What the End of the Universe Will Look Like According to Scientists

Kind: captions Language: en Right now, you're sitting on a planet orbiting a star completely unaware that a killer is hunting you. There's nothing you can do about it. There's nothing to stop it. The fabric of space is unrelenting. The universe is going to end. It's going to be slow, methodical, and suffocating. Astrophysicists have already mapped it out. They know how the stars will die and what the last terrifying moments of reality will look like. It's the ultimate cosmic autopsy. The clock is already ticking. And when it hits zero, the universe and its septillion stars won't even notice that we are gone. Think of your house and how many lights are inside of it. There's probably over a dozen with some rooms having multiple lights. If one goes out, it might be an inconvenience, but you won't really notice. But if they all go out one after another, the house starts getting dimmer and dimmer until you're sitting in the darkness. Now, scale that up to the entire universe. For billions of years, it's been a kaleidoscope of light with new stars replacing old ones. For scientists looking out through the world's most powerful telescopes, it's like watching a miracle until they start going out and they don't get replaced. Stars form slowly over millions of years and they are primarily composed of helium and hydrogen. 70% of the average stellar mass comes from hydrogen. The complex process of star formation requires these elements to mingle and form giant molecular clouds for eons until they collapse into hyper-dense energy that then forms the base of a star. A single interstellar event can destroy the entire stellar cloud instantly and the potential solar system that would have formed is erased. But if the universe changes, the lights could go out completely. Without hydrogen, there's no star. Without stars, there is no universe. And that's a problem. There's a cap on the amount of hydrogen in the universe. It is finite. Scientists estimate that around 75% of hydrogen gas in the universe formed by the Big Bang has been used up. Stars don't just need it in the creation period, but they consume it at every stage of their life cycle. It's not like the universe will run out of hydrogen completely as there will always be clouds floating around, but as the consumption increases they'll get fewer and further in between. And so the cosmos is faced with some hard choices. The peak of star creation happened at around 11 billion years ago. While they continue to be born today, the rate today is only around 3% of what it was during what scientists call the cosmic noon. Today stars are smaller, further apart, and face longer odds before they're born due to the decreasing number of hydrogen clouds available. This isn't something that can be avoided or mitigated like climate change. It's part of a cycle of existence that the universe has been building towards since its creation. In around a billion years it'll become much clearer. Around 95% of the stars that will ever be born have already been formed. And those that are created in the future are unlikely to build to the level of our sun. Instead, they're more likely to become red dwarfs, one of the smallest forms of fusing stars in the universe. Not a single star classified as a red dwarf is visible to the naked eye. And due to their cooler nature and limited range, it's highly unlikely they could serve as the primary star for a circling planet capable of life. As each one dies, the universe becomes quieter. Instead of brighter stars, eerie low light red dwarfs create a vague path through the cosmos. And just because something is dead, it doesn't mean it's gone. The stars have gone out, but they don't simply evaporate into air. The stellar bodies are composed of massive amounts of mass with the average red dwarf being just under a tenth the mass of the sun. All around the universe their ghosts lingers. This is the next stage of the death of the universe, but evidence of it is fairly thin right now. Red dwarfs are hard enough to observe, and as they shrink and dim it becomes even harder. When they burn through their fuel, they get hotter and they shrink, eventually becoming a super dense white dwarf that burns down the remainder of its energy. Eventually they'll cool and fade out of existence altogether that we know of. But, scientists have another theory, one where they evolve into a new form, one that no longer emits significant heat or light, a black dwarf. Why haven't we seen one of these mysterious stars yet? Because the working theory is that the universe hasn't existed long enough for one of these to form. For a super dense white dwarf to lose all of its heat, it would take more than the 13.79 billion years the universe has existed. And the temperature of a white dwarf is often used to gauge the universe's age, but the sheer density of white dwarfs means that for them to simply disappear is incredibly unlikely. Instead, [music] what would form in their place is a massive, ultra-dense orb of carbon floating in the universe. These celestial bowling balls would be nearly invisible in the cosmos, but each one would weigh hundreds of thousands of times more than the Earth. And each one could cause untold destruction. Where once there was a star, there's now a silent, dead wrecking ball, detached from any possible solar system, rolling along regardless of anything in its path. They would still have a powerful