# Nancy Grace Roman Galactic Plane Survey – Gravitation signals from many alien civilizations

Nancy Grace Roman Space Telescope, If I were going to look at the Galactic Plane now, I would look for evidence of civilizations of two types. The human species is going to produce intelligent machines. Their size and shapes and abilities are open. But in terms of human knowledge one very likely outcome is that human knowledge, in machine form, could last forever. Or at least a few million years. Maybe longer. The intelligent machines of humans could populate a galaxy. The intelligent machines of any organic or inorganic species that evolves naturally, then produces intelligent machines — those machines can colonize a whole galaxy.

At (1/10) C (1 light year in 10 years) it would take a million years for human knowledge to travel across the 100,000 light years of the Milky Way Galaxy. There are a lot of million years in the life of the Universe of galaxies we can see now. So any galaxy that produces one species of our ability to produce machine intelligence, could likely turn that skill to sending machines to all parts of their galaxy – if they think in terms of what can be accomplished in a million years.

At (1/(10*1000) C it takes 1000 Million years. So even at (2.99792458E5 km/second)/10000 = 29.9792458 km/second, a species like humans could send intelligent, self-reproducing machines (and themselves) to all parts of a galaxy the size of the MWG.

Now humans, or organic/inorganic naturally evolved intelligent species can get to nearby stars if they are willing to make one way trips. Or work across human generations. They can send knowledge back. When humans have children, those children go their own way and might seldom call. Some human children leaving our heliosphere to travel and live near a close by sun can send messages home and receive messages over long distances, but energy being limited, they might beam the messages precisely and it would only be available to them. Point to point communication is more likely than broadcast.

Now our machine offspring would take a longer view, since with 3D printed offspring (SEMI can do it now in a broad sense), they could create entire civilizations in shorter time, live in space – do not require water or air, are more resistant to poisons and radiation.

Both of those kinds of intelligences can communicate. The machine intelligence (they way we created them) uses electromagnetism, nuclear and atomic skills. We also can use gravitational signals, in a few more years.

I would propose to look for gravitational signals, in the nanoHertz to GigaHertz range, which is accessible by todays gravitational, electromagnetic and quantum groups.

When I was studying gravitational and astrophysics and mathematics at University of Maryland at College Park from 1975-1979, Charles Misner was my advisor on paper. But soon after I met Joe Weber. Now the academic groups at that time (rather small number looking at gravitational technologies) blasted him because his early attempts at gravitational wave detection raised more questions than he could answer on his own. Rather than jumping in to help him, they stood around and did nothing. Joe told me that the purpose of his detector was to create communication systems and he described how that worked. But knowing the character of the people then, (or lack of character) he warned me NOT to follow him directly, but to follow Robert Forward. So I did. That was about 1977/1978. Robert Forward proposed a practical way to combine researchers working in gravitation, electromagnetism, and all the engineering fields – by mapping out a set of common units for all. He particularly suggested using the gravitational energy density as a starting point, and that is what I did. In the last 26 years, with the Internet Foundation, I have been promoting global and heliospheric common units and open formats for sharing all knowledge.

I worked with Steve Klosko at Wolfe Research and Development on the NASA gravitational potential models. I had already worked on satellite orbit determination to track all things in orbit in 1970, so I helped Steve to adapt new data sources and derive good estimates so he could run his full models. I would get it started and close enough, and he would go from there. It was a good partnership, because I created analytic and data driven models and only needed to get him within the convergence regions of his model. Now that is true of dozens of gravitational detection methods – atom interferometers, atomic clocks, Bose Einstein gravimeters, atomic force gravimeters, and now many kinds of entanglement, magnetic resonance and other technologies that have already been adapted to measure or estimate 3D acceleration fields, or can be.

