Astrum Space - Scientists Put a Time Limit on the End of the Universe

Episode Date: September 11, 2026

Scientists are predicting the end of the universe, and it could happen much sooner than we thought. For the first time, scientists have measured how dark energy is behaving right now, in the local universe, by measuring subtle shifts within our own solar system. How long do we actually have left? The answer might surprise you…Upgrade your online protection with an all-in-one security app! Get an exclusive NordVPN deal + 4 months extra here ➼ https://nordvpn.com/astrum. It’s risk free with NordVPN’s 30-day money-back guarantee! ▀▀▀▀▀▀A huge thanks to our Patreons who help make these videos possible. Sign-up here to support the channel: https://bit.ly/4aiJZNF To stay on top of space news, sign up to the Astrum newsletter: https://astrumspace.kit.com

Could the universe end tomorrow? It sounds like a ridiculous question. After all, the end of everything is supposed to be billions of years away in the future. But what if that's not the case? What if the end is actually coming far sooner? A recent paper explores this idea and worryingly, it turns out there could be more truth to it than you might think. Most of what we know about the cosmos comes from old light, distant galaxies,

ancient supernovae, the cosmic microwave background. But this light doesn't tell us what the universe is doing right now. What if dark energy has changed recently? What if it's become stronger, stranger, or even crossed into a new and dangerous phantom state? The universe could be headed towards an unfathomably violent death before cosmology has even had time to warn us. So perhaps the question is, how much time are we guaranteed before the universe's countdown reaches zero? And will we know when the end is coming? I'm Alex McColgan and you're watching Astrom. Join me today as we follow dark energy into its most extreme form, examine the terrifying physics of supercharged expansion, and investigate

whether the end of the universe could be much closer than we expect. All good things come to an end. Stars burn through their fuel, galaxies grow old and dim, even black holes given enough time, slowly evaporate away into nothing. But when we talk about the end of the universe itself, things become far stranger. There are a number of possibilities that could bring about the end of the universe. I'll come to them in a moment, but there is one that is particularly horrifying, one where space itself becomes the destroyer. In this very very, version of the universe's death, everything from the largest of structures to the smallest of particles is torn apart by a supercharged expansion. At first, the damage starts on scales

too large for us to notice from Earth, galaxy clusters, the biggest bound structures in the universe begin to slowly unravel. The galaxies inside them start slipping away. Stars that had orbited together for billions of years drift into darkness. Then the destruction moves inward. Solar systems come apart and planets are pulled away from their stars. Eventually, even matter itself would no longer be safe. The expansion of space would overcome even the most powerful fundamental forces we know of, the electromagnetic and strong forces that hold atoms together. Any two points in space, even fingers on the same hand, would be torn apart, infinite far away from each other. This is the Big Rip, a hypothetical future where the universe's expansion tears apart every single thing inside it. But for a long time, despite the horror of it all, there was at least one comforting thought. If the Big Rip scenario happens at all, it should be unimaginably far away, billions of years in the future, so distant that for us,

It may as well be fiction. But in May 26, Robert Scherer and Uwem Trevedi from Vanderbilt University published a paper with a fittingly ominous title, Apocalypse When? And this paper poses some rather unsettling questions. What if we're wrong to assume the end of the universe isn't just around the corner? If dark energy, the force driving cosmic acceleration, had changed very recently, would, our usual observations even tell us. Could the universe be heading towards a big rip before distant cosmology has had time to warn us? Hear that? It's your money calling. It wants a promotion.

Elevate your savings with the Scotia high-interest savings account. Always earn high regular interest rates that grow the more you save and invest. Conditions apply. Visit scotiabank.com slash H-I-S-A to learn more. Scotia Bank, you're richer than you think. These may sound like impossible questions, but this new research suggests there may be a way to answer them. To understand how scientists can put any limit at all on cosmic destruction, we first need to understand the driving force behind it, namely dark energy.

