Astrophysics

On September 14, 2015, the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) observed a gravitational-wave signal from the merger of a pair of black holes. While this impressive technological triumph was celebrated...

The next time you are enjoying the sun’s warm rays, think of the tremendous voyage those photons have taken to get to you. Traveling, by definition, at the speed of light they left their point of origin about eight minutes previously in a furious...

“How big” is almost always an easier question to answer than “how old.” Though we can measure the sizes of animals and plants easily enough, we can often only guess at their ages. The same was long true of the cosmos. The ancient Greeks Eratosthenes...

Un-Biased Cosmology from Biased Tracers, a workshop held at the Institute from September 24–26, 2012, explored the astrophysical issues associated with simple bias models, which ignore crucial clustering properties and can neither describe data nor...

In 1913, Victor Hess measured the background level of atmospheric ionization while ascending with a balloon. By doing so, he discovered that Earth is continuously bathed in ionizing radiation. These cosmic rays primarily consist of protons and...

Light is the great unifier. John Wheeler, the beloved Princeton physicist, used to draw the universe as a big capital U with a little eye on one leg, signifying that we, human beings, are the eyes of the universe looking back at itself. The universe...

The theoretical astrophysicist and Princeton University professor is well known for his work on NASA’s 2001 Microwave Anisotropy Probe—he conceptualized the mission and deciphered the radio telescope’s data to measure the age of the universe, the...

On the evening of November 11, 1572, twenty-six-year-old astronomer Tycho Brahe was about to make a discovery that would change his life and consequentially boost the scientific revolution significantly. While casually staring at the night sky, he...

Pluto, the ninth planet in our solar system1 was discovered in 1930, the same year the Institute was founded. While the Institute hosted more than five thousand members in the following sixty-five years, not a single new planet was discovered during...

The story of the “data explosion” is by now a familiar one: throughout science, engineering, commerce, and government, we are collecting and storing data at an ever-increasing rate. We can hardly read the news or turn on a computer without...