Why don’t we get younger rather than older?
A scientist answers this and other great mysteries of life...
POPULAR SCIENCE EXISTENTIAL PHYSICS by Sabine Hossenfelder (Atlantic £16.99, 272pp) MARCUS BERKMANN
Here’s an intellectual challenge, a book that has much the same effect as putting your brain in a blender and pressing ‘HIGH’.
sabine Hossenfelder is a German scientist working in quantum gravity and, more importantly, a science populariser writing for an educated lay audience.
Not short of ambition, she has asked herself some of life’s biggest questions and set out to answer them, as well as she can.
The effect is nothing short of bracing, a little like going for a swim in a scottish loch in January with a mouthful of ice cubes and wearing only the skimpiest pair of speedos.
so pay attention at the back. Her first question is a biggie: does the past still exist?
Hossenfelder says that when we look at the light of ancient stars, we are literally looking back into the past.
THE North star in the night sky, when we look at it, shows us what was going on with the North star 434 years ago. ‘According to the currently established laws of nature, the future, the present and the past all exist in the same way. That’s because, regardless of exactly what you mean by “exist”, there is nothing in these laws that distinguishes one moment of time from another.
‘The past, therefore, exists in just the same way as the present.
‘While the situation is not entirely settled, it seems that the laws of nature preserve information entirely, so all the details that make up you and your grandmother’s life are immortal.’
Do you understand that? I do to an extent, and I accept what she is saying, but little of it crosses over into the realm of lived experience.
We probably have to accept that physics often doesn’t, and that’s not its aim. Its aim is to explain the world and, if most of us don’t understand those explanations, that’s our lookout.
Hossenfelder, it seems, stands between us and total incomprehension. I’m guessing it’s quite a lonely place to stand.
Question two is this, or rather these: ‘ How did the universe begin? How will it end?’
The first thing to say is that no one really knows, although there are hypotheses aplenty. We now have a remarkable amount of information going back to, maybe, a second or two after the Big Bang, but further back than that we cannot go and, reports Hossenfelder, we might never be able to go.
At the other end of the scale, the universe is expected to last for three trillion years, and long before that all life will have ceased, making it quite difficult for anyone to observe the last knockings.
And who or what caused the Big Bang? No answers there either.
One theory has it that the universe is cyclical, that as soon as one ends, another begins, and on and on for ever. Hossenfelder advises: ‘Don’t take these stories too seriously, but feel free to believe them if you want.’
Next up is ‘Why doesn’t anyone get any younger?’
she has the most elegant explanation, all to do with entropy and the universe’s natural tendency to decay. ‘We get older because it’s the most likely thing to happen.’ I love this. It’s always possible we’ll get younger, but it’s simply against the balance of probabilities.
she says: ‘ Current theories are described well by the onedirectional nature of time and our perception of now. some physicists consider existing explanations unsatisfactory, and it is worth looking for better explanations, but we have no reason to think this is necessary, or even possible.’
In other words, you can’t fight it. even Cher will get older, one day.
Do you need a brain the size of a planet to read this book? I’d say not, but it wouldn’t do any harm.
Hossenfelder may popularise science but she doesn’t dumb it down, and when she doesn’t really answer a question (which can be quite often) she at least gives a reasonable explanation for not having done so.
I ended up really enjoying her book, although it takes no prisoners. I also like her slight irascibility, which suggests she doesn’t take any prisoners either.
Who else would say, in her chapter about quantum mechanics, ‘ I’ll spare you the mathematical details because they don’t really matter’? she says she’s a maths-head but she doesn’t want to burden us with any. That’s my kind of science writer.