Genesis summary

Every society has its own account of how the universe came into existence. Whether it involves titans and Greek gods, Shiva the Destroyer, or the Creator of the Book of Genesis, it seems there’s a natural, human urge to tell stories about how we got here, why the sun shines, and why the night sky looks the way it does.

These accounts are often moving – but we don’t need religious narratives or myths in order to imbue the universe with splendor. The bare facts alone are wonderful enough!

These blinks set out to show that the real, scientific story – a story about a primordial void, about billions of galaxies circling black holes, and about vast, exploding megastars – is every bit as breath-taking as any religious or mythological account.

In these blinks, you’ll learn

• why the total energy of the universe is actually zero;
• what the Higgs boson really is; and
• why our galaxy depends on a huge black hole.

In an instant, the universe has finished its initial phase of inflation – but if we could see this early world, we’d recognize nothing of what surrounds us.

All that exists at this stage is a formless sea of gas, composed of tiny particles, each devoid of mass and moving at the speed of light. In fact, from every angle and at every single point, the universe appears exactly the same.

If things had remained in this state, the universe would have been eternally barren. But just as the inflaton intervened to expand an initial tiny fluctuation, now another particle comes into play, and once again changes everything for good: this time, it’s the Higgs boson.

The key message here is: The Higgs boson gives particles mass and creates variation in an otherwise uniform and indistinct universe.

Many particles that come into contact with the Higgs boson field undergo profound changes: their speed diminishes as they move through it, and they acquire mass.

In fact, some particles end up acquiring so much mass that they become unstable and cannot survive in the universe. Others gain mass but still stay light enough to survive – these particles will play a key role in the development of matter in the universe.

Because different particles acquire different masses when they come into contact with the Higgs field, the uniformity of the early universe is suddenly shattered.

Where everything had once been the same, variety now prevails. As the universe continues to expand and cool down, the environment becomes inhospitable for the Higgs bosons – without the heat they’re used to, they can no longer exist.

At this stage, with their job complete, they disappear for 13.8 billion years.

It won’t be until 2010, after eons, that a Higgs boson will eventually resurface. Then, when a team of scientists at CERN engineer collisions of enormous intensity, the primeval particle will briefly reappear – confirming the existence of what was until then a mere hypothesis.

The Higgs field was important for several reasons. First of all, as we’ve seen, it allowed particles to acquire mass, and varied a universe that until then had been completely uniform.

But that isn’t all that this incredible particle did. It also affected the very forces of the universe, allowing two of them, the weak interaction and electromagnetic force, to separate for good.

The effects of this separation are huge. Subatomic particles, some of the elementary components of the universe, now begin to take more stable forms of organization – forms that are, in turn, the ancestors of the material world around us.

The universe, at this juncture, grows a little more familiar.

The key message here is: Subatomic particles form, and eventually, there is light.

One of the most important developments during this early phase of the universe is the emergence of the first protons – tiny particles that are one of the basic elements of other more complex forms of material.

You can think of protons as some of the basic building blocks of the universe: simple but enduring particles that play a key role in the formation of grand and intricate cosmic constructions.

Electrons also play a vital role in this period. As temperatures drop, these particles become tamed and domesticated: From now on, electrons are destined to orbit protons stably, in a union that allows atoms and molecules to develop.

With electrons kept busy orbiting protons, another important milestone is reached. Until now, photons had been unable to move freely. At every turn, they were absorbed and expelled by great clouds of electrons that stopped their passage and restricted their movement.

Now, with electrons taking on a new role, photons are rid of their interference. Newly liberated, these photons run free – and spread throughout the universe the first light it’s ever contained.

At this stage in the development of our universe, the tempo slows, and things begin to drag. Until now, much had taken place in a kind of headlong rush – but now the development becomes much more gradual: Instead of hundreds of thousands of years, processes are measured in hundreds of millions.

As well as a change of pace, this period also sees the emergence of a new central character: gravity.

Until now, gravity has played a peripheral role in the formation of the universe. But in this new slower phase, this familiar force starts to take center stage.

In order to make itself felt, gravity must act on matter – and so, at this juncture, it acts on gas.

The key message here is: Gravity acts on gas to create the first stars.

Because the universe now contains the building blocks of atoms, matter can begin to take the form of stable elements: hydrogen and helium, at this initial stage.