We've covered this before, but here's a quick recap. Gravity, as we know it, likes to bring things together. It pulls planets into orbit around stars, stars into galaxies, and galaxies towards each other. And if it were all up to gravity, some models say the universe would be a very small place. Galaxies would eventually attract each other and merge, star systems would collide, the whole universe would come together squeezing everything into a single, infinitely small point. A dramatic ending, with a slightly flippant name, the big crunch. But thankfully, that does not seem to be.

to be the universe we live in. There are numerous ways scientists predicted the universe might end, the big rip, the big crunch, or when the wrong people get access to your computer. We might be powerless in the face of the first two, but if you're worried about the last one, the sponsor of today's video, NordVPN, can help. NordVPN is more than just a world-leading VPN. In the face of modern threats, Nord bundles several useful cybersecurity features into one comprehensive package to protect yourself while online. NordVPN's built-in next-generation antivirus program stops threats before they even start by warning you when you're about to click on a dodgy fishing link, go on a fake store,

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subscription. With its 30-day money-back guarantee, it's risk-free, so why not give it a try? won't be the end of the world. Despite the best efforts of gravity, there is something powerful working against it on the largest scales, something that permeates every inch of the universe, including the air you're breathing right now,

and it makes up nearly 70% of the universe's total energy budget. Unfortunately, whatever it is, it isn't well understood, and that lack of knowledge is what gives it its name, dark energy. For now,

we define it as a mysterious component that is defying gravity and driving space to expand. And as per the best of our knowledge, it's quite a one-sided battle. Not only is dark energy stretching the universe, it is speeding up that expansion, leading to an accelerated expansion. To work out what this means for the future, we need to understand one small number. Every major ingredient of the universe can be described by something called the equation of state parameter. This sounds like jargon, but it is really just a way of asking, what does this stuff do as the space around it expands? In cosmology, the equation of state parameter, written as the letter W, tells us how the density of something, in this case dark energy, changes as the universe expands.

And to work it out, we need to take into account its pressure, like water pressure, and energy density. The higher the value of W, the faster something dilates as the universe grows in size. Ordinary matter with a W of zero is like dust in a room. If the room gets bigger, but you have the same amount of dust, the dust just spreads out more. In the same way, as the universe expands, matter gets diluted. Radiation has a W of a third, and also spreads out as space expands, losing even more energy as the wavelengths get stretched, fading even faster. But dark energy is different. The current standard model of cosmology puts the dark energy parameter at minus 1,

which means dark energy doesn't dilute at all. A useful way to picture this is with a bucket of water mixed with blue paint. If ordinary matter were the blue paint, then expanding the universe would be like pouring it into a bigger and bigger bucket of clear water. The color would, of course, become more diluted and turn into a fainter shade of blue. blue. If we then imagine dark energy as the paint, something bizarre happens. Every time the bucket gets bigger and more water appears, there's more blue paint with it, and as such, the colour doesn't fade at all. As the universe expands, every fresh new centimetre of space

comes with dark energy already inside it. So instead of thinning out, dark energy stays constant. This This is strange, but it is the version of dark energy, right or wrong, that we have more or less made peace with, and it will never stop. Things will keep getting further and further apart, and galaxies will keep on drifting away from each other. Matter and heat will become more and more diffuse, and eventually the universe will start freezing. As the stars die out and even the black holes evaporate, there will be little heat left in the cosmos. And so comes the name of this theory, the heat death. As the T.S. Eliot poem says,

this universe ends not with a bang, but with a whimper. The heat death or big freeze is currently considered the most likely fate of the universe under the assumption of constant dark energy. But there is another possibility, an even darker side of this mysterious force, an evil twin that is far more violent and far more dangerous. The equation of state parameter can be thought of like a dial. At W equals minus 1, dark energy behaves like a constant background presence. Let's put this at the top of the dial. This boundary is often called the phantom divide. If the parameter remains at this divide,

dark energy never dilutes and brings on our cold end. But some recent results have raised the possibility that dark energy may not be perfectly constant. You can watch my video about that here, but such an equation of state means our parameter, W might go above minus 1. And if it does, dark energy can weaken over time. In some models, where W goes above minus a third, Dark energy can become weak enough to start losing its battle against gravity. The universe will stop expanding, and everything in the universe comes together.

