The Cosmos Explained

Charting the time when space was created

Charles Liu

• Editorial: Ivy Press
• Año: 2022
• ISBN:
  9780711252752
• Categoría: Sciences physiques
• Categoría: Astronomie et astrophysique

The Cosmos Explained is an exciting and beautifully designed book that charts the life of our universe from the Big Bang to the present day and beyond. Starting with the moment of the Big Bang—at exactly one ten-millionth of a trillionth of a trillionth of a trillionth of a second—this book charts a history of space and time all the way through the evolution of our solar system, the birth of stars and the formation of life on Earth, to the future of our galaxy and beyond. With deeply insightful and fascinating text by Hayden Planetarium Associate Professor Charles Liu, who also hosts the immensely popular StarTalk podcast, this book is an accessible and enthralling gateway into the mysteries of space, time and the universe. Pinpoint exactly where you are in space and time using the timeline at the bottom of every page, and explore the history of the cosmos and the science behind it through beautiful telescope images and striking illustrations. Packaged in a unique retro design that reflects the 1960s cosmonaut era but still feels modern and relevant today, this title is as rich with information as it is with stunning visualisations of the concepts and bodies detailed within. An ideal gift for anyone interested in space or curious about the cosmos, The Cosmos Explained is a unique and entertaining timeline of life, the universe, and everything!

1

The First Quadrillionth of a Quadrillionth of a Second

The Cosmos is Born

A birth, as a mother will tell you, is momentous, miraculous – and messy.

The first instants of a life are filled with activity that should follow a reasonably predictable order of events, but always winds up wrapped in the utter chaos of unexpected occurrences that seem to arise from nowhere. In the blink of an eye, something that does not have its own existence comes into being – and history will never be the same again.

The birth of time has exactly this character, although it’s wilder by far than our own modest beginnings. At the origin of everything, the life of the universe begins with a dazzling, explosive expansion – the Big Bang. The laws of physics predict that the expansion should continue without interruption, at a smoothly changing rate; but then, an unpredicted infusion of energy, seemingly coming from nowhere, inflates the universe almost beyond recognition. The nascent patterns in the dense energy within space and time freeze into place. The universe eventually settles back into smooth expansion – but not before its size, shape, character and history have been irreversibly transformed as the cosmos comes into existence.

One huge difference, however, contrasts the beginning of a person’s life and the beginning of the cosmos. Time, space, matter, energy and the rules of nature that govern them exist while a human baby is a foetus, or an embryo, or even a blastocyst. There is, on the other hand, no prenatal phase for the universe – there is no ‘before’. So what made time begin to tick? Nothing comes from nothing. Or does it? Could the universe truly have arisen from a void?

Incredibly, we must look beyond time and space for the answer. It boggles the mind to have to get to grips with the idea that the universe arose from an environment where our current laws of physics do not apply – yet it is the best way, and maybe the only way, to make sense of it all. With our limited grasp of what is and can be, we return to our own human birth process for analogies. A pre-person is nurtured in a womb; was there a super-dimensional multiverse that provided the conditions to produce our universe? An event – perhaps a set of events and conditions – causes one special human cell to grow, multiply and ultimately develop into a unique human being. What event or conditions could possibly make a universe?

How fitting that we should begin the timeline of the universe with some of the most challenging mysteries that humanity has ever faced. Undaunted, we do our best to apply the tools and methods of science – the remarkably successful system we have developed over the centuries to seek answers about the natural world – to the very start of cosmic time. So far, we have many more questions than we have answers – exactly what we’d expect at the earliest possible edge of discovery.

The Planck Time

At the moment of the Big Bang, the universe had zero volume and infinite density.

Such an object is called a singularity, and the laws of nature as we understand them don’t work in it. How long was it, then, before the laws of nature did start to work?

We don’t yet know for sure, but we know of an upper limit to that time interval. We are guided by two fundamental scientific theories: quantum theory and the general theory of relativity. Each theory has a length scale, called the Compton wavelength and the Schwarzschild radius respectively, within which certain fundamental measurements are impossible. When those limits match one other in a single object, they are each about 10^–35 metres – 1 hundred-millionth of a trillionth of a quadrillionth of a metre – in size and the time that it would take a beam of light to span that distance is just 10^–43 seconds – 1 ten-millionth of a billionth of a trillionth of a quadrillionth of a second!

That almost unimaginably short duration is called the Planck time, after the German physicist Max Planck. Whatever happened during that earliest moment in time can’t be explained by any of physical rules we currently know. Nevertheless, it set up everything that has happened since then in the history of the cosmos.

The general theory of relativity describes the motion of objects through space and time in the universe. First published by Albert Einstein in 1915, the theory shows how space isn’t just empty nothingness, but rather a flexible medium like a jelly that can bend, dimple or even twist. Things with mass curve space towards them; that curvature is gravity, which changes the motion of objects just as if they’re being pulled by a force. More massive objects (such as stars or planets) curve space more than less massive objects (such as people or pebbles) and thus create more gravity. Perhaps most amazingly, space and time are tied together into a four-dimensional fabric called space-time; thus, time is a dimension, much like length, width and height, just with different properties.

Quantum theory describes the behaviour and interaction of the tiny particles that comprise all of the matter and energy in the universe. Developed during the first decades of the twentieth century, the theory shows how atoms and molecules absorb and release energy only in specified amounts known as quanta, with different substances exhibiting different patterns of quanta depending on their properties and their surroundings. Quantum theory also describes how energy and matter can be both particles and waves – so, for example, a beam of light can be both a stream of energetic particles and an energy-carrying wave at the same time.

BIOGRAPHY

Max Planck (1858–1947) was a German physicist who, in 1900, discovered a solution to a problem about radiation from warm objects that used the concept of light quanta. His work pioneered the field of quantum mechanics. Today, Germany’s leading institution of scientific research is named the Max Planck Society in his honour.

The Big Bang – What Happened

The Planck time has elapsed. The Big Bang begins in earnest now.

The Big Bang isn’t an explosion that occurs in the universe; it is the explosion of the universe. Whatever happened within that tiny window of time between 0 and 10^–43 seconds to cause the liberation of space has done its work – and now the volume of the cosmos is growing, starting at the Planck scale of 10^–35 metres and getting larger with each passing instant. Every bit of space that exists today was once encompassed in that tiny kernel; so today, if someone asks yo...