The Action Lab: Energy Density in a vacuum, Temperature in a vacuum in a box

The Action Lab: What Is The Temperature in a Vacuum Chamber? Is it Hot, Cold or Neither? at https://www.youtube.com/watch?v=-hTAr2GkhpM

There are three fields inside your box after the air is removed. There is an electromagnetic field in equilibrium with the walls of the box, and with the light and electromagnetic waves in the room. If you shine a strong light on the thermometer you can heat it up. The spectrum of all those electromagnetic sources include infrared, visible, some ultraviolet, TeraHertz, and many many human and natural sources of “radio”, “television”, “cell phone”, “computer”, “wireless”, “bluetooth”, power system. The list if very long. The total energy density from those sources is what is normally connected to the “radiation temperature” inside the box. If your “thermometer” does receive or detect those the freuquencies of those many radiation sources, it will not show the full “temperature” of the field inside the box.

Since the temperature of surfaces in the room is roughly room temperature, one would expect the vacuum in the box to eventually come to that temperature. The energy density of those sources is roughly (4*StefanBoltzmannConstant*T^4)/SpeedOfLight. At 300 Kelvin that is about 6 microJoules/meter^3

The box contains “magnetic field” from the earth as a whole, from the magnetosphere. And this will change constantly. The energy density from “magnetic” sources is relatively small. That is calculated by B^2/(2(mu0) where B is in Tesla. and mu0 is the magnetic permeability of the vacuum. The Earth magnetic field is about 65 microTelsa. That energy density is about 1.68 milliJoules/meter^3

The box contains a very powerful gravitational field. We do not normally think how fine grained and powerful it is to do the work that it does. But it has an energy density based on the acceleration is can produce. That is g^2/(8*pi*G) and for g = 9.8 meters/second^2, that is 5.72540968E10 Joules/meter^3 or roughly 565,000 atmospheres. The radiation temperature of the gravitational field is about 1500 electron Volts so it is in the soft x-ray region but covers the TeraHertz and other parts of the spectrum. The gravitational spectrum will vary according to the materials near the detector. The gravitational field is many ways like a supercritcal fluid or superfluid. It permeates all matter at the surface of the earth, down to much smaller than an electon size. The “stuff” that makes up the gravitational fluid is very likely the same as the “stuff” that makes the magnetic field.

When they do the laser vacuum experiments, it will cause the vacuum to “cavitate”. That is my simple way of thinking of the laser heating the vacuum to where it forms single or multiple particles. The big accelerators do that all the time, usually where there is matter (particles or fields) to make the strong magnetic gradients needed. It is no coincidence that the gravitational field can be “slowed” or “nullified” or reversed by magnetic gradients. The force of a magnet is from the magnet field strength times the gradient. You can use a permanent magnetic to provide the magnetic field and then add strong electromagnetic gradients.

There is a lot I would like to know about the picometer and attometer properties of the gravitational field. For most everyday situations, it is easiest to think of a global radiation field, where the XUV and soft x-ray portion is “gravitational”, the infrared downto microwave is “heat” and all the frequencies are detectable now and there are groups who can tell you what each part is doing. To put it all together, after 45 years working at it, ,my recommendation is to use the energy density, and keep measuring and cross checking. If you would not wave hands, but put your hands to doing calculations, you can do science that will benefit the roughly 5 billion humans using the Internet.

I am trying to work out how to lift the SpaceX Starship or smaller or larger things to orbit using these magnetic gravitational methods. I call that “gravitational engineering”. And we finally have sensors and models and people enough to sort it out and do “engineering”, not guesswork. The box is connected to the ground, so there will be energy because of vibration, earth tides, seismic activity and motion of matter in the atmosphere, plus people waking around disturbing all the fields. It is possible to sort out, just a bit tedious sometimes.

Richard Collins, The Internet Foundation