A visualization of the polarization of the Cosmic Microwave Background, or CMB, as detected by ESA's Planck satellite over the entire sky. ESA and the Planck Collaboration hide caption

itoggle caption ESA and the Planck Collaboration

Some physicists are pushing back against ideas like string theory and the multiverse. Here, we see a computer-generated image of a black hole, which might, ultimately, be explained by ideas like string theory. Alain Riazuelo/IAP/UPMC/CNRS hide caption

itoggle caption Alain Riazuelo/IAP/UPMC/CNRS

The sun rises behind the cosmic microwave background (CMB) radiation telescopes at the National Science Foundation'€™s South Pole Station. Steffen Richter/Harvard University hide caption

itoggle caption Steffen Richter/Harvard University

The Dark Sector Lab (DSL), located 3/4 of a mile from the Geographic South Pole, houses the BICEP2 telescope (left) and the South Pole Telescope (right). Steffen Richter/Harvard University hide caption

itoggle caption Steffen Richter/Harvard University

Observing the multitude of galaxies in our own universe is a piece of cake. Observing the multiverse, if such a thing exists, seems impossible. Above, the Milky Way rises above the ESO's ALMA observatory in Chile. Y.Beletsky/ESO hide caption

itoggle caption Y.Beletsky/ESO

This image released Monday by Harvard-led researchers represents the gravitational waves in the Cosmic Microwave Background in the microsecond after the Big Bang. Harvard-Smithsonian Center for Astrophysics hide caption

itoggle caption Harvard-Smithsonian Center for Astrophysics

Part of the ALMA array on the Chajnantor plateau of Chile points skyward to the Milky Way, our own galaxy. The center of our galaxy is visible as a yellowish bulge crossed by dark lanes, which are themselves huge clouds of interstellar dust. José Francisco Salgado/ESO hide caption

itoggle caption José Francisco Salgado/ESO

The Milky Way dominates the sky over Chile's Atacama Desert, home to the European Southern Observatory. John Colosimo/ESO hide caption

itoggle caption John Colosimo/ESO