What Is a White Hole? || Wormholes Explained - Poruk

 What Is a White Hole?

A celebrated astrophysicist is intently studying the skies in search of his elusive quarry, combing through the thousands of images coming to him from the state-of-the-art International Event Horizon telescope. Finally, after months and months of searching, he thinks he may have found what he’s been looking for all this time - in the images he sees the telltale signs of a mysterious phenomenon called a black hole. But as he scrutinizes the images captured by the powerful telescope, something doesn’t seem quite right. There, right in front of his very eyes, the black hole appears to be … burping!? The scientist knows that this should be impossible: nothing can escape from a black hole, not even light - that’s why they’re so hard to find - but here is photographic evidence of matter coming out of a black hole! Could it be that this is not a black hole at all, but the black hole’s neglected twin - a white hole? Could this be his chance to once and for all answer the questions that have been nagging at him throughout his whole career - What is a white hole? How do they form? How do they work!? And, do they even exist at all? In 1915, Einstein’s field equations turned the world of physics on its head. His theory of relativity described the force of gravity and shattered the prevailing paradigm of the nature of reality - rather than being rigid, space and time can actually bend and fold, along with the mass of stars and planets. Within a year, scientists had calculated how space-time curves around a single ball of mass - the seeds of what today is called the singularity. Physicists were able to describe how a spherical mass shrunken down to infinitely dense point could wrap space around it so tightly that a region of space is effectively pinched off from rest of universe, creating a no-mans land beyond the event horizon where the laws of physics no longer apply and the link between cause and effect is shattered. A black hole is an incredibly dense area of space where all matter has been squeezed into an impossibly tiny space, called the singularity. This creates such an intense gravitational pull that nothing, not even light, can escape from the black hole’s clutches. A tiny black hole might be the size of a single atom, but have a mass equal to a large mountain. Stellar black holes, formed when a dying star collapses in on itself in a supernova, can have a mass up to 20 times greater than our sun. The largest black holes are called supermassive black holes, and they can be found at the center of every galaxy in our universe. The supermassive black hole at the center of our Milky Way galaxy, named Sagittarius A*, has as much mass as 4 million of our suns, all condensed into a tiny ball only as big as a few million Earths. A black hole’s event horizon is what we would consider the surface of the black hole, although it’s not a surface in the true sense of the word - it’s not a membrane or barrier, but rather, the threshold beyond which there is no going back. 

The event horizon is the point of no return - nothing that crosses the event horizon can ever come back. Even light cannot escape the black hole once it’s passed the event horizon. Once something - or someone - has crossed the event horizon, they will begin the inevitable process of falling towards the black hole’s singularity, eventually dissolving into the singularity itself. We can only guess what happens after that. Physicists have been studying black holes for decades and are only just beginning to understand them. Only recently have they turned their attention to the black hole’s neglected twin - the white hole. From a far, a white hole would appear identical to its better-known cousin, a black hole. Like a black hole, a white hole might be big or small, might spin or remain stationary, and might be electrically charged. 

A white hole would also be surrounded by a ring of dust, and a cloud of gas and debris would gather at its event horizon. The key difference between a black hole and a white hole is that white holes burp. Yes, burp. Unlike a black hole, from which nothing can escape, matter actually can cross the event horizon and come out of a white hole. It’s only in these moments, when objects emerge from the white hole, that scientists can definitively say that what they are looking at is a white hole, and not a black hole. If a black hole’s event horizon is the point of no return, then the event horizon of a white hole could be described as the point of no admission - nothing can ever cross the event horizon of a white hole and reach the interior. In a black hole, objects in the space outside can cross the event horizon and affect the interior of the black hole, but matter inside the black hole can never again interact with space outside. In a white hole, the reverse holds true - objects from inside the white hole can cross the event horizon and interact with objects in the space outside of it, but nothing on the outside can ever enter the white hole or affect the inside. This is because a white hole is a black hole’s time reversal, according to physicists. A black hole’s singularity exists in the future, whereas a white hole’s singularity exists in the past. Since the interior of the white hole is cut off from the universe’s past via its event horizon, no outside object or event will ever affect the inside of a white hole. James Bardeen, a black hole pioneer and professor emeritus at the University of Washington explains the magnitude of this difference: “Somehow it’s more disturbing to have a singularity in the past than can affect everything in the outside world”, he says. 

