> Just as light can be bent and magnified when it passes through the gravitational fields of galaxies and other massive objects, gravitational waves should be warped in the same way, too.
So, imagine you have a massive celestial body floating out in space, with a large gravitational field. Its gravitational field is always propagating. Now, take that celestial body, and make it completely and instantaneously disappear. There's now a gravitational differential between the now-gone body, and its previously propagated gravity field. You should be able to detect that if you're close, say through tidal differences.
Very similar happens with black holes colliding, except the gravity differential comes from the two black holes oscillating near each other, close to the speed of light.
Edit: this obviously isn't exactly how this works, since it makes a lot of assumptions, such as the ability to instantaneously remove something. So, don't think of this as how "things actually work", but as a model to help build your intuition.
Gravitational lensing occurs because spacetime is curved/stretched by an amount relative to it's distance to a massive object which changes the local geometry.
Since light and gravitational waves both propagate through spacetime, both will try to go straight but will get bent since they're traveling through curved spacetime.
It's sort of analogous to how your path gets bent as you try to walk straight along the earth, making you walk in a really big circle. Except that in General Relativity, time is getting bent too and trajectories aren't through space, but spacetime.
Oh yes, me too. I learnt that gravitation bends space-time and that's why light rays seem to be bent. If gravitation is just waves too, then how does that work and who bends the gravitational waves. This gets even more puzzling if we assume gravitation is mediated by particles[1].
On the other hand if gravitation is just wave and not particle it would be completely unlike the other fundamental interactions including those mediated by photons, aka light.
[1] LIGO detected gravitational waves but we don't know if gravitation particles (gravitons) exist. Detection of gravitons might not be practically possible.
Gravitational waves can be measured and can transmit information. If the sun disappears, you don't immediately know about it or feel the gravity loss for about 8 minutes, otherwise that would break c and would imply that you could signal information faster than c.
I recommend watching videos by Rana Adhikari if you want to know about gravitational waves. I went down a rabbit hole about a year ago with his video's, he is increasingly engaging. Also even in a short time his predictions for the field are coming to pass.
The fundamental thing about gravitational waves is that those are a new form of data that the universe has always been sending towards us, and that we can read now. It's like being able to read the radio waves coming from the universe for the first time, not just the visible spectrum, or close to the visible spectrum.
If future advances in this field permit we may even use those to communicate. Who knows, perhaps someone is already talking in that language.
Communicating with gravity waves would be very inefficient given how weak Gravity is. I don't see any reason why you would want to use gravity for communications... but who knows.
I am a complete neophyte regarding these topics. I did notice that the detected events (black holes merging, neutron stars merging) seem really exotic, while I assume gravitational waves are all around us all the time. Is our instrumentation for detecting gravitational waves simply very insensitive compared to the instrumentation used to detect electromagnetic waves? Or are they harder to detect for some more fundamental reason?
Gravitational waves are hard to detect because of their scale, speed and required precision.
Some of the most precise lasers built are repeatedly bouncing light over miles in a tunnel to track changes in arrival significantly less than a trillionth of a second different.
Doing this while filtering out noise from miscalibrated sensors or just small vibrations outside the chamber is HARD, but improving. It gets better as more come online around the world to confirm detections and aid in better directional targeting.
As far as I understand it, the primary reason is that gravity is a much weaker force than any of the others, so detecting gravitational effects is difficult unless the scale of the event is colossal. These instruments are extremely sensitive; the effects they detect are just that small.
Gravitational waves are indeed everywhere. If the early universe underwent inflation, they should be everywhere. Any object orbiting another object emits gravitational waves. These exotic events, however, are the only gravitational waves that are observable using the terrestrial light interference technique (LIGO and Virgo). A space based mission would be sensitive in a different frequency range (satellites bouncing light off one another over millions of kilometers). The primordial gravitational waves from inflation might be observed indirectly -- there was much excitement about the BICEP telescope observing indirect evidence of these gravitational waves, but I believe that other explanations have come forth.
A revolution would imply there has been a breakthrough that would potentially lead to new theory. However, as with most modern physics experimental breakthroughs, it seems gravitational waves provide just further support for existing theories (with a few minor exceptions.)
Not to say that this isn’t exciting, but it seems long overdue for us to stumble upon something major that is unaccounted for.
Seems dark energy and matter are what you are thinking about. We knew with good certainty that they exist but nobody knows what they are. It’s a wide open field.
Just having "waves" is not enough for a laser. You need bosons--i.e., quantum particles with integer spin. To see the quantum aspects of gravitational waves that would correspond to this, you would need extremely strong sources--much stronger even than the black hole mergers that LIGO has observed. Nobody has any expectation of observing any quantum aspect of gravitational waves in the foreseeable future, much less being able to control such sources in order to make a laser.
This is giving me chills after reading Dark Forest. I hope this sparks a new era of SETI with gravitational waves as the medium. I believe a civilization advanced enough would use gravitational waves for communication.
What are the advantages of using gravitational waves for communication? They seem incredibly difficult to produce or detect, and don't travel any faster in a vacuum than electromagnetic waves.
Unlike Electromagnetism, gravitation is boring because it is only a positive quantity. If you had positive and negative you could have maxwell's equations for gravitation and gravitational circuits and conductors and stuff.
They're listening on a really noise channel. It seems premature to talk about the frequency of the detected events matching some expected rate when they keep tuning their filters to the expectations.
