If the observable Universe is our world, the Local Group of galaxies our neighborhood, the Virgo Supercluster our city, and the Milky Way our house, the Pisces Cetus Supercluster Complex is our country. The PCSC is a “galaxy filament” — a cluster of galaxy superclusters — and the largest known structure in the Universe. The PCSC, our home filament, is one billion light years across, and it’s thought to contain mass equivalent to 10^18 Suns. Our “city”, the Virgo Supercluster, only comprises 0.1% of the PCSC’s total mass.
The Solar system. Our home in space. We live in a peaceful part of the Milky Way. Our home is the Solar system, a 4.5-billion-year-old formation that races around the galactic centre at 200,000 km/h and circles it once every 250 million years. Our star, the Sun, is at the centre of the Solar system. It’s orbited by eight planets, trillions of asteroids and comets and a few dwarf planets. The eight planets divided into four planets like ours: Mercury, Venus, Earth and Mars, and four gas giants: Jupiter, Saturn, Uranus and Neptune. Mercury is the smallest and lightest of all the planets. A Mercury year is shorter than the Mercury day, which leads to enormous fluctuations in temperature. Mercury does not have an atmosphere or a moon. Venus is one of the brightest objects in the Solar system and by far the hottest planet, with atmospheric pressure that is 92 times higher than on Earth. An out-of-control greenhouse effect means that Venus never cools below 437 °C. Venus also doesn’t have a moon. Earth is our home and the only planet with temperatures that are moderate enough to allow for a surplus of liquid water. Furthermore, it’s so far the only place where life is known to exist. The Earth has one moon. Mars is the second smallest planet in the Solar system and hardly massive enough to keep a very thin atmosphere. Its Olympus Mons is the largest mountain in the Solar system, more than three times as high as Mount Everest. Mars has two small moons. Jupiter is the largest and most massive planet in the Solar system. It consists largely of hydrogen and helium and is the theatre for the largest and most powerful storms we know. Its largest storm, the Great Red Spot, is three times as large as Earth. Jupiter has sixty-seven moons. Saturn is the second largest planet and possesses the smallest density of all the planets. If you had a sufficiently large bathtub, Saturn would swim in it. Saturn is also known for its extended, very visible ring system. It has sixty-two moons. Uranus is the third largest planet and one of the coldest. Of all the gas giants, it’s also the smallest. The special thing about Uranus is that its axis of rotation is tilted sideways in contrast to the seven other planets. It has twenty-seven moons. Neptune is the last planet in the Solar system and is similar to Uranus. It’s so far removed from the Sun that a Neptune year is 164 Earth years long. The highest wind speed ever measured was in a storm on Neptune, at just under 2,100 km/h. Neptune has fourteen moons. If we compare the sizes of the planets, the differences between them become even clearer. Jupiter is the leader in terms of size and weight; small Mercury, on the other hand, is even smaller than one of Jupiter’s moons, Ganymede. Jupiter is so massive that alone it contains roughly 70% of the mass of all the other planets and has a massive impact on its surroundings. That’s a blessing for Earth, since Jupiter draws most of the dangerously large asteroids that could wipe out life on Earth. But even Jupiter is a dwarf in comparison to our star, the Sun. Calling it massive does not do justice to the Sun. It makes up 99.86% of the mass in our Solar system. For the most part, it consists of hydrogen and helium. Only less than 2% is made up of heavy elements, like oxygen or iron. At its core, the Sun fuses 620 million tons of hydrogen each second and generates enough energy to satisfy mankind’s needs for years. But not only the eight planets orbit our Sun. Trillions of asteroids and comets also circle it. Most of them are concentrated into two belts: the asteroid belt between Mars and Jupiter and the Kuiper belt at the edge of the Solar system. These belts are home to countless objects, some as large as a dust particle, others the size of dwarf planets. The most well-known object in the asteroid belt is Ceres; the most well-known objects in the Kuiper belt are Pluto, Makemake and Haumea. Usually we describe the asteroid belt as a dense collection of bodies that constantly collide. But in fact, the asteroids are distributed across an area that is so indescribably large that it’s even difficult to see two asteroids at once. Despite the billions of objects in them, the asteroid belts are fairly empty places. And nonetheless, there are collisions over and over again. The mass of both belts is also unimpressive: the asteroid belt has a little less than 4% of our Moon’s mass, and the Kuiper belt is only between 1/25 and 1/10 of Earth’s mass. One day, the Solar system will cease to exist. The Sun will die, and Mercury, Venus and maybe Earth too will be destroyed. In 500 million years it will become hotter and hotter until at some point it will melt Earth’s crust. Then the Sun will grow and grow and either swallow Earth or at least turn it into a sea of lava. When it has burnt up all its fuel and lost most of its mass, it will shrink to a white dwarf and burn gently for a few billion more years before it goes out entirely. Then, at the latest, life in the Solar system will no longer be possible. The Milky Way will not even notice it. A small part of it in one of its arms will become just a tiny bit darker. And mankind will cease to exist or leave the Solar system in search of a new home.