gravitational pull, drawing in any remnants of worlds that lay in their wake. And as one star after another dies, becoming a black dwarf, the lights of the universe don't just go out, they become entropy itself, pulling any remnants of light left, dragging them toward the inevitable end. Sound familiar? That's because black dwarfs have a cousin, and it could spell the end of everything. Much like white dwarfs eventually collapse into black dwarfs, larger stars have their own life cycle. They too die out slowly, but the much larger mass and gaseous nature means that their final form looks very different. Rather than transforming into an incredibly dense ball of carbon, they collapse upon themselves, forming a vortex of sorts with the most intense gravitational pull in the universe. These strange formations can also be created by supernova explosions of stars or the merger of two neutron stars, and they're called black holes. And absolutely nothing escapes their iron grip. The more there are, the less there is of anything else. When a star's internal pressure can no longer withstand its own gravity, and there is no more hydrogen to burn, the star starts to burn other elements. Eventually, nuclear fusion ceases, and the ensuing collapse resembles a whirlpool. They're far larger than any planet, and their gravitational pull is more than enough to swallow any planetary or stellar corpse that gets pulled into their drift and consumed. The scary part is, they are not done eating. Black holes are insatiable, and with each new mass they absorb, they slowly grow. The process of being swallowed in a black hole is often described as spaghettification, where anything absorbed by them ceases being biology or geology, and just becomes physics. The very atoms that make up the object come unwound by pressure that nothing in existence was meant to endure. As this cosmic monster continues to feed, the pull becomes stronger, evolving into a supermassive black hole. Nothing, not even light, can escape from one of these. Surprisingly though, we have been coexisting with them for a long time. Studies show that almost every major galaxy, including our own Milky Way, features a supermassive black hole at its center. As interstellar gas accumulates around the black hole, the processes for creating star systems and planets are activated. This concentration of energy helps to create life. But what happens when there simply isn't enough fuel left to do that? Eventually, these supermassive black holes will be the only thing left, absorbing every scrap of matter into an endless vortex. They will be the ultimate apex predator drifting through the endless void until they collide with another in the darkness of space. So, will the universe end with a whimper or a bang? For billions of years, the universe will be an open void, a vast wasteland where life is a distant memory, and consumption of what little remains is the only thing left. But lurking under the surface of this freezing endless blackness is something else. A trapdoor that could open at any time and spell the end of not just the few remaining stars and massive black holes, but of everything, including the very concept of existence. It's known as the false vacuum decay. A vacuum on Earth is the absence of air, but in space it becomes much more complicated. What happens in a true vacuum where there is absence of everything. No energy, no air, no light, just true nothingness. It's a void where nothing could exist. The closest we get is the center of a black hole, something so devoid of light and so dense that no instrument could ever get close. Some scientists say that this is the natural state that the universe is slowly marching toward with each new black hole that opens. But another theory says that a true vacuum has never existed. If it did, we wouldn't have time to study it. This theory states that we are in a false vacuum, a temporary bubble of space that feels stable, but is balancing on a cosmic edge. A true vacuum, by contrast, would be completely stable. Our entire existence is teetering depending on a thin margin of error to stop the collapse of the entire universe. If that balance fails, a bubble of true reality would expand at the speed of light, deleting the laws of physics instantly. It would happen so quickly that even if anyone was alive, they would be obliterated before their brain could register it. The closest comparison example we have is the Titan submersible disaster. The official accident investigation confirmed the crew were killed instantly when the hull collapsed in a fraction of a second. Because the failure happened under immense deep-sea pressure, the sub and everyone inside it disintegrated, leaving virtually nothing behind. One second they were there, and in another they were gone. Is this the fate that awaits the universe? If a true vacuum would emerge, in one second a galaxy could be there, and in the next there would only be a void. This is the kind of universe-ending catastrophe you hear about in science fiction. While most theories about the death of the universe involve a slow, grinding end as the last lights in the universe are snuffed out, this is different. This is an unstoppable, invisible force that wipes out everything in its path and takes us with it. The scariest part is this isn't guaranteed to happen in the far future. The universe is highly volatile. We're assuring ourselves that its slow death is billions of years away, but all around us