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It could be possible to transfer data through gravitational waves (2018)
- trenchgun 6y agoProbably not the most practical way to transfer data though.
- nkrisc 6y agoI was just thinking the same thing, given the mass required (orbiting black holes) to generate waves that can just barely be detected by kilometers long detectors, there's going to have to be some significant developments to make this practical. Theoretically it's very interesting, however.
- newsbinator 6y agoYou may not need orbiting black holes. We can now generate radio waves in a pocket-sized device, without involving celestial objects. We only just recently managed to detect gravity waves at all, and it took several kilometers of vacuum tubes to do it. There’s a lot of room for discovery and miniaturization left.
- username90 6y agoDetectors are much much much cheaper to build than transmitters, humanity will never build a detectable gravity wave transmitter unless a new breakthrough on the scale of quantum mechanics is discovered or we have access to many orders of magnitude energy than we have today. The main problem is how weak gravity is, two electrons have a greater influence on each others movement than two 1 kilogram objects at the same distance has. So unless we figure out a way to decouple gravity from mass we will never solve this problem, and doing that isn't possible with the theoretical physics we have today.
- nkrisc 6y agoI didn't say we'd need black holes not any celestial object. Either we'd need a transmitter with as much mass or energy as black holes, or we need to improve our detection by many orders of magnitude. Sure it's theoretically possible, but it doesn't seem very likely any time soon. As I said in my post you replied to: > there's going to have to be some significant developments to make this practical.
- contravariant 6y agoWell unless you're willing to burn a few solar masses of energy on a message that is nigh impossible to block.
- emerged 6y agoThe medium is the message. The mere fact that a message was sent this way tells you all you need to know about the sender.
- deleted 6y ago[deleted]
- p1mrx 6y ago"I like gravity."
- AtomicOrbital 6y agoPurely because it is so difficult to modulate gravitational waves it's a great medium through which Uber tech societies could communicate
- hexbinencoded 6y agoIn the case of no line-of-sight, yes, but lasers would be more effective.
- yodon 6y agoLasers are great for transmitting, but not great for being received at interstellar distances. The person (being?) at the other end is looking at your solar system through a telescope that they use as part of their photo detector communication system. There's a huge bright star they can see (the sun that you and the planet your laser is on are orbiting), and there is this little tiny laser also shining towards them, its beam completely hidden in the light from the star. It doesn't matter how big your laser is, from a practical standpoint it's still tiny compared to the brightness of that sun you're orbiting. This problem is well understood and is why SETI primarily uses radio telescopes rather than regular optical telescopes to look for signals.
- yodon 6y agoOf course you can transfer data through a gravitational wave. I had a long series of conversations about this with Rai Weiss (of LIGO fame) back in the mid 1980's when I was an undergrad with a crazy idea to turn a cyclotron or synchrotron accelerator into a high frequency gravitational wave generator. The question isn't whether a wave can carry information, it's how you can modulate the carrier wave when the carrier wave is a gravitational wave generally requiring a pair of closely orbiting black holes to produce. I learned a ton of math and physics in the process of asking whether you could turn CERN or the superconducting supercollider into a gravitational wave generator, the most interesting being that conventional laboratory proposals for rotating bar gravitational wave generators and high frequency accelerator based gravitational wave generators are both in the end limited by the same quantity, the physical strength of materials. If you try to spin a bar faster than the point where its tip velocity is moving at roughly the speed of sound in the material, the bar will be ripped apart because the centrifugal force exceeds the tensile strength of the material, and if you try to increase the number of electrons or protons too high in the bundle being accelerated in your accelerator, you are similarly ultimately limited by the physical strength of the magnets responsible for bending the path of the particles into a circle. The other interesting observation is that the rotating bar obviously has a much higher mass (technically quadrature moment) than you can get circulating in an accelerator, but the angular velocity of the accelerator is so much higher and the exponent on the angular velocity term in the gravitational wave strain calculation is so high (fifth power? I forget, it's been many years) that the magnitudes of the strain producable in a laboratory setting by a rotating bar and by an accelerator are actually very close (and both, unfortunately, are too small to be of interest). When I went to grad school, my explicit interest was to build a tiny detector to look for high frequency gravitational waves on the grounds that if you wanted to communicate over Inter stellar or larger distances high frequency gravity waves were the best choice for avoiding the dispersion, scattering, and noise background that makes the the E/M spectrum a hard place to talk on long distances (essentially a variant on the SETI "watering hole" frequency choice but pushed into a different medium). I never had a design for a generator, but the idea was to build a table-top size Weber bar or laser interferometer tuned for the kind of high frequency waves you'd want to use for a communication system, and see if anybody happened to be talking on those channels.
