Posts tagged gravity
For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed. The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (9:51 a.m. UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.
Image from a simulation of two black holes merging and the resulting emission of gravitational radiation, published by NASA in 2012.
Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein’s field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction, and the influence of decoherence.
Geoid 2011 - Potsdam Gravity Potato
Reaching back across 13.8 billion years to the first sliver of cosmic time with telescopes at the South Pole, a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric of space-time — so-called gravitational waves — the signature of a universe being wrenched violently apart when it was roughly a trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.
A warning for future space colonizers: Babies born in space might not ever figure out how to deal with gravity. Jellyfish babies, at least, have to deal with massive vertigo on Earth after spending their first few days in space. NASA first started sending jellyfish to space aboard the Columbia space shuttle during the early ‘90s to test how space flight would affect their development. As cool as being an astronaut baby sounds, the jellies didn’t develop the same gravity-sensing capabilities as their Earthly relatives.
gravitystool13.jpg (via http://www.designboom.com/design/jolan-van-der-wiel-gravity-stool/)