Author Archives: Keishinrei

How Evolution Works

Mechanisms of Evolution

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.

Largest Known Quasar Group

8.99 BILLION LIGHT YEARS

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!

https://play.google.com/store/apps/details?id=org.kurzgesagt.app.Universe

Distance to Hubble Deep Field

13 BILLION LIGHT YEARS

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.

https://play.google.com/store/apps/details?id=org.kurzgesagt.app.Universe

History of Our Cosmos – The Beginning of Everything

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.

https://play.google.com/store/apps/details?id=brychta.stepan.universe

History of Our Cosmos – Introduction

By all accounts, we seem to live in a universe whose arrow of time only goes in one direction – forward. Whether we like it or not, adventurous journeys into ancient history may forever remain a mere figment of human imagination. But what if we had the opportunity to travel back in time? We could live through yesterday or the year 2000. We could participate in the Second World War, spectate the development of first civilisations, or even observe the formation of our own planet. But how far would we be able to go? If our universe were static and eternal, we could travel as long as we would like. But from what we know, we do not live in such a universe. That is to say, on your journey, we would eventually arrive at the very beginning of time.

However, if we want to accept the theory that our universe had a beginning, we should focus on one crucial question – what was the universe formed from? Unfortunately, nobody knows the answer to this question yet, and there is a possibility that it is going to stay this way forever. But there are two options.

The first possible answer is that the universe was simply created out of nothing. It is not a great surprise that this idea, which defies both fundamental laws of physics and common sense, is not very likable. The second and a much more interesting option is that our universe was created because of a certain impulse. What impulse? Today, nobody knows. In the future, we might reach sufficient technological advancement that we will be able to study such an impulse. But right now, we can only argue and devise hypotheses. Perhaps the creation of our cosmos was caused by a collapse of a different (prior) universe, and thus we are just a link in an infinite set of universes, each one being created when the previous one dies. Perhaps the universe was born in a collision of two different universes. Perhaps.

Even though we do not know the answer to this great question, there are certain things we do know about the evolution of the cosmos. Or – to be scientifically accurate – there are some things that we suspect. The essence of science is trying to understand the world around us as well as we can. We may achieve that by constructing hypotheses and authenticating them using the scientific method.

Anybody can devise a hypothesis. We can construct a simple thought experiment as an example – a prehistoric man sees strange dots in the night sky (today known as stars) and draws a conclusion that somebody must have painted them on the firmament – he has just created a hypothesis. To check the hypothesis, the prehistoric man builds a rocket (let us neglect the fact that the technical advancement of prehistoric people, whose apogee is knowing how to make fire, is nowhere near the level necessary to construct something as immensely sophisticated as a rocket) and sends this rocket far away, so that it can meet those mesmerizing dots – he is authenticating his hypothesis using the scientific method. Much to his dismay, the rocket is serenely wandering through space with no firmament in sight. His hypothesis has just been disproved.

However, if a hypothesis does pass all trials we impose on it, it is promoted to a theory. Now, we are finally talking about science, which is – in its purest form – a simple collection of such theories. Whether we are dealing with physics, psychology, biology, chemistry or astronomy, this element is common for all sciences. The entire human knowledge is just a large pile of theories, which are categorized into individual branches of science.

But there is another very important factor at play – some people consider theories an absolute, unshakeable truth. This view is incorrect. Science perceives theories merely as a collection of fragments, each of them trying to describe a tiny piece of reality. Some fragments are very precise, others not so much. If a theory is found insufficiently accurate, scientists are immediately ready to replace it with a different, better one. A good example is the multitude of theories which are trying to describe one of the most common phenomena in the universe – gravity. For many years, the best description of this mysterious entity by far was provided by Newton’s theory of gravity. However, it has been found somewhat inaccurate in some extreme cases. Eventually, it has been overthrown by Einstein’s general theory of relativity.

However, it was not such a long time ago that scientists realised that even general relativity is not perfect – it is not able to describe the gravitational interaction at the submicroscopic level. Unfortunately, no valid alternative has been found yet and general relativity is still awaiting its successor.

This example shows us the cruel truth about science – we can never be sure of anything. Even though we might think that we have revealed some tiny piece of reality, there is always a possibility that we have neglected a certain aspect of the cosmos in one of our theories, and thus something completely unexpected might happen. Who knows? Perhaps there is a space constant – whose existence is hidden from us – which will annihilate all of us. Perhaps the universe will die today.

There is nothing to worry about though. It is pointless to think about such things, since we are again finding ourselves in the treacherous world of hypotheses. Let us go back into the scientific world of theories, which still provides by far the best description of reality – despite its potential drawbacks. Specifically, let us devote our attention to a great theory that provides the best summary of everything we suspect about the creation of the universe itself – the Big Bang theory.

https://play.google.com/store/apps/details?id=brychta.stepan.universe

Observable Universe

93 BILLION LIGHT YEARS

The age of the Universe and the speed of light combine to limit our vision to a 93-billion-light-year spherical bubble of what may be a far greater place. We hope that one day we can learn what else is out there beyond our bubble. Until then, there should be enough going on in the observable Universe to keep us busy: at least 2 trillion galaxies and a septillion stars.

If the observable Universe were a sphere 1 km across, so it would stretch a bit higher than the tallest skyscrapers, our Milky Way would be a tiny disk 2 mm across. On that scale, our Sun is the size of a proton, orbited by a subatomic rocky planet, where the neutrino—size primate reading this is capable of imagining the sheer wonder of it all.

https://play.google.com/store/apps/details?id=org.kurzgesagt.app.Universe