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Monster gravitational waves spotted for first time

nature.com

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Re: Monster gravitational waves spotted for first time

#91

Post by beginning_end »

lucgommans wrote: post #82
beginning_end wrote: post #76

I'm curious what the amplitude of these waves are: what's the (order of magnitude) change in the distance to a 1000 light year distant pulsar, as the gravitational wave passes through? Edit: Being told by @Dr_CMingarelli on twitter that it's 10 meters pr lightyear.

You mean in like meters? > Each observatory has two light storage arms that are 4 kilometers in length. [...] A passing gravitational wave will slightly stretch one arm as it shortens the other. [...] Even with such long arms, the strongest gravitational waves will only change the distance between the ends of the arms by at most roughly 10⁻¹⁸ m. With the nominal hair value being 75 µm, `apt install qalc` tells me tha…

I was referring to the latest results using pulsars.

Re: Monster gravitational waves spotted for first time

#92

Post by kennywinker »

lucgommans wrote: post #82
beginning_end wrote: post #76

I'm curious what the amplitude of these waves are: what's the (order of magnitude) change in the distance to a 1000 light year distant pulsar, as the gravitational wave passes through? Edit: Being told by @Dr_CMingarelli on twitter that it's 10 meters pr lightyear.

You mean in like meters? > Each observatory has two light storage arms that are 4 kilometers in length. [...] A passing gravitational wave will slightly stretch one arm as it shortens the other. [...] Even with such long arms, the strongest gravitational waves will only change the distance between the ends of the arms by at most roughly 10⁻¹⁸ m. With the nominal hair value being 75 µm, `apt install qalc` tells me tha…

That's for the gravitational waves we can detect from LIGO. These new ones, as I understand it, are being detected by changes in pulsar frequency over 15 years of measurements - so they have a pretty different character than the ones wikipedia's talking about... I don't know how that translates to anything that makes any sense tho

Re: Monster gravitational waves spotted for first time

#93

Post by pantulis »

dangond wrote: post #86
pantulis wrote: post #72

Earlier quoted context omitted.

Space itself means the metric of spacetime: how you measure distances. Locally, if there was no gravity, you could think of space as a plain reticule where distances would be calculated through eucledian geometry: that means cartesian distances, parallel lines would be parallel and the angles of a triangle would sum 180, and the shortest path between two points is the straight line. General Relativity successfully es…

Out of curiosity, from someone who has never worked with non-euclidean geometry, what does it mean for a path to be curved in non-Euclidean space? My outsider understanding of curvature is that the inside of a curve is shorter than the outside of the curve, whereas a line has the same length on either side (assuming we give these curves and lines some thickness). But, if the shortest path can be curved, what do we me…

I cannot be of help here but I'd say that your concept of curvature is too informal, but more formal maths can deal with it, take a look at the wikipedia page for "Geodesic", the maths are way above my head but the diagrams are cool :D

Re: Monster gravitational waves spotted for first time

#94

Post by AprilArcus »

zackmorris wrote: post #80
anonym29 wrote: post #3

EDIT as a commenter below has kindly pointed out, our current models indicate that the answer to this question is "no", per https://www.youtube.com/watch?v=QMFLcmsjOBg ------ This is all firmly outside my technical discipline, but aren't there some theories that faster-than-light travel might be achieved by bending spacetime around a spacecraft, as opposed to trying to propel the spacecraft through space? I really wa…

This video might help understand where mass comes from and how to potentially modulate it, because mass can be thought of as bound energy creating voids in the gluon field: https://m.youtube.com/watch?v=Ztc6QPNUqls The Higgs mechanism affects electrons, not quarks, and is only responsible for about 1% of matter's mass. Most mass comes from the binding energy between quarks, which creates flux tubes between quark-anti…

>The Higgs mechanism affects electrons, not quarks

It effects both. The LHC produces Higgs particles through the annihilation of top-antitop pairs, which works because the top quark couples strongly to the Higgs field.

Re: Monster gravitational waves spotted for first time

#95

Post by chorsestudios »

seventhson wrote: post #70
chorsestudios wrote: post #63

These ‘monster’ gravitational waves have supposedly been ‘spotted’ by calculating disparities in pulsar timings. The article didn’t have as much information as I was hoping - were any of these waves detected/confirmed by LIGO?

The wavelengths are too large for LIGO. The wave measurements were correlated with data collected from many pulsars. https://arstechnica.com/science/2023/06/nanograv-picks-up-si...

Thank you for this article link, I found it much more informative than the parent article. The video at the bottom was well made.

Re: Monster gravitational waves spotted for first time

#96

Post by samstave »

pantulis wrote: post #87
bumby wrote: post #79

Earlier quoted context omitted.

If this is ELI5, we hang around very different kinds of five year olds :-) Joking aside, thank you for the deeper explanation. The idea that spacetime isn’t fundamental is a very non-intuitive concept given how we’ve evolved to interact with the world. Any suggested reading on this topic for laypeople?