Scientists had theorized about the existence of black holes for hundreds of years before Einstein’s theory of relativity paved the way for physicists to prove their existence - theoretically, at least. Since no light escapes from a black hole, they are invisible to the naked eye. Until very recently, the only way scientists have been able to find evidence of black holes has been to look for signs of their impact on the surrounding universe. Stars, gasses and other space objects behave differently near a black hole than they do elsewhere in the universe as the black hole’s intense gravity pulls on them. Using telescopes equipped with special tools, scientists can pick up a type of high-energy light emitted by objects that interact with a black hole’s gravitational forces, and reverberation mapping can measure the radiation given off by the ring of debris that surrounds the black hole, helping physicists pinpoint the location of a black hole, even if they can’t see the black hole itself. Finally, in 2019, scientists made a stunning breakthrough in the study of black holes when the International Event Horizon telescope captured the world’s first image of a black hole. Technically, what they captured was the black hole’s shadow, since the absence of light reflecting from a black hole makes the black hole itself impossible to see, but nevertheless, this was the world’s first solid, photographic proof of the existence of black holes. If black holes have finally been proven to be real, does that mean that white holes are a proven fact of the universe, too? Well, not exactly. While Einstein’s theory of general relativity does describe the existence of both black and white holes, it doesn’t explain how a white hole might actually form in space. 

A black hole forms when a dying star implodes in a supernova, collapsing all of the star’s matter into an impossibly tiny area cordoned off from the rest of space. The reverse doesn’t quite make sense - the idea of a white hole exploding into a fully-functioning star would be a bit like unscrambling an egg: it just wouldn’t work. This idea also violates the statistical law that entropy must increase over time. Furthermore, if a white hole did form, the matter it releases when it “burps” would collide with the matter in orbit around the white hole. These collisions would cause the entire system to collapse into a black hole. Perhaps if white holes do exist, they don’t remain as a white hole for long. Hal Haggard, a theoretical physicist at Bard College in New York, has said that “a long-lived white hole, I think, is very unlikely.” Other scientists have different theories about white holes that help explain some of the inconsistencies. Steven Hawking discovered back in the 1970s that black holes leak energy, which led him to wonder - how do black holes die? And what happens to everything that’s been trapped inside of a black hole when it dies? The theory of general relativity holds that nothing can get out of a black hole, but quantum mechanics prevents any information inside a black hole from being deleted. So where does it go? Some have taken this to mean that a white hole is actually the result of the death of a black hole. As a black hole dies, it may become so small - as small as one microgram in size, about the mass of a human hair - that it would no longer obey the laws of physics as we know them. This infinitesimally tiny object would be so small that it would defy gravity, but inside it would hide a cavernous interior full of everything it swallowed in its previous life as a black hole. It’s small size and gravity-defying behaviour could allow it to remain stable enough to eventually spit out information and matter that had been swallowed by the black hole, becoming a “burping” white hole instead. If this theory holds true, the universe could one day come to be dominated by white holes. After all of the stars in the universe have burnt out and imploded into black holes, and then after all of those black holes themselves have all died, the universe might be nothing but a sea of burping white holes. Thankfully, this could only happen in a universe countless trillions of times older than our universe currently is, so it’s not a scenario we need to worry about any time soon. There are many more questions than answers when it comes to white holes, and that leaves room for plenty of imaginative theories about what a white hole actually is. Some scientists actually think that we are currently living inside the ultimate white hole. To these black hole physicists, the behavior of a white hole looks suspiciously similar to a little thing we call the Big Bang. The explosion of matter and energy resulting from the Big Bang that created our universe is remarkably similar to the way theorists suspect that white holes release matter. “The geometry is very similar in the two cases," Hal Haggard, the physicist from Bard College, has said. "Even to the point of being mathematically identical at times.

"This theory has attracted plenty of criticism, but Haggard intends to follow this rabbit hole to the very end, saying “Why wouldn’t you investigate whether white holes have interesting consequences? It may be that those consequences aren’t what you expected, but it would be foolhardy to ignore them.” We may still be a long way off from being able to look into a telescope and watch with our own eyes as a white hole burps out matter into the surrounding universe. Although we’ve only just gotten our first glimpse of a black hole - and though we have yet to even lay eyes on a white hole - scientists will undoubtedly discover more about these mysterious phenomena in the future. If the past has taught us anything, it’s that just because we can’t see something doesn’t mean it isn’t out there. Only time will tell which theory about white holes will prove to be correct - or if we had it completely wrong all along. One day we may get an answer to the question “What is a white hole?” but until then, it remains yet another of the countless as-yet-unsolved mysteries of our vast and unknowable universe.

What is the Wormholes? -Wormholes Explained

If you saw a wormhole in reality, it would appear round, spherical, a bit like a black hole. Light from the other side passes through and gives you a window to a faraway place. Once crossed, the other side comes fully into view with your old home now receding into that shimmering spherical window. But are wormholes real, or are they just magic disguised as physics and maths? If they are real, how do they work and where can we find them? For most of human history, we thought space was pretty simple; a big flat stage where the events of the universe unfold. Even if you take down the set of planets and stars, there's still something left. That empty stage is space and it exists, unchanging and eternal. Einstein's theory of relativity changed that. It says that space and time make up that stage together, and they aren't the same everywhere. The things on the stage can affect the stage itself, stretching and warping it. If the old stage was like unmoving hardwood, Einstein's stage is more like a waterbed. This kind of elastic space can be bent and maybe even torn and patched together, which could make wormholes possible. Let's see what that would look like in 2D. Our universe is like a big flat sheet, bent in just the right way, wormholes could connect two very, very distant spots with a short bridge that you could cross almost instantaneously. Enabling you to travel the universe even faster than the speed of light. So, where can we find a wormhole? Presently, only on paper. General relativity says they might be possible, but that doesn't mean they have to exist. General relativity is a mathematical theory. It's a set of equations that have many possible answers, but not all maths describes reality. But they are theoretically possible and there are different kinds. EINSTEIN ROSEN BRIDGES The first kind of wormholes to be theorized were Einstein Rosen Bridges. They describe every black hole as a sort of portal to an infinite parallel universe. 

