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Matters of substance What is the universe really made of? Katharine Sanderson contemplates dark matter, dark energy and the nature of everything. Illustrations Rian Hughes

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T I S S O M E T H I N G O F A W O N D E R that astronomers and physicists don’t wander around in a state of permanent existential crisis. Why? They spend their working lives looking out into the vastness of the universe, trying to understand how and why it came into being, delving into the very substance of matter to discover what it, and consequently what humans, are made of at the most fundamental level. When facing these questions, the scientist has to routinely grapple with concepts about time, space and matter that make the head spin. It doesn’t seem to trouble them that all the matter that we can see, all the planets and stars, make up only a tiny 5% of the universe. Or that the rest is made up of one thing that is slightly understood, and another that is barely understood. Those things are dark matter, making up around 25%, and dark energy, making up the remaining roughly 70% of the universe. Neither has been directly detected. Scientists appear happy with the idea that the universe is flat and constantly expanding. But where is it expanding to, given that the universe is, well, everything? And if it’s expanding, does that mean it started out as nothing? Was it a singularity of infinite energy and density? Despite fine minds pondering this question, no answer has been found. So what is the universe made of? What is the answer to everything? There is a strong contender for an explanation about what triggered the universe’s expansion, from whatever it was: a huge burst of energy known as the big bang, which happened 13.8 billion years ago. This event produced the debris that became the matter we are made of today. It led, by chance, to our sun, our planet, our atmosphere, our plants, our animals. Us.

CAM 69  
CAM 69  

Cambridge Alumni Magazine Issue 69