> Any suggested reading on this topic for laypeople? Carlo Rovelli is a bona fide theoretical physicist, very involved in the development of Quantum Loop Gravity (one of the attempted approaches to bridge GR and QM). Turns out he is also a good pop-sci writer, so I would begin there. His book "The Order of Time" deals with the nature of time, which is not about the nature of space, but then again reading it you see t…

I find /r/cosmotology a hairy subject hard to swallow...

I think they push string theory too much, and try too hard to braid it into the fabric of our societies, with their little shops and what not... It gets everywhere, and tomorrow is their favorite day "Friday"!

Re: Monster gravitational waves spotted for first time

#97

Post by sunshinerag »

nyrikki wrote: post #90
derefr wrote: post #61

Earlier quoted context omitted.

Acoustic waves propagate through what are essentially elastic deformations of the material they travel through. Can gravitational waves be thought of as propagating by elastically deforming spacetime? If this analogy holds, then can it be taken further? Acoustic waves dissipate their energy insofar as they trigger plastic deformation in a material. Could gravitational waves plastically deform... spacetime itself? Or…

Hard or impossible to visualize, but as the temporal dimension is so much larger, most of the deformity is in the time dimension. But yes, spacetime itself is jiggly like Jell-O. As we can't visualize 4d spacetime, most analogies will be wrong. But as photons don't experience time themselves, thinking about the geodesic path is probably less error prone than thinking of it as squishing physical objects. Objects being…

what does "photos don't experience time themselves.." mean? why not?

Re: Monster gravitational waves spotted for first time

#98

Post by ajkjk »

dangond wrote: post #86
pantulis wrote: post #72

Earlier quoted context omitted.

Space itself means the metric of spacetime: how you measure distances. Locally, if there was no gravity, you could think of space as a plain reticule where distances would be calculated through eucledian geometry: that means cartesian distances, parallel lines would be parallel and the angles of a triangle would sum 180, and the shortest path between two points is the straight line. General Relativity successfully es…

Out of curiosity, from someone who has never worked with non-euclidean geometry, what does it mean for a path to be curved in non-Euclidean space? My outsider understanding of curvature is that the inside of a curve is shorter than the outside of the curve, whereas a line has the same length on either side (assuming we give these curves and lines some thickness). But, if the shortest path can be curved, what do we me…

Picture curves on the surface of the earth. They seem flat locally, but if you go a mile north, a mile east, a mile south, and a mile west, you don't end up _exactly_ where you start. (In the northern hemisphere you end up a little east of where you start; in the southern, a little west.)

Same thing in general relativity: the metric tensor measures the failure of closed loops on each axis to not close perfectly, the way they would in Euclidean space.

Basically even as a small creature on earth you can 'figure out' about the curvature by carefully measuring small-ish loops. The same is true for spacetime, but the loops' deformities are even smaller.

Re: Monster gravitational waves spotted for first time

#99

Post by olddustytrail »

dangond wrote: post #86
pantulis wrote: post #72

Earlier quoted context omitted.

Space itself means the metric of spacetime: how you measure distances. Locally, if there was no gravity, you could think of space as a plain reticule where distances would be calculated through eucledian geometry: that means cartesian distances, parallel lines would be parallel and the angles of a triangle would sum 180, and the shortest path between two points is the straight line. General Relativity successfully es…

Out of curiosity, from someone who has never worked with non-euclidean geometry, what does it mean for a path to be curved in non-Euclidean space? My outsider understanding of curvature is that the inside of a curve is shorter than the outside of the curve, whereas a line has the same length on either side (assuming we give these curves and lines some thickness). But, if the shortest path can be curved, what do we me…

It's not too complicated. Get a round ball of some sort. When you draw on the surface, that's a "non-Euclidean space".

Take a straight line down from the "north pole" of your ball to its equator. Draw another straight line around a quarter of the equator. Draw a third line back to the pole. You've just drawn a triangle with 3 straight lines and the angles add to 270 degrees.

A non straight line is just not the shortest distance between two points on that surface.

Re: Monster gravitational waves spotted for first time

#100

Post by alfiopuglisi »

sunshinerag wrote: post #97
nyrikki wrote: post #90

Earlier quoted context omitted.

Hard or impossible to visualize, but as the temporal dimension is so much larger, most of the deformity is in the time dimension. But yes, spacetime itself is jiggly like Jell-O. As we can't visualize 4d spacetime, most analogies will be wrong. But as photons don't experience time themselves, thinking about the geodesic path is probably less error prone than thinking of it as squishing physical objects. Objects being…

what does "photos don't experience time themselves.." mean? why not?

Photons travel at the speed of light, and at that speed, any "subjective" time is zero. In Einstein's theory of special relativity, the faster you go, the slower your proper time appears to an external observer. At the speed of light, this effect reaches infinity.
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