Home  

Wonders of the Universe Destiny

a story that you couldn't tell without something so fundamental that it's impossible to imagine the universe without it. It's woven into the very fabric of the cosmos. Time. The relentless flow of time has driven the evolution of the universe and created many extraordinary wonders. These wonders take us from the very first moments in the life of the universe to its eventual end. This is Chankillo on the north-western coast of Peru. And it's one of South America's lesser known archaeological sites. These familiar timescales mark the passing of our lives. But the life of the universe plays out on a much grander scale. When you look up into the night sky, you don't just see stars. Those tiny points of light are a million different clocks, whose lifespans mark out the passage of time over billions, or even trillions, of years. This film is about the greatest expanses of time. The deep time that shapes the universe. From its fiery beginnings, through countless generations of stars, planets and galaxies, to its eventual demise, the fate of the universe is determined by the passage of time. Timescales in the cosmos seem so unimaginably vast, it's almost impossible to relate to them. Yet there are places on Earth where we can begin to encounter time on these universal scales. Permanent change is a fundamental part of what it means to be human. We all age as the years pass by. People are born, they live, they die. I suppose it's part of the joy and tragedy of our lives. But out there in the universe, those grand and epic cycles appear eternal and unchanging. But that's an illusion. You see, in the life of the universe, just as in our lives, everything is irreversibly changing. By building change upon change, the arrow of time drives the evolution of the entire Universe. And as we look out deep into the cosmos, we can see that story unfold. This is an image of a tiny piece of night sky in the constellation of Leo. It's actually where the mouth of the lion would be. And, despite appearances, it is one of the most interesting images taken in recent astronomical history. The interesting thing is this little red blob here, which looks very unremarkable. But what that red blob is is the afterglow of an enormous cosmic explosion. It's the death of a star. That was about 40 or even 50 times the mass of our sun. Poetically named GRB 090423, it was once a Wolf-Rayet star. Shrouded by rapidly swirling clouds of gas, it burned 10,000 times more brightly than our sun. But because it burned so brightly, it was extremely short-lived. As it died, the giant star collapsed in on itself. That caused massive jets of light and stellar material to be ejected from its poles, in an explosion that shone with the light of 10 million billion suns. And it's the afterglow of this catastrophic explosion that is just visible from this planet as a faint red dot. But that's not what's so interesting about GRB 090423. You see, when we look up into the sky, at distant stars and galaxies, then we're looking back in time because the light takes time to journey from them to us. And the light from that red dot has been travelling to us for almost the entire history of the universe. You see, what we're looking at here is an event that happened 13 billion years ago. That's only about 600 million years after the Big Bang. After the universe began. So this is something incredibly early in the universe's history. In fact, this is the oldest single object that we've ever seen. What we're looking at here is the explosive death of one of the first stars in the universe. As it evolves, the universe passes through distinct eras. Vast ages, whose beginnings and endings are marked by unique milestones. The births and deaths of its wonders. The moment the first stars were born is one of the most important changes in the evolution of the cosmos. It signals the end of the Primordial Era and marks the beginning of the second great age of the universe. The time in which we live. The Stelliferous Era - the age of the stars. Starlight illuminates the night sky and starlight illuminates our days. It's an age of astonishing beauty and complexity in the universe. The cosmos is absolutely awash with stars surrounded by nebulae and systems of planets. Countless billions of worlds that we've yet to explore. But the cosmos isn't static and unchanging. It won't always be this way. Because, as the arrow of time plays out, it produces a universe that is as dynamic as it's beautiful. We've seen stars born and we've seen stars die. And we know that tomorrow won't be the same as today because the arrow of time says the future will always be different from the past. But what drives this evolution? Why is there a difference between the past and the future? Why is there an arrow of time at all? We all have an intuitive understanding of the arrow of time. It seems obvious to us that things change and the future will be different to the past. We know that because we see the effects of the passing years all around us. Our sun will have become a white dwarf. With no fuel left to burn, a white dwarf's faint glow comes from the last residual heat from its extinguished furnace. The sun is now dead. Its remains slowly cooling in the freezing temperatures of deep space. Looking at it from where the Earth is now, it would only generate the same amount of light as the full moon on a clear night. The fate of the sun is the same as for all stars. One day, they must all eventually die and the cosmos will be plunged into eternal night. And this is the most profound consequence of the arrow of time. Because this structured universe that we inhabit, and all its wonders - the stars, the planets and the galaxies - cannot last forever. The cosmos will eventually fade and die. First will come the end of the Stelliferous Era. The end of the age of starlight. The largest stars are the first to disappear, violently collapsing into black holes. Just a few million years after their formation. But long after they're gone, just one type of star will remain. This is a picture of the nearest star to our solar system, Proxima Centauri. It's only 4.2 lightyears away. But the reason it doesn't stand out against the much more distant stars in this photograph is that Proxima Centauri is incredibly tiny. It's a kind of star known as a red dwarf star. It's only about 11-12% the mass of our sun. But to our eyes it would appear to shine 18,000 times less brightly. But red dwarfs do have one advantage over their much more luminous and magnificent stellar brethren. And that's because they're so small, they burn their nuclear fuel incredibly slowly, so they have lifespans of trillions of years. And that means that stars like Proxima Centauri will be the last living stars in the universe. If we survive into the far future of the universe, then it's possible to imagine our distant descendants building their civilisation around red dwarfs to capture the energy from those last fading embers of stars, just as our ancestors crowded around campfires for warmth on cold winter's nights. The reason why Proxima Centauri burns so slowly is because its small size and low gravity mean its core is under much lower pressure than larger stars. This also means that its interior is constantly churning, whipping up the surface into a fiery turmoil. Explosive solar flares occur almost continually, even though it burns so dimly. But Proxima Centauri will eventually die. And like our sun, it too will become a white dwarf. As the age of starlight ends, all but the dimmest flicker of light in the universe will go out. The faint glow of white dwarfs will provide the only illumination in a dark and empty void, littered with dead stars and black holes. By this point, the universe will be 100 trillion years old. And yet, even now, the vast majority of its lifespan still lies ahead of it. There are few places on Earth where you can get an inkling of what the far future has in store. This is Namibia's Skeleton Coast, where the cold water to the South Atlantic meet the Namib Desert. And it is one of the most inhospitable places on Earth. Back in the 17th century, Portuguese sailors used to call this place the gates to hell because this dense fog that you see pretty much every morning along this coast, coupled with the constantly shifting shape of the sandbanks, meant that over the years, literally thousands of ships were wrecked along this coastline. And even if you made it to shore, that wasn't the end of your problems because the currents are so strong here that there is no way of rowing back out to sea. If you look that way, there's just hundreds of miles of inhospitable desert. So, it genuinely was a place of no return. If you were shipwrecked here, this WAS the end of your universe. This is the Eduard Bohlen.


