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Everything You Need to Know About Black Holes
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Black holes are some of the most mysterious objects in the universe. How big are they? What do they look like? Are there any other black holes near Earth? This page will cover everything you need to know about black holes, from their history to why no human has ever been sucked into one by one. Let’s get started!
A brief history of black holes
Einstein's theory of general relativity predicted their existence, but it wasn't until 1974 that astronomer John Archibald Wheeler coined them. Since then, scientists have discovered numerous black holes throughout space and have continued to develop new theories about how they form and what exactly happens in their mysterious interiors. While there is still much we don't know about these objects, we've come a long way in our understanding of black holes over time: here's everything you need to know on the subject!
Types of black holes
Astronomers classify black holes based on their size and shape. The smallest ones are stellar-mass black holes, which have a mass of about 10 Suns and can be found in binary star systems. Supermassive black holes (SMBH) exist at the center of most galaxies; they are millions or billions of times more massive than our Sun. They can often be spotted by their effect on nearby stars and gas clouds: SMBHs act as incredibly strong galactic gravitational lenses that warp space-time around them in ways that can briefly magnify, brighten, or even distort light coming from objects behind them. This effect is called gravitational lensing . Another way scientists observe SMBHs is through their effect on background objects like quasars.
Where can I find them?
The strongest evidence for black holes is actually in objects where they are theorized, but not yet confirmed: supermassive stars and active galactic nuclei. Supermassive stars are very large and bright; they have an enormous gravitational pull, causing them to defy all known laws of physics. Active galactic nuclei light up when gas around a supermassive star collides with other matter (such as stars), which generates light that we can see on Earth. They're called active because, unlike a normal galaxy, these ones generate new energy constantly. The sources of energy are believed to be from a massive black hole.
Are there bigger ones than those discovered so far?
Only black holes of a certain size are created when a star dies. Scientists believe that black holes exist in various sizes, from stellar-mass ones as massive as our sun (so huge they would completely swallow Mercury), to supermassive ones hundreds of thousands times more massive than our sun. All galaxies seem to have a supermassive black hole at their center, including ours: The Milky Way’s is called Sagittarius A* (pronounced A-star). It weighs 4 million solar masses and is 26,000 light-years away from Earth. There could be even bigger supermassive black holes out there, but we haven't observed them yet—and for now, we don't know how massive these megablack holes can get.
How do we know about them?
Will black holes disappear? Not quite. This is because they are based on a fundamental law of physics that suggests that any given body's gravitational pull will get stronger as it gets smaller. In other words, if you continue to make a black hole smaller and smaller, its gravity will become more and more powerful as you draw it together. Theoretically, therefore, it would be possible for a black hole to become infinitely small – but not disappear. The only way for one of these time-warping monsters to be truly annihilated would be for them all to merge together into an even bigger black hole! (Another pretty unlikely scenario.)
Is it possible for us to be sucked into one?
It is possible, but not likely. For starters, there are only a few black holes in our galaxy that are large enough and close enough for it to be possible. So you'd have to somehow find yourself very close (maybe on a spaceship) near one of these black holes in order for it to be an issue. The other thing that's important is understanding that most black holes are dormant, meaning they don't really attract things toward them too much--they're just sitting there doing their thing. To get sucked into a black hole would take something on your ship (or perhaps inside your body) hitting one of those dormant ones at just the right angle/speed so that you're drawn into its orbit without any chance of escaping.
Will they ever disappear completely?
For now, black holes continue to pose an intriguing and mysterious topic in astronomy and physics. It is also speculated that they may hold knowledge about other phenomena in space, such as dark matter. These dark matter particles are believed to make up 85% of our universe and be responsible for some objects’ mass but have never been directly observed. Because black holes are so densely packed with objects and due to their gravitational pull, perhaps it is here that scientists will discover insight into these previously unobserved particles.