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Researchers find gravitational lensing has significant effect on cosmic birefringence
https://www.spacedaily.com/reports/Rese … e_999.html
Future missions will be able to find signatures of violating the parity-symmetry in the cosmic microwave background polarization more accurately after a pair of researchers has managed to take into account the gravitational lensing effect, reports a new study in Physical Review D, selected as an Editors' Suggestion.
How far does the universe extend? When and how did the universe begin? Cosmology has made progress in addressing these questions by providing observational evidence for theoretical models of the universe based on fundamental physics. The Standard Model of Cosmology is widely accepted by researchers today. However, it still cannot explain fundamental questions in cosmology, including dark matter and dark energy.
In 2020, an interesting new phenomenon called cosmic birefringence was reported from the cosmic microwave background (CMB) polarization data. Polarization describes light waves oscillating perpendicularly to the direction it is traveling. In general, the direction of polarization plane remains constant, but can be rotated under special circumstances. A reanalysis of the CMB data showed the polarization plane of the CMB light may have slightly rotated between the time it was emitted in the early universe and today. This phenomenon violates the parity symmetry and is called the cosmic birefringence.
Because cosmic birefringence is challenging to explain with the well-known physical laws, there is a strong possibility that yet to be discovered physics, such as the axionlike particles (ALPs), lies behind it. A discovery of cosmic birefringence could lead the way to revealing the nature of dark matter and dark energy, and so future missions are focused on making more precise observations of the CMB.
To do this, it is important to improve the accuracy of current theoretical calculations, but these calculations so far have not been sufficiently accurate because they do not take gravitational lensing into account.
A new study by a pair of researchers, led by The University of Tokyo Department of Physics and Research Center for Early Universe doctoral student Fumihiro Naokawa, and Center for Data-Driven Discovery and Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Assistant Professor Toshiya Namikawa, established a theoretical calculation of cosmic birefringence that incorporates gravitational lensing effects, and worked on the development of a numerical code for cosmic birefringence that includes gravitational lensing effects, which will be indispensable for future analyses.
First, Naokawa and Namikawa derived an analytical equation describing how the gravitational lensing effect changes the cosmic birefringence signal. Based on the equation, the researchers implemented a new program to an existing code to compute the gravitational lensing correction, and then looked at the difference in signals with and without the gravitational lensing correction.
As a result, the researchers found that if gravitational lensing is ignored, the observed cosmic birefringence signal cannot be fitted well by the theoretical prediction, which would statistically reject the true theory.
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There are Ideal Orbits for Space-Based Interferometers
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centrifugal force
Former astronaut says it’s “extremely important” to study artificial gravity
https://arstechnica.com/space/2023/07/f … l-gravity/
"We have nothing in between one and zero."
A little more than 15 years ago, astronaut Garrett Reisman was among a crew of seven who launched into orbit aboard Space Shuttle Endeavour. The shuttle remained attached to the Space Station for nearly two weeks, but when the orbiter departed, it left Reisman behind for an extended stay.
During his time at the station, Reisman would often pass through the Harmony module, which serves as a corridor connecting laboratory modules built by NASA and the European and Japanese space agencies. Sometimes, he would look up and see a small placard that said, "To CAM." The arrow, however, pointed out into space.
"When I was up there on the space station, there was still the sign that says, 'To CAM,'" Reisman said in an interview. "But there's just a closed hatch. It was tragic. It was just kind of taunting me when I saw that because I think that could have been one of the most important scientific discoveries that we made."
The "CAM" was the Centrifuge Accommodation Module, originally built by the Japanese space agency. It was intended to provide an environment for artificial gravity experiments, from just slightly above zero gravity all the way to 2 gs. However, NASA canceled the final development and launch of the centrifuge module in 2005 due to budgetary concerns.
OPINION: NASA Needs to add some ‘weight’ to spaceflight
https://web.archive.org/web/20150308040 … aceflight/
EVA training in simulated 1/6G
https://www.youtube.com/watch?v=HOE5sqgJDyg
as for the spooky exotic stuff
3-sigma or “five sigma” in their results?
NANOGrav group or North American Nanohertz Observatory for Gravitational Waves a consortium of astronomers, a measurement of the Hellings–Downs curve
http://astro.vaporia.com/start/hdcurve.html
Ripples in space-time, pulsars, blackholes and waves of the intensity of gravity that are generated by the accelerated masses of binary stars
Einstein Telescope: the next generation Gravitational Wave observatory in Europe
https://home.cern/events/einstein-teles … ory-europe
LIGO and Virgo detectors received gravitational wave signals within 2 seconds of gamma ray satellites and optical telescopes seeing signals from the same direction so they say they confirmed that the speed of gravitational waves is the same as the speed of light
https://www.ligo.caltech.edu/page/press … e-gw170817
Evidence of a universal gravitational wave background
https://archive.today/20230804144053/ht … ts-source/
Chasing gravitational waves
https://www.nature.com/articles/nphoton.2008.186
New results coming combining the measurements of several collaborations
https://cloud.mpifr-bonn.mpg.de/index.p … nZaKWnn3Ti
In quantum gravity the graviton is the hypothetical quantum of gravity it mediates the force of gravitational interaction while in string theory, believed by some to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string.
Last edited by Mars_B4_Moon (2023-12-29 13:18:38)
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