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OUR universe was shaped by origami. Gravity took a primordial paper sheet and folded it to form galaxies, thus bringing light and life to the cosmos.

This original take on the creation myth is more than just empty metaphor. One astrophysicist is discovering how origami can tell us a few things about how galaxies are created, why they tend to spin in unison 鈥� and how in their early days they may have been nested within vast, dark polygons.

of Johns Hopkins University in Baltimore, Maryland, studies how galaxies and other structures form. Specifically, he looks at how dense spots of invisible dark matter suck in enough normal, gassy matter to create galaxies. In 2011, Neyrinck went to a talk by origami master and former physicist . 鈥淗e described spacecraft solar panels that unfold origamically,鈥� he says. 鈥淚 wondered if some of the origami mathematics he described could be of use in cosmology too.鈥�

To see why it might be, we must take a trip to the sixth dimension. All matter in the universe has a position in the three dimensions of ordinary space. It also has motion, which can be plotted in an abstract space with three dimensions of its own. Physicists often seek insights by plotting position and motion together in one grand 6D arena called phase space.

Immediately after the big bang, matter was spread almost evenly throughout the three dimensions of position. Although space-time was itself expanding at a tearing pace, the matter wasn鈥檛 moving much relative to this stretchy background, so all its motion coordinates were zero. In 6D phase space, it forms a flat 3D sheet.

Then gravity began to pull matter towards any slightly denser patches. Viewed in phase space, movement means that the 3D matter sheet bends out into the dimensions of motion. As these movements become more pronounced, the sheet twists around and overlaps itself 鈥� a bit like a fold.

More folds mean higher density as more matter is overlapping. Rather as when you fold a sheet of paper by hand, what tends to happen is that many-folded florets (very dense) tend to be joined up by less folded strips (less dense), with big gaps in between where the matter sheet is still flat (least dense). The result looks much like the large-scale structure of the universe today, where dense galaxy clusters are joined by filaments into a network of matter, with voids in between.

Origami isn鈥檛 exactly the same as the real universe, of course. Paper can鈥檛 stretch, while gas and dark matter can. But the idea captures a lot of the essential physics, while being much simpler than the gargantuan simulations required to model galaxy formation. A couple of years on from those first folds, the approach is now promising dividends. 鈥淔inally we鈥檙e getting to the point where origami mathematics should directly help in comparing theory to observations of galaxies,鈥� says Neyrinck.

鈥淥rigami captures a lot of the essential physics of galaxy formation鈥�

For one thing, it could help map dark matter. Dark matter far outweighs the ordinary stuff of interstellar gas, dust, stars and us. Being invisible, however, it is only known through its gravitational influences, such as the way it bends the light reaching us from distant galaxies, slightly distorting our view of them.

We can use this 鈥渨eak lensing鈥� effect to trace dark matter, but the method would be improved if we knew what the galaxies actually look like. While the simplest assumption is that they are oriented randomly, simulations and observations both hint that galaxies line up a little with their neighbours.

Origami and the art of the cosmos (Image: Origami design and folding by Mark Neyrinck. Photography by Ching-Wa Yip)

Origami agrees. When you fold a set of galaxies from a single sheet of paper, they tend to have similar orientations 鈥� because of those folds representing the filaments of inflowing matter that connect them. These streams of matter piling into a galaxy are what sets it spinning, so being joined together by filaments causes neighbouring galaxies to spin around similar axes of rotation. This in turn affects their shapes, flattening them out. So origami theory could give a better idea of the true orientations of distant galaxies, and help in tracing the distortions caused by intervening dark matter.

Cosmic origami also has a rather beautiful consequence. We know that every galaxy sits at the centre of a blob of dark matter called a halo. Analysis of simulations in 2014 shows that . This, too, comes naturally out of the origami approximation. But while most researchers assume that these boundaries are rounded ellipsoids, 狈别测谤颈苍肠办鈥檚 origami simulations suggest something different, more like an irregular polyhedron. 鈥淎 real halo would be in between a polyhedron and sphere 鈥� plus some other small-scale structure,鈥� he says. If so, then each new galaxy is formed within a vast faceted gem of dark matter.

You can see 狈别测谤颈苍肠办鈥檚 patterns for a single galaxy, and a cluster of six surrounding a void, above. If you鈥檇 like to test how it feels to play gravity by folding your own, see 鈥�Fold your own galaxy鈥�, below.

If you are an origami novice like me, you may struggle to make a neat job of even the six-galaxy cluster. Neyrinck himself has become an old hand at paper folding. He uses a computer to simulate origami galaxies, but backs it up by hand, using a blueprint printer to lay down the pattern of creases. You can see one result at the top of this page. The background image is a slice through the universe showing the position of galaxies stretching across a few billion light years, courtesy of VIPERS, an ongoing galaxy survey being performed by the telescopes of the European Southern Observatory in Chile. Superimposed is 狈别测谤颈苍肠办鈥檚 origami pattern that neatly reproduces the distribution of galaxies within it 鈥� with each node in the folding pattern not a single galaxy, but a supercluster of galaxies.

狈别测谤颈苍肠办鈥檚 , however. 鈥淣ot much decorative stuff. Mainly galaxies,鈥� he says. This may have to change one day when astronomers find a distant cluster of galaxies that takes the unmistakable form of a flying crane.

This article appeared in print under the headline 鈥淔old your own universe鈥