A “cold spot” in the direction of the constellation Eridanus has led to speculation that it may be a space void one billion light years across – so vast it would be 1,000 times larger in volume than the Great Nothing. The loneliest place in the Universe.
A “Great Wall” is a type of galaxy filament – a cluster of galaxy superclusters – in the rough shape of a wall. The Sloan Great Wall, about a billion light years from us, is one of the biggest filaments we’ve discovered, with a length of 1.37 billion light years. That’s the equivalent of about 7,000 Milky Ways lined up next to each other.
Every single object you see around you is made up of various atoms – tiny grains of matter. The human body, for instance, is composed predominantly from oxygen, carbon, hydrogen and nitrogen atoms. However, all atoms consist of even smaller grains – protons, neutrons and electrons. The number of protons inside an atom determines what kind of atom (or chemical element) we are dealing with. If you see an atom with only one proton in its core, it is surely hydrogen. If you encounter an atom with two protons, you are without any doubt dealing with a helium atom. Six protons? Carbon. Eight? Oxygen. We could go like this all the way to the number 92 – the number of protons in uranium, which is the heaviest natural element of the universe.
Your own atoms make up almost your entire mass. Every time you step on a scale, you measure the collective mass of all tangible subatomic particles that inhabit your body. But there is one important question – where do all of these particles come from?
To comprehend the sudden appearance of matter in the early cosmos, we first need to focus on the most famous physical equation on the planet, whose author is a world-renowned physicist Albert Einstein. E = mc2. Energy is equal to mass times the speed of light squared. Nice, you might say, but what exactly does it mean? Simply said, this brief equation daringly states that energy and mass are nearly the same thing. The only “converter” between the two quantities is the speed of light squared.
Take any object and multiply its mass by approximately 90 million billion – the value of the speed of light in meters per second squared. If you do that, you discover the immense amount of energy hidden inside the object. And you can do it in reverse too – if you take an arbitrary amount of energy and divide it by 90 million billion, you get its mass.
Exactly. Every form of energy weights something. A hot cup of tea is heavier than a cold one, as it contains more heat energy. However, you do not need to experiment and try to verify this fact by carefully weighing various tea cups at different temperatures – that is unless you live in a distant future where humanity is so technologically advanced that it can manufacture a hugely impressive scale which is able to detect differences of about a millionth of a millionth of a gram. Heat energy is far less concentrated than the energy we can find in matter. You would need to heat your cup to millions of degrees for a perceptible difference to appear.
The previous paragraphs could be summarised into one sentence – energy and matter are very closely related. So related, in fact, that you can create one out of the other. How? Well, if we consider the fact that each tiny bit of matter contains an enormous amount of concentrated energy, it would be logical to focus an unimaginable volume of energy to a single spot and hope that all of this energy would somehow “unite” and create a tangible particle. However, it is incredibly difficult to achieve that in today’s universe.
But if we consider how much condensed energy the early universe contained during the cosmic inflation (its temperature reached impressive billion billion degrees Celsius), we get stunning conditions for the creation of matter. The energy of the early cosmos was simply so concentrated that tangible particles started spontaneously forming.
The formation of matter definitely did not take long though – all of it was created during the unbelievably quick cosmic inflation. At its end, the universe contained nearly all the matter you can see around you. Every single one of billions of stars and galaxies consists of the same matter that was created just a fraction of a second after the Big Bing, when the universe was about the size of a grape.
