GOD does not play dice, or so said Einstein. But might he knit? If so, physicists seeking to explain the fundamental nature of the universe think they may have spotted a point at which a stitch became tangled, creating a flaw in the fabric of reality.

The universe was born in the Big Bang some 14 billion years ago. The first snapshots of the infant universe, showing it aged a mere 300,000 years, before the first stars coalesced, are taken in the light (or, rather, the microwaves) from that explosion. The cosmic microwave background, as it is known, reveals the early universe to have been a remarkably uniform fireball. Today's universe looks very different. It is lumpy, with clusters of galaxies scattered through it. Physicists have therefore spent years examining the baby pictures in the hope of discerning telltales of how the change happened.

What they have found are subtle variations in the cosmic microwave background, including a large spot that is distinctly colder than the rest. Over the past year, several ideas as to what caused this spot have been proposed and then quashed. The latest suggestion, made by Neil Turok of the University of Cambridge, in England, and his colleagues, and published this week in Science, is that the spot is a blemish which formed as reality crystallised, rather as ice cubes contain irregularities and air bubbles.

At the precise moment the universe began, its constituents—which today appear as fundamental forces such as gravity and electromagnetism, and subatomic particles such as electrons and quarks—were unified into a single substance in the extreme heat of the explosion. As the universe expanded, though, it cooled. And as it did so, it went through phase changes, just as steam condenses to liquid water that then forms ice as the temperature falls. At each point at which the phase of the universe changed, one of the forces of nature became distinct, or a type of matter emerged as being different from the others. Only when this process was complete did the familiar pattern that makes up the laws of physics properly emerge.

One theory, devised several years ago, has it that each of these phase transitions is marked by the formation of defects. Such imperfections are analogous to the misalignments between ice crystals that often form when water freezes. These can be seen both in ice cubes and on frost-covered windowpanes in the places where growing crystals have met. Cosmic-defect theory, as it is known, holds that a similar process would have happened as the newborn universe cooled.

One type of defect proposed by Dr Turok is called a “texture”—a knot of energy that could be anything between a few millimetres and many light years across. Like other cosmic defects, once formed, textures would unravel at the speed of light. They would, however, leave behind a trace of their existence. That is because the process of unwinding concentrates mass into a rapidly shrinking region, creating a gravitational field that attracts nearby matter. This, in turn, would lower the frequency of microwaves (or any other form of electromagnetic radiation) in the region by a process called gravitational red-shifting. A lower frequency corresponds to a lower temperature, so these spots would appear cold.

Of course, the explanation for the cold spot could be something else entirely. The team are being careful not to claim they are certain they have seen a cosmic defect. Indeed, they propose further tests that might show them to be wrong. If the cold spot is merely a random fluctuation in the cosmic microwave background, for example, that could be revealed by examining the polarisation of the microwaves coming from it. But, having conducted a statistical analysis of the microwave background, the team reckon that it is most likely that the cold spot is, indeed, caused by a defect.

If they are correct, it would be a boon not only for cosmologists but also for particle physicists. Spots such as this (if more can be found) would give them a way to study how fundamental forces and particles formed that is far beyond the capabilities of the puny (but very expensive) machines they use on Earth. And, based on Dr Turok's results, the pattern they eventually discover might look surprisingly like “knit one, purl one”.