UNIVERSE

MACROCOSMOS

The origin of the Universe

is unknown -- it is the ultimate mystery of this whole story. The laws of physics which applied in the beginning are not clear, so it is hard to guess where it might have come from. There are several theories of how the Universe began. This web site follows the inflationary theory of creation, which seems the most plausible.
We use the word Macrocosmos to mean "everything there is". We will see that the

Cosmos and the Universe are just small parts of the Macrocosmos. So how could it have begun?
Perhaps it was created out of nothing. To us, used to the idea that energy cannot be created, this seems impo

ssible, but even today we find two kinds of matter (matter and antimatter) being created together out of nothing in quantum fluctuations. What is more, gravitational energy is equal and opposite to the matter energy in

a closed space. This means that starting from nothing gravity and matter might have separated to create the Macrocosmos.
The amounts of energy in the Macrocosmos were small. The inflation theory predicts the Universe began with only 25g of matter! However this matter was crammed into a very very tiny space, creating an ext

remely high energy density

ATOMS

About 300 t

housand years after the Big Bang, the Universe had cooled enough for electrons to be captured by protons and alpha particles to form atoms.

An

electron is pulle

d towards a proton because their opposite electric charges attract each other. They stick together to form a totally new kind of object called an atom of hydrogen. In the same way two electrons were attracted to each alpha particle, which contained two protons, and were held close to it. The atom they made is called a helium atom.

Atoms are fantastic things. Around the outside of the atom the electron forms a large thin shell. Inside the atom is empty space, except for the tiny heavy proton at the center. An atom is like a football.

The electron in an atoms is li

ke the skin of the football. Under this skin the atom is almost empty. At the center is something a football doesn't have. Held at the center by the electric force is the tiny proton. This is called the nucleus of the atom. The young Universe was full of hot atoms, moving around and b

ouncing off each other. They made a gas

Once all the electrons were atoms trapped in atoms, the fog of the Universe cleared.
To get an idea of the size of atoms why not visit Soccearth?

GALAXIES

A galaxy is an island of billions of stars, separated from other galaxies by a vast ocean of almost empt

y space. In this story we look at one particular galaxy (the Milky Way), since that is the one we know best, the one where we live. But we should not forget that, scattered far and wide across the Universe, there are billions of other galaxies, probably very similar to ours.

Galaxies are either spiral (about 70% of galaxies - similar to the Milky Way) or elliptical (about 30%). A few are other shapes. It is not clear how the different shapes arose. Spirals are probably more interesting than ellipticals, since stars are formed continuously in them. It is probably this which has allowed life to form in the spiral galaxy where we live.

STAR
After a while the stars forme

d in an open star cluster drift apart, probably pulled by the attraction of passing stars. Let's focus down on one star and see how it works.

A star (such as the Sun) is a ball of

gas which has, at its heart, a nuclear fusion reactor. It is important to know something about how stars work, for several reasons.

The Sun, is the source of almost all the energy used

by living things, including humans. We could not survive without it. If we could copy the Sun in a small and controlled way, we believe we could obtain a great deal of energy on Earth without creating a lot of pollution.

Stars are the places where large atoms are built. Past generations of stars formed the gas and dust from which the planets and life were made.
So stars play a key part in our sto

ry.

SUPERNOVA

We have seen that a small red giant, up to 1.5 times the size of the Sun, turns into a white dwarf when it dies. Larger red giants, however, die in a m

ore spectacular way.

Once the nuclear fuel is exhausted in a red giant, the core starts to cool and the internal pressure falls, leading to contraction. In large red giants this is a sudden and catastrophic event so that the star collapses. As the outer layers of the star fall they gain heat. This triggers nuclear fusion in these outer layers and they e

xplode in a spectacular explosion called a supernova, becoming for a few days brighter than a whole galaxy.

With so much energy it is possible to fuse iron nuclei into even heavier ones such as uranium nuclei. As the star explodes it throws out the nuclei which it has made. On their way out they pick up electrons and become atoms. Th

e helium, oxygen, carbon, nitrogen, iron, uranium and other heavy atoms made by the star are scattered back to dust in the disc of the galaxy. In this way the atoms made in one generation of stars are passed on to be used by the next.
So all

the atoms in your body (except hydrogen) were made in a supernova 5 billion years or more ago.