unpredictable dark matter looms. The physics of the universe spin on the head of a pin. If an atom gets bent the wrong way, the delicate balance of the universe that allows us all to exist could be upended. Not only would all of human existence be erased in the blink of an eye, but there would be no trace that we were even here. But if this doesn't happen, the end will find us anyway. Nothing in the universe lasts forever. Even the last thing remaining. Eventually, as they consume the remaining dead stellar bodies and planetoids around the universe, the black holes themselves begin to expend the energy that formed them. Originally, it was assumed that the radiation emitted by black holes couldn't escape its extreme gravitational pull and the vortex would essentially keep feeding itself endlessly. But in 1974, one of the smartest men in the world looked at those celestial objects and they came up with a completely different theory. And it could put one more nail in the universe's coffin. The roots of this study came from the Soviet Union where scientists observed that rotating black holes should emit particles of their own. A year later, another scientist argued that black holes had an entropy proportional to their surface area. Stephen Hawking built on those theories to argue that the black hole does emit particles, but these are standard elementary particles like photons and neutrinos. Rather than having a gravitational energy-absorbing power, they literally radiate the black hole's mass as heat back out to the cosmos. Every particle emitted by a black hole drains the carried-away mass, causing the black hole to slowly shrink. Black holes might not just be absorbing the universe, they might be propagating its end. Imagine a creature that consumes everything it encounters. As it eats, it spews out little versions of itself into the cosmos, and they begin consuming as well. The black hole isn't alive, but its life cycle isn't that different if Hawking's theory is correct. Known as Hawking radiation, these particles slowly bleed out into the void. Every particle carries thermal energy away from the dying star until the black hole drops its very last bit of mass. What happens when a black hole runs out of energy? Scientists believe that it would create a sudden burst of gamma rays, marking the end of its long evaporation. The expulsion would release energy equivalent to a few megatons of TNT. It would be immense to humans, but smaller than a standard supernova. It would be another blow to a universe that had been in its death throes for billions of years longer than the Earth had even existed. It would be the beginning of the end, but not the end. This would be the last leaching of energy out of the universe, the last light leaving the universe when the black hole completes its cycle, and in its wake, nothing. This is known as the heat death of the universe. Nothing is left. The universe settles into a permanent stasis with no stars to change the temperature, the universe settles into a baseline temperature of absolute zero. With no energy, all movement ceases forever. And this goes on forever. If a universe dies in the dark, does anyone notice? Does it even exist anymore? In the wake of one supermassive black hole after another eating everything in its wake only to ultimately consume itself, what will be left? The odds are nothing more than an infinite void. We don't know how large the universe actually is or even if there's an outer bound to it. We can only measure it by the objects we can observe, and those will have all been snuffed out eons ago along with us, of course. So, does time even exist anymore? There's no movement, no light, no thought, just endless stillness with no objects to mark it by. Without energy, the universe simply stops existing forever in a state of entropy. It's the conclusion of a cycle that begins when the first stars began to use up the hydrogen in the universe. Ironically, every single spark of life is the first step toward bringing the entire universe to a slow, frozen, infinite end that lingers in the great infinite space. It is a grim ending to everything we see now. Or, is it a return to the norm? One of the big mysteries of the world we live in is that we simply don't know what came before the Big Bang. The universe was created out of it, but what created the process that caused the Big Bang? Did it come from an empty, silent universe like the one we're all destined to become eons from now? And if that's the case, will that same process begin once again and spawn a new universe out of an infinite void caused by the end of the last one? In the end, we're ultimately just specs on the sand of time. Humans have only been on the Earth for a tiny slice of cosmic time, meaning the cycle is just beginning. There are going to be billions, maybe trillions of years until the universe breathes its last and fades into the infinite void. The existence of life on Earth is the consequence of a star lining up with a planet just right and avoiding disaster for a few billion years, long enough for something unique to evolve. But no matter how long it takes, this world is headed for the same end as every other planet among the stars. Nothing lasts forever, not this planet and not this universe. The universe is full of silent killers that'll destroy everything in their path. Watch what's actually inside a black hole to find out what scientists think goes on inside these monsters. Or, click on this video.