From what I know, gravitational waves are produced when accelerated massive bodies move through space-time and create ripples in the gravitational fields throughout the space-time. This is significant on a cosmological scale. What about in small scale experiment? Is it possible to produce gravitational waves using some amount of a gas in a very small volume of space?
[Physics] Is it possible to produce gravitational waves in a very small space using some gas? If so, how
gravitational-waves
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Gravitational waves are generated in a manner analogous to electromagnetic waves.
Classically, changing electric or magnetic fields can generate electromagnetic waves, a radio antenna being a good example, and also radiation is emitted by accelerating or decelerating particles. Maxwell's equations are "simple" enough as one is dealing with vector fields. This is reflected in the quantum mechanical carrier of the electromagnetic field, the photon, which has spin one.
In General Relativity the mathematics is more complex, still, gravitational waves are expected for "changing gravitational fields" , in quotes, because the gravitational field emerges from the space curvature posited by GR. Since one is dealing with tensor fields , the quantum mechanical carrier (in the effective quantizations of gravity used up to now) is the graviton of spin two.
gravitational waves transport energy as gravitational radiation. The existence of gravitational waves is a possible consequence of the Lorentz invariance of general relativity since it brings the concept of a limiting speed of propagation of the physical interactions with it. By contrast, gravitational waves cannot exist in the Newtonian theory of gravitation, which postulates that physical interactions propagate at infinite speed.
This illustrates the space distortions as the wave passes:
The effect of a plus-polarized gravitational wave on a ring of particles.
So, as with electromagnetic waves,
In general terms, gravitational waves are radiated by objects whose motion involves acceleration, provided that the motion is not perfectly spherically symmetric (like an expanding or contracting sphere) or cylindrically symmetric (like a spinning disk or sphere). A simple example of this principle is a spinning dumbbell. If the dumbbell spins like a wheel on an axle, it will not radiate gravitational waves; if it tumbles end over end, as in the case of two planets orbiting each other, it will radiate gravitational waves. The heavier the dumbbell, and the faster it tumbles, the greater is the gravitational radiation it will give off. In an extreme case, such as when the two weights of the dumbbell are massive stars like neutron stars or black holes, orbiting each other quickly, then significant amounts of gravitational radiation would be given off.
So under certain conditions an accelerating mass can radiate gravitational waves. The effect on planetary orbits , though present due to the emission of gravitational waves, is very small , because of the great weakness of gravity.
Gravitational radiation is another mechanism of orbital decay. It is negligible for orbits of planets and planetary satellites, but is noticeable for systems of compact objects, as seen in observations of neutron star orbits.
For a vibration to exist, something has to vibrate. In the water vibrations it is water molecules. In light it is electric and magnetic fields that vibrate.
In gravitational waves it is the space itself that changes , (x,y,z,t) between points becomes larger and smaller and the wave is seen as a distortion of the ring of partilces, the image is of one wavelength passing.
The mainstream gravitational theory is General Relativity which assumes that what we called gravitational field is an effect on the space time fabric created by the presence energy and masses. The space itself is constructed by the existence of these. Gravitational waves arose from the solutions of the differential equations of general relativity for specific boundary conditions. The "medium" you are looking for is space time itself.
Best Answer
Yes, even waving your hand creates gravitational waves. But the waves produced by non-astronomical sources are far too weak to detect.
The relevant formula for calculating the metric perturbation is the quadrupole formula in case you want to try out a particular scenario. For example, suppose we suddenly move 1 gram of gas by 1 centimeter in 1 microsecond. The metric perturbation 1 meter away is on the order of $10^{-39}$.
A device like LIGO can detect metric perturbations as small as about $10^{-21}$, so it would need to be made 1,000,000,000,000,000,000 times more sensitive and shrunk down considerably.
Physicists spent a billion dollars of taxpayers’ money building LIGO because they knew, based on this formula derivable from Einstein’s field equations, that a tabletop experiment would not work. And now we have a way of observing some of the universe’s most amazing events, like the merger of two black holes, rather than just observing something boring like a bit of gas moving in a lab. A new era of astronomy has begun. We can now study gravity under extreme conditions, and perhaps eventually find that General Relativity needs corrections.