What happens next depends on the size of the original star.

MOLECULE

Molecules are of atoms held together with covalent bonds. Molecules play a major part in this story. The first molecules were formed in space. Some atoms which came out of a supernova were too light, and so moved too fast, to glue together with ionic bonds. They t

raveled out of the star until they were cool enough to attach to a dust grain. There these light atoms met and join together with a new type of bond called a covalent bond. Molecules are the building blocks of life, made mostly of the atoms hydroge

n, oxygen, nitrogen and carbon. The shell model of the atom explains what molecules can be formed by which atoms.

In molecular clouds in the Galaxy we can identify many of the molecules which life uses: methane, ammonia, water and formaldehyde have been identified. Amino acids, purines, and pyrimidines a

re possibly out there too, all forming on dust grains and eventually getting frozen into comets. This means that the raw materials of life are common in the Universe. Is life common too?

PLANETS

Planets are lumps of gas and rock held close to a star by the force of gravity.

We live on planet Earth going round star Sun, along with eight other planets. Together these are called the solar system.

Because stars form in dark clouds of dust and molecules in open star clusters, it is difficult to watch them form. So the story of how planets formed which we have just given has not been confirmed by observation.

About 20 planets have been discovered near Sun-like stars, although they are hard to see. Looking for planets near a star is a bit like trying to watch a moth flying around a spotlight which is pointing at you -- you get dazzled by the light. See the article Giant Planets Orbiting Faraway Stars for an explanation of how they are found.

Since discs of gas and dust have been detected around some young stars, we guess that planets might be common. But none of the planets so far discovered are like our Solar System. Indeed these discoveries are challenging current theories of the origin of planets.

EARTH

In this web site we will focus down on one tiny planet: the Earth. Notice from our diagram and model of the solar system how small it is compared to the Sun and the giant planets Jupiter and Saturn. If we

didn't live here we probably wouldn't even notice it! Yet there is a very good reason why we should look at this planet and no other. The Earth is the only planet on which water forms a liquid, which is essential for life. The reason has to do with its distance from the Sun. A planet further from the Sun, like Mars, is so cold that water freezes into ice. Closer to the Sun, like Venus, water boils and all the molecules fly apart. Only on the Earth can

water form that marvelous substance, liquid water. The Earth, like most of the other planets in the Solar System, has an almost perfectly circular orbit. This is unusual. In most of the other planetary systems studied the planets have oval (elliptical) orbits. If the Earth had an oval orbit, travelling sometimes near to the Sun and sometimes far from it, life could not have evolved on the planet. At times the oceans would have boiled and at times they would have frozen, and life as we know it would have been difficult if not impossible.

Because they were made from a spinning disc, all planets spin like tops and they orbit (go round

) the Sun. The Earth spins once a day and orbits once a year. The points which the Earth spins round are called the north and south poles.

LIFE

Life is a chemical system involving two types of molecules, proteins and nucleic acids, working together in a very special way. First we will look at these two types of molecule in turn. Next we will look at how they work together to make life. Then, when we know a little about what life

is, we will think about how this beautiful chemistry might have started.

BACTERIA

The first cells

speared

on Earth about 3.5 billion years ago. These early cells were very similar to the simplest cells we find on Earth today, called bacteria (sometimes called germs). Note that one of these is called a bacterium. Later bacteria evolved many new features. For example bacteria could swim. They used a long twisted whip-like tail called a flagellum

fixed to a wonderful tiny rotating motor. This made the flagellum twist round and so pushed or pulled the bacterium along!

Bacteria have only one cell each. They can be round (coccus), rodlike (bacillus), or curved (vibrio, spirillum, or spirochete). Bacteria live almost everywhere on Earth, including the soil, water, organic matter, and the bodies of multicellular animals (eukaryotes). Some bacteria benefit humans and other plants and animals. Others are harmful; bacteria are the chief cause of infectious diseases in huma

ns.

