This is something every single one of us is finally able to say to our children and grandchildren later in the future. What a magnificent feat by mankind!
If you follow scientific news and trending topics, you probably have noticed lately the hype about the first photo ever of a Black Hole. Well that happened yesterday; it is real! If you haven’t noticed that, well, allow me to blow your mind by taking you on a journey into deep space to explore together what a black hole is, what it looks like and why it took us all the way until now to actually see one in reality.
What is a black hole?
A black hole is one of the weirdest yet most fascinating cosmic objects ever discovered. It is literally absorbing not just our attention and interest, but also everything that comes close to it. Here’s a definition that you probably heard somewhere. A black hole is a point in space that has a very large amount of gravity that not even light can escape it. In simpler words, it is a place in space that sucks anything that passes by it, even the fastest thing in the universe – light; thus the name black hole. Consider Earth’s gravity, for example. If you throw a ball upwards in the air, because of the effect of gravity, the ball slows down until it reaches a point where it stops mid-air and then falls all the way back to Earth. If it weren’t for gravity, the ball would ideally continue going upwards, away from Earth. In fact, all of us would be moving away from Earth if it weren’t for gravity. Anyway, back to the point. Instead of throwing a ball, consider flashing light into the sky. If you were to do this close to a black hole instead of on Earth – provided that you’re still alive and not spaghettified into it – the light wouldn’t have the chance to even go upwards. Its fate is to fall into the hole, just like you and everything else, due to the immense gravity there is.
Can it get any weirder? Why of course it can! At the center of a black hole is something that scientists call a singularity. It is a point that has zero size and infinite density. Yes, zero size and infinite density! Are you confused? Don’t worry. At this point, almost everyone’s mind starts to malfunction, because we cannot really comprehend in our brains such amounts. But that’s okay, at least the math checks out, and so far, this has been the most accurate depiction of what a black hole is.
I’m going to kick it up a notch. Are you ready? Anything can become a black hole. Yes, anything – well, at least in theory. You see, in reality, a black hole forms when a star collapses into itself because its gravity becomes stronger than the forces pushing it outwards. This means, all that gigantic mass gets cramped into smaller and smaller sizes, which makes it denser and denser, all the way until it reaches zero size and infinite density – which we all know by now as a singularity. Now, don’t worry. Your “beautiful” dog and that “awesome” cat of yours are not going to collapse into themselves and become black holes, unless you feed them enough that they become the mass of a star, like the sun, for example. That’s highly unlikely, though.
What does a black hole look like?
To you, an observer from afar, a black hole would look like a wholly black sphere in space; which means it’s pretty darn difficult to see one. You see, it is not possible to observe a black hole using conventional methods, let alone your naked eye, because it is by definition, the absence of light; plus it’s quite far from us. Lucky us! All those pictures of black holes around the web that you might have seen (until yesterday) are simply illustrations and simulations that have been generated by artists and scientists based on indirect observations of the space surrounding the black hole. So, you might ask, “What about all this bright light around it in those pictures if all what it is supposed to be is a black sphere?” And that is a great question.
Look again at my explanation of what a black hole is. It absorbs everything that comes close to it, but how close is that? Let’s ask this in a more interesting way. How close to a black hole could I be that I can still escape its gravitational pull and not fall into it? That’s a question that scientists have asked themselves, and the answer they came up with was an “imaginary shell around the singularity” that they called the Event Horizon – it’s that bright light you’re asking about. Let’s think about in this way. If you sit on the beach, sunbathing, enjoying a drink and looking ahead at the waters, the farthest you can actually observe is defined by your horizon – or as the song “How Far I’ll Go” from the Disney movie Moana would say, “…where the sky meets the sea.” Anything that lies behind your horizon cannot be seen by you.
Similarly, when you look at a black hole, the farthest you can see is defined by the event horizon. Anything that crosses that horizon cannot escape the black hole’s gravitational pull and would disappear into oblivion. That’s why, the closest we could be to a black hole is the event horizon, which is pretty awesome until you find out that in order to stay there or get away from the black hole, you would need an unimaginable velocity to escape from the gravity pulling you in – which in complex scientific terms is called the “Escape Velocity”. If you cannot reach that velocity, the black hole would eat you alive. Let me explain that last bit.
Earlier, you read the word spaghettified, and you might’ve asked, “What does spaghetti have to do with black holes?” Well, since the gravitational pull of a black hole is unbelievably powerful, the force it exerts on your feet is way stronger than that on your head. So, your feet start falling faster into the black hole than your head does, and your body begins to extend more…and more…and more…all the way until you look like a strand of spaghetti, thus the word spaghettification. It’s a funny concept to think about, but I’m pretty sure it’s majorly painful to experience.
The first photo ever of a black hole: Why now?
Here’s a brief history lesson. Massive cosmic bodies that even light could not escape them were first proposed in 1784 by natural philosopher Jon Michell. Albert Einstein later in 1916 established his theory of general relativity, which was the basis for two other physicists, Shchwarzschild and Lorentz, to mathematically describe black holes. Black holes were not called black holes until 1967 when John Wheeler coined the term.
So, all this time, all those studies, calculations, discoveries and technologies…why did it take us until now to actually be able to take a photo of a black hole? Well, because black holes are relatively tiny. Yes, from our perspective, they’re so small it’s so hard to see them. Astrophysicist Dimitrios Psaltis said once that “taking a picture of [the black hole in the center of the Milky Way],” which is the largest one in our sky, “would be equivalent to taking a picture of a DVD on the surface of the moon.” Plus, we kinda need a big enough telescope.
So, in 2017, astronomers turned 8 ground-based radio telescopes distributed on the top of different mountains and volcanoes around the world, towards a black hole at the center of a galaxy called Messier 87 (M87), and synchronized them to create an Earth-sized telescope known as the Event Horizon Telescope (EHT). Using the EHT, they took measurements from radio waves, analysed them and compiled them into the image released yesterday: The first photo ever of a black hole. Fun fact about the EHT is that the resolution it can achieve is 20 micro-arcseconds. The fun thing about it is that it’s extremely high, “enough to read a newspaper in New York from a sidewalk café in Paris” [NSF]. Moreover, of the amazing team that brought into being this breakthrough image is a 29-year old computer scientist named Katie Bouman, who was the one who led the development of a computer program that allowed this to happen. People like Katie are a source of inspiration to all of us.
The story of the first photo of a black hole reminds me of a story that astrophysicist Neil deGrasse Tyson once gave in a talk at The Origins Project in Arizona State University, under “The Great Debate: The Storytelling of Science.” He explained the era when photography was born, an era when “a portrait of you did not require an artist.” Now we can tell this story to black holes. Watch the video below to listen to it. Last but not least, I’m so happy to say it again and I urge you to say it to yourself:
“I was alive when the first photo of a black hole was taken.”
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Born in 1992 in El Chouf, Lebanon, Samir grew up dreaming of becoming a scientist and an explorer. Today, he is a former bioengineering and nanotechnology research engineer who has contributed to award-winning projects on cancer diagnosis and silicon-based nanofabrication. He is currently a science communicator and content writer, and is influenced by scientists such as Carl Sagan, Richard Feynman, Richard Dawkins and Stephen Hawking.
Living between Lebanon and Germany, he aims to inform, inspire, educate and entertain readers in various areas of science and engineering by simplifying complex topics, triggering curiosity, provoking thoughts about science and the natural world, and as he says, “gradually bridging the information gap.”