Back then, however, matter was far from forming atoms. For those, we have to wait several hundred thousand years. At that time, all matter was represented by the simplest of particles called quarks and leptons.
But there is a catch – the formation of matter is not that simple. There is a rule that with each particle of matter, its counterpart in the form of antimatter has to be created. Antimatter is just like normal matter, except that some of its properties are opposite – electric charge, colour or flavour. (The last two properties have obviously nothing to do with “our classical” flavour and colour – elementary particles cannot actually have any colour, since they are much smaller than the wavelength of visible light, not to mention flavour. They are just names physicists have given to various types of charges.)
But what is more interesting – matter and antimatter cannot stand each other. If they come into contact, both of them are destroyed in a violent explosion (this process is called annihilation) and all of their energy is transformed into photons – the particles of light.
Let us go back to the creation of matter in the early cosmos. It follows from the previous paragraphs that all the matter which was produced just a moment after the Big Bang had to be accompanied by the same amount of antimatter – each tangible particle was created along with its antiparticle. And since the universe was so incredibly small back then, the contact of particles and antiparticles was simply inevitable. Most of the newly created tangible particles crashed into an antiparticle and perished just a moment after their birth.
But there is one significant question. Why is there still matter in the universe today? By the laws of physics, the exact same amount of matter and antimatter should have been created. Theoretically, it follows that mutual destruction of all matter and antimatter should have occurred in the young universe. But that did not happen – otherwise we would not be here.
Nobody knows why, but it seems that for every several million antiparticles, one extra particle was created. Each of these surplus particles avoided annihilation and formed all matter we can see in today’s universe. It is staggering when we realize that the early universe not only contained nearly all matter it does today, it contained much more of it. And all of that was squeezed into a volume that would fit into a human palm.
However, the energy released in matter-antimatter collisions did not disappear. It was transformed into photons of high-frequency radiation. These photons then kept on roaming the newly created universe, which was packed with charged tangible particles. These particles prevented the photons from moving freely. It took 380 000 years before the universe became transparent due to the formation of atoms and photons were finally able to travel unimpeded. Many of these photons keep on cruising the universe to this very day and constitute the cosmic microwave background – living evidence of the Big Bang.
At the very beginning, there was a peculiar object called the singularity, floating in nothingness. How did it get there? That is a mystery. However, before we start exploring this immensely interesting object, we should focus on a different, seemingly trivial expression – nothingness.
Some might think that all the “empty” space around us could be considered nothingness. But that can hardly be the case, given that each centimetre of air contains billions of atoms.
Others might argue that the vacuum of space could be classified as nothingness. After all, vacuum is empty by definition – it contains no matter whatsoever. But there is a catch – vacuum is inside the universe just like everything else around us. And the universe is interwoven with space-time filaments. But space-time certainly is something. It is a specific area where all the laws of our universe are in effect.
For this reason alone, one cannot consider vacuum as complete nothingness, not to mention the immense amount of particles that are being created each second in every single tiny bit of vacuum as a result of quantum mechanics.
But the nothingness around our initial singularity was special and unique – time and space were non-existent and the laws of physics powerless. We would never be able to find such nothingness in our cosmos.
Back to our singularity. It would be fitting to say that it was an exceptionally peculiar object. We do not get to see such objects every day – never, in fact (unless we find ourselves in the centre of a black hole, which would probably not be an unduly pleasant experience – we are going to look into that in one of the following chapters).
Why was the initial singularity so peculiar? First of all, it may have been infinitely small, which is more than remarkable. On top of that, it was infinitely dense and infinitely hot, which makes good sense given that the entire universe had to fit into its heart. Exactly – everything you see around you has once been squeezed into this ancient singularity, though in a somewhat different form.
Suddenly, something incredible happened. Something that may be considered the strangest and most mysterious event of all time. The singularity started rapidly expanding and created the entire unbelievably huge universe. This incident is known under the majestic name of the Big Bang. However, it is rather ironic that we are using this name. First of all, this expression was coined by a man named Fred Hoyle, who was a tremendous opponent of the Big Bang theory (he favoured the competing Steady State theory). He only used this expression to mock the theory. In addition, the term “Big Bang” is incredibly inaccurate – it is far from representing the event that actually occurred.