Let's try to picture them in 2D again. Empty space time is flat, but curved by objects on it. If we compress that object, space-time gets more curved around it. Eventually, space-time becomes so warped that it has no choice but to collapse into a black hole. A one-way barrier forms: the event horizon, which anything can enter but nothing can escape; trapped forever at the singularity at its core. But maybe there is no singularity here. One possibility is that the other side of the event horizon looks a bit like our universe again but mirrored upside down, where time runs backwards. In our universe things fall into the black hole. In the parallel universe, with backwards time, the mirror black hole is spewing things out a bit like a big bang. This is called a white hole. Unfortunately, Einstein-rosen bridges can't actually be crossed. It takes an infinite amount of time to cross over to the opposite universe and they crimp shut in the middle. If you go into a black hole, you won't become the stuff coming out of the white hole. You'll only become dead. So, to travel the cosmos in the blink of an eye, humans need a different kind of wormhole; a Traversable Wormhole. VERY OLD STRING THEORY WORMHOLES If string theory or one of its variations is the correct description of our universe, then we could be lucky and our universe might even have a tangled web of countless wormholes already. Shortly after the Big Bang, Quantum fluctuations in the universe at the smallest scales far far smaller than an atom may have created many, many traversable wormholes. Threaded through them are strings, called cosmic strings. In the first billionth of a trillionth of a second after the Big Bang, the ends of these tiny, tiny wormholes were pulled light-years apart; scattering them through the universe. If wormholes were made in the early universe, whether with cosmic strings or some other way, they could be all over; just waiting to be discovered. One might even be closer than we realize. From the outside, black holes and wormholes can look very similar; leading some physicists to suggest the supermassive black holes in the center of galaxies are actually wormholes. It will be very hard to go all the way to the center of the Milky Way to find out though, but that's okay. There might be an equally extremely hard way to get our hands on a wormhole, we could try to make one. 

MANMADE WORMHOLES To be traversable and useful, there are a few properties we want a wormhole to have. First, it must obviously connect to distant parts of space-time. Like your bedroom and the bathroom, or Earth and Jupiter. Second, it should not contain any event horizons, which would block two-way travel. Third, it should be sufficiently sized so that the gravitational forces don't kill human travelers. The biggest problem we have to solve, is keeping our wormholes open. No matter how we make wormholes, gravity tries to close them. Gravity wants to pinch it closed and cut the bridge; leaving only black holes at the ends. Whether it's a traversable wormhole with both ends in ours, or a wormhole to another universe, it will try to close unless we have something propping it open. 

For very old string theory wormholes, that's the cosmic strings job. For man-made wormholes, We need a new ingredient. Exotic matter. This isn't anything like we find on earth, or even antimatter. It's something totally new and different and exciting, with crazy properties like nothing that's ever been seen before. Exotic matter is stuff that has a negative mass. Positive mass like people and planets and everything else in the universe, is attractive because of gravity. But negative mass would be repulsive; it would push you away. This makes a kind of anti-gravity the props open our wormholes. And exotic matter must exert enormous pressure to push space-time open, greater even than the pressure of the centers of neutron stars. With exotic matter, we could weave space-time however we see fit. We may even have a candidate for this exotic matter, the vacuum of space itself. Quantum fluctuations in empty space are constantly creating pairs of particles and antiparticles, only for them to be annihilated an instant later. The vacuum of space is boiling with them, and we can already manipulate them to produce an effect similar to the negative mass we're looking for. We could use this to stabilize our wormholes. Once we're keeping it open, the ends would start together. So, we'd have to move them around to interesting places. We could start by wiring the solar system; leaving one end of each wormhole in orbit around the earth. We could flick others into deep space. 

The earth could be a wormhole hub for a vast interstellar human civilization spread over light-years, but only a wormhole away. However, wormholes have a dark side. Even opening a single wormhole, kind-of breaks the universe in fundamental ways, potentially creating time travel paradoxes, and violating the causal structure of the universe. Many scientists think that this not only means they should be impossible to make, but that it's impossible for them to exist at all. So, for now, we only know that wormholes exist in our hearts, and on paper in the form of equations. We know you want to know more about universe stuff, so, we're trying something new.

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