Let's Understand Wormholes

Whether it’s Star Trek, Stargate or Babylon 5 wormholes have been showing up in science fiction for a long time. They are just a super convenient tunnel to another part of the universe, a way for sci-fi writers to send their characters across huge distances in the blink of an eye. And it turns out that they are not just science fiction: wormholes could really exist. But if they do, they are much weirder than anything we could make up.

In physics, a wormhole is known as an Einstein-Rosen bridge. It is named after Albert Einstein and another physicist, Nathan Rosen. They came up with the idea together in 1935 and showed that according to the general theory of relativity, wormholes are a definite possibility. A wormhole acts like a tunnel between two different points in spacetime, which is just the continuum of space and time that makes up the fabric of the universe.

According to general relativity, gravity works by bending spacetime. Planets and Stars act like a weight in the fabric of the universe, creating a curve. It can be kind of hard to picture what spacetime is, let alone what it would mean for it to bend, so physicists often talk about it by using weights on a stretched bedsheet as an analogy. Earth would be like a big bowling ball making a big dip in the sheet and when something gets too close to the planet and it’s pulled in by the gravity, it’s like it’s falling into that dip in the sheet. 

But if spacetime can be curved, it can also be twisted and shaped in other ways, like by connecting two different places with a tunnel. It’s kind of like poking two holes into that bedsheet, folding it over and then stretching the fabric so that the edges of the holes can get together and you just sew them into a tunnel. That’s a wormhole in a bedsheet. But because wormholes don’t seem to violate the laws of physics does not mean that they actually exist; they are just technically possible. And unfortunately, we haven’t yet detected any and we aren’t even sure how they would form.

If wormholes do exist, one reason we might not have spotted them is that they could be hiding behind black holes. A black hole is what happens when there is so much mass squeezed into an object that it ends up with such a strong force of gravity that even light can’t escape its pull. Once you get too close to a black hole, you are toast: there is no escaping from being smashed into oblivion. In the bedsheet model, black holes and wormholes look very similar, they both have a steep falloff that seems to go on forever. Except, with a wormhole, the steep drop actually leads somewhere.

According to general relativity, wormholes could have black holes at each end, meaning that after diving into a black hole on one end, the energy that was once your body could get spewed out somewhere totally different in the universe. Of course, you would not survive that trip. All that would be left is radiation and subatomic particles. Then there are white holes, which are the opposite of black holes: They spew out matters with such force that it would be impossible to enter them. If black holes are infinite weights on a bedsheet, white holes would be like hills: objects pushing up on the bedsheet.

Like wormholes, these are a thing that could exist, the math does check out, we are just not sure how they would form. But we know that if they exist, they could be found at either end of a wormhole, too. So, maybe if there was a black hole at one end of the wormhole and a white hole at the other, we could go in the black hole end and be blasted out the white hole end, Maybe. But you would still probably be crushed by the black hole in the process. Not to mention it would definitely be a one-way trip.

There are a few other problems with wormholes. For one thing, they would probably be dangerous. Sudden unexpected collapse, weird exotic particles, a ton of radiation. In fact, travelling through a wormhole could instantly collapse it, because they would probably be unstable. And then there is the fact that wormholes might not be a shortcut at all. A random wormhole could easily be a longer-than-normal path. Size is also a problem. A real-life wormhole could be too small for us to travel through. Not to mention the travel time, which could be millions or billions of years, making some wormholes pretty useless.

So, that’s a lot of problems. The biggest hope actually comes from how little we know. A lot of this depends on physics that we haven’t quite worked out yet or on facts about our universe’s history and geometry that we just don’t know for sure. Once we have all that figured out, the final barrier would be technology and opportunity. Right now, we definitely don’t know how to make a wormhole and we would have to be super lucky to find one that is useful to us if they exist at all.

So, it’s pretty clear that we won’t be sliding through any wormholes anytime soon. But we know that they could be out there, hiding in some of the most extreme places in the universe. And who knows? Maybe our ideas about wormholes will be totally different in the future. People living just a few hundred years ago couldn’t have even imagined particle accelerators or internet. Until we find one or build one Let's will keep exploring the universe.