  BBC Wonders of the Universe Destiny a story that you couldn't tell without something so fundamental that it's impossible to imagine the universe without it
 
She was once an ocean-going steamer, ferrying passengers and cargo between here and Europe. On 5th September, 1909 she ran aground in thick fog. Yet, like all the vessels wrecked along this shoreline, the time it takes her to decay to nothing will be far longer than her time at sea. In the far future of the cosmos, a similar destiny awaits the remaining white dwarfs. A black dwarf will be the final fate of those last stars. White dwarfs that have become so cold that they barely emit any more heat or light. Black dwarfs are dark, dense decaying balls of degenerate matter. Little more than the ashes of stars. Their constituent atoms are so severely crushed that black dwarfs are a million times denser than our sun. Stars take so long to reach this point, that after nearly 14 billion years we believe there are currently no black dwarfs in the universe. But despite never seeing one, we can still predict how they will end their days. Just as the iron than makes up this ship will eventually rust and be carried away by the desert winds, so we think that the matter inside black dwarfs, the last matter in the universe, will eventually evaporate away and be carried off into the void as radiation, leaving absolutely nothing behind. With the black dwarfs gone, there won't be a single atom of matter left. All that will remain of our once rich cosmos will be particles of light and black holes. After an unimaginable length of time, even the black holes will have evaporated and the universe will be nothing but a sea of photons, gradually tending towards the same temperature, as the expansion of the universe cools them towards absolute zero. And when I say "unimaginable period of time," If I were to start counting with a single atom representing one year then there wouldn't be enough atoms in the entire universe to get anywhere near that number. Once the very last remnants of the very last stars have finally decayed away to nothing, and everything reaches the same temperature, the story of the universe finally comes to an end. For the first time in its life, the universe will be permanent and unchanging. Entropy finally stops increasing because the cosmos cannot get any more disordered.
 