We are back to where we were headed before dark energy graced our universe, the big crunch that I mentioned earlier. Scientists are still torn about whether this is a possibility, and future data may change the picture, but it has reopened an age-old question. What is? if dark energy evolves. And if it can evolve in one direction, it's only natural to wonder what happens if it evolves the other way? Let's go back to our phantom dial. What happens if W drops below the phantom divide? This is where we start to enter strange territory. Remember, the higher the W, the faster it dilutes. That also means the lower the W,

the faster it builds up. If W goes below minus 1, it enters into a supercharged state. The more the universe expands, the higher the proportion of dark energy becomes. This time, every time our bucket grows and more clear water is added, even more blue paint appears than before. Instead of fading, the water becomes darker and darker blue. In this scenario, there is simply no stopping this form of energy. The universe is now controlled by a monster of a force called phantom dark energy. And it gets worse. The universe expands, which makes phantom dark energy stronger.

Stronger phantom dark energy in turn makes the universe expand faster. And faster expansion creates even more phantom energy. The cycle keeps feeding itself, creating a so-called runaway effect. It's this state that leads to the big rip, where supercharged expansion tears everything apart. But even if dark energy goes phantom, there is still one obvious question. How do we calculate when the big rip would actually happen? Well, the paper I mentioned earlier proposes an innovative way to find the answer, and they use this equation to do it. At first, this might look a bit complicated, but for our purposes, we can strip it down to the basics,

and then it looks a bit more manageable. Essentially, this tells us the stronger the phantom strength, the less time we have left in the universe. But it also depends on how strong dark energy is today. The more of it there is already filling space, the faster the runaway process reaches its catastrophic end. And this is where we run into problems, because we don't actually know how strong dark energy is right now. Dark energy doesn't interact with anything in the universe in the way radiation or ordinary matter does. Cosmologists can't scoop it up, place it in a detector and measure it. So they do something more indirect.

They measure the historical expansion of the universe. And for that, they rely on some of the most powerful observations in cosmology. Telescopes and data sets like Hubble, WMap, Planck, supernova surveys, and large-scale galaxy maps have helped us reconstruct the history of the universe. They tell us how fast the universe has expanded what it was made of at different stages. when matter dominated, when dark energy began to take over, and how cosmic structures grew over time. But there is a strange limitation hidden inside all of this. The cosmic microwave background, mapped in extraordinary detail by WMAP and Planck, is one of the most important

pieces of evidence in all of cosmology, but it is a relic from when the universe was only about 380,000 years old. Supernovae are more recent. yet even they are not truly present-day measurements. When we observe a distant supernova, we're seeing light that may have traveled for billions of years before reaching us. Large-scale galaxy surveys work in a similar way. They map the structure of the universe across cosmic time, but the further away we look, the older the information becomes.

So, it is theoretically possible that the dark energy we infer from these ancient observations is not exactly the dark energy acting in the universe today. It may have weakened, it may have strengthened, or, in the most extreme case, it may have crossed into a dangerous phantom state very recently. And if that happened, we cannot rely on these distant probes to warn us. It would be like trying to work out someone's current health by looking only at photographs of them from childhood.

What if dark energy behaved calmly for billions of people? of years, staying close to w equals minus one, but only very recently crossed into a far more dangerous phantom state. It sounds like the plot of a science fiction story, and in a way it is. Professor Scheheris says he has been thinking about this question for years, partly inspired by a story in which scientists discover that a big rip is imminent and humanity prepares for the end. Meanwhile, his PhD student, Orm Trevedi, had been exploited. how other procession tools like atomic clocks might constrain dark energy models. Their paper brings those threads together, and in so doing, it deals with a very important

question. If distant observations cannot give us a real-time warning, how can we know how much time we have left? To know whether something dangerous is happening right now, we need a different kind of test, something local, something precise, and something that responds to changes in real time. And that brings us to the solar system. While the distant universe might fail to act as our doomsday clock, the planets in our solar system can be handy for such measurements. Their orbits are, in cosmic terms, close by, so they can give us something much more immediate. As dark energy fills space, it also fills our solar system, but its effects here are incredibly tiny. That said, they can, show up in orbital motion, such as the shift of a planet's closest approach to the Sun,

