Gravitational engineering, invisible matter and energy, not only “dark”.
Ben,
I worked out the mass of “dark energy” that makes up gravity. It is not “dark” which implies a lack of intensity of light. Rather it is “invisible” or “not in the visible part of the spectrum”. Most of the mass of the gravitational energy density field is in the ultraviolet, extreme ultraviolet, soft x-ray and other “invisible” parts of the electromagnetic spectrum. There is a lot of “dark matter” that has little visible light. But much of that will slowly emerge as we view with other parts of the electromagnetic spectrum like UV, IR, mmwave, microwave, radio, and frequencies down to attoHertz and smaller. Gravitational force has mass. You calculate the gravitational energy density, and convert that to mass units. At the surface of the earth the mass comes to about (5510/6 = 918.3) Kilograms/meter^3. It has very little viscosity and we work in air, so it is not apparent until you get to “relativistic” or “Bremsstrahlung” energies and accelerations. Black holes hide visible light from the interior, it is not in the visible frequencies but can be seen using gravity. Those groups are not on my priority list, because they work on things that benefit the human species almost not at all.
“invisible energy” and “dark or too bright matter” would be close to the normal situation = energy that humans cannot see, and matter that is too dim or too bright for human eyes.
Particle-antiparticle pairs will be invisible but have mass and they are stable. Cold matter at microKelvin or nanoKelvin temperatures would only be visible at frequencies below radio waves. E = h*frequency = h*c/wavelength = k*Temperature_Kelvin, in SI units where h is Planck’s constant, k is Boltzmann’s constant, and c is the speed of light and gravity.
When you think about it, that makes a lot of sense. The UV, XUV, EUV, soft x-ray and infrared spectrum (it does go down into the IR, THz, mm wave, radar, microwave and regular electromagnetic part of the spectrum, down through the audio range (electromagnetic waves with frequencies in MHz down to Hertz and milliHertz, microHertz, nanoHertz and smaller) But those are usually spread out. Lasers with infrared frequencies but high power, Radar and radio beams with high energy density, pulsed electromagnetic fields of many sorts — can heat and move things. The “gravitational engineering” field I defined covers things like using those new fields for sensing, 3D imaging, communication, power transmission, creating and manipulating and using powerful 3D electromagnetic fields to move things, compress things, cut things. The example I have been using is to use electromagnetic fields to beam power to Starship second stage so it does not have to carry all that weight of chemical fuel and cryogenic oxygen. Eliminating the whole first stage and the cost of carrying fuel to the moon to use for slowing down and landing.
So when you hear “dark matter” or “dark energy”, in your mind translate that to “matter with little or no electromagnetic energy in the visible region: or “energy is not in the visible region of the electromagnetic spectrum”. An infrared beam would be invisible, but would burn through steel. A UV beam or soft x-ray beam of high intensity would burn you and you would never see it by human eyes that mostly only pick up “visible light from 300 to 900 nanometers wavelength.
I keep repeating that the gravitational field at the surface of the earth is equivalent in energy density terms to a magnetic field of 379 Tesla. Magnetic fields are invisible, because they use IR, UV, soft x-ray and other frequencies, down to very tiny fields and long wavelengths. I use B^2/(2*mu0) = g^2/(8*pi*G) in SI units to make routine estimates of fields. B = g* sqrt(2*mu0/8*pi*G)
B_Tesla = g_meterspersecondsquared * 38.7 Telsa/(m/s^2)
For g = 9.8 meters/second^2) that is about 379 Tesla.
So magnetism and magnetic forces and gravitational forces are all just part of one field. Using one consistent set of units for all things (SI, Standard Internet, Systeme International) saves a LOT of time and effort and show that many things are related and the same, even if people use a lot of human and jargon languages to describe them. It took me 45 years to sort out, mostly because I had to learn and test and check every existing set of units for each part of the electromagnetic spectrum and many applications of electromagnetism. I really disliked those “gravitational” groups that used arcane mathematics, symbols like magic, and smoke and mirror techniques. When they should have used engineering best practices. I started out at Case Institute of Technology, rather than MIT, or Carnegie or Berkeley, or CalTech – (I could have gone to any of them) because it was practical engineering, not academic “paper mill”.