The story of our universe may be starting to unravel

Not long after the James Webb Space Telescope began beaming back from outer space its stunning images of planets and nebulae last year, astronomers, though dazzled, had to admit that something was amiss. Eight months later, based in part on what the telescope has revealed, it’s beginning to look as if we may need to rethink key features of the origin and development of the universe.

Launched at the end of 2021 as a joint project of Nasa, the European Space Agency and the Canadian Space Agency, the Webb, a tool with unmatched powers of observation, is on an exciting mission to look back in time, in effect, at the first stars and galaxies. But one of the Webb’s first major findings was exciting in an uncomfortable sense: It discovered the existence of fully formed galaxies far earlier than should have been possible according to the so-called standard model of cosmology.

According to the standard model, which is the basis for essentially all research in the field, there is a fixed and precise sequence of events that followed the Big Bang: First, the force of gravity pulled together denser regions in the cooling cosmic gas, which grew to become stars and black holes; then, the force of gravity pulled together the stars into galaxies.

The Webb data, though, revealed that some very large galaxies formed really fast, in too short a time, at least according to the standard model. This was no minor discrepancy. The finding is akin to parents and their children appearing in a story when the grandparents are still children themselves.

It was not, unfortunately, an isolated incident. There have been other recent occasions in which the evidence behind science’s basic understanding of the universe has been found to be alarmingly inconsistent.

Take the matter of how fast the universe is expanding. This is a foundational fact in cosmological science — the so-called Hubble constant — yet scientists have not been able to settle on a number. There are two main ways to calculate it: One involves measurements of the early universe (such as the sort that the Webb is providing); the other involves measurements of nearby stars in the modern universe. Despite decades of effort, these two methods continue to yield different answers.

At first, scientists expected this discrepancy to resolve as the data got better. But the problem has stubbornly persisted even as the data have gotten far more precise. And now new data from the Webb have exacerbated the problem. This trend suggests a flaw in the model, not in the data.

Two serious issues with the standard model of cosmology would be concerning enough. But the model has already been patched up numerous times over the past half century to better conform with the best available data — alterations that may well be necessary and correct, but which, in light of the problems we are now confronting, could strike a skeptic as a bit too convenient.

Physicists and astronomers are starting to get the sense that something may be really wrong. It’s not just that some of us believe we might have to rethink the standard model of cosmology; we might also have to change the way we think about some of the most basic features of our universe — a conceptual revolution that would have implications far beyond the world of science.

A potent mix of hard-won data and rarefied abstract mathematical physics, the standard model of cosmology is rightfully understood as a triumph of human ingenuity. It has its origins in Edwin Hubble’s discovery in the 1920s that the universe was expanding — the first piece of evidence for the Big Bang. Then, in 1964, radio astronomers discovered the so-called Cosmic Microwave Background, the “fossil” radiation reaching us from shortly after the universe began expanding. That finding told us that the early universe was a hot, dense soup of subatomic particles that has been continually cooling and becoming less dense ever since.

Over the past 60 years, cosmology has become ever more precise in its ability to account for the best available data about the universe. But along the way, to gain such a high degree of precision, astrophysicists have had to postulate the existence of components of the universe for which we have no direct evidence. The standard model today holds that “normal” matter — the stuff that makes up people and planets and everything else we can see — constitutes only about 4 percent of the universe. The rest is invisible stuff called dark matter and dark energy (roughly 27 percent and 68 percent).

Cosmic inflation is an example of yet another exotic adjustment made to the standard model. Devised in 1981 to resolve paradoxes arising from an older version of the Big Bang, the theory holds that the early universe expanded exponentially fast for a fraction of a second after the Big Bang. This theory solves certain problems but creates others. Notably, according to most versions of the theory, rather than there being one universe, ours is just one universe in a multiverse — an infinite number of universes, the others of which may be forever unobservable to us not just in practice but also in principle.

There is nothing inherently fishy about these features of the standard model. Scientists often discover good indirect evidence for things that we cannot see, such as the hyperdense singularities inside a black hole. But in the wake of the Webb’s confounding data about galaxy formation, and the worsening problem with the Hubble constant, you can’t be blamed for starting to wonder if the model is out of joint.

A familiar narrative about how science works is often trotted out at this point to assuage anxieties. It goes like this: Researchers think they have a successful theory, but new data show it is flawed. Courageously rolling up their sleeves, the scientists go back to their blackboards and come up with new ideas that allow them to improve their theory by better matching the evidence.

It’s a story of both humility and triumph, and we scientists love to tell it. And it may be what happens in this case, too. Perhaps the solution to the problems the Webb is forcing us to confront will require only that cosmologists come up with a new “dark” something or other that will allow our picture of the universe to continue to match the best cosmological data.

There is, however, another possibility. We may be at a point where we need a radical departure from the standard model, one that may even require us to change how we think of the elemental components of the universe, possibly even the nature of space and time.