known as perihelian procession, and even as subtle changes in the orbital speed. Don't get me wrong, the Sun's immense gravity is still, by far, the dominant influence on the movement of the planets. Compared with that, normal dark energy is almost invisible, but almost invisible is not the same as zero. It still leaves a tiny, gravitational fingerprint on planetary motion, one that, under phantom conditions, could become stronger and change quickly enough for us to notice. This is exactly what the authors aim to look for, using solar system dynamics as a local dark energy detector. Thankfully, with our fleet of satellites and a ray of excellent telescopes on Earth, we can measure the orbits of planets with incredible

precision. Multiple papers have used these measurements to work backwards through the equations and place limits on dark energy. Now, with those constraints in place, Chiera and Trudei could turn the solar system into a kind of clock to predict the time limits of impending doom, and their calculations revealed a countdown. That might not be what you expect. The first checks for changes in the orbits came from Mars. Estimates by Mauro Sereno and Felipe Jetser from the University of Zurich tell us that dark energy cannot already be too strong locally. If it were, the planet would not move quite the way we observe it moving today.

They quote this constraint as the upper limit on the local dark energy density, but this figure is much weaker than the standard cosmological value, about 10 billion times weaker to be precise. The authors then looked up how fast dark energy has changed in recent years. This is key to timing the big rip, as a phantom energy would rise sharply over a very short time. For that, they turned to the works of Lorenzo Yorio, who used the orbit of Saturn to constrain changes in cosmic acceleration over time. Using those results, and working under some strict assumptions, the authors were finally able to place a solar system given lower limit. on the equation of state parameter to a negative 400 million.

I know that sounds weird. After all, for most of this video, I've been talking about W values around minus 1. So minus 400 million feels almost too phantom for us to go calmly about our daily lives. But it's important to remember this is just a lower bound, however extreme. As per their calculations, the solar system alone is enough to rule out any dark energy strength more severe than this.

And most importantly, it is not infinite, which allows us to place actual mathematical constraints on the time we have left. The authors now had all the planetary pieces of their big cosmological puzzle. Plugging these values back into the time left equation, they were ultimately able to put a limit on the big rip countdown. The result? 30 years. This number surprised even the researchers,

but it comes with a lot of caveats. This is not a prediction that the universe will end in 30 years. It is instead a lower limit, saying it will not end in the next three decades. Professor Gerr admitted he was a little disappointed by the result, not because he thinks the big rip is imminent, but because he had hoped even the local measurements would push the limit much further away. But the real victory of their research lies elsewhere. They show that two fields, which seem completely separate, the motion of the planets and the evolution of the

universe, can be tied together in a meaningful way. Of course, by cosmic standards, 30 years is an absurdly short amount of time. But scientifically, the surprise here isn't the size of the limit. it's the fact that we can place any limit at all using just our solar system. Our neighbourhood might be the only place where we can look for a real-time warning, and as we make better and longer measurements of the planetary orbits, this lower bound will, hopefully, be pushed at least a couple billion years into the future. So no, the universe is, thankfully and fairly certainly, not ending tomorrow. And the big rip may never come.

Phantom dark energy may turn out to be nothing more than a mathematical solution, but I think it's important that we explore all the possibilities. After all, it forces us to investigate a key question. If the universe did something this extreme, would we even be able to tell? A scientist looked for new ways to probe dark energy locally. One proposal from the same authors suggests placing a laser interferometer on the moon to listen to dark energy by measuring tiny, disturbances in space-time.

Plus, if phantom dark energy has even a slight coupling to electromagnetic physics, its warning signs might appear as small changes in constants like the electron proton mass ratio. But if it only speaks through gravity, then the solar system may remain the only local avenue to understand the power that controls us, and ultimately our fate. A fate that may not only be written in the oldest light we can see, but hidden in the quiet, precise motion of worlds much closer to home. I'll see you back here in 31 years to check in if we make it. Thanks for watching.

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