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Let's Understand Naked Singularities

When people talk about black holes, there is one thing that pretty much always comes up is that Black holes get their name because the infinitely tiny, infinitely dense point in the centre has a gravitational pull so strong that even light can’t escape. The thing is, that might not always be true. For the past half-century — basically, as long as we have known black holes are a thing — astrophysicists have been debating the existence of something that should be a black hole, except it’s neither black nor a hole. They are called naked singularities and if they exist, they will rewrite physics as we know it.

When a star dies, it undergoes a gravitational implosion and starts to collapse in on itself. If the star is massive enough, nothing can stop the collapse and all that matter turns into a single point in space. We call that point a singularity and it has zero volume and basically infinite density. Like with basically everything involving infinity, it’s hard to even imagine what that means. But that’s astrophysics for you things get weird.

A singularity isn’t the same thing as a black hole, but it is what causes the black hole. The term “black hole” refers to everything inside the event horizon, the point where the singularity’s gravitational pull becomes so strong that light can’t escape. It is impossible to see anything inside it from the outside. And if you decided to go inside the event horizon to check out what is going on, you would never get out again. So, sure, for a moment you would be the only person in the universe to actually know what’s happening down there, but you would never be able to tell anyone and you’d be stuck until you died.

In 1965, an astrophysicist named Roger Penrose demonstrated that all black holes must have singularities within them. Makes sense, But he couldn’t prove that all singularities need to have a point-of-no-return event horizon and therefore a black hole surrounding them. In other words, he couldn’t prove that it was impossible for a singularity to be naked. He was pretty sure naked singularities couldn’t exist though, even if he couldn’t mathematically prove it. Four years later, he coined what’s known as the conjecture of cosmic censorship, which basically just says that it’s impossible for a singularity to exist without a black hole around it.

Again, he couldn’t prove it, it was just a conjecture. But it was really hard to imagine how an infinitely dense point could exist without a black hole around it and all these decades later, many astrophysicists still subscribe to cosmic censorship. But not all of them. We have obviously never observed a naked singularity, but that doesn’t mean it’s impossible for them to exist.

This long-running debate actually led to one of many wagers Stephen Hawking has publicly made about astronomical discoveries. In the early 1990s, he bet Caltech Kip Thorne and John Preskill that naked singularities can’t exist. The loser had to, quote “reward the winner with clothing to cover the winner’s nakedness,” which was definitely on-theme. Months later, Hawking actually found mathematical evidence, though, not definitive proof that when a black hole finishes evaporating, it might leave behind a naked singularity.

If the idea of a black hole evaporating sounds super strange well, it is. But it is one of the many quirks of quantum mechanics, which predicts that a pair of particles can spontaneously pop into existence with one on either side of the event horizon. If the one outside has the right trajectory, it will escape off into the universe, leaving the black hole with a teeny tiny little bit less mass. But! Quirks of quantum mechanics didn’t fall within the confines of the bet, so Hawking technically hadn’t lost. 

He had to concede in 1997, though, when computer models found a special case for fine-tuned parameters that would produce a naked singularity from an imploding star. Basically, it’s like trying to balance a sharpened pencil on the pointy end Highly improbable, but not impossible. Hawking made the most of his loss, though — he gave Thorne and Preskill T-shirts featuring a woman in nothing but a towel, along with the words “Nature Abhors a Naked Singularity.”

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So, simulations are able to suggest naked singularities might form if conditions are just right, but what about more general cases? Well, researchers have found that if our universe had a different number of dimensions or was shaped differently than it is, then yes — it could form naked singularities. But all this could mean that naked singularities only work on paper, not in practice. 

We are kinda stuck with the universe we have got. If by chance we actually learn of a real naked singularity floating around out there in the cosmos, though, it could change our understanding of the universe. Mainly because we would be able to study something that’s governed by both quantum mechanics (the science of the very small) and general relativity (the science of the very massive). 

As it stands, these two theories work almost perfectly when you are using each of them on their own, but they don’t play well together. When you try to apply them both at the same time, like when something is both super duper massive and super duper tiny — basically, a singularity — they spit out nonsense answers. But being able to directly observe a singularity would give us the data to either unite them or scrap them for a different theory entirely. A unified theory of the universe would do more than just reveal the secrets hiding in black holes.

Right now, anything that happened before 10^-43rd seconds after the Big Bang is a big mystery because both quantum mechanics and general relativity would apply to it. That is such a tiny fraction of time that you might think it wouldn’t really matter anyway, but, like, those were the very first moments of our universe. In other words, for being infinitely tiny, naked singularities are a pretty big deal.

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