Bacteria differ from more advanced cells such of those found in animals and plants because they have no membrane around their nucleus nor any organelles. Simple cells like this are called prokaryotes. Bacteria make up the group which biologists call monera.
Archaebacteria are probably living fossils, similar to the earliest bacteria.

CONTINENTAL DRIFT

At some stage in history a process called continental drift began. We do not know when because the rocks have been s

quashed and changed so much since then, but it is important because it is still happening today. Some people think that it is one cause of ice ages.

It is the heat generated by

radioactive decay inside the Earth which drives this process. Today the theory of plate te

ctonics, which includes continental drift, forms a framework for the study of geology and the earth. For the evidence that continental drift is happening, Hot rock rises up from the mantle and spreads out on the surface to form the ocean floor. As the ocean floor spreads it pushes the continents around. They move one or two centimeters each year.
As the continents move around

they sometimes hit each other, creating mountains. This is how the Alps and the Himalayas were created. Mountains like this are on the inside of continents.

INVERTIBRATES

It seems that the evolution of all successful animals began with ancestors similar to modern flatworms. Around 570 million years ago more advanced animals appeared.

Three types of animals were so successful that they are still the commonest animals today. All three types had hard outer coverings on their bodies. We call them

Molluscs
Arthropods
Vertebrates
All animals which do not have backbones (everything except the vertebrates) are called invertebrates.
The molluscs and arthropods belong to a group of animals called the protostomia, while the vertebrates are deuterostomia.

FISH

The animals we lump together as fish actually consist of several very different groups of vertebrates:

Jawless fish
Fish without jaws were the first vertebrates. Just like the molluscs and arthropods, the early fish had a hard outer covering. This armor plating around their front ends was made of bone. Perhaps it was a defense against sea scorpions. They first appeared around 500 million years ago, during the Ordovician period as small fish-like animals called ostracoderms.
They had probably ate by sucking in mud through their mouths. They filtered out particles of food as the water left through their gills. Jaws appeared later, and so did paired fins which were used for swimming. Some had two fins, some four or more. Many of them had flattened bodies, and were probably not very agile.
Early fish contained a swim bladder -- a bag of air to help them float. The strong bone casing around the head allowed the brain, eyes and other senses to develop.
Some jawless fish still survive today. They are the lampreys and hagfish.

Bony fish
Sharks, skates and rays evolved from jawless fish about 390 million years ago. Although their ancestors had bone, the shark group at some stage lost the ability to make bone, and their skeletons are made of cartilage. Cartilage is what we call "gristle" and in humans it makes the ears, nose and much of the skeletons of babies.
Sharks have no swim bladder and must swim perpetually to keep from sinking to the bottom.

sharks
Sharks, skates and rays evolved from jawless fish about 390 million years ago. Although their ancestors had bone, the shark group at some stage lost the ability to make bone, and their skeletons are made of cartilage. Cartilage is what we call "gristle" and in humans it makes the ears, nose and much of the skeletons of babies.
Sharks have no swim bladder and must swim perpetually to keep from sinking to the bottom.



ray finned fish
These are the animals we normally think of as fish. They evolved about 390 million years ago. Unlike the lobe finned fish, their fins are adapted for swimming, not crawling.

Lobe finned fish

Lobe finned fish evolved from jawless fish about 390 million years ago. They lived in fresh waters subject to seasonal droughts. Their swim bladder evolved into a sac able to breathe air, similar to the lungfish of today. They had fleshy bases to their fins which were strong and flexible, letting them leave drying pools to find those ponds with water. They evolved into the amphibians. Most are now extinct, except for coelacanths and the lungfishes. They were the ancestors of the amphibians and all higher types of vertebrates, including man.
Contrast this with the other main group of fish, the ray finned fish.
The first fish appeared about 500 million years ago.

