Fri, Apr 12, 2019 - Page 8 News List

EDITORIAL: Taiwanese help prove black holes

Two-hundred-and-thirty-six years after British scientist and philosopher John Michell put forward the theory of black holes in 1783, a team of scientists from around the world — including experts from Academia Sinica — have finally proven their existence.

On Wednesday, Taiwanese researchers participating in the Event Horizon Telescope (EHT) project shared the first-ever image of the edge of a black hole — known as an event horizon — during a news conference held at the same time as others in Washington, Santiago, Brussels, Shanghai and Tokyo.

It is a significant accomplishment by Taiwan’s scientific community and an achievement that all Taiwanese can rightfully feel proud of.

A black hole is a region of space where the gravitational pull is so strong, everything that crosses its event horizon — even light — is sucked inside.

The evolution of the science behind black holes over several hundred years has been a truly international effort.

Michell’s initial theory built upon British physicist Isaac Newton’s concept of escape velocity and James Bradley’s work on the speed of light. Applying German-born Albert Einstein’s formula of special relativity, in 1931, Indian astrophysicist Subrahmanyan Chandrasekhar provided a mathematical calculation — now known as the Chandrasekhar limit — which predicted that white dwarf stars could theoretically collapse into black holes.

Several years later, US theoretical physicist Julius Robert Oppenheimer built upon Chandrasekhar’s work, and in 1972, US and British astronomers discovered evidence of what is generally recognized as the first positively identified black hole, the Cygnus X-1.

The black hole photographed by the international team of scientists working on the EHT project is “supermassive,” with a mass 6.5 billion times that of the sun. It is located in the center of the galaxy M87, which is about 16 megaparsecs (55 million light years) away from Earth. The achievement has been likened to finding a doughnut on the surface of the moon.

Obtaining photographic evidence provided a unique challenge, since astronomers had previously calculated that such a task would require a telescope the size of the Earth.

However, researchers found a way around this by using a technique called interferometry, which involves using a network of widely distributed telescopes simultaneously trained on the same object.

Experts from Academia Sinica helped install three of eight radio telescopes, which form the EHT project’s global network of radio observatories across four continents. The observatories’ combined power is equivalent to a telescope almost the size of the Earth.

It is a truly collaborative effort to further humanity’s understanding of the universe. This stands in stark contrast to the actions of some nations to militarize space for their own benefit.

In 2007, China drew international condemnation after it destroyed one of its satellites, generating a large cloud of hazardous space debris in the process. The action was widely believed to be a test by the Chinese military of an anti-satellite missile designed to disable vital satellite communications systems of its enemies, such as the US’ global positioning system.

Last month, India destroyed one of its satellites in a similar test, albeit at a low orbit so that any debris should fall quickly to Earth, experts have said. Nevertheless, it is a worrying development and signals the beginning of a new space race.

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