The initial quantum fluctuations spread matter unequally through the universe, so there exist pockets of greater material density scattered here and there. The force of gravity means that this matter attracts more matter – leading to a slow but steady growth in the density of gas in these particular areas.

The process is slow but, over millions of years, it’s staggeringly consequential. Huge gaseous spheres take shape, with dense, hot, and highly compressed cores.

Eventually, the heat becomes too much, leading to nuclear fusion between hydrogen and its isotopes. The result is unprecedented. There’s a huge profusion of heat, a great fire – and with that, after 200 million years, the first star is born.

These early stars are of such immense proportions that they’re known as megastars – but they’re not simply impressive to look at. The nuclear processes that sustain these stars also function as furnaces, producing the increasingly heavy elements that will form other, subsequent stars – and, eventually, planets.

Hundreds of millions of years have passed since the universe began, and space is now studded with a bright network of stars.

These fiery aggregations of gas have limited lifespans, however, and from time to time they extinguish themselves in great pyrotechnic displays – scattering hydrogen and helium, along with heavier elements, into the space around them.

Once again, this dispersed matter is subject to that slow and familiar force named gravity – so that over time the areas of the greatest density attract more and more material toward themselves. From the scattered material of the universe, a new and more complex entity is about to emerge: a galaxy.

The key message here is: The first galaxies grow out of stars, gas, and dust.

It’s now widely accepted that there’s a supermassive black hole at the center of almost every galaxy; our own, the Milky Way, circles one named Sagittarius A*, a gargantuan object that weighs 4 million times more than the sun.

As these central black holes draw matter toward themselves, momentum keeps a number of stars and agglomerations of matter from being swallowed by the powerful caverns that they’re circling. Instead of disappearing into the dark core, they revolve around that central nucleus in what’s called a rotation disc.

Our Milky Way is a revolving collection of stars, dust, and gas held in place by an enormous halo of invisible dark matter. In comparison to most galaxies, it’s huge, with its vast dimensions gathered into a great spiral structure, like a seashell. All in, it contains approximately 200 billion stars.

Incidentally, 200 billion is also the figure astronomers have arrived at when estimating the number of galaxies in existence. Think about that for a second: There are as many galaxies in the universe as there are stars in our own galaxy.

At this stage, about 4 billion years have passed since the universe began, and space now plays host to many, many galaxies.

Among them is a particularly calm galaxy, whose central black hole has grown docile and dormant. Here, in the Milky Way, something extraordinary is about to occur.

It’s been billions of years since the Milky Way formed. Everything has assumed a relatively stable orbit around the supermassive black hole at the galaxy’s center, and its turbulent initial period has long since ended.

In short, Sagittarius A*, having swallowed some stars, gas, and probably even some other black holes, has now entered a quiet period, no longer threatening the bodies that orbit it.

In these circumstances, in this galactic calm that prevails in the Milky Way, conditions are just right for entities to start organizing themselves in increasingly complex ways.

The key message here is: Our solar system forms during a period of peace in the Milky Way.

In one particular region of our galaxy, frequent explosions have scattered gas and dust into space in vast quantities, forming what are known as molecular clouds. Mostly composed of helium and hydrogen, these nevertheless contain traces of all the elements in the periodic table – from carbon and nitrogen through to oxygen and iron.

Gradually, these molecular clouds begin to cool down, and gravity increasingly slows their expansion, drawing all of the diverse material together into ever-growing lumps of matter.

Eventually, a large proportion of this great molecular cloud collapses into the red-hot, dense star we know as the sun – and the remaining matter moves around it in a circle known as a protoplanetary disc.

As this matter accumulates, it begins to form the planetary bodies we’re familiar with. First come the gas planets, Jupiter, Saturn, Uranus, and Neptune, and then the rocky ones – Mercury, Venus, Earth, and Mars – that form when smaller celestial bodies collide.

One of these planets, the third one from the sun, exerts a gravitational force strong enough to keep a gaseous atmosphere in orbit around itself. As this planet is pummeled by water-rich asteroids and comets over billions of years, more and more of its surface area will be covered by oceans.

The planet in question is, of course, Earth – and deep in its oceans about 3.5 billion years ago, life began to develop.

At the time, the organisms in question were no more than simple single-cell algae. But in the intervening period, life on Earth has developed, growing in complexity over eons – to the extent that one species, humankind, is capable of looking at the world around it, and tracing its origins back 13.8 billion years.