Charles Liu - 30-Second Universe

50 most significant ideas, theories and events that sum up everything

Charles Liu

Karen Masters

Sevil Salur

Illustrations

Steve Rawlings

Charles Liu

Universe. Most of us connect that word with the heavens above the planets, stars, nebulae and galaxies that we gaze upon with wonder in the darkness of the night. We are absolutely justified in doing so, for the story of humanity is inextricably linked with our collective realization, gradually over the millennia, that our species occupies only a tiny volume within a vast and possibly limitless expanse of space that extends far beyond our worlds firm earth and flowing water.

Awesome and amazing as all that out there may be, however, that vision of the cosmos is incomplete. The universe comprises all of space, time, matter and energy in existence. It includes everything that has emerged from the interaction of all its constituents including all that is physical, chemical, biological, psychological, intellectual and societal. The universe would not be whole without every particle, every wave, every creature and every idea that has ever appeared or ever will appear, whether it has vanished or persisted, whether we perceive it or not, and whether it affects us or not.

Only by contemplating all of this staggering content and complexity can we even begin to grasp the enormity that is the universe. And through that contemplation, we realize that the greatest, deepest and profoundest questions we ask are reserved for the universe itself. How did it all begin? How has everything become what it is today? What is out there, beyond our ken, and how much? What are the smallest and most basic building blocks of everything? Will the universe go on forever? What exists beyond the limits of infinity? And, perhaps most self-servingly and most frustratingly, why are we here?

Piece by painstaking piece, over hundreds of generations we humans have been trying to put together the vast and nearly unknowable cosmic puzzle and, remarkably, we have been making real progress. As Albert Einstein famously observed, The most incomprehensible thing about the Universe is that it is at all comprehensible. Today, we know how long ago our universe started to exist 13.8 billion years ago, when time began. We know what the universe was like at that time, and how it reflects the microscopic underpinnings of all matter and energy today. We know how planets spin, how stars shine, and how galaxies can crash and combine even as space itself expands ever faster, spreading matter ever more thinly throughout the cosmos.

Our insights about the universe have often been gained with amazing machines built for discovery: the Hubble Space Telescope for finding dark matter and dark energy; the Large Hadron Collider for revealing the Higgs particle and quark-gluon plasma; and LIGO for detecting the gravitational waves released by colliding black holes rippling through the fabric of space-time. Building on these and other scientific results, we have furthered theories that, despite their solid scientific foundation, sometimes feel almost unrealistically fantastical: the Big Bang, cosmic inflation, string theory, supersymmetry and even a multiverse where our universe is just one among possibly infinitely many others.

Alas, deciphering the cosmos can be an achingly slow process and humanity is not a particularly patient lot. So even when the data have not been available, we have, throughout history, reached beyond the tangible with our minds alone. This, too, is part of the universe the realm of metaphysics, where we wonder what lies beyond even the most distant cosmic horizons. What, if anything, supersedes all there is? Does thought, consciousness or even existence have any larger meaning? Can we really know everything or, for that matter, anything at all?

This book sets forth a seven-step path along humanitys quest of cosmic enquiry. Beginning with the Origins of the Universe, we travel from the very first moment of existence to the time when stars and galaxies illuminate the vastness of space. We next examine the properties of our curving, ageing and expanding Observable Universe, then peer into the Quantum Universe of submicroscopic particles and strangely predictable uncertainty that govern the cosmos at its most fundamental levels. We zoom out again to view the stars, galaxies and other cosmic objects that populate the Physical Universe; and mindful of that grand perspective, we contemplate what may extend beyond it all, into the Metaphysical Universe. We face the Fate of the Universe as our lives, our world and all the nestled pieces of the cosmos refuse to go gently into that good night; and, finally, we look beyond all there is to the Multiverse that just might be and perhaps glimpse the edges of an unbounded reality where there will never be the dying of the light.

angular size A term that refers to how large an object appears to be in your field of view. The closer an object the larger it appears to be: if a coin a metre from your eye has an angular size of about 1 degree; at 0.5 metre it is 2 degrees; at 2.5 centimetres away, it is about 40 degrees.

black body In physics, an object that is emitting light because it is glowing hot. Black bodies emit a characteristic spectrum of light with the peak moving to shorter wavelengths as they get hotter. Most people are familiar with the idea of lumps of metal glowing red hot or white hot: this glow is the black body radiation from the heated metal, and the white (or blue) light has shorter wavelength than the red.

cosmic horizon The distance from which light has had time to travel to us since the beginning of the universe. Any part of the universe more distant is not possible for us to have observational knowledge of.

cosmological constant See dark energy.

cosmic rays High-energy particles moving through the solar system that hit Earths upper atmosphere and produce showers of other particles, which can be detected.

dark energy A mysterious energy source in the universe, with negative pressure, that can speed up cosmic expansion. No one knows what it is but all constraints suggest it is constant with time and space (the cosmological constant).

fusion/fission The processes by which atomic nuclei either join together (fusion) or break apart (fission), regulated by the strong force. Atomic nuclei up to about the mass of iron release energy by fusion. Those more massive than iron release energy by fission.