ESO/VVV Survey/D. Minniti. Ackno
Since the opening act of the universe 13.8 billion years ago, a diverse set of characters have trod the boards – stars, planets, moons, quasars. But if you tend to get fidgety at the theatre, there is bad news: this cosmic performance has at least 100 billion years to go. Which raises a question: are we living at a special moment – the cliffhanger before the interval – or is this just an inconsequential moment in the mid-plot?
One hint that this is a special instant involves a swathe of observed properties of the universe known as fundamental constants. These include the strength of gravity, for example, and the fine-structure constant, known as alpha, which determines the way matter and light interact and thus how stars burn. If these numbers were just a shade different from how they are, then life might be impossible.
Why is it all so perfect? One possible answer is that these constants aren’t so constant. Perhaps they have been gradually changing over the life of the universe and we happen to live at an auspicious blip in time. John Webb at the University of Cambridge has spent decades investigating this idea, in his case in relation to alpha. Based on precision measurements of the cosmos, Webb has claimed in the past that alpha has indeed morphed – although he now thinks those claims were wrong…
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