Browse Physics

Surface waves in a trough of flowing water provide an analog system in which to study Hawking radiation.

More than a decade’s worth of data collected from the LAGEOS II satellite is offering a new way to test general relativity.

Evidence for radiation analogous to that predicted near black holes by Hawking has been found in the emission of optical filaments propagating through glass.

How do gravitational singularities avoid being trapped by event horizons?

The mysterious slowing down of some newborn, fast-moving, black holes may result from gravitational waves emitted by a bulge in the event horizon.

A quantum field propagating in a curved spacetime can have fluctuations in its vacuum energy density that are large enough to completely dominate its classical energy density.

A three-dimensional version of gravity might lend itself to a quantum treatment.

The insights of a provocative connection between general relativity and quantum field theory, called the AdS/CFT correspondence, have been extended to rotating black holes that can occur astrophysically.

A mathematical formulism makes a step forward in proving the AdS/CFT correspondence that connects quantum mechanics with gravity.

Can quantum electronic devices offer an experimental system that mimics the behavior of black holes?

Finding a quantum theory of gravity remains one of the great unsolved problems in modern physics. Two papers present a quantum gravity theory that, while making different assumptions than general relativity, still reproduces Einstein’s theory in certain limits.

A “simple” closed-form Hamiltonian for a relativistic system of n gravitating particles, which depends only on the particles’ momenta and coordinates, is developed.

Researchers have long sought to detect quantum effects in macroscopic objects, analogous to the superposition of states in Schrodinger’s cat that is both dead and alive. The development of ultrasensitive measurement techniques used in quantum computing and gravity wave detection may offer a way to experimentally test these ideas. Vinante et al. have used amplifier feedback to cool oscillation modes in a one-metric-ton aluminum bar that forms the active element in the AURIGA gravity wave detector. The effective temperature was 0.2 mK . Although other experiments have achieved lower temperatures, the AURIGA resonator is orders of magnitude more massive. Such feedback techniques may enable researchers to approach a regime where quantum effects become apparent.

Two black holes can merge and then shoot out of their galaxy, according to computer simulations, and the streaking black hole ‘rocket’ might be visible to astronomers if conditions are right.

The radiation emitted at the edge of a black hole might exist even if the hole doesn’t possess an “event horizon” from which nothing can escape.

Reports of the discovery of spacetime ripples known as gravitational waves in 1969 and 1970 proved erroneous but inspired efforts that continue today.

A tiny black hole could briefly appear in a particle accelerator and then vanish into its own separate universe.

In 1960 physicists finally verified Einstein’s 1911 prediction that gravity could change light’s frequency. Understanding the effect is essential to modern navigational technology.

A 1935 idea from Albert Einstein and Nathan Rosen for unifying electromagnetism with gravity lives on in the minds of science fiction fans.

Simulations show that two observers near a cosmic singularity such as a black hole cannot communicate.