The FBI started spying on renowned German-born scientist Albert Einstein when he moved to America in 1933, shortly before Adolf Hitler rose to power. Agents listened to the physicist‘s phone calls and searched his mail and trash, suspecting he was a Soviet spy. The surveillance, totalling 1,800 pages, ended with Einstein‘s death on April 18, 1955, with no supporting evidence.
Archiv: Albert Einstein
Giant gravitational waves: why scientists are so excited
On 29 June, four separate teams of scientists made an announcement1–4 that promises to shake up astrophysics: they had seen strong hints of very long gravitational waves warping the Galaxy.
Gravitational waves are ripples in the fabric of space-time that are generated when large masses accelerate. They were first detected in 2015, but the latest evidence hints at ‘monster’ ripples with wavelengths of 0.3 parsecs (1 light year) or more; the waves detected until now have wavelengths of tens to hundreds of kilometres.
Here Nature reports what these monster gravitational waves could mean for our understanding of the cosmos, and how the field could evolve.
The Cosmos Is Thrumming With Gravitational Waves, Astronomers Find
(June 28, 2023)
The scientists strongly suspect that these gravitational waves are the collective echo of pairs of supermassive black holes — thousands of them, some as massive as a billion suns, sitting at the hearts of ancient galaxies up to 10 billion light-years away — as they slowly merge and generate ripples in space-time.
“I like to think of it as a choir, or an orchestra,” said Xavier Siemens, a physicist at Oregon State University who is part of the North American Nanohertz Observatory for Gravitational Waves, or NANOGrav, collaboration, which led the effort. Each pair of supermassive black holes is generating a different note, Dr. Siemens said, “and what we’re receiving is the sum of all those signals at once.”
Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I
(Published 29 June 2023)
Observing and timing a group of millisecond pulsars with high rotational stability enables the direct detection of gravitational waves (GWs). The GW signals can be identified from the spatial correlations encoded in the times-of-arrival of widely spaced pulsar-pairs. The Chinese Pulsar Timing Array (CPTA) is a collaboration aiming at the direct GW detection with observations carried out using Chinese radio telescopes. This short article serves as a „table of contents“ for a forthcoming series of papers related to the CPTA Data Release 1 (CPTA DR1) which uses observations from the Five-hundred-meter Aperture Spherical radio Telescope. (…)
A Pulsar Timing Array (PTA; Foster & Backer 1990) is an array of pulsars, which are regularly observed. The times-of-arrival (TOAs) are measured for pulses that we see beams of electromagnetic waves emitted by the pulsars sweeping over the Earth. As the directions of the radiation beam and the pulsar rotational axis do not coincide, we observe this radiation as regular pulses synchronized to the pulsar rotation (Gold 1969).
About the nature of gravitational and gravity waves
(March 20, 2018)
Gravitational waves, which Albert Einstein predicted in 1916.2 were a riddle until 14 September 2015. Gravitational waves are small deformations of the four dimensional space–time geometry. They propagate with the speed of light and they are generated by catastrophic events in the Universe, in which strong gravitational fields and sudden acceleration (or deceleration) of asymmetric distribution of large masses are involved. In the other words, according to the theory of relativity, any accelerating or decelerating massive object that isn’t spherically or cylindrically symmetrical generates detectable gravitational waves. That object could be for example neutron star or black hole binary system. Gravitational waves are also produced by cosmological explosions such as supernova. Gravity is the weakest of the four fundamental forces, it is known for a very long time, but still there is no a good unique gravity force (field) theory.
FBI spied on Albert Einstein for 22 years until his death
The FBI started spying on renowned German-born scientist Albert Einstein when he moved to America in 1933, shortly before Adolf Hitler rose to power. Agents listened to the physicist‘s phone calls and searched his mail and trash, suspecting he was a Soviet spy. The surveillance, totalling 1,800 pages, ended with Einstein‘s death on April 18, 1955, with no supporting evidence.
FBI spied on Albert Einstein for 22 years until his death
The FBI started spying on renowned German-born scientist Albert Einstein when he moved to America in 1933, shortly before Adolf Hitler rose to power. Agents listened to the physicist‘s phone calls and searched his mail and trash, suspecting he was a Soviet spy. The surveillance, totalling 1,800 pages, ended with Einstein‘s death on April 18, 1955, with no supporting evidence.