of neutron star pairs. But for the first time in June 2021, scientists announced the detection of a colossal merger of a black hole and a neutron star taking place about 900 million light-years away from Earth, and that too, twice. 

An illustration depicts the warping of time and space as a black hole is about to swallow a neutron star | Image: Soheb Mandhai/LIGO India/AP

 

The first merger involved a black hole about nine times the mass of the Sun and a neutron star about two solar masses. Ten days later, the second collision was detected involving a black hole nearly six times the Sun’s mass, devouring a neutron star of 1.5 solar masses. The observations further predicted that a merger between a black hole and a neutron star occurs once every month within one billion light-years of Earth.

Traversable Wormholes

Wormholes are portals in spacetime that serve as shortcuts for long interstellar travels. Having its origin in Einstein’s theory of general relativity, a wormhole is a highly curved region of spacetime that connects two extremely distant points in space, just like a tunnel. However, these exotic structures are theoretical and haven’t been directly observed in nature. Moreover, mathematics suggests that such wormholes would be extremely unstable, and if anything tries to pass through them, they would immediately collapse. Eventually, the matter passing through it would disappear, and the connection that the wormhole provided to other places in the universe would be cut off forever. 

Previous models suggested that the only way to keep a wormhole open is with an exotic form of matter with a negative mass. But in 2021, two different theories were proposed according to which time travel could actually be possible via wormholes and that too for normal matter, provided we follow some constraints.