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- basementcat 6y agoA Kardashev Type III civilization can just bang black holes together in a Morse code sequence. However that wouldn’t make particularly efficient use of energy or spectrum.
- Aperocky 6y agoWell, that civilization need a sport too. Flying 100s of huge dudes across the country for a football game isn't a particular efficient use of energy, neither is a Quidditch game with blackholes, all of galaxy tunes in with their gravity wave receivers for the games.
- hexbinencoded 6y agoEvent horizon surfing is probably a thing somewhere too.
- heimatau 6y ago> Well, that civilization need a sport too. This legit made me laugh. Thanks for this.
- basementcat 6y agoI’ve read of one planet off in the seventh dimension that got used as a ball in a game of intergalactic billiards. Got potted straight into a black hole. Killed ten billion people. Yes, only scored thirty points too.
- segfaultbuserr 6y agoAll of galaxy tunes in with their new gravitational wave receivers that their scientists just built, and got a bunch of spam messages on rocket booster enlargement, and how you can contact a prince in Alpha Centauri to claim some money... I've seen a short story based on this plot...
- segfaultbuserr 6y agoLiu Cixin, the author of The Three Body Problem had a short story (2002) on communication with gravitational waves. In a distant future, just before the human started the largest, continent-scale particle accelerator (capable of reaching 10^20 GeV) to collect the final data for the Theory of Everything (ToE), an alien agent Risk Eliminator intervened at the last second and dismantled the accelerator, transforming it into a bunch of trees and grass. The alien told humans that the experimental verification of Theory of Everything was extremely dangerous - This was the experiment that triggered the Vacuum Decay [0] event and destroyed all galaxies in the previous universe. Despite the existential risk that was clearly known prior to the experiment, all civilizations in that universe believed discovering ToE was the ultimate peruse of intelligent life (evolution took a different path), it was allowed to proceed and destroyed the universe. As their brain was the ultimate supercomputer, there were speculations that that civilization found the ToE in the last microsecond before destruction, it was unlikely. Nevertheless, the experiment was designed to transfer data via powerful gravitational waves as a one-way broadcast, which preserved the history of their existence and the experiment. Being the first scientific civilization of the current universe, the Risk Eliminator's world received the gravitational waves from the previous universe before it was dampened out to undecodable level, successfully reconstructed the data and derived the ToE. Since then, their civilization was known as the Risk Eliminator, and their goal was to silently monitor all intelligent lives, and to destroy all ToE experiments when necessary - evolution took a different path, unlike the previous world, not everyone valued the ToE, such as experiment would be unjust to other civilizations. The human civilization, or any other civilization, was also forbidden to learn the ToE. First there was the Star Trek-style principle that forbids the transfer of any technical knowledge from a civilization to another, which was well understood. But it's still forbidden even when said civilization already had the capability to derive the ToE experiment via experiment due to practical reasons - it was too risky. The practical applications of ToE would allow a civilization to manipulate an even higher energy level - the energy level reachable by a pre-ToE civilization was already deadly. Also, ToE showed the existence of parallel universes, and that the ToE was only a limited model within an individual universe. The curiosity of the intelligent lives may lead them to start researching super-ToE in experiments with even higher energy level, and this could destroy not one, but multiple universes, which was unacceptable. Finally, the human physicists and the Risk Eliminator made a deal - similar to how the civilizations in the previous universe may have found the ToE in the last microsecond, the human physicists who saw ToE as the lifetime goal could be allowed to learn it in a lecture, but after they've understood the lecture, they would be killed in a giant plasma fireball. Many prominent physicists agreed. After it was on the news, other researchers, such as some mathematicians who wanted to know the proof of the Goldbach's conjecture, or paleontologists who wished the learn the true reason that caused dinosaur to go extinct, also joined the party. The last physicists who went to the lecture was Stephen Hawking. "What is the purpose of the universe?" "How the heck should I know? You are allowed to leave, Professor." [0] https://en.wikipedia.org/wiki/False_vacuum https://en.wikipedia.org/wiki/False_vacuum
- mdifrgechd 6y agoLike another poster, I had this thought some time ago. What I wondered was if there is a gravitational equivalent to metamaterials (in electromagnetism, periodic structures that have specific bulk properties not otherwise achievable), that could be used to focus gravitational waves is some useful way. I remember reading that the overall power radiated as gravitational waves by the earth orbiting the sun is in the tens of Watts, so they are probably to weak to be practical however produced.