Let us focus on the word Bang first. This word seems to represent a grand explosion accompanied by stunning sound effects. Much to the dismay of action movie fans, the actual “Big Bang” could be considered the exact opposite of such an explosion. There is no sound in vacuum, so let us forget about amazing sound effects. But more importantly, the Big Bang was not an explosion at all – it was more like an inflation of space (incredibly fast inflation indeed).
A great parallel is the inflation of a balloon. Imagine that our universe is represented by the surface of a balloon. If we inflate it, the distance between any two points on its surface increases. This is what the Big Bang and the following expansion of space looked like – it started off as an infinitely small point in the form of a singularity, and ended up as the surface of a gigantic “space balloon”. (Except that the surface of a balloon is a two-dimensional space curved in a third dimension, while our own universe is most likely a three-dimensional space curved in a fourth dimension. However, our primitive three-dimensional brains are not capable of imagining fourth-dimensional space – that is why we are using a simple balloon analogy.)
Now that we grasp the issues with the word Bang, let us focus our attention on the word Big. While the word Bang is utterly inaccurate, the word Big is correct. However, it is a tremendous understatement. The Big Bang was not only big, it was everywhere – every single tiny bit of space used to be condensed in an infinitely small singularity and underwent a whopping expansion. To augment our balloon metaphor, imagine that you are a two-dimensional ant inhabiting the surface of the expanding balloon. For such an ant, the surface of the balloon is the only thing in existence – the ant cannot escape it on its own. From its point of view, everything is inflating. For the sake of accuracy, it would be appropriate to replace the word Big with the word Huge – or even better, Omnipresent.
However, if we put these two accurate expressions together, we get something like the Omnipresent Inflation, which, let us admit, does not sound nearly as good as the Big Bang. We will therefore stick with the usual term, now with the knowledge of its imperfections.
One of the greatest questions is when exactly the Big Bang occurred. This immensely interesting question has been subject to discussion for decades. Today, it is assumed that the singularity started expanding astounding 13.8 billion years ago. You do not even have to try to understand how long ago it was – for the human brain, it is practically impossible. But we can at least try to present this information in a different way – imagine that you put marbles one centimetre (0.4 inches) in diameter next to each other into a single row. If each marble represented one year of the universe’s existence, your row of marbles would go around the entire Earth. Three times. And if you by any chance wanted to live through the whole age of the universe, you would have to live incredible 200 million average human lives. For comparison, the Earth is about 4.6 billion years old – about 67 million lives.
Let us come back to the very beginning now. No one really knows why the Big Bang occurred, but we do know quite well how exactly this process took place. 13.8 billion years ago, the singularity, containing the entire energy of the cosmos, started rapidly expanding. This moment is considered to be the beginning of space-time as well as the universe itself.
But what happened before the Big Bang? This seemingly interesting question is actually pointless. Time is inherently woven into the structure of our universe. Before the Big Bang, it simply did not exist. Asking this question is like wondering about what is located north of the North Pole.
As you have surely already understood, most things about the singularity are extreme and unimaginable. And the super-rapid expansion of the early cosmos right after the Big Bang is surely no exception. Trying to imagine any of the numbers bellow is simply impossible.
About a billionth of a billionth of a billionth of a second after the Big Bang, the universe entered a monumental state known as the cosmic inflation. It should be noted that the temperature of the cosmos at that time was respectable 100 million million million million degrees Celsius! During the cosmic inflation, the universe increased its size in an unimaginable manner. From the initial size of less than a billionth the size of a proton, it inflated to a comparatively huge sphere 1 centimetre (0.4 inches) in diameter. But even more remarkable is the fact that it has managed to alter its size like this in a mere fraction of a second – the cosmic inflation started about 10-37 seconds after the Big Bang and ended somewhere between 10-35 seconds a 10-32 seconds after the birth of the cosmos.
And in a blink of an eye, the cosmic inflation was gone forever. Space-time continued on its expanding journey (in fact, it continues expanding to this day), but much more slowly. At the end of the inflation, the temperature of the universe was about a 100 thousand times smaller than at its beginning. It is mesmerizing that in a moment much shorter than anyone can even imagine, the universe changed so dramatically. But what is most important – once the cosmic inflation was over, the cosmos already contained a crucial component which makes our very existence possible – matter.
