“Gravitational Machines”, 1963 (; backlinks):
[background] David Darling encyclopedia:
A Dyson slingshot is a technique proposed by Freeman Dyson for accelerating a spacecraft to high speeds by using the gravitational field of binary star systems in which the components are collapsed stars. Dyson found that a ship dispatched towards a two-star system with a velocity v where the stars are rotating around each other with velocity V could perform a slingshot maneuver (see gravity assist) and be flung out of the system with a velocity equal to v + 2V. The final velocity that can be achieved depends critically on the mass and orbital velocity of the paired stars. For example, two white dwarf stars, each with a diameter of 20,000 km and a mass of one solar mass, and with a combined orbital period of 100 seconds, could provide a departure velocity of 0.009c (2,700 km⁄s). However, two neutron stars, each with a diameter of 20 km and a mass of one solar mass, and with a combined orbital period of 0.005 sec could provide a departure velocity of 0.27c (81,000 km⁄s).
…Dyson’s article made a series of other remarkable scientific leaps that are rarely cited. He offered what is apparently the first published speculation on the existence of tight binaries comprising two neutron stars; his comment predated the discovery of pulsars by 5 years. He also calculated the gravitational-wave signal strength of those binaries and identified them as an observable source of gravitational waves, even at intergalactic distances. He did not imagine that such binaries could form naturally, but he speculated that they could be the by-product of deliberate energy extraction and argued that the detection of a merger event would constitute evidence for alien technology.
Despite having presaged the discovery of gravity waves from the inspiral of binary neutron star GW170817 by more than 50 years, Dyson’s work is not cited in that paper…
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