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The original title of this article is: "Mathematicians confirm the possibility of data transfer via gravitational waves." (October 2018) I think the word "Math
by tobinfricke 6y ago
The 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?
- tobinfricke 6y agoI think you might be confused about what we mean when we say that gravitational waves are "small." Their amplitude is small. I suppose the wavelength can be anything, but the wavelengths of gravitational waves generated by known physical processes are large. This is because frequency and wavelength are inversely proportional, and things need to be moving wicked fast (high frequency) to get a short wavelength: lambda=c/nu, where lambda is wavelength, nu is frequency, and c is the speed of light in vacuum. If two black holes are spinning around each other 50 times per second (which is already crazy to think about), then they will generate gravitational waves at 100 Hz, which have a wavelength of (3e8 m/s)/(100 1/s) = 3e6 meters. Three million meters. Next: What do you propose is going through the double slit experiment here? The gravitational wave? Matter is transparent to gravitational waves, so it would be difficult to build such a double slit experiment. As another poster here mused, you could probably make some kind of interesting meta-material analogous to a crystal lattice and get some interesting gravitational-wave diffraction pattern. But I'm not sure if this is what you're getting at. The point of the famous double slit experiment for photons is that it shows the dual wave/particle nature of photons (or other elementary particles like electrons). Since we don't have a quantum theory of gravity I suppose it's an open question what the outcome of such an experiment with gravitational waves would be.
- qubex 6y agoI think the OP is musing about the idea that as it passes through a micro double-slit setup, a gravitational wave would alter the distance between the slits, and thus alter the interference pattern. Basically an interferometer.