Man, I really had some misconceptions about how the gravity of the Earth, Sun, and planets really works. I was very surprised by how many things I had been thinking about either in too simplistic a way or I was just wrong about.
I had not known that there was such a significant gravitational difference between cities, or that the big gaseous planets had so little pull, or that it’s best to think of astronauts in space as being in free-fall rather than in a low-gravity environment.
Great galloping guacamole! I had no idea the whole topic was so complex. That first graphic of the color-coded globes was a mind-blower.
(Insert obvious joke about moving to lower-gravity area to lose weight.)
Even on Ceres a 40-story fall could do serious damage (17 mph on impact).
We’re so brainwashed by easy-to-manufacture globes that we don’t realize the lumpiness on the outside and the high density bubbles-high mass on the molten inside. The GRACE image of the deviation of local gravity from theoretical is striking in how it matches up in a cockeyed fashion with surface or undersea mountain ranges.
Two other facts about gravity that I find fascinating:
Gravity is an incredibly weak force. The gravitational force between two protons is 10^39 times smaller than the electrostatic force between them. 10^39!!! Where did that come from? No one knows.
An accelerating mass emits gravitational waves that travel at the speed of light, just as an accelerating charge emits electromagnetic waves. Gravitational waves carry away energy from the accelerating particles. (This energy loss has been observed in a neutron star binary system (the Hulse-Taylor system).) But Einstein says energy and mass are equivalent, so, because they carry energy, gravitational waves are gravitationally attracted to themselves! There is even a possibility that, for waves of sufficient intensity, the waves could be self trapped by their own mass-energy (a “gravitational soliton”)!
Yeah, Booman, there’s all kinds of tricky stuff in this Universe.
For example, do you realize that right at this very moment you are standing/sitting DIRECTLY ABOVE the Center Of The Earth??1?
Okay, cheap shot. However, realize this: the Solar System is just at the brink of instability. for the very simple reason: an unstable system (as it started as) will keep changing until it just barely reaches a stable equilibrium, then it stops changing.
No telling how big a kick it takes to go unstable again, but probably a bit more than a butterfly flapping its wings.
actually, boo’s link explains why we can’t take that for granted:
most folks don’t realize that gravity is one of the weakest forces we know and what that implies about what we can now conclude about the universe. in my 2013 blog post “better than science”, wherein i contrast the ravings of a real-live modern day geocentrist with the current findings of physics, sean carroll explains why we can safely discard (or at least grant an enormous burden) non-scientific and pseudo-scientific explanations: any alleged forces other than the ones we already know about would be too weak to matter.
(unfortunately the video his remarks are transcribed from has disappeared from youtube, but he has given this lecture several times.)
Gravity doesn’t kill you during a fall.
It’s the strong nuclear force.
I like it! But actually, the force holding together materials (which keeps us from falling through the floor, for instance) is electrostatics, plus Pauli exclusion. The strong force holds nuclei together but doesn’t otherwise affect the strength of materials.
As a skeptic, I’m always impressed when people honestly question their misconceptions.
Other than Kthug, who else does this publicly?
Booman you are assertive on Philosophy (critical thinking – premises) data based on PoliSci (see Boehner on debt ceiling) and demure on Economics (see Helicopter Ben apologia)
Kewl beans.