This boundary, the innermost stable circular orbit (or ISCO for the lovers of astronomical jargon), is a firm prediction of Einstein's general theory of relativity, the same theory that predicts the existence of black holes in the first place. But if you're a hapless chunk of gas, you're doomed to fall freely toward the waiting dark nightmare below. You have only two choices: if you have rockets or some other source of energy, you can propel yourself away to safety. Once you reach this region, you cannot remain in placid orbit. Just outside the black hole, but before reaching the event horizon, the gravitational forces are so extreme that stable orbits become impossible. But still, if it weren't for those frictional forces, the material would be able to orbit around the black hole in perpetuity, the same way that the planets can orbit around the sun for billions of years.Īs you get closer to the black hole's center, though, you reach a certain point where all hopes of stability are dashed against the rocks of gravity. In the accretion disk, individual bits of material rub up against other bits, draining them of rotational energy and driving them ever-inward to the gaping maw of the black hole's event horizon. In the case of the most massive black holes, the accretion disks around them glow so intensely that they get a new name: active galactic nuclei (AGN), capable of outshining millions of individual galaxies. That disk spins and spins, with heat, friction, and magnetic and electric forces energizing it, causing the material to glow brightly.
As material falls toward the black hole, it tends to get squeezed into a razor-thin band known as an accretion disk. Once these foolhardy adventurers get caught in the black hole's gravitational embrace, they begin the journey toward the end. Indeed, lots of stuff in the universe finds itself orbiting around black holes. Gravity is just gravity, and orbits are orbits. A particular black hole will have a certain mass (anywhere from a few times the mass of the sun for the smaller ones in the galaxy up to billions of times heavier for the true monsters roaming the cosmos), and orbiting the black hole is just like orbiting anything else of identical mass. You wouldn’t feel anything different as you fell in, but to anyone watching, you would appear to slow.Ĭircling down the drain of this cosmic plughole, all the photons being pulled alongside you would create a stream of blinding light orbiting a hole of total blackness – as we saw in the Event Horizon Telescope team’s image.Outside a black hole, however, everything is just dandy. A black hole is so massive that time itself starts to warp. In the case of black holes, the pull is so strong that nothing – not even light – can escape. So what are your possible fates, should you ever be so unlucky as to have a close encounter of the black hole kind?Īll objects exert a gravitational pull on one another, but for the most part, this force is pretty weak. But as to what happens inside one – well, there physicists are still mightily in dispute. With the publication of the first ever picture of a black hole this week, any residual doubt that these monsters of space-time exist is banished. “That’s when the universe starts to go bizarre on you,” says Priyamvada Natarajan at Yale University. Before you know it, you have entered a black hole.
Suddenly, you feel a tug, faint at first, but getting ever stronger as it pulls you towards an empty region of the sky. It is quiet and cold, serene but slightly terrifying.
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