the weekday commute of humans on earth is a large movement of mass. this movement, because it is not spherically symmetric, generates gravitational waves.
our movement is somewhat periodic but not quite: weekends, Daylight Saving Time, holidays, leap days, and leap seconds cause deviation. distant aliens with very sensitive gravitational wave detectors could observe these deviations from periodicity and determine that the source must be intelligent life: a civilization sophisticated enough to coordinate their actions with a calendar. many holidays, and the start and end of DST, are engineered to fall on a certain day of the week so are more complicated than yearly periodic. Easter (computus) is even more complicated, but it always occurs of a Sunday, so it probably does not affect people commuting to work. but maybe other holidays of major religions.
perhaps aliens will wonder what happened on Earth in March 2020 that caused our gravitational wave emissions to suddenly decrease. but those waves have yet to even reach Alpha Centauri.
our weekday commute being somewhat periodic and repeated many times helps boost signal to noise, though our signal will likely be dwarfed by (say) a pair of black holes, somewhere in the universe, orbiting each other with a period of 1 day (generating a gravitational wavefront every half day, mimicking to the round trip of a daily commute). a pair of supermassive black holes, each 1 million solar masses, circularly orbiting around each other at a distance of 2.47 au or 125 Schwarzschild radii would produce such waves:
You have: ((day / (2 pi))^2 G (1 mega sunmass)*2)^(1|3)
You want: au
* 2.4657235
You have: ((day / (2 pi))^2 gauss_k^2 au^3 day^-2 (1 mega)*2)^(1|3)
You want: au
* 2.4657235
You have: ((day / (2 pi))^2 gauss_k^2 au^3 day^-2 (1 mega)*2)^(1|3)
You want: 1 mega sunmass 2 gauss_k^2 au^3 day^-2 c^-2 / sunmass
* 124.90205
instead of the gravitational constant G, the second and third calculations use the standard gravitational parameter which is known to greater precision than G.
our weekday commute is much less than millions of solar masses.
is it appropriate to use the Newtonian formula of orbital period? how quickly do the orbits of such a pair of black holes decay? (do the black holes change faster than the commuting behavior of human civilization?) what is the expected number of binary systems with this period in the observable universe, i.e., how loud is the background noise at this frequency?
previously on using a single car as a gravitational wave generator.
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