Now Robert Forward used the gravitational energy density as g^2/(8*pi*G) where g is in meters/second^2 and G in SI units. For g=9.8 m/s^2, the energy density can be calculated using Google search as (9.8 m/s^2)^2/(8*pi*G) = 5.72540968E10 Pascals or 5.72540968E10 Joules/Meter^3. Since the magnetic energy density is calculated from B^2/(2*mu0) you can solve for an equivalent magnetic field. Since both g and B are squared, they have a linear relationship and the constant can be calculated as 1/sqrt(8*pi*G/2*mu0) = 1/sqrt((8*pi*6.67430E-11)/(2*1.25663706212E-*6)) = 38.7076796657 Tesla/(meter/second^2).

So 9.8 (m/s^2) * 38.7076796657 Tesla/(meter/second^2) = **379.**335260724 Tesla. Over 46 years I followed out the implications and places where anyone used the magnetic energy density or where they tried to make magnetic fields at the surface of the earth clos to or exceeding **380 Tesla**. I only mention it here in case anyone reading this wants to try. I have written most of that down. Whether I do it or someone else, already you will find “gravitational engineering” and “speed of gravity” deeply embedded in the Internet with as many links and resources as I could find.

About 20 years ago, I used the network of superconducting gravimeters (SGs) to put a stronger bound on the speed of gravity. The signal at these stations is what I call “vector sun moon tidal signal”. It is a three axis signal that matches the signal at the SG stations almost exactly. It is vector GM/r^2 for the sun acting at the station minus the sun acting on the center of the earth, plus the moon acting at the station minus the moon acting on the center of the earth, plus the earth rotational (or earth moon barycenter) acceleration translated to station north east vertical. That is easy to do with Jet Propulsion Labs Horizon systems tools online. I made YouTube videos to show how to do that.

It only requires a linear regression of each axis, then the calibrated detector can be used to measure and report local gravitational potential events. The sensors measure the gradients of the changing gravitational potential. The earth signal is about +/- 1000 (nanoMeters/Second^2) and the residual is +/- 50 (nm/s2). Most of that is atmospheric, ocean, seismic, magnetic and electromagnetic. Gravitational arrays of this sort can image seismic sources in near real time. And calibrated sources can be used to calibrate new speed of gravity experiments and higher precision detector arrays. High precision arrays can image the surface of the sun (with radio telescopes) and the interior of the moon (I propose to do that as a quick check with earth based gravimeters arrays). Grav im et et is how I pronounce it. With “et” as in “I et eggs for breakfast”

The gravitational field in the solar system (at least for the earth for everyday gravitational engineering) is almost perfectly linear. To fit the SG data, only requires a linear regression for each axis. There are several groups who have made MEMS gravimeters (MEMS accelerometers with improved sensitivity, but three axis) and many of the broadband, three axis seismometers can operate as gravimeters and have a clear vector sun moon signal on all three axes. With time of flight methods, it is possible to use array methods to image.

The nonlinear effects are well known and models available for correcting. The gravitational potential changes the rate of atomic clocks and other types of detectors. There are groups making gravitational tensor detectors now. And all the groups can use essentially the same machine intelligence, correlator and “data engineering” methods. Those are exploding right now, I can write separately about those things happening on the whole Internet.

“Almost perfectly linear”. I found one readily accessible reference on Wikipedia that should be fairly stable. Under Gauss’s law for gravity, there is “Derivation from Lagrangian” it gives the Lagrangian density for Newtonian gravity” as two terms. One is the gravitational potential times the mass density (the gravitational potential we modeled at NASA and is now published once a month in accessible model form). The second term is g^2/(8*pi*G) where g = Grad(Phi) is the vector gradient of the gravitational potential. All these things are part of the practical “gravitational engineering” you need to move things and navigate from earth and in the solar system. It has to be precise and reliable or it is not engineering. I am fairly certain that is what Robert Forward was using.

https://en.wikipedia.org/wiki/Gauss%27s_law_for_gravity#Derivation_from_Lagrangian

