# I Gravitational waves as means for communication

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1. Apr 7, 2016

### Karlox

Hi all, this is my first post so before my question I want to show my appreciation to this community for offering a great framework to talk physics between experts and others who chose different life career paths, such as me. I have always loved physics but the math... not that much. English is not my native language, so if at some point I don't make myself clear feel free to correct me.

From my understanding gravitational waves travel through spacetime itself, the 'fabric' in within which our reality exists. Therefore, gravitational waves travel through matter contained in the universe (spacetime) 'as if it wasn't there'.

If I am not terribly wrong with the pressumption above, an advanced civilization that could somehow generate this waves artificially, even if it was just at an infinitesimal scale, could use them to communicate with far away realms, since there is virtually almost no ressistance, interference or decay in the wave as it 'flows' towards the receptor.

Is this conceivable? Shouldn't we humans try build a sensor as accurate as technology allows to try to pick something artificial up? Maybe SETI has been listening at the wrong channel?

thank you,
I don't know how the preffixes work, does intermediate fit?

2. Apr 7, 2016

### Orodruin

Staff Emeritus
This should also tell you that gravitational waves are extremely hard to detect. Consider the fact that the merger of two black holes which released several solar masses worth of energy in gravitational waves resulted in a strain which was $10^{-21}$ at Earth. It is simply not feasible to generate any sizeable gravitational waves artificially for communication purposes.

Prefixes should specify your level of understanding so that answers can be directed towards that level.

3. Apr 8, 2016

### fizzy

Banging two black holes to together is the kind of thing super-intelligent, pan-dimensional beings like, the white mice, do from time to time to study human behavioural responses. [ see Douglas Adams for more details. ]

4. Mar 15, 2017

### Agliomby

My thinking is that the discovery of gravitational waves is something like the discovery of light waves outside the visible spectrum (for instance radio waves) and could in time have as big an impact. The manipulation of radio waves for communication did take some decades, perhaps only perfected recently. Similarly detectors and generators of gravity waves may be used for communication.
Given that they are postulated as ripples in space time, is there any reason gravity waves must be limited to the speed of light?
I wonder that a potentially monumental discovery, while trumpeted by cosmologists, is being missed by the general public.
It needs to be stressed that I have deep interest in this field, but shallow expertise.

5. Mar 15, 2017

### Chronos

There is no good reason to believe the speed of gravity is any different than c and plenty of reasons to believe it is the same. Assuming gravity is mediatied by a massless partice [graviton] GR insist it can only travel at c. While a confirmed direct measurement has not yet been achieved, binary pulsars suggest gravity does indeed propogate at c, as discussed in this paper; https://arxiv.org/abs/1703.00307, Limits on the anomalous speed of gravitational waves from binary pulsars. It appears safe to assume gravity is not a good candidate for FTL communication. For communication at the boring speed of c, neutrinos look more promising. Like gravity they too appear virtually immune to interference or attenuation. They also demand considerably less power than gravity waves.

6. Mar 16, 2017

### nikkkom

It is incredibly difficult, probably not feasible even for very advanced civilization.
If some advanced civilization does need very penetrating communication methods, neutrinos are a better choice than grav waves. For relatively short distances, such as 100 km, even we, today, can send a crude neutrino signal and detect it.