杂志汇中国与非洲

On February 11, science journal Nature announced the discovery of gravitational waves (GWaves) by scientists of the U.S.-based Advanced Laser Interferometer Gravitational-Wave Observatory.

The concept of G-Waves is not new. Albert Einstein predicted their existence 100 years ago in his now famous general theory of relativity, but they had never been directly observed before. This discovery confirms Einstein’s theory once again and begins a new era in astronomy.

What are G-Waves?

To understand what G-Waves are, imagine space-time as a rubber sheet. Massive objects on this sheet can cause distortions; a large mass like the Sun can be imagined as a steel ball bending the sheet. G-Waves are ripples on the fabric of space-time caused by objects with mass. They are often visualized as ripples in a pond.

Detecting these ripples is not easy. This explains why G-Waves were the last prediction in Einstein’s theory to be verified. Since G-Waves can pass through most matter unhindered, an outstandingly sensitive instrument is needed to detect them. In addition, only a cataclysmic event can release enough energy to produce detectable G-Waves, such as the merging of two black holes or stars in a binary star system, and these events are very rare. Justin Greenhalgh, a contributor to the observatory, confirmed the complexity of the task to the IFLScience website, saying, “While waves are always being produced, most are not of a scale that would allow them to be measured.”

Collision of two black holes

From 2002 to 2010, the observatory was unable to discover any G-Wave. The project was suspended, only to start again in 2015 with improved technology able to detect tiny vibrations from G-Waves passing the Earth. Two identical detectors were installed in the states of Louisiana and Washington, in the United States. Finally, on September 14, 2015, both detected passing GWaves, confirming each other’s findings. The discovery was announced on February 11, 2016.  

The event had to be extraordinary to be detected and it was two black holes merging into a single larger one. This was actually the first direct observation of black holes. Each was about 30 times the mass of the Sun, so the fusion released enough energy to create the first G-Waves ever detected by humans, 1.3 billion years after the fusion. As G-Waves have very little interaction with matter, they propagate throughout the universe for billions of years. When they finally reached the Earth, scientists interpreted their characteristics to determine what kind of phenomenon had caused them. 

New era in astronomy

The study of G-Waves opens a new window into the universe. Like radio waves, G-Waves allow scientists to unravel some of the deepest mysteries of the cosmos. If a prime G-Wave is ever observed, we might even be able to better understand the famous Big Bang theory of evolution. This discovery is definitely a revolution since it offers a completely new way to study the universe, opening an era of gravitational wave astronomy. Some say it’s the biggest discovery of the century and already believe the Nobel Prize for Science this year will go to the observatory’s scientists. In 1993 physicists Russell Hulse and Joseph Taylor were awarded the Nobel Prize in Physics for their discovery of a new type of pulsar, opening up new avenues for studying gravitation.

The discovery thrilled scientists around the world, who hope to participate in this new chapter of astronomy and physics. Thanks to the Square Kilometer Array project to be hosted in South Africa and Australia, Africa will be part of this new era.

China too wants to be involved in this new adventure. On February 16, a new G-Waves research program, Taiji, was announced. It will see three satellites launched around 2030 to study G-Waves from space. Tianqin, another G-Waves research project initiated in July 2015, will also launch high-orbit satellites to detect G-Waves within 20 years. These space-based detectors will be sensitive to much lower frequencies, allowing scientists to study larger objects than those detected from the Earth. CA