The Ledger
Every statement that passed quotation and attribution checks. Mix any filter with any other: certainty 1/5, debate potential 5/5, or both at once.
why aren't all 12 resolved? a statement only gets an assessment when the public record can support or contradict it. opinions and what-ifs never can, and 0 checkable ones are still open, waiting for their date. predictions held up or didn't; assertions are supported or contradicted. on every card: ▮▮▮▮▮ certainty · ▮▮▮▮▮ debate potential. speakers are clickable
Adhikari: LIGO stabilizes lasers ten million times beyond commercial models
“So we take the best laser in the world that we can find, and then we stabilize it and make it about ten million times more stable than what you can buy, and then it's kind of just barely good enough, and we're gonna have to do better if we want to do better.”
Adhikari: Laser radiation pressure physically moves LIGO's 40-kilogram mirrors
“There's so much laser power that when you, it's weird to think about, but there's so much laser power when we hit the mirror, it moves the mirror. And the mirror, if you, to imagine it, is about this big. And it is 40 kilograms”
Adhikari: LIGO laser only costs around $100,000
“The laser itself is cheaper. You can do, probably you could do the whole thing with a 100,000 dollar laser. That's about the laser cost.”
Adhikari: LIGO's detectable gravitational waves fall into human audio band
“It happens to be that the waves that we're detecting and the waves which are easiest to detect are exactly in the human audio band. So the waves that you and I can hear with our ears, that's the whole frequency range for gravitational waves that we can detect.”
Adhikari: LIGO has not seen another signal matching its first detection
“We've not seen anything of that size since then, since that first one.”
Adhikari: LIGO's first black hole detection measured a 10^-18 meter displacement
“About 10 to the -18 meters, which means one billionth of a, about the size of a atom.”
Adhikari: LIGO cannot detect the largest black holes due to environmental noise
“So the biggest black holes we can't find right now, because This kind of technical noise feedback and the vibrations from the environment are bigger than the fundamental quantum physics limits of measurement.”
Adhikari: LIGO mirrors store vibrational energy 10,000 times longer than glass
“The mirrors we have are more like They store the energy better, something like. About 10,000 times longer. So if I were to ping one of those would last for, you know, hours. They would just keep ringing and ringing.”
Adhikari: Welder's glass effectively absorbs LIGO's one-micron infrared laser light
“It has a wavelength of one micron, and so for it some of the things that look black don't work, but if you have a special kind of welder's glass, it really works. Welder's glass is good as, good at absorbing pretty much everything with a longer wavelength than…”
Adhikari: Earth's vibrations limit ground detectors to frequencies above 5-10 Hz
“On the ground, kind of, we're limited to measure things that are that have a signal frequency, which is more than five or 10 hertz or something like that, so we can go a little bit below the human audio band, but not much, and the reason for that is that the e…”
Adhikari: The LISA space interferometer aims to launch in 16-17 years
“There's a project called LISA, which is aimed to launch in 16 years, 1617 years from now, and that will put a system, a triangular interferometer in space, which is several interferometers, and that will measure gravitational waves at around a millihertz”
Adhikari: An Alpha Centauri black hole merger would overwhelm LIGO electronics
“Like the ones we detected were at, let's say several hundred million light years, and Alpha Centauri is only four light years, I believe, so it would be stronger by that factor of a hundred million. And, which sounds like a lot, it is a lot, but that means tha…”