The idea of black holes was proposed as far back as the 1780s, and in 1915 Albert Einstein predicted their existence in his general theory of relativity, however the name ‘black hole’ wasn’t coined until the 1960s.
According to NASA, a black hole is a cosmic body of extremely intense gravity from which nothing, not even light, can escape. A black hole can be formed by the death of a massive star, but only the most massive stars—those of more than three solar masses—become black holes at the end of their lives. Stars with a smaller mass evolve into less compressed bodies such as white dwarfs or neutron stars. When such a star has exhausted the internal thermonuclear fuels in its core at the end of its life, the core becomes unstable, gravitationally collapses inward upon itself, and the star’s outer layers are blown away. The crushing weight of constituent matter falling in from all sides compresses the dying star to a point of zero volume and infinite density called the singularity.
The story of the theory of relatively began when Einstein found a new way to describe gravity. It was not a force, as Sir Isaac Newton had proposed, but a consequence of a distortion in space and time, conceived together in his theory as ‘space-time’. According to Einstein, matter and energy exist on a background of space and time. There are three spatial dimensions (backwards-forwards, left-right and up-down) and one time dimension (which flows at one second per second). Objects distort the fabric of space-time based on their mass- more massive objects have a greater effect.
Black holes represented the limits of physics, as they are impossibly dense, deep, and powerful and nothing can escape one, not even light.
Although black holes excite the imagination in a way that few other concepts in science can, the truth is that no astronomer has actually seen one. We have “heard” them, so to speak as scientists have recorded the gravitational waves emanating from black holes that collided with one another billions of years ago.
To obtain the first picture of a black hole, it was necessary to connect no less than eight radio telescopes spread across the Globe. In 2006, this formed a virtual telescope as big as the Earth whose objective was very clear; obtain pictures of black holes. Thirteen years later, it’s done!
Here's a photo of (some of) the #EHTBlackHole team and the first post-viral message from Prof. Katie Bouman about the team's scientific breakthrough: https://t.co/LEcQOZpgqX pic.twitter.com/40RsbUSS7U
— MIT CSAIL (@MIT_CSAIL) April 11, 2019
However collecting the data to make a picture took two long years, keeping the astrophysicists on their toes. It took 4 days of clear atmosphere – because water vapor also absorbs millimeter waves, the same wavelength as that used for observation – in April 2017 the perfect moment presented itself and the eight radio telescopes, each equipped with their own internal atomic clock, were able to turn towards the black hole exactly at the same time, to within one ten-thousandth of a billionth of a second.
— MIT CSAIL (@MIT_CSAIL) April 10, 2019
Hajar, Consultant, Leyton France
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