Well I don’t know how good a physicist Chronos is, but he is certainly outstanding at one-up-manship.
So what would happen if you were a lot closer to this merger? Would you alternate between being very tall and very squashed? Does it weaken so quickly because it’s quadrupole radiation?
What do you call the disturbance in spacetime that would be generated by an up and down movement of a large mass? I realize it wouldn’t be dipole radiation, but it seems it would create some sort of traveling disturbance. What would that be called?
From an up-and-down movement of a single large mass, it’s like the old joke about the dog with no legs: You can call it whatever you want, but it won’t come. A single mass moving up and down would violate conservation of momentum. If, instead, you connected two masses together and set them oscillating (so one goes down when the other goes up and vice-versa to conserve momentum) then you’ll have quadrupole (and higher order) gravitational waves.
More or less, on what would happen to you, though the precise calculations are extremely ugly and it’s only recently that clever-enough algorithms have been devised to perform them even on the most powerful computers. And you’re also correct that the rapid fall-off is due to the waves being quadrupolar, since it’s not possible to get a monopole or dipole wave in gravity (the monopole is prohibited by conservation of mass, and the dipole is prohibited by the lack of negative mass).
Actually, I knew that. A few years ago in another forum an astronomer explained it to me. But, since physics is the realm of the frictionless surface and weightless string, I propose the following:
Two almost infinitely strong people (you know what I mean) synchronize their clocks, and leave a planet in opposite directions, carrying a weightless unbreakable string attached to the planet.
They accelerate and decelerate exactly the same, travel the same distance and arrive at identical extremely massive planets.
Taking into considerations all relativistic effects they time their pulls to move the original planet up and down. As I said earlier I know this can’t be dipole radiation but it seems you’d get a local, oscillating, traveling. gravitational wave of some kind or another? What’s my error-the weightless string?
At a guess, the problem isn’t actually that the string is massless, but that you’re neglecting the tension in the string when calculating the gravitational effects. Everyone knows that mass is a source for gravity, but it’s less well-known that stress is, as well. The contribution from stress is typically negligible, but here you’re talking about sufficient tension to wiggle a planet around, which is a lot more stress than in familiar real-world situations.