I recently read an article deploring the missing confirmation of the mergers through light-based astronomy. I can't find the article now, so I'm just going to list another one: https://www.newscientist.com/article/mg24032022-600-exclusiv... Has anything changed from what is described in the article?
[+] [-] joeyrideout|6 years ago|reply
This line needs to be made into a motivational poster, or a statistics meme.
[+] [-] eukaryote31|6 years ago|reply
[+] [-] perl4ever|6 years ago|reply
[+] [-] wwarner|6 years ago|reply
[+] [-] ksangeelee|6 years ago|reply
https://www.preposterousuniverse.com/podcast/2018/11/26/epis...
[+] [-] hinkley|6 years ago|reply
I'm gonna need a refresher course on that.
[+] [-] bpchaps|6 years ago|reply
So, imagine you have a massive celestial body floating out in space, with a large gravitational field. Its gravitational field is always propagating. Now, take that celestial body, and make it completely and instantaneously disappear. There's now a gravitational differential between the now-gone body, and its previously propagated gravity field. You should be able to detect that if you're close, say through tidal differences.
Very similar happens with black holes colliding, except the gravity differential comes from the two black holes oscillating near each other, close to the speed of light.
Edit: this obviously isn't exactly how this works, since it makes a lot of assumptions, such as the ability to instantaneously remove something. So, don't think of this as how "things actually work", but as a model to help build your intuition.
[+] [-] Enginerrrd|6 years ago|reply
Since light and gravitational waves both propagate through spacetime, both will try to go straight but will get bent since they're traveling through curved spacetime.
It's sort of analogous to how your path gets bent as you try to walk straight along the earth, making you walk in a really big circle. Except that in General Relativity, time is getting bent too and trajectories aren't through space, but spacetime.
[+] [-] weinzierl|6 years ago|reply
Oh yes, me too. I learnt that gravitation bends space-time and that's why light rays seem to be bent. If gravitation is just waves too, then how does that work and who bends the gravitational waves. This gets even more puzzling if we assume gravitation is mediated by particles[1]. On the other hand if gravitation is just wave and not particle it would be completely unlike the other fundamental interactions including those mediated by photons, aka light.
[1] LIGO detected gravitational waves but we don't know if gravitation particles (gravitons) exist. Detection of gravitons might not be practically possible.
[+] [-] anonytrary|6 years ago|reply
[+] [-] buboard|6 years ago|reply
[+] [-] vanattab|6 years ago|reply
[+] [-] ollybee|6 years ago|reply
[+] [-] H8crilA|6 years ago|reply
If future advances in this field permit we may even use those to communicate. Who knows, perhaps someone is already talking in that language.
[+] [-] ravar|6 years ago|reply
[+] [-] de_watcher|6 years ago|reply
[+] [-] AstralStorm|6 years ago|reply
[+] [-] jackcosgrove|6 years ago|reply
[+] [-] gibolt|6 years ago|reply
Some of the most precise lasers built are repeatedly bouncing light over miles in a tunnel to track changes in arrival significantly less than a trillionth of a second different.
Doing this while filtering out noise from miscalibrated sensors or just small vibrations outside the chamber is HARD, but improving. It gets better as more come online around the world to confirm detections and aid in better directional targeting.
[+] [-] chousuke|6 years ago|reply
[+] [-] hardtke|6 years ago|reply
[+] [-] JohnBooty|6 years ago|reply
Every time you lift an object, you are overcoming the gravitational force of an entire planet. Gravity is that weak.
Meanwhile, the incredible destruction caused by a nuclear bomb is the product of the energy stored in just a handful of atoms.
[+] [-] hansen|6 years ago|reply
[+] [-] Retric|6 years ago|reply
[+] [-] Jerry2|6 years ago|reply
[1] https://backreaction.blogspot.com/2019/09/whats-up-with-ligo...
[2] https://news.ycombinator.com/item?id=20881986
[+] [-] gfodor|6 years ago|reply
Not to say that this isn’t exciting, but it seems long overdue for us to stumble upon something major that is unaccounted for.
[+] [-] ganzuul|6 years ago|reply
[+] [-] Ididntdothis|6 years ago|reply
[+] [-] wwarner|6 years ago|reply
[+] [-] jobseeker990|6 years ago|reply
[+] [-] pdonis|6 years ago|reply
[+] [-] typon|6 years ago|reply
[+] [-] aqme28|6 years ago|reply
[+] [-] Ar-Curunir|6 years ago|reply
[+] [-] schaefer|6 years ago|reply
[+] [-] platz|6 years ago|reply
The Technical Challenges of Measuring Gravitational Waves – Rana Adhikari of LIGO
https://blog.ycombinator.com/the-technical-challenges-of-mea...
[+] [-] z3t4|6 years ago|reply
And here I am on a blue planet, surfing the web.
[+] [-] Khelavaster|6 years ago|reply
[+] [-] narrator|6 years ago|reply
[+] [-] mhh__|6 years ago|reply
[+] [-] SiempreViernes|6 years ago|reply
[+] [-] izzydata|6 years ago|reply
[+] [-] lolc|6 years ago|reply
I recently read an article deploring the missing confirmation of the mergers through light-based astronomy. I can't find the article now, so I'm just going to list another one: https://www.newscientist.com/article/mg24032022-600-exclusiv... Has anything changed from what is described in the article?
[+] [-] kryptiskt|6 years ago|reply
[+] [-] unknown|6 years ago|reply
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