A parsec is a length unit used to measure the huge distances of astronomical objects outside the Solar System. A billion parsecs, or about 3.3 billion light years, are called a gigaparsec. Until we discover a multiverse, this is the largest unit of length measurement we’ll ever need. A gigaparsec makes the observable Universe seem quaint, as it stretches only about 28 gigaparsecs across, or about 14,000 cubic gigaparsecs in volume.
Galaxy filaments are clusters of galaxy superclusters, which makes them the largest known structures in the Universe. The appropriately—named Hercules Corona Borealis Great Wall is the largest known galaxy filament — making it the largest known structure in existence.
Galaxy filaments are kind of like the Universe’s countries. If our home country, the Pisces Cetus Supercluster Complex, is the size of Germany, the Hercules Corona Borealis Great Wall is around the size of Russia. An outrageous 10 billion light years across, the HCB Great Wall stretches over a tenth of the way across the observable Universe!
What is evolution? Evolution is the development of life on Earth. This is a process that began billions of years ago and is still continuing to this day. Evolution tells us how it was possible for the enormous diversity of life to develop. It shows us how primitive Protozoa could become the millions of different species that we see today. Evolution, then, is the answer to the question that we have all asked on seeing a Daschund and a Great Dane together: how is it possible for ancestors to have descendants that look so very different to them? In answering this question, we want to focus on animals, excluding other forms of life such as fungi and plants. The first question to ask is therefore: how can one animal develop into a whole new species of animal? Ah, but just a quick question: what exactly is a species? A species is a community of animals that is capable of producing offspring with one another, with those offspring also being capable of reproducing in turn. To understand this answer better, we need to take a closer look at the following points: the uniqueness of living creatures, guaranteed through the excess production of offspring and heredity, and as a second key point, selection. Let’s begin with uniqueness. Every creature that exists is unique, and this is essential for evolution. The members of a species may strongly resemble each other in appearance; however, they all have slightly different traits and characteristics. They may be a bit bigger, fatter, stronger, or bolder than their fellow animals. So, what is the reason for these differences? Let’s take a closer look at a creature. Every creature is made up of cells. These cells have a nucleus. The nucleus contains the chromosomes, and the chromosomes hold the DNA. DNA consists of different genes, and it’s these genes that are life’s information carriers. They contain instructions and orders for the cells, and determine the characteristics and traits that living creatures have, and it’s precisely this DNA that is unique to every creature. It’s slightly different from individual to individual, which is why each has slightly different characteristics. But how is the enormous range of DNA created? One key factor is the excess production of offspring. In nature, we can observe that creatures generally produce far more offspring than is necessary for the survival of their species, with many offspring dying an early death as a result. Often there are even more offspring than the environment in which they live is able to support. This is one factor in increasing diversity within a species. The more offspring that are produced, the more little differences occur, and this is what nature wants: as many little differences as possible. The second major cause of the uniqueness of individuals occurs in heredity itself. By the way, heredity means the passing on of DNA to offspring. Two very interesting factors come into play in this process: recombination and mutation. Recombination is the random mixing of the DNA of two creatures. When two creatures fall in love and mate, they recombine their genes twice. The first time, they do this separately when they generate the gametes – that is, sperm and egg cells. The gametes take half of the genes and shuffle them. The second recombination occurs when a male inseminates a female. The parents each provide 50% of their DNA, in other words, 50% of their unique traits and characteristics. These are then recombined, or mixed, and the result is new offspring. These offspring have a random mix of the DNA, and therefore the traits and characteristics of their parents. This increases the diversity and differences within a species even further, but mutations are also important for evolution. Mutations are random changes in DNA. These can also be described as copying errors within the DNA, triggered by toxins or other chemical substances, or by radiation. A mutation exists when part of the DNA is altered. These changes are often negative, and may result in illnesses such as cancer. However, they may also have neutral or positive effects, such as the blue eye colour in humans, which is one such random mutation. In all cases, a mutation has to affect a gamete, that is a sperm or egg cell, because only the DNA in the gametes is passed on to the offspring. This is also the reason why we protect our sexual organs during x-rays, whilst other parts of the body are not at risk. In summary then, in the heredity process, creatures pass on their characteristics to their offspring in the form of DNA. Recombination