Полосы зебры это — бесполетная зона для мошек

φ is the Newtonian or «gravitoelectric» potential: φ = −Gm/r.…
In the Newtonian theory there will not be any gravitomagnetic effects; the Newtonian potential is the same irrespective of whether or not the body is rotating. Hence the gravitomagnetic field is a purely relativistic effect. The gravitoelectric field is the Newtonian part of the gravitational field, while the gravitomagnetic field is the non-Newtonian part.
—Grøn, Øyvind; Hervik, Sigbjørn. Einstein's General Theory of Relativity with Modern Applications in Cosmology. Springer, 2007, pp. 201, 203

From Maxwell equations (6.20) it follows that the electric field is potential: E(r ) = −gradφ(r ).
—Soviet Physics, Uspekhi. Vol. 40, issues 1–6, American Institute of Physics, 1997, p. 39

Finally, let us consider the use of a space-like energy-momentum transfer mechanism for sending signals that travel faster than light. By a signal, we mean a statement, possibly in some code, whose sense is not predetermined before the instant at which it is sent. A beam of negative energy that travels into the past can be generated by the acceleration of the source to high speeds. A beam of this sort could be used to send a signal into the past; if such signals were possible, we could determine the sense of the signal long before we decide upon the signal. This contradiction shows that we cannot use a negative-energy energy-momentum transfer mechanism to send signals. This does not mean that such energy-momentum transfers cannot occur; it means only that we cannot control those energy-momentum transfers to the extent that we can use them for signaling.
—Skinner, Ray. Relativity for Scientists and Engineers. Courier Corporation, 2014, pp. 188–89

Concluding Philosophical Comment
Zeldovich and Novikov have made the following intriguing philosophical point about the picture of the formation of a neutron star sketched here. They note that stars begin their lives as a mixture mostly of hydrogen nuclei and their stripped electrons. During a massive star's luminous phase, the protons are combined by a variety of complicated reactions into heavier and heavier elements. The nuclear binding energy released this way ultimately provides entertainment and employment for astronomers. In the end, however, the supernova process serves to undo most of this nuclear evolution. In the end, the core forms a mass of neutrons. Now, the final state, neutrons, contains less nuclear binding energy than the initial state, protons, and electrons. So where did all the energy come from when the star was shining all those millions of years? Where did the energy come from to produce the sound and the fury which is a supernova explosion? Energy is conserved; who paid the debts at the end? Answer: gravity! The gravitational potential energy of the final neutron star is much greater (negatively; that's the debt) than the gravitational potential energy of the corresponding main-sequence star (Problem 8.7). So, despite all the intervening interesting nuclear physics, ultimately Kelvin and Helmholtz were right after all! The ultimate energy source in the stars which produce the greatest amount of energy is gravity power. This is an important moral worth remembering and savoring. If we regard the neutron star as one gigantic atomic nucleus, we may also say that nuclear processes plus gravity have succeeded in converting many atomic nuclei into one nucleus. Problem 8.7 then shows that the ultimate energy source for the entire output of the star is the relativistic binding energy of the final end state.
—Shu, Frank H. The Physical Universe: An Introduction to Astronomy. University Science Books, 1982, p. 157

From the foregoing examples, we can deduce the principle of minimum potential energy: The potential energy of a conservative system is at its minimum in a stable equilibrium position.
—Pytel, Andrew; Kiusalaas, Jaan. Engineering Mechanics: Statics. Cengage Learning, 2009, p. 550