Watch in ASL to learn about black holes, and the history behind the ground-breaking image and its significance!
Transcript:
Last week, a historical moment in the field of physics and astronomy took place! An international collaboration of over 200 researchers from all over the world produced the first image of an ever-elusive black hole at the center of a galaxy known as Messier 87 or M87!
What is a black hole you ask? A black hole is an extremely dense region with a gravitational pull so strong that nothing, not even light, can escape. The black hole is a hungry beast. It swallows up everything too close, too slow or too small to fight its gravitational force. With every planet, star, gas, or a bit of mass consumed, the black hole grows. A black hole normally forms when a star dies.
How does this happen? A star is born when a cloud of molecules of gas and particles of dust become concentrated enough that gravity contract the cloud further. The contraction produces heat and the temperature at the cloud’s core becomes hot enough to fuse hydrogen atoms and thereby ignite nuclear reactions. The star lives on for billions of years because the inward pull from the star’s own gravity is balanced by the outward pressure from nuclear reactions. When the nuclear fuel has been used up, a star cannot withstand its own gravity and collapse to form a black hole.
Why haven’t we seen an image of a black hole before? Because no light can escape a black hole, black holes are invisible and the light surrounding the black hole is often obscured by materials. Additionally, taking an image of a black hole at the center of our Milky Way galaxy is like taking a picture of a DVD on the surface of the moon. Now, we have the technology of eight ground-based radio telescopes located in the United States, Mexico, Chile, Spain and Antarctica. These telescopes are collectively known as the Event Horizon Telescope and they work together as one giant telescope to produce an high resolution image.
These telescopes simultaneously measure the radio waves being emitted from the event horizon of the black hole – a boundary beyond nothing can escape. These measurements are fed into a series of algorithms on a computer, which Dr. Katie Bouman was instrumental in developing, to produce the image that we see and the image is not an actual photograph. The image we see shows the dark circle in the middle, which is the “shadow” of the black hole, with the glowing light sitting at the event horizon. The colors represent intensity of radio-wave signals emitted from the region. Yellow with the most intense emissions to red with the lower emissions to black with little to none.
Why is the image of a black hole such a ground-breaking moment for the world? For years, black holes are more like science fiction than fact. There have been theories and indirect evidences supporting the existence of black holes. Now, we have the first direct visual evidence that black holes do exist. Albert Einstein’s theory of general relativity states that 1) black holes exist, 2) each of these holes has an event horizon, 3) the event horizon should be roughly circular, 4) and of a predictable size, which depends on the black hole’s mass.
We should revel in the fact that this amazing feat required a global collaboration to turn the Earth into one giant telescope and capture the uncapturable black hole trillions of kilometers away! And, this achievement will not be possible without a dizzying array of researchers of different genders, backgrounds and career stages working together toward a common goal!