AMPHIBIAN

Once the plants and arthropods were living on land there was plenty of food for any vertebrate which could manage to come out of the water. Some fish lived in ponds which dried up in summer. Their swim bladders evolved into lungs which they used to breathe air. They used their fins to crawl from one pond to another and these evolved into legs, two at the front and two at the back.
The vertebrates which emerged from the water and became land animals around 350 million years ago we call amphibians "am-fib-ee-ans". Their name means "both lives" because they lived both in water and on land at different times in their lives. Leaving the water was one of the greatest steps ever taken by our ancestors. It needed changes in every part of the body. The most obvious changes were the appearance of legs and the ability to breathe. Other changes were not so obvious but were just as important. For example the way the blood flowed round the body had to change.
Amphibians were still not totally free from the water. They needed to return to it to reproduce (like the ferns and the arthropods before them). Their eggs were laid and fertilized in water and the young developed in the water just like their fish ancestors. But when amphibians grew up they left the water to live on the land. Most frogs and newts are still at this stage of evolution.

PLANTS

By 350 million years ago ferns the size of trees were common. They had solved most of the problems of living on land but were still tied to moist ground for their reproduction. Many ferns grew in swamps. They grew from a small underground growth called a prothallus. The sperm swam from one prothallus to fertilize the egg on another. Without water or wet ground they could not reproduce.
When they died some ferns fell into the swamp. Decomposition could not happen because there was no oxygen in this water so the plants were buried and eventually turned into the stone we call coal.
The ferns we see today are still among the most primitive of plants. Their fronds uncurl and carry spores on their undersides.
REPTILES

Soon a group of vertebrates called reptiles solved the problem of how to reproduce without water, and they did it in exactly the same way, as the insects. Fertilization occurred before the eggs were laid, by the male injecting sperm into the female's body.
She used it to fertilize her eggs which she then covered with a tough water-proof skin and laid on land. No surface water was needed for reproduction.
Reptiles had scaly skin. They probably could not keep themselves warm when the weather was cold or at night-time, and may have become slow and sleepy at these times, although there is some debate about this.

FRUITING PLANTS
Plant seeds could not grow or spread very quickly. They needed the wind to carry the pollen to the egg. Also it took over a year for the plant to store enough food in the seed to make sure the baby plant could grow.
About 200 million years ago a new kind of plant evolved. It attracted insects using colored flowers, and gave them sugary nectar to eat. Bees, butterflies and other animals evolved to eat the nectar offered by the flowers. While eating they picked up pollen on their bodies which they carried to other flowers.
The pollen itself was different. It carried two sperm. One fertilized the egg. The second fertilized the flower which then grew rapidly into a fruit. The seed used this for food. These flowering plants could grow and make fruits in just a few weeks, so they spread much faster than the seed plants. Fruits, berries and nuts appeared, so there was lots of new food for animals. New animals evolved to eat the fruit. The land became filled with the color and scent of many beautiful blooms. The hardwood trees and other plants of the tropical rain forest, now being so rapidly destroyed by people, are of this kind.

MAMMALS
Improvements in reproduction were happening in the vertebrate world too. Instead of laying their eggs, female mammals kept them inside their bodies while they developed. In this way they protected their young, feeding them and giving them oxygen. The young could develop larger brains and more advanced bodies than any reptile.
After birth the young were looked after by their mothers, who fed them a rich food called milk. Mammals were the only animals able to make this wonderful food. Then began a long period of care and training when the young learnt from their parents. Unlike dinosaurs, who probably needed the Sun's heat to keep them warm, the mammals had fur to keep them warm. They also had a better blood system.

Mammals were also far more intelligent than dinosaurs. Even the stupidest mammal is a genius compared to the brightest reptile. Their long development, when they are cared for by their mother, is what lets mammals' brains grow so much more than reptiles'. Mammals first appeared about 200 million years ago. It is strange that while the mammals had better bodies and brains than the dinosaurs, even so for a long time they were unable to spread. This was probably because most life-styles were already taken by the less advanced but more common dinosaurs. Mammals stayed as small shrew-like insect-eating animals, perhaps only coming out at night.

