The Sunday Telegraph - Sunday

Is the entire universe really no more than a hologram?

- By Steven Poole

Stephen Hawking explained how, thanks to quantum physics, time in a sense runs backwards

ON THE ORIGIN OF TIME: STEPHEN HAWKING’S FINAL THEORY by Thomas Hertog 352pp, Torva, T£16.99 (0844 871 1514), RRP£20, ebook £9.99


“Who knows where the time goes?” asked Sandy Denny, though as good a question is where it came from in the first place. According to the standard picture of modern cosmology, we are encouraged to think that the Big Bang, roughly 13.7 billion years ago, created time itself along with space, so that it is meaningles­s to talk of what came before it.

In this sense, time is like a compass direction. Once you are at the South Pole, you cannot walk any further south. Similarly, once you’ve journeyed back in time to the Big Bang, there is no further left to travel. It’s the beginning of the idea of beginning.

This answer has not always satisfied scientists, some of whom prefer to think of our cosmos bubbling into existence from elsewhere and elsewhen. This idea, however, requires a multiverse – a higher sphere of many (perhaps infinitely many) universes, constantly being born from a seething quantum sea – a concept toyed with in the Oscar-winning, universe-hopping romp Everything Everywhere

All at Once.

It’s an idea to which our very own celebrated black-holebother­er Stephen Hawking was hostile. The multiverse, he once remarked to his protégé and collaborat­or Thomas Hertog, was “outrageous”.

As Prof Hawking noticed, the notion of an infinite number of universes seems to violate Occam’s Razor, which states that entities should not be needlessly multiplied just to prop up an explanatio­n. In his view, the idea shouldn’t even count as real science, on the grounds that it’s unfalsifia­ble: evidence of other universes completely inaccessib­le to our own would be impossible to come by. Not mentioned in this book, however, is the idea promoted by the AlbanianAm­erican cosmologis­t Laura Mersini-Houghton that the birth of our universe from the multiverse might have left visible “scars” on the so-called “cosmic microwave background” – the fossil echo of the Big Bang that still permeates the sky.

So, On the Origin of Time gentle polemic, selling a particular theory, but no less rich and fascinatin­g for that. The Belgian cosmologis­t Hertog, a theoretica­l physicist at KU Leuven university, draws a vivid and philosophi­cal picture of the evolution of beginning-times theorising in the latter half of the 20th century, including the changing opinions of Hawking himself. It alternates between gnomic conversati­ons over tea with Hertog’s famous late mentor and deliciousl­y mind-bending ideas, such as that time itself stops inside a black hole, meaning that to enter one (if that were possible before you were torn apart by gravitatio­nal forces) would be to experience the last moment.

In the intriguing cosmologic­al picture that emerges here, joint brainchild of Hawking and Hertog,

what we call the “laws of physics” themselves evolved and changed as the early universe cooled. They are therefore, as Hertog puts it poetically, simply “frozen accidents”, not amenable to any more fundamenta­l explanatio­n. So much for the kind of “Grand Unified Theory” of physics that Hawking had looked forward to in A Brief History of Time (1988) but then later abandoned.

What’s more controvers­ial is the view that time must be thought of in some ways as running backwards. Science, you see, is the name we give to the activity of some bits of the universe (the ones we call “human scientists”) looking at other bits. According to Hertog and Hawking, what we observe today retrospect­ively calls into being the universe’s whole past, because of the quantum rule of indetermin­acy (that being the rule that things are not definitive­ly one way or another until measured). It’s a form of cosmologic­al idealism in which fuzziness increases with distance: as we look ever further back in time, the universe becomes, as it were, more and more lowresolut­ion, until we arrive at the singularit­y of the Big Bang, where informatio­n runs out.

Most striking, perhaps, is how willing Hertog is to bite the bullet of backwards causation, in which, as he explicitly says, “the past [is] contingent on the present”. He does not even shy away from accepting that this view is teleologic­al, implying as it does that the universe was always somehow aiming at the glorious bio-friendly present, so that there could be theoretica­l physicists in Leuven to study it.

It can all sound quite hippyish in précis, and often in detail too, especially when Hertog asserts that the entire universe is also a holographi­c projection. In that case, it turns out, we don’t need to worry about the origin of time because time itself is “illusory”. This recalls Einstein’s picture of the “block universe”, in which there was no flow of time as we seem to experience it.

It also furnishes a kind of cosmic therapy: picturing ourselves as essential enablers of the evolution of the universe, or so Hertog argues, “counters the relentless alienating forces of modern science”. I’m not sure that comforting thought alone will be sufficient to persuade the antivaxxer­s and the Flat Earth crew.

Eccentrica­lly inspiratio­nal as it may be, Hertog’s peroration also shows how difficult it is for us to let go of time as a fundamenta­l concept. Shortly after he declares that time is in some sense not real, he’s seen continuing to use time-based vocabulary such as “when” and “become” and “gradually” to describe the goings-on down there in the quantum realm. It’s not so easy, after all, to get rid of the old “first this, then that”.

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 ?? ?? Numbers game: the late Stephen Hawking in 2012
Numbers game: the late Stephen Hawking in 2012
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