At the beginning of the 20th century, science could explain almost all physical phenomena then known. Isaac Newton’s laws of mechanics described the heavens; the Industrial Revolution both inspired and was driven by thermodynamics; and Maxwell’s theory of electromagnetic waves explained light. The atomic nucleus, relativity and quantum mechanics were not yet in the lexicon, but soon would change everything.

As the 21st century begins, a similar story might be told – of far-reaching theories with tantalising implications, and of ambitious experiments with the potential for discoveries beyond our present imaginings.

Long ago Galileo looked into the heavens and saw their wonder. Modern telescopes explore deeper into space – and back in time, because it takes time for light to get here; look far enough and you are peering towards the start of time. Which inspires the question: could we look into the big bang and witness the act of creation itself?

We cannot do so with ordinary telescopes because the whole Universe then was hotter, and brighter, than the Sun is now: we would be blinded by the light. However, we can recreate those extreme conditions, for brief moments in regions smaller than atoms, and with special detectors learn how things came to be.

Twenty years ago CERN began to show what the Universe was like when a billionth of a second old. Trying to reach time zero is like finding the end of the rainbow, and the Large Hadron Collider (LHC) will take us ten to a hundred times farther than before.

Things evolved very fast back then. Our theories imply that within a billionth of a second the seeds of our Universe had been sown. And by opening a window on the conditions that existed then, the LHC may answer many of the questions about the nature of things that physicists have yet to resolve.

Whereas relativity and quantum mechanics, the pillars of theoretical physics, work in a Universe where mass and gravity can be ignored, they are incompatible in the first moments of time when gravity was overwhelming.

We see hints of a unified theory, but what it is and how the structures that led to the particles and forces that moulded us are still perceived only vaguely.

Why are there three spatial dimensions; could there be more? If dimensions beyond our ken are revealed at the LHC this would be one of the greatest cultural shocks of all. Our theories work if everything is massless and flits around at the speed of light, yet if it were so we could not be here. How did mass emerge; what indeed is it?

We know how the seeds of normal matter emerged in the relatively cool afterglow of creation. However, it appears that “normal” matter is but 1 per cent of the whole; we are but flotsam on a sea of “dark matter”, whose existence has been inferred from theoretical cosmology but remains undetected. What that dark sea consists of, how it was formed, why there is any matter at all rather than a hellish ferment of radiation, are unknown.

After that first billionth of a second, the material particles from which we are made, and the disparate forces that act on them, had become encoded into the fabric of the Universe. The events that led our Universe to win the lottery of life were decided earlier than this. Some of them we believe occurred in the epoch now within reach.

That is what the LHC promises to reveal. It will bring into sharp focus what are currently but vague shadows of possibility. What actually took place in that long-ago dawn, only nature knows. Soon humans will too.

Frank Close is Professor of Physics at the University of Oxford, and author of The Void (Oxford University Press)

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