There is a fairly high probability (in my mind at least) that much of what we ascribe to magnetism at frequencies below 1000 Hertz might be “gravitational”. In Aug 2017 there was merger of two neutron stars that is labeled in the gravitational wave community as GW170817. The merge started a race between the “gravity” signals and the “electromagnetic signals” that lasted 130 Million years. And the two signals arrived at the same time. To me that meant that the speed of light and the speed of gravity are identical. Not just close, but identical. And that can only happen if they share the same underlying potential field.

https://en.wikipedia.org/wiki/GW170817

The properties and behaviors of gravitational signals and electromagnetic signals might be different at different frequencies and different sources, but the potential is the same. At low frequencies, where the detector array is smaller than the wavelength it will be “near field” and timing matters. You use “time of flight” methods and geometry more and measure the power and events. And it means that gravity and electromagnetic signals will both cover the full range of frequencies.

There will be MHz gravitational signals, GHz gravitational signals, THz gravitational signals, nanoHertz gravitational signals and so forth. In accelerator, nuclear, atomic, chemical terms there are electronVolt (eV), Kilo_eV, Mega_eV, Giga_eV gravitational signals. All the units are consistent. And many of the systems for one group using one set of units can be readily connected and used by any other. Combining gravitational engineering with electrical engineering was not technical it was more administration and communication.

Now how are “gravitational” and “electromagnetic” signals different, if they have the same underlying potential? It is polarization mainly and frequency and energy density dependent, at least when you go to choose methods. I personally have been keeping in mind for about 50 years that “gravity is spin two” or “gravity is quadrupolar”. That is not very well taught, but it does work. If you go to nuclear data and look at nuclear transitions they can be monopole, dipole, quadrupole and higher moments. From chemistry I learned to calculate and use solutions of the Schrodinger equation. And those use orthogonal representations for 3D fields of any kind. Earth or atom or nucleus, you use the current best model from each field, convert units and connect them together where there is data to calibrate and inter-compare.

So most likely “gravity” at a tiny scale like inside the electron, or inside the atomic nucleus, or inside the electron shells of atoms is multipolar and that starts with dipole. And “dipole” will be an approximation you can use for engineering purposes then when you get to the details, you find groups with better or more useful models.

Much of the 26 years of the Internet Foundation, I have been finding all the computer and mathematical models (in symbolic and computational from) and translating all those into one universal (now I call it “global” since we are not off the earth yet, and “heliospheric” when writing about the near and further future) set of units that I call “Standard Internet” to extend and make SI available to all Internet users, in all human and domain specific languages

Looking at places with high energy density (the Earth’s gravitational energy density is approximately 1 KeV (Kilo_eV) as a radiation temperature. It peaks in the soft x-ray region and extends over the UV and to all frequencies. It is almost all multipolar, so unless you exactly match in timing and orientation, no binding. Same with fusion reactions. Those can be modeled easily with magnetic dipole and quadrupole potentials and binding energies.

At nuclear distances (femtometers) the magnetic dipole energy is attractive and 1/r^3 and vectors. So if you do the vector math and simulate, it works. But the speeds are such that it requires better methods for simulation. For “atomic and nuclear chemical reactions like fusion and fission” you can get pretty good engineering results with just the tabulated magnetic dipole values. They are supposed to be permanent and universal. The electron and proton and neutron magnetic moments, the muon magnetic moments are supposed to be stable.

And those allow for bonding between particles based solely on their magnetic and electric properties. Two electrons can bind by magnetic attraction and Coulomb repulsion. Two protons. A proton and electron can bind by electric (Coulomb) potential, and by magnetic dipole potential. An electron and positron. A proton and anti-proton, any two particles with magnetic moments can bind (size, speed, timing, energy — lots of very very very specific details).

I treasure a letter from Emilio Segre that I got in Jan 1981 where he encouraged me to work out the details of the positronium spectrum. Since he got his Nobel prize for the anti-proton, it caused me to look carefully at all particle-antiparticle stable bonding states.

