This creates a boundary inside the black hole, called the inner horizon. And in general relativity, strong enough centrifugal forces act like antigravity: they push, not pull. The singularity, stretched into a ring, is rotating at such a fantastic pace that it has incredible centrifugal force. The problem with rotating black holes is that, well, they rotate. And this is according to the very same math that leads to the prediction of the traveling-to-a-new-universe stuff. One challenge: the interiors of rotating black holes are catastrophically unstable. And according to the math of Einstein's theory of general relativity (which is the only math we've got), once you pass through the ring singularity, you enter a wormhole and pop out through a white hole (the polar opposite of a black hole, where nothing can enter and matter rushes out at the speed of light) into an entirely new and exciting patch of the universe. The spin of a rotating black hole stretches the singularity into a ring. Real black holes are much more interesting characters, especially when they spin. The idea of a single point of infinite density comes from our conception of stationary, non-rotating, uncharged, rather boring black holes. So maybe there's a more mundane explanation for singularities, one that's based on a more nuanced - and realistic - view of black holes in our universe. Planck stars and gravastars may have awesome names, but the reality of their existence is in doubt. The hunt for wormholes: How scientists look for space-time tunnels Let's go for a spin Einstein's theory of general relativity What are black holes? Facts, theories and definition ![]() The universe: Big Bang to now in 10 easy steps While gravastars aren't exactly a no-go in our universe, they are definitely on thin ice. However, recent observations of merging black holes with gravitational wave detectors have potentially ruled out the existence of gravastars, because merging gravastars will give a different signal than merging black holes, and outfits like LIGO (the Laser Interferometer Gravitational-Wave Observatory) and Virgo are getting more and more examples by the day. (A black hole's event horizon is its point of no return - the boundary beyond which nothing, not even light, can escape.) But outside that surface, gravastars look and act like normal black holes. It sounds like sci-fi, but it's real: dark energy is currently in operation in the larger cosmos, causing our entire universe to accelerate in its expansion.Īs matter falls onto a gravastar, it isn't able to actually penetrate the event horizon (due to all that dark energy on the inside) and therefore just hangs out on the surface. Dark energy is a substance that permeates space-time, causing it to expand outward. The difference between a black hole and a gravastar is that, instead of a singularity, the gravastar is filled with dark energy. It's such a theoretical concept that my spell checker didn't even recognize the word. So we're all set for now.Īnother attempt to eradicate the singularity - one that doesn't rely on untested theories of quantum gravity - is known as the gravastar. But because of the extreme time dilation effects around black holes, from our perspective in the outside universe it takes billions, even trillions, of years before they go boom. This resistance to continued compression eventually forces the material to un-collapse (i.e., explode), making black holes only temporary objects. Perfectly microscopic, but definitely not infinitely tiny. All the material that has ever fallen into the black hole gets compressed into a ball not much bigger than this. ![]() The discreteness of space-time prevents matter from reaching anything smaller than the Planck length (around 1.68 times 10^-35 meters). And two, it makes it impossible for singularities to form inside black holes.Īs matter squishes down under the immense gravitational weight of a collapsing star, it meets resistance. One, it takes the dream of quantum mechanics to its ultimate conclusion, explaining gravity in a natural way. This theoretical chunkiness of space-time provides two benefits. In the world of loop quantum gravity, space and time are quantized - the universe around us is composed of tiny discrete chunks, but at such an incredibly tiny scale that our movements appear smooth and continuous. This is called a Planck star, and it's a theoretical possibility envisioned by loop quantum gravity, which is itself a highly hypothetical proposal for creating a quantum version of gravity.
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