Never mind the Big Bang – scientists are talking about a Fiery Crunch

Earth may not end up a frozen wasteland but encounter a reverse Big Bang. Scientists now talk of a coming Fiery Crunch. But don’t wait up.

Just after the Big Bang, the universe began expanding pushed along by a mysterious force called dark energy. Illustration: Dan Ritchie

At last some good news from scientists. All that is of value in the universe – all civilisation, thought, achievement and consciousness – may not end up ravaged in a frozen and eternal wasteland of meaninglessness after all. There is at least a chance, new findings suggest, that it might instead be obliterated in a fiery and ferocious crunch.

Researchers have produced the most precise measurements yet of dark energy, a mysterious thing mooted to power the expansion of the universe – and they have found tantalising but tentative evidence that it is changing. If so, it might even be changing in such a way that in billions of years the universe will stop expanding and crush in on itself.

For Professor Carlos Frenk, an astrophysicist at England’s Durham University, that is an appealing prospect. “I’d much rather have a big crunch. That death makes more sense.”

He is one of a team who last week, using a machine called the Dark Energy Spectroscopic Instrument, produced a three-dimensional map of the universe. This allowed them to assess dark energy – which he concedes is a “bizarre concept” – at different times through history.

Dark energy exists as a way to account for one of the most surprising findings in recent cosmology. After the big bang, the universe expanded. Scientists had assumed that this rate of expansion would decrease, through the gravitational pull of the universe.

In 1998, measurements on distant exploding stars showed it was doing the reverse – the expansion was accelerating.

“Something is pushing everything apart,” says Dr Philip Wiseman, a physicist at the University of Southampton. “We don’t know what causes it.” But they needed to give it a name. “Because it appears to be acting with some positive push, some repelling action, we call it dark energy.”

If, as most supposed, the pressure exerted by dark energy was fixed, then it would have a knock-on consequence. The universe would expand indefinitely, in an outcome referred to as “heat death”. As all matter spread apart, everything would reach the coldest possible temperature. Chemistry, atoms and even time itself would cease to exist.

Professor Carlos Frenk. Picture: LinkedIn

Dr Philip Wiseman. Picture: Facebook

A lot of people do not like this idea. “This is about the most boring possible universe,” Frenk says. “Everything decays, you can no longer tell past from future, there wouldn’t even be artificial intelligence – just a vast frozen expanse. It’s not a jolly place.”

Now, different strands of evidence are suggesting something happier may be possible. In January, by looking at 1500 exploding stars, Wiseman and his colleagues found hints that dark energy was changing – that, he says, “it is thawing”. This week, Frenk and his colleagues added to the evidence.

Their work looks at ripples in the distribution of mass in space. These ripples are echoes of processes from the start of the universe and crucially they are the same distance apart. “The universe provided us with a ruler,” Frenk says. This means that, like stretch marks on the body of the universe, their variation tell us how it is expanding. And, when they looked at how stretched the ripples were over time, it didn’t quite fit with theory. Dark energy appeared to be opposing gravity less strongly as time went on.

A composite photograph of the Ultra Deep Field taken by the Hubble Space Telescope, showing the universe at the edge of the Big Bang, which was released by NASA in 2004.

So far, physicists caution, the findings are far from the level required to justify a discovery. Much more certainty is required.

Even if they can show that dark energy is changing, it’s a leap to extrapolate that change into the future – given that we have no idea what dark energy is. “We don’t know if it will stay changing like this or do some capricious U-turn,” Frenk adds.

But even so, he is hopeful. If the change is real, and continues, then it would imply eventually dark energy works with gravity, to suck the universe into a singularity – like a Big Bang in reverse. It is even conceivable that from this cataclysm a new universe would emerge, ready to begin the process all over again.

“Conceptually, this is a lot more attractive,” Frenk says. “It is renewal.”

THE TIMES