- pa7x1 6y agoWe don't think so, a very important property of gravity is that it interacts with everything in the exact same way. This property is behind Einstein's Equivalence Principle and in turn on our ability to interpret gravity as curvature of spacetime. Metamaterials with special properties under the gravitational interaction would break this. On the other hand, violations of the Equivalence Principle could point into ways of achieving it.
- croissants 6y agoDumb question, is the idea that gravitational waves are not very common from natural sources, so there's less...interference? I didn't get why this method of communication is somehow special (beyond being theoretically interesting)?
- tobinfricke 6y agoIt's special because it's a different field. Radio/light are oscillations of the electromagnetic field, and sound is an displacement in a physical medium. This is an entirely different medium: the metric tensor of spacetime itself. And the universe is, by and large, completely transparent to gravitational waves. So these signals would not be blocked by intervening matter. A similar thing could be said about the prospect of sending messages using neutrinos. But it is only just now barely possible to detect the loudest gravitational wave signals with extreme difficulty and machines costing on the order of a billion dollars. It will remain impossible for humans to generate gravitational wave signals of a detectable amplitude for the foreseeable future. Source: PhD in gravitational wave detectors.
- ry454 6y agoA lame question from someone who barely remembers college-level physics: isn't that "electromagnetic field" just waves in the spacetime metric-tensor?
- tobinfricke 6y agoThe electromagnetic field is a function F(x), where F is the field tensor (which groups together the electric field E and the magnetic field B) and x is the position in space. Maxwell's equations tell you how F (or E and B) evolve in time, and give you wave-like solutions. In a continuous medium like air, water, or a solid, you could describe a "displacement field" d(x) that tells you how far the piece of material that used to be at position x is displaced from its equilibrium position. This is governed by the equations of physical acoustics, which also have wave-like solutions: sound. The Riemmann curvature tensor R is a function R(x) of spacetime coordinates x, which tells you the curvature of spacetime at location x. Einstein's equations tell you how R evolves, and it also turns out to have wave-like solutions: gravitational waves. In radio, it's F (or E and B) that's waving. In gravitational waves, it's R. What's confusing is that R also tells you "the shape of space," and you need to use it to figure out "where" the coordinate x corresponds to.
- tobinfricke 6y agoThe original title of this article is: "Mathematicians confirm the possibility of data transfer via gravitational waves." (October 2018) I think the word "Mathematicians" here is pretty important. :-) No physicist doubts that gravitational waves can transfer information, but we all doubt that it will ever be practically possible to generate gravitational waves of an amplitude that we can also detect. For what it's worth, here is the paper that this press release is touting: https://iopscience.iop.org/article/10.1088/1361-6382/aace79 https://iopscience.iop.org/article/10.1088/1361-6382/aace79 The abstract: "A definition of an affine-metric space of the plane wave type is given using the analogy with the properties of plane electromagnetic waves in Minkowski space. The action of the Lie derivative on the 40 components of the nonmetricity 1-form in the 4-dimensional affine-metric space leads to the conclusion that the nonmetricity of a plane wave type is determined by five arbitrary functions of delayed time. A theorem is proved that parts of the nonmetricity 1-form irreducible with respect to the Lorentz transformations of the tangent space, such as the Weyl 1-form, the trace 1-form, and the spin 3 1-form, are defined by one arbitrary function each, and the spin 2 1-form is defined by two arbitrary functions. This proves the possibility of transmitting information with the help of nonmetricity waves."
