Can We Extract Energy From Gravitational Waves?

[Tom Kirkman + 8,860]

Some unusual reading material.  Good for poking one's grey cells a bit, if you are bored.  Good graphics, too.

Ask Ethan: Can We Extract Energy From Gravitational Waves?

Whenever any two things in the Universe interact at the same location in spacetime, one thing always remains true about that interaction: it conserves energy. But what if one of those things is an entity inherent to the fabric of spacetime itself, like a ripple, also known as a gravitational wave? When a gravitational wave interacts with matter, energy, or a complex apparatus like a gravitational wave detector, can the wave itself transfer energy into whatever it's interacting with? It's a fascinating thought, and it inspired Patreon supporter Paweł Zuzelski to ask the following question:

When we detect an electromagnetic wave (be it a radio antenna, an eye or a camera sensor) we extract energy from the wave. Does the same happen for gravitational waves?

It must be so. Here's why.

This graph, of photon energy as a function of electron energy for an electron bound in a zinc atom, establishes that below a certain frequency (or energy), no photons are kicked off of a zinc atom. This is irrespective of intensity. However, above a certain energy threshold (at short enough wavelengths), photons always kick electrons off. As you continue to increase the photon energy, the electrons are ejected with increasing velocities. WIKIMEDIA COMMONS USER KLAUS-DIETER KELLER, CREATED WITH INKSCAPE

It might seem counterintuitive, because we use the term all the time, but what does "energy" actually mean? There are many ways to define it, but physics is always interested in the quantitative meaning of terms: "what is it doing" and "by how much" are the answers that we hope a good definition will reveal. For energy, some of the more common ones are:

• energy is the amount of power that comes into or goes out of a system sustained for a period of time,
• energy is the ability to perform work (to exert a force that pushes an object a certain distance in the direction of the force), or
• energy is what's required to cause changes in the motion or configuration of a system.

It comes in many different forms — potential (stored), kinetic (of motion), chemical (of electron bonds), nuclear (released from atomic nuclei), etc. — but it's universal to all forms of matter and radiation.  ...

 

... Well, if that's how electromagnetic waves work, then what about gravitational waves? There are some similarities between the two of them, as both are generated when a charged particle (either electrically charged or massive, i.e., "gravitationally charged") moves through a changing field (either electromagnetic field or gravitational field, i.e., curved space). Electrons in a particle accelerator generate light; black holes orbiting one another generate gravitational waves.

But there may be differences, too. Electromagnetic waves exhibit inherently quantum behavior, as the energy in those waves is quantized into individual photons that compose this light. Gravitational waves may exhibit quantum behavior, and these waves may yet be quantized into individual particles (gravitons) composing these waves, but we have no evidence for this picture and no practical way to test for it.  ...

< interesting gif too big to post on this forum >

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(much more in the link)

 

[markslawson + 1,057]

On 5/9/2020 at 8:48 AM, Tom Kirkman said:

Ask Ethan: Can We Extract Energy From Gravitational Waves?

Only just saw this.. it may be possible to extract energy from gravitational waves but I doubt whether it would be worth the trouble to do so.. such waves went undetected for a long time because they are so hard to detect. The instrument that eventually detected grav waves cost billions.. makes even a single PV panel look good by comparison and that's saying something.. 

[specinho + 457]

On 5/9/2020 at 6:48 AM, Tom Kirkman said:

Gravitational waves may exhibit quantum behavior, and these waves may yet be quantized into individual particles (gravitons) composing these waves, but we have no evidence for this picture and no practical way to test for it.  ...

gravitational force has been used e.g. in micro hydro electrical projects.............. But the cousin, wave........... Shall energy is required to accelerate object or particle before it can do anything small like showing signal or energy, it might be likely costly  and good for fun at the labs.....??