and mutation change the DNA so that each child looks different to its siblings, and receives a random mix of the characteristics of its parents. There’s a key word here: random. All of these processes are based on chance. Random recombination and mutations result in individuals with random mixes of traits and characteristics, which in turn mix these randomly, and pass them on. But how can so much be down to chance, when all living creatures are so perfectly adapted to their environment, for example, the stick insect, the hummingbird, and the frogfish? The answer is provided by the second key point: selection. Each individual is subjected to a process of natural selection. As we have learned, each individual is somewhat different to its fellows, and there is extensive variation within a species. Environmental influences have an effect on living creatures. These so-called selection factors include: predators, parasites, animals of the same species, toxins, changes in habitat, or the climate. Selection is a process that each individual is subjected to. Every creature has a unique mix of traits and characteristics. This mix helps them to survive in their environment, or not, as the case may be. Anyone with an unsuitable mix will be selected from the environment. Those with the right mix survive, and can pass on their enhanced traits and characteristics. This is why diversity is so important. This is why creatures make so much effort to produce offspring that are as different as possible. They increase the likelihood that at least one of their offspring passes nature’s selection process. They maximize their chances of survival. A good example of this can be seen in a group of finches living on a remote island. They are some of the most famous animals in the world of science, and are known as Darwin finches, after their discoverer, Charles Darwin, and this is the story of those finches. A few hundred years ago, a small group of finches was blown onto the Galapagos Islands in the middle of the Pacific, probably by a big storm. The finches found themselves in an environment that was completely new to them, a real finch paradise: an abundance of food and no predators. They reproduced rapidly and numerously. The islands were soon heaving with finches. This meant that food supplies became increasingly scarce. The finch paradise was threatened with famine, and finch friends became competitors. This is when selection intervened. Their individuality and small differences, in this case their slightly different beaks, meant that some of the birds were able to avoid competing with their fellow finches. The beaks of some of the finches were more suitable for digging for worms. Other finches were able to use their beaks better for cracking seeds. The finches consequently sort out ecological niches. In these niches, they were safe from excessive competition. They soon began to mate primarily with other finches that used the same niche. Over the course of many generations, these characteristics were enhanced, enabling the finches to exploit their niches successfully. The differences between the worm-diggers and the seed-crackers became so large that they were no longer able to mate with one another. Different species emerged as a result. Today, there are 14 different species of finch living on the Galapagos Islands, all of which are descended from the same group of stranded finches. This is how new species are created by evolution: through the interaction of unique individuals, the excess production of offspring, recombination and mutation in heredity, and finally, through selection. Why is this so important? It tells us where the variety of life comes from, and why living creatures are so perfectly adapted to their habitats. But it also effects us personally. Every person is the result of 3.5 billion years of evolution, and that includes you. Your ancestors fought and adapted in order to survive. This survival was an extremely uncertain thing. If we consider the fact that 99% of all the species that have ever lived are extinct, then you can consider yourself part of a success story. The dinosaurs have disappeared, but you are alive, watching this video, because you’re incredibly special, just like all the other creatures that exist today: irreproducible and unique in the universe.
In 1995, scientists picked out a tiny section of the night sky — the amount that would be covered by a tennis ball 100 m above you — that was unusually devoid of stars. To the naked eye, and even in a normal telescope, this region looked empty and black.
The scientists used the Hubble Telescope to take a 10—day long exposure of the empty region to find out what was out there deep in the blackness. They came back with an astonishing photo of over 10,000 galaxies, each one perhaps containing 100 billion or more stars. All in a pinpoint little square of the night sky.
Scientists used the info from this photo to postulate that the observable Universe contains over 100 billion galaxies. Today, that galaxy estimate has risen by 20 fold to 2 trillion, and it may continue to rise as we learn more. That suggests the total stars in the observable Universe to be somewhere between 10^33 and 10^25, or around 1 septillion stars.
To put that in perspective, people at the University of Hawaii spent an unreasonable amount of time calculating an estimate for the number of grains of sand on every beach in the world — 7.5 x 10^18 or 7.5 quintillion. That means that for every grain of sand on every beach on Earth, there are about 100,000 stars in the observable Universe.
Keishinrei 