- ry454 6y agoCan we just use a variation of the double-slit experiment? Gravity waves modulate distance between two quantum-scale slits and that in turn changes the interference image, that can be captured at a relatively large distance to magnify the otherwise quantum-scale pattern.
- tobinfricke 6y agoWe don't have to involve quantum mechanics here at all. In fact, we don't yet know how to combine general relativity and quantum mechanics.
- ry454 6y agoSure, but what would actually happen in the experiment I've described? I admit that perhaps those gravity waves are so tiny that even a nanometer-scale double-slit device would be too large, but if we had some hypothetical material (not atom based with those fat electron orbitals), that we could construct a 0.001nm wide device with two 0.000001nm wide slits, would it produce the interference image?
- ChuckMcM 6y agoSalesman slaps a black hole, "When you modulate this baby you can send a signal clear across the galaxy!" That you can detect a modulation on a wave, and thus transfer information, is something of a tautology, the tricky bit is modulating gravity. If you can do that we're in a whole different ball game and sending data is probably the least amazing thing you can do with that capability :-)
- kijin 6y agoThe movie Interstellar was based on the premise that one can modulate gravity. What does Matthew McConaughey do as soon as he learns how to do it? (Spoiler alert) He sends data to his daughter. It's almost like human nature. If anything can be used to send data, we will send data, no matter how inefficient. We will send an entire ICBM with a thermonuclear warhead to send the rather low-entropy message, "Do as I say, or else."
- sterlind 6y agoIf you're sending an ICBM, you're done talking.
- DarkmSparks 6y agoa single ICBM probably doesnt have enough energy to even get a dial tone.
- virgulino 6y agoMaybe not only human nature? https://xkcd.com/1642/ https://xkcd.com/1642/
- person_of_color 6y agoHow are UFOs travelling FTL?
- AlexDanger 6y agoImagine the applications for the military and the intelligence services; - Completely bypass any EM shielding / faraday cages designed to stop spies / bugs from transmitting information out of secure facilities - Transmit information out of underground facilities or caves deep in Afghanistan without worrying about RF attenuation. Indeed, communicate anywhere in the world (or under the sea) without worrying about RF attenuation. Bypassing the limitations of sending information by RF would be hugely advantageous for the military and intelligence services. The resources of the military industrial complex are staggering. What is the state of the art in unclassified technology regarding generating these waves and modulating them? What would be required to make such transmitters/receivers practical? A breakthrough in materials / fabrication technology? It sounds like the theory is solid, and it's a now an applied science problem?
- klunger 6y agoIn that case, you would need to be the only actor who has the technology. Otherwise you have to worry about all the issue you cited again.
- deleted 6y ago[deleted]
- 3tmnw 6y agoIf it takes huge amounts of energy to create the signal, won't we already 'see' the other civilization anyway when stars disappear because their matter is turned into energy to create the gravitational waves?
- omnibrain 6y agoI can‘t remember the details but I think I may have read a (hardish) science fiction story where gravitational waves got used to communicate with a parallel universe.
- tinus_hn 6y agoIs gravity limited by the speed of light?
- jordz 6y agoYes https://www.newscientist.com/article/dn3232-first-speed-of-gravity-measurement-revealed/ https://www.newscientist.com/article/dn3232-first-speed-of-g...
- danbruc 6y agoWith the stiffness of spacetime being orders of magnitude higher - I found claims of 20 as well as 100 orders of magnitude, no idea what the correct value is - than the stiffest known materials, one would have to bang on spacetime pretty hard to produce a measurable signal.
- thro1 6y ago1973, Larry Niven: "The Hole Man" https://en.wikipedia.org/wiki/The_Hole_Man https://en.wikipedia.org/wiki/The_Hole_Man: "In this story, a team of explorers and scientists on Mars encounter an alien base, in which there is a still-functional communication device. One scientist believes that at the center of the device is a tiny black hole.." (Niven didn't know yet about Hawking radiation discovered next year..)