The Most Mind-Blowing Part of the New Black Hole Picture
By Sean D'Mello
This article may be long but it will blow your mind!!!
W H E N our average-sized Sun dies, it will be pretty unspectacular. Once all the hydrogen in our Sun’s core is burnt, it will shrink into a cold, Earth-sized remnant of its glory days called a white dwarf. However, look to a star about 20 times bigger than our Sun and its end is much more spectacular. The outer layers are blasted into space, exploding into an event called a supernova and for a couple of weeks, this supernova will be one of the brightest objects in the universe. Detonate a Hiroshima bomb once a millisecond for the entire lifetime of the universe and you won’t come close to the amount of energy released in this cosmic explosion. What remains is a mysterious object of science fiction; one that has escaped physicists till just the last few decades of science—a black hole—an object of immense mass and gravitational force.
For the first time, radio telescopes from across the globe x-rayed the cosmos, focusing on the gas cloud G2 as it approached the event horizon of our Milky Way’s very own black hole—Sagittarius A. All these telescopes together create the planet-sized observatory called the Event Horizon Telescope, which produced this spectacular image that has traversed the internet:
Although it may look like a coffee stain, this image holds massive scientific importance and is a huge leap for the field—but what is it?
It’s the world’s first image of a black hole. Previously, humans relied solely on illustrations such as the one below to visualize a black hole.
An illustration or artistic interpretation of a black hole before the first picture was taken
Looking at the official picture at the very top, you can easily see the black hole in the middle. Surprise, it’s black. The ring of fire surrounding the black hole is matter from the gas cloud orbiting the hole at millions of miles per hour, creating massive amounts of friction which sends energy out into space in the form of x-rays. The brighter underbelly is the matter that is orbiting towards us at a fraction of the speed of light, releasing huge amounts of energy and, because it is facing us, it appears brighter.
In the image, the fine line between the black hole and light is what’s called the event horizon, also known as the point of no return. To overcome the Earth’s gravitational pull, you must accelerate to about 7 miles per second—a large number for sure, but humanity’s been achieving escape velocity since 1961. The universal speed limit is 186, 282 miles per hour, the speed of light, and even that lacks the acceleration to overcome the pull of a black hole.
While this is mind-blowing and is happening on a scale that is millions of times bigger than our sun in almost every single galaxy, the most fascinating aspect of the image is its confirmation of Einstein's theory of general relativity, which states that mass causes spacetime to curve, as well as what it means for the future of the physics.
Looking at this illustration, you can see a cosmic-scaled flat disk of matter orbiting the black hole. This is because black holes spin, like the Earth or Sun, at a much faster speed of about 80% the speed of light, and that spinning force spreads out the matter in a flat circle—imagine spinning pizza dough on your finger. The dough will push out to the sides until it forms a flat disk.
If you look at the picture of the black hole, you can faintly see the straight line, the accretion disk, going from the top left corner to bottom right. But if the illustration above shows the single flat disk, and almost all the matter is located in this disk, then why is there the ring of fire surrounding the event horizon? And no, it’s not because it’s viewed from the “top”. It’s due to general relativity.
Image oriented to show the faint accretion disk on a horizontal plane… and a mysterious ring around the event horizon
According to Einstein's theorem, if a space body has enough mass, it is able to curve spacetime so much that it even curves light. The same concept is applied to black holes. The light is actually always traveling in a straight line, but the gravity of the black hole curves space-time itself and so the light appears to curve.
This applies to any gravitational body, including Earth. Place highly accurate atomic clocks on each floor of a skyscraper, and time will tick faster on those closer to the bottom, where the force of gravity is strongest (a billionth of a second difference). Clocks on GPS satellites have to be manually set to tick slightly slower than those on Earth, otherwise, GPS wouldn’t be accurate. The same idea applies to Sagittarius A, but to a greater extreme: come close to the event horizon, but don’t cross it, and for every minute you spend there, a thousand years pass on Earth.
Back to the picture: the reason a circle of light surrounds the hole is because, as Sagittarius A curves both 3-dimensional space and time, the light from the accretion disk behind the black hole is curving around the black hole, and coming straight at us. This GIF exemplifies this concept:
This would happen on both the top and bottom of the black hole. The black hole from Christopher Nolan’s film Interstellar beautifully demonstrates this, years before this revolutionary picture was taken.
The back of accretion disk reflecting around the top and bottom of the black hole in Interstellar.
T H E natural question one must have after reading this is, how does the image affect science, humanity, and most importantly, me? You may be surprised how by much it does. Recall the massive supernova described at the beginning of the article. The colossal gravitational pull of the star’s exploded core, stripped of its outer layers and heated to billions of degrees Celsius, compacts hunks of iron larger than the size of Everest into grains of sand. Atoms are shredded into electrons, protons, and neutrons, and those pulped into quarks, leptons, and gluons, and those even further and further, tinier and tinier, until … well, we don’t know, but we call it a singularity. In the center of each black hole is a point so dense that if you magnified it a trillion trillion times, no microscope on Earth could come close to see. But like a mad Chihuahua, this dot is tiny but scary; the singularity is where all our known physics fall apart.
Currently, the study of physics is focused under 2 main fields: Einstein's general relativity, which dictates how our human-sized world behaves, as well as the massive world of the cosmos, and quantum mechanics, which tells us how atoms and anything smaller than that behaves. Both work well and result in near accurate, reliable results during experiments, but the results remain slightly off and the theories have no relation to one another. Uniting these 2 theories into a single theory, as any James Marsh fan can tell you, is the Theory of Everything, the overall goal of physics for the past few decades. Uniting these fields would be the greatest scientific discovery of the past hundred years, if not of all time.
This illustration combines the symbol of quantum mechanics—the behaviour of particles after fusion—with the symbol of general relativity—Einstein himself—a combination that has been the goal of modern physics.
The image of the black hole provides physicists with more data and information to work on this theory and understand the singularity so deep in the black hole that spacetime is warped to the most extreme. Understanding this would provide humanity with a complete understanding of the universe, access to infinite energy, simulate anything from the scale of atoms to large masses, from the human body to the Big Bang, to the entirety of the Universe, advancing modern civilization into a new age. And though this may just sound like science fiction, we have seen the tangible results of physicists getting closer to that ultimate theorem: quantum computing, nanotechnology, nuclear power, lasers, the ISS, and more. Every year, you get more than cool interesting facts and pictures on your Instagram, you get ingenious technologies that are applied to every field of your life. This picture represents much more than a public-relations expenditure to increase public funding, it represents humanity’s collective knowledge rapidly approaching the supreme discovery of the century and full understanding of our universe, big and small.