PEOPLES

Some people find it hard to accept that humans have evolved from animals. Yet there are many facts leading to that idea. Human cells are eukaryotic, the same as animal cells. Our chromosomes and genes are almost identical to some of the apes. So are our tissues and organs. Fossil bones have been found, showing how people evolved. The main difference between people and other animals is their ability to think, which comes from the large size of their brain, and their use of language.
Modern people (Homo Sapiens) seem to have evolved in Africa about 100 thousand years ago (although the date is far from clear) and lived there while the Neanderthals were spreading around the world. An interglacial (warm period) began 35 thousand years ago. Then modern people came out of Africa and spread. Within a few thousand years they replaced the Neanderthals in Europe and Asia. Then about 25 thousand years ago the weather turned cold again and a glacial began. During the glacial, people improved the tools used by Neanderthals, developing specialized tools for different jobs. But the thing which really set them apart from Neanderthals was their use of art and decoration. Cave paintings, beads, clay statuettes, carvings on the handles of tools, all show a more developed sense of art than Neanderthals ever did.
Many animals were hunted to extinction and people spread around the world. The weather turned warm 11 thousand years ago and the present interglacial began. Many of the glaciers melted, it rained heavily, and the oceans rose 100 meters. New animals and plants replaced the old. People took up two different ways of life: Nomads and farmers.

In future

Energy

There is no shortage of energy if we can learn how to use it. The Sun gives us a thousand times more energy than people use. Controlled nuclear fusion offers the promise of large amounts of energy with little pollution. As the oil runs out more resources will be spent until a suitable source of energy of found.
Humanity

I believe this story shows several trends for life. The most obvious is that life evolves. When you consider how long life has been on Earth, how many different forms it has been through, and how recently people have appeared, it seems inevitable that people will evolve into other forms of life, however much they may struggle to stay as they are now.
One major force driving evolution has been changes in methods of reproduction. We have seen how the appearance of methods of reproducing without the need for surface water, for example, led both plants and animals into new environments. The domination of mammals today is due to their improved reproduction over reptiles. With test-tube babies and genetic engineering we will probably see a new wave of evolution. Genetic engineers will be able to control the evolution of people and of other forms of life For the first time in world history, life will be able to control its own evolution.
Another trend we have seen is for cells in plants and animals to live and work more closely together and to become more specialized. Democracy, capitalism and industrialization seem to me to be part of that trend, and (I hope) world government will be another.
Just as dinosaurs were replaced by the more efficient mammals, so it seems likely that organic life will be replaced by more efficient computers, especially in the biologically unwelcoming environment of space.


claimate
Once the oil and coal run out the greenhouse gases will reduce. Then the climate will probably get colder and head towards the next glacial period as it has been tending to do for the past 5000 years. The next glacial will probably start within a few thousand years. This will be an even greater challenge to the world than global warming.

Computer
Computers and telecommunications are already giving us access to large amounts of information This is increasing our brain power, just as steam engines increased our muscle power. As computers become more powerful they will grow more intelligent There seems no reason why machines should not become more intelligent than people in the future. Computers will start to design and build other computers. They will then be able to evolve, just as life evolves. There will then be two forms of "life". Many thousands of years in the future there might be competition for power between computers and life. Which will win?
Well, computers certainly have many advantages over life. They can
process large amounts of information quickly
be switched off for years, then start to work perfectly when they are switched back on (very handy for travelling over stellar distances)
be made very small, and control tiny machines
work together in networks to solve big problems
Furthermore
Electronics is much simpler than life's chemistry and does not need liquid water.
Unlike animals, which rely on plants to turn sunlight into chemical energy, semiconductors (the material that computers are made from) can turn sunlight directly into electricity.
When you compare computers to people the advantages are even more obvious.
Computers do not have the instincts to fight which people seem to have.
It takes only a few seconds to load a program into a computer but years to educate a human.
When computers get out of date their information can be passed to new computers, but when people get old and die all their knowledge is lost.
For all these reasons I believe computers will be more successful and important than life many thousands of years in the future. I expect computers, not people, to colonize the other planets and explore the Galaxy. Life will be left behind on Earth, as a treasured relic of where computers came from. However it is possible that computers and life might merge to make a new, even more powerful form of intelligent being.