This object is now the fastest thing humans ever made

making it the fastest human-made object in history

Not according to my chosen reference frame!

Lol hey I am not sure on the rules here with time travel. I just know a bird of prey would have been back in the 80’s moving like that I think. :slight_smile:

How much is that in orcas per football pitch?


The relativistic correction for GPS satellites is a combination of their relative velocity and general relativistic effects because they are farther away from the Earth. These work opposite to each other; relative velocity alone would cause their clocks to appear to run slower than a clock on the surface of the Earth, but altitude alone would make their clocks appear to run faster. The general relativistic effect actually dominates, the GPS clocks run 45 microseconds per day faster due to their altitude, but 7 microseconds slower due to their velocity, for an overall difference of 38 microseconds per day.


I like this claim because it hinges on the definitions of “object” and “made,” neither of which will I touch with a ten-foot pole.

This far and no one has compared it to an unladen swallow?


Just as a comparison:

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If I recall “Elmo Saves Christmas” correctly, yes. Someone (Elmo and/or Santa?) had to travel backwards around the earth to go back in time to correct a wish for Christmas every day.

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Yeah, this was not a stereotypical gravity slingshot. Normally you drop into a planetary gravity well, let the falling spacecraft accelerate until accelerate the spacecraft until it’s going faster than the planet’s escape velocity, and then make very sure you miss the planet. If the planet has atmosphere you’re going to want to miss hitting it by a lot, so you don’t get slowed down or burnt up. :slight_smile:

@stevev points out below that my oversimplification crossed the line into being misleading so hopefully I fixed it. (I wish I could remember who I’m misquoting so I could look up the original.)


If you weren’t already traveling above the escape velocity of a planet at the altitude where you started falling toward it, you won’t exceed its escape velocity from falling toward it. By definition escape velocity is the minimum velocity you need at a given distance from the center of mass of a planet that will cause you to escape to infinity, rather than staying in orbit around the planet. If you start at rest at a great distance from a planet, as you fall toward it you’ll be traveling infinitesimally under the escape velocity from any given altitude at the time you pass through that altitude.

Gravity assist trajectories used by spacecraft involve passing near a planet to exchange some angular momentum with the planet; if you start out behind the planet in its orbit, you’ll gain speed, or if you pass in front of it in its orbit, you’ll lose speed. The planet correspondingly loses or gains some orbital angular momentum equal to the amount gained by the spacecraft, but since the planet is very much more massive than the spacecraft the change in its orbital speed is basically not measurable. Usually gravity assist trajectories have been used to accelerate spacecraft toward the outer Solar system by passing by Jupiter or Saturn, but in the case of spacecraft like the Parker Solar Probe or the Messenger Mercury orbiter passes by Earth and Venus were used to slow the spacecraft to lower the periapsis (closest approach) of their orbits around the Sun.

A “slingshot maneuver” basically takes advantage of the Newtonian physics rule that work = force * distance. If your spacecraft is falling toward a planet in an elliptical or hyperbolic orbit, it will gain much more velocity from an impulse if that impulse is applied when it is moving at maximum speed at the time of its closest approach. This means that the most fuel-efficent way for a spacecraft to enter or leave orbit around a planet is to apply thrust during its closest approach to the planet.


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