Posted on 04/06/2016 7:36:51 PM PDT by MtnClimber
Gravity: we barely ever think about it, at least until we slip on ice or stumble on the stairs. To many ancient thinkers, gravity wasn’t even a force—it was just the natural tendency of objects to sink toward the center of Earth, while planets were subject to other, unrelated laws.
Of course, we now know that gravity does far more than make things fall down. It governs the motion of planets around the Sun, holds galaxies together and determines the structure of the universe itself. We also recognize that gravity is one of the four fundamental forces of nature, along with electromagnetism, the weak force and the strong force.
The modern theory of gravity—Einstein’s general theory of relativity—is one of the most successful theories we have. At the same time, we still don’t know everything about gravity, including the exact way it fits in with the other fundamental forces. But here are six weighty facts we do know about gravity.
Illustration by Sandbox Studio, Chicago with Ana Kova 1. Gravity is by far the weakest force we know. Gravity only attracts—there’s no negative version of the force to push things apart. And while gravity is powerful enough to hold galaxies together, it is so weak that you overcome it every day. If you pick up a book, you’re counteracting the force of gravity from all of Earth.
For comparison, the electric force between an electron and a proton inside an atom is roughly one quintillion (that’s a one with 30 zeroes after it) times stronger than the gravitational attraction between them. In fact, gravity is so weak, we don’t know exactly how weak it is.
Interesting article for science geeks.
It's not a force to modern thinkers as well. At least not those who believe in Einstein's General Relativity theory. According to it gravity is the warpage of space-time.
Simple - we have gravity because the earth sucks
Gravity undoubtedly exerts force on all objects. It is easily measured and all successful structures were designed to withstand that force.
“Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915) which describes gravity not as a force but as a consequence of the curvature of spacetime caused by the uneven distribution of mass/energy; and resulting in gravitational time dilation, where time lapses more slowly in lower (stronger) gravitational potential.
However, for most applications, gravity is well approximated by Newton’s law of universal gravitation, which postulates that gravity causes a force where two bodies of mass are directly drawn (or ‘attracted’) to each other according to a mathematical relationship, where the attractive force is proportional to the product of their masses and inversely proportional to the square of the distance between them.”
https://en.wikipedia.org/wiki/Gravitation
It’s a microaggression, man! It’s holding me down!
“Use the warpage of space-time, Luke!”
“May the warpage of space-time be with you.”
I don’t think of it as picking up a book. I think of it as moving the earth away from the book.
...for most applications on the surface of the earth, yes. But if NASA had used Newton's equation to plot the course of the Apollo missions to the moon, they would have missed.
As I recall Newton wasn’t good enough for the GPS System either.
Sometimes I think that Gravity is the aspect of God that is everywhere, always.
Pretty heavy.
That's a new one on me! Where do you get that? You know, they had "course corrections" in flight, and surely the uncertainties that these accounted for were much greater than the discrepancy between Newton and Einstein.
I believe this is in