This film is about the greatest expanses of time
This film is about the greatest expanses of time
  The births and deaths of its wonders
The births and deaths of its wonders
 
Nothing happens and it keeps not happening. Forever. It's what's known as the heat death of the universe. An era when the cosmos will remain vast and cold and desolate for the rest of time. But that's because there is no difference between the past, the present and the future. There's no way of measuring the passage of time because nothing in the cosmos changes. The arrow of time has simply ceased to exist. It's an inescapable fact of the universe, written into the fundamental laws of physics. The entire cosmos will die. Every single one of the 200 billion stars in our galaxy will go out. And just as the death of the sun means the end of life on our planet, so the death of every star will extinguish any possibility of life in the universe. The fact that the sun will die and it will incinerate the Earth and obliterate all life on our planet in the process, might sound a bit depressing to you. You might legitimately ask, "Well, surely you could build a universe in a different way? "Surely you could build it so it didn't have to descend from order into chaos?" Well, the answer is no, you couldn't, if you wanted life to exist in it. The arrow of time, the sequence of changes that slowly leads the universe to its death, is the very same thing that creates the conditions for life in the first place. Because it takes time for matter to form and it takes time for gravity to pull it together into stars and planets. The arrow of time creates a bright window in the universe's adolescence. During which, life is possible. But it's a window that doesn't stay open for long. And that's why, for me, the most astonishing wonder of the universe isn't a star or a planet or a galaxy. It isn't a thing at all. It's an instant in time. And that time is now. Humans have walked the Earth for just the smallest fraction of that briefest of moments in deep time. But in our 200,000 years on this planet, we've made remarkable progress. It was only 2,500 years ago that we believed that the sun was a god and measured its orbit with stone towers, built on the top of a hill. Today, the language of curiosity is not sun gods, but science. And we have observatories that are almost infinitely more sophisticated than the 13 towers, that can gaze out deep into the universe. And, perhaps even more remarkably, through theoretical physics and mathematics, we can calculate what the universe will look like in the distant future. And we can even make concrete predictions about its end. And I believe it's only by continuing our explanation of the cosmos and the laws of nature that govern it, that we can truly understand ourselves and our place in this universe of wonders. And that's what we've done in our brief moment on Planet Earth. In 1977, a space probe called Voyager 1 was launched on a grand tour of the solar system. And it visited the great gas giant planets - Jupiter and Saturn - and made some wonderful discoveries before heading off towards interstellar space. 13 years later, after its mission was almost over, it turned around and took one last picture of its home solar system. This is that picture. And the beautiful thing about this picture is this single pixel of light suspended against the blackness of space. Because that pixel, that point, is Planet Earth. The most distant picture of our planet ever taken. 6 billion kilometres away. And whilst I suppose it has very limited scientific value, for me, this tiny point of light is the most powerful and profound demonstration of perhaps the most human of qualities. Our unique ability to reflect on the universe's existence and our place within it. Just as we, and all life on Earth, stand on this tiny speck adrift in infinite space, so life in the universe will only exist for a fleeting bright instance in time because life, just like the stars and the planets and the galaxies, is just a temporary structure on the long road from order to disorder. But that doesn't make us insignificant because we are the cosmos made conscious. Life is the means by which the universe understands itself. And, for me, our true significance lies in our ability and our desire to understand and explore this beautiful universe.
 
The Stelliferous Era - the age of the stars
The Stelliferous Era - the age of the stars
  In the far future of the cosmos, a similar destiny awaits the remaining white dwarfs
In the far future of the cosmos, a similar destiny awaits the remaining white dwarfs