ONE way to look at why the universe is intelligible is to ask where we would be if it weren’t. We certainly wouldn’t be asking the question; we probably wouldn’t be aware of it being a sensible question to ask. “What we call ‘intelligibility’ is a cognitive relation we happen to have with the universe,” says Carlo Rovelli at Aix-Marseille University in France. “This isn’t a question about the universe, it is a question about ourselves.”
We are natural pattern-seekers, this argument goes, because seeking and understanding patterns in the world around us has survival value. “Our species, in its evolution, found it advantageous to be curious, so we are curious,” says Rovelli. Applying that curiosity to the universe allows us to see patterns there. Its intelligibility is a product of biological evolution.
Advertisement
For others, that is only half the story. “The remarkable thing is that the world is not arbitrary or absurd,” says Paul Davies at Arizona State University. “There’s a scheme of things that we can uncover using science and mathematics – that’s already one enormous thing.” It seems a fair bet that an inverse-square law of gravity, say, exists in our universe without us being there to say so. Why?
One answer might be some form of anthropic selection principle (see “Why is the universe just right?”): only a regulated, predictable universe is likely to provide the conditions for questioning observers to arise. Then again, some specific aspects of our universe aid our comprehension of it, but don’t seem to be particularly crucial for our existence. Take the fact that our universe is expanding and evolving from a big bang (see “Why is there something rather than nothing?”). That, plus light’s finite speed, means we can peer out to different distances and get a sense of what the cosmos looked like in different eras right back almost to the beginning.
Granted, that leads us to some pretty dark places. To square what we see with our models, we end up proposing that 95 per cent of the stuff in the universe comes in two entirely mysterious forms, dark matter and dark energy. Aren’t they a problem for claims of an intelligible universe?
Not really, says Priya Natarajan at Yale University. We might not know what they are, but observation demands something like them exist. “I would call them placeholders,” says Natarajan. “They are reminders science is inherently provisional.”
For her, all of this leads us to a glorious paradox. “Here we are with a gelatinous thing the size of a cantaloupe inside our head, and yet we have figured all this out,” she says. That makes us very significant – and yet these investigations have revealed our sheer insignificance in a vast, apparently lonely cosmos (see “Why do we exist?“).
Davies thinks that leads in a profound direction. “The universe is able not only to be self-aware, but self-comprehending: a microcosm of the universe is able to comprehend the whole,” he says. He thinks a pathway from matter to the existence of mind and comprehension is built into the structure of the universe in some fundamental way – a speculation he admits puts him out of step with most of his colleagues. “It’s the closest I will get to any sort of religion,” he says.
Then again, there might be limits to our comprehension. One big question mark comes from quantum theory: not least from the way it seems to blur the strict separation between subject and object, the observer and the observed, that has allowed us to make progress in understanding the wider world (see “Why is quantum theory so strange?“). “We don’t actually have a framework to think about science without these dichotomies,” says Natarajan.
“The remarkable thing is that the world is not arbitrary or absurd”
Perhaps the enormous progress we have made in the past 300 years or so in understanding the universe using cast-iron physical laws is an aberration that results from selecting a subset of problems amenable to such an approach. The quantum realm, our own minds and complex systems generally might be far tougher nuts. “We could envisage in another 500 years people thinking: ‘That was a quaint, old-fashioned way of investigating the world, writing down your equations and hoping to make discoveries of Earth-shattering importance’,” says Davies.
Already there are signs that the only way to tackle such problems might be using the data-crunching power of artificial intelligence to uncover patterns of correlation. Does this mean that, in future, the universe will be intelligible, but only by machines, not directly by humans? Davies thinks it is a possibility. “I hope that’s not the case, I really do,” he says. “But I can’t give you a proof.”
New Scientist audio
You can now listen to many articles – look for the headphones icon in our app
