New methods will allow for better tests of Einstein's general theory of relativity using LIGO data:
Albert Einstein's general theory of relativity describes how the fabric of space and time, or spacetime, is curved in response to mass. Our sun, for example, warps space around us such that planet Earth rolls around the sun like a marble tossed into a funnel (Earth does not fall into the sun due to the Earth's sideways momentum).
The theory, which was revolutionary at the time it was proposed in 1915, recast gravity as a curving of spacetime. As fundamental as this theory is to the very nature of space around us, physicists say it might not be the end of the story. Instead, they argue that theories of quantum gravity, which attempt to unify general relativity with quantum physics, hold secrets to how our universe works at the deepest levels.
One place to search for signatures of quantum gravity is in the mighty collisions between black holes, where gravity is at its most extreme. Black holes are the densest objects in the universe—their gravity is so strong that they squeeze objects falling into them into spaghetti-like noodles. When two black holes collide and merge into one larger body, they roil space-time around them, sending ripples called gravitational waves outward in all directions.
[...] Now, two new Caltech-led papers, in Physical Review X and Physical Review Letters, describe new methods for putting general relativity to even more stringent tests. By looking more closely at the structures of black holes, and the ripples in space-time they produce, the scientists are seeking signs of small deviations from general relativity that would hint at the presence of quantum gravity.
"When two black holes merge to produce a bigger black hole, the final black hole rings like a bell," explains Yanbei Chen (Ph.D. '03), a professor of physics at Caltech and a co-author of both studies. "The quality of the ringing, or its timbre, may be different from the predictions of general relativity if certain theories of quantum gravity are correct. Our methods are designed to look for differences in the quality of this ringdown phase, such as the harmonics and overtones, for example."
The first paper, led by Caltech graduate student Dongjun Li, reports a new single equation to describe how black holes would ring within the framework of certain quantum gravity theories, or in what scientists refer to as the beyond-general-relativity regime.
[...] The second paper, published in Physical Review Letters, led by Caltech graduate student Sizheng Ma, describes a new way to apply Li's equation to actual data acquired by LIGO and its partners in their next observational run. This data analysis approach uses a series of filters to remove features of a black hole's ringing predicted by general relativity, so that potentially subtle, beyond-general-relativity signatures can be revealed.
[...] Chen added: "Working together, Li and Ma's findings can significantly boost our community's ability to probe gravity."
Journal Reference:
Dongjun Li, Pratik Wagle, Yanbei Chen, et al. Perturbations of Spinning Black Holes beyond General Relativity: Modified Teukolsky Equation [open], Physical Review X DOI: 10.1103/PhysRevX.13.021029
Sizheng Ma, Ling Sun, Yanbei Chen. Black Hole Spectroscopy by Mode Cleaning, Physical Review Letters DOI: 10.1103/PhysRevLett.130.141401
(Score: 4, Interesting) by gznork26 on Thursday June 01 2023, @01:53PM (1 child)
Since I've been reading old SF lately, the ringing from the merging of black holes gave me an idea...
If the gravitational ringing lasts a long time and is broadcast a great distance, then the interaction between gravity waves from various sources could form standing wave patterns that gradually change as the ringing subsides. That pattern of standing waves might then cause corresponding patterns in the position of mass, which we'd observe as the skein of stars, and star groupings which we imagine as the edges of bubbles in space that are empty inside and look like strands of star formation.
Using the resultant pattern of bubbles, we could project backwards to predict the direction, distance, and time of the black hole mergers which gave rise to what we observe, and to predict the future behavior of those patterns in the cosmos.
Khipu were Turing complete.
(Score: 0) by Anonymous Coward on Thursday June 01 2023, @05:00PM
I believe the ringdown happens pretty quickly and not at a constant tone, so you wouldn't be able to set up standing waves with sources like that. And with the tone changing and at different rates, I think two separated sources would be uncorrelated and their resulting interfering wave pattern would unfortunately look pretty random.
(Score: 3, Interesting) by Gaaark on Thursday June 01 2023, @03:27PM
Einstein gave us the beginning to AC/DC's Hells Bells!
https://www.youtube.com/watch?v=etAIpkdhU9Q [youtube.com]
God doesn't play dice, but is he/she/it/nonexistent a carillonneur?
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2) by bzipitidoo on Friday June 02 2023, @08:02PM (1 child)
I'm used to thinking of space as utterly empty. Instead, maybe a better analogy is that space is the blank parts on the sheet of paper that is the universe. This "sheet" is 4D and can stretch and twist, and has a propagation velocity of c. How else could gravitational. light, or any other kind of waves propagate? Has to be a medium.
(Score: 2) by legont on Saturday June 03 2023, @06:00AM
Better think of "ether"
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.