Arthur Kosowsky

In its first moments, the universe resembled dough beginning to rise. If the yeast is unevenly distributed, the rolls come out in different sizes. Astronomers are hunting for such 'clumps' in the oldest light and in the arrangement of galaxies to understand what the recipe was.

Take two heavy balls and place them a meter apart: they attract each other with a force that weakens by a factor of four when you double the distance. Newton discovered this law, and it works in a room, in the solar system, in a galaxy. But does it still hold when we're talking about hundreds of millions of light-years? Astronomers found a way to test this directly.

Moving clumps of galaxies and invisible dark matter create wakes in the afterglow of the Big Bang, like boats stirring a pond. This wake, the moving lens effect, is so subtle it shifts the light’s temperature by only a few millionths of a degree: comparable to detecting a candle’s heat from across a continent.

From childhood, we're used to thinking of space as infinite and isotropic. But Einstein and Lemaître were already asking: could the Universe be closed in on itself, like a Möbius strip or a 3-torus?