Julian Muñoz has come up with a ruler to measure the early universe.
A theoretical physicist, Muñoz studies the distant, dim period in the universe’s history known as cosmic dawn. That’s when stars first began flickering on, a few hundred million years after the Big Bang, infusing the universe with initial glimmers of starlight and forming the first galaxies.
Before the first stars, the universe was cold and dark — as Muñoz describes it, “boring.” Then, starlight began to reshape the universe. “It is a very dramatic epoch,” says Muñoz, of the University of Texas at Austin.
That epoch is also poorly understood. Cosmic dawn is so unexplored that Muñoz compares it to an uncharted area on early maps of Earth. There, Muñoz says, “there could be dragons.” By studying this era, he hopes to reveal the behavior of one dragon of the cosmos, dark matter, the inscrutable substance whose mass binds galaxies.
But to understand the cosmos, scientists have to be able to measure it. Looking far into space means looking deep into the past. The trouble is our 2-D view of the sky doesn’t readily reveal how far away things are. “When we look at the night sky, we’ve got no depth perception,” says cosmologist Adrian Liu of McGill University in Montreal.
Scientists have devised a variety of methods to get a handle on distances, including standard candles and standard rulers — objects of known brightness or length. If you know how bright an object is (compared with how bright it appears) or you know how long a particular feature is on the sky (compared with its apparent length), you can tell how far away it is. A ruler looks smaller from 20 meters away than from 10 meters away, and a 20-watt lightbulb looks dimmer the farther away it is. The same applies over cosmic distances.
Scientists use certain types of exploding stars, for example, to estimate distances, because the blasts put out a predictable light show (SN: 5/8/12). Standard rulers or standard candles can be used to trace out how far away other objects of interest are and reveal how rapidly the universe has expanded over its history.
But none of the known standard objects reach back to the cosmic dawn era. That’s where Muñoz’s ruler comes in. “This ability to reach that far back,” Liu says, “that’s the really valuable thing.”
To read more, click here.