Why is this important? Because it is likely that the action of the gravitational field at the surface of the earth (and elsewhere) is related to the individual collisions and relations between small particles. And if the gravitational energy density is any indication, the gravitational energy density sets the limit for those reactions. The peak of the statistical distribution depend on the local gravitational energy density. On earth one sees an upper bound on locally derived maximum energies and anything else is likely from outside. On the sun, the gravitational energy density is going to be close to 38.7 Telsa/(m/s^2) * 274 (m/s^2) = 10,603.8 Tesla.

I am getting tired writing this from memory and notes from a lifetime of work. I started this for Nancy Roman and searching for MANY alien civilizations where whole galaxies might have aliens and their machines talking to each other. And that means signals going in all directions. With nuclear powered, gravitational drives very likely, then that means point sources of very bright gravitational signals for propulsion. Or point events. I will have to think about it some more. The time for these comments is May 20 so I am just squeezing this in as I have a few hours in the middle of the night.

Now mm wave detectors with local processors and storage are cheap and small now. You could probably stick a few on the Nancy Grace Roman Space Telescope just to have some there. If you put some in orbit around the Moon and Mars, then today. The moon-earth distance is 395,495 Kilometers. The Earth-Mars distance is 289,493,623 Kilometers.

One accessible Wikipedia article (if they don’t keep changing things constantly) on angular resolution of telescope arrays is at https://en.wikipedia.org/wiki/Angular_resolution#Telescope_array.

AngularResolution_Radians = Wavelength_Meters/Baseline_Meters

AngularResolution_Radians(1 mm, 395,495 Kilometers) = (1E-3/395,495E3) = 2.528477E-12 radians = 2.528477 picoRadians

(use lowercase for small things like pico, femto, nano, micro, milli. Use uppercase for big prefixes like Giga, Mega, Tera, Yotta and uppercase ALL units. That is what I do in order to be able to keep all the units on the Internet, from ALL disciplines and groups separate, easy to remember and easy to combine).

AngularResolution_Radians(1 mm, 289,493,623 Kilometers) = (1E-3/289,493,623E3) = 3.4543075E-15 radians = 2.528477 femtoRadians

At 1000 light years = 1000 years * 2.99792458E8 (m/s)*365.25 *days/year)*86400 (seoonds/day) = 9.46073047E18 meters

1000 light years * AngularResolution_Radians(1 mm, 289,493,623 Kilometers) = (9.46073047E18 meters)*(3.4543075E-15 radians) = 32,680.2722 Meters = 32.6802722 KiloMeters.

(1 Astronomical Unit = 149,597,870,700 meters = 1.49597870700E10 Meters) * AngularResolution_Radians(1 mm, 289,493,623 Kilometers) = (1.49597870700E10 Meters)*(3.4543075E-15) = 5.16757047E-5 meters

Yes I know the geometry is strange with Mars and Earth to the sun, as two nodes in the array and more needed. But the radio astronomers are smart and precise. I trust them to do it well, but I do NOT trust them now to share in open and accessible formats and units that all can understand and get to use.

I am tired and can only indicate that using Earth Moon, Earth Mars, and Moon Mars baselines alone (ask Elon Musk to help or one of the many space companies and countries now) to help get some detectors that can see VERY precisely.

I only wanted to give a rough outline of a proposal to look at things with solar system baselines, and chip scale, low cost technologies. And also, using the same array methods — look at the polarization and time of arrival and angle of arrival of at least the signals from the Milky Way Galaxy in the nanoHertz to TeraHertz electromagnetic and gravitational frequencies with vector and tensor polarization and correlation data.

Nancy Grace Roman could be a space borne solar system baseline radio telescope/gravitational node. And all the smart people out there can help – if they put a 10th the effort into communicating and sharing and collaborating as they do finding things in the first place.

Filed as (Nancy Grace Roman Galactic Plane Survey – Gravitation signals from many alien civilizations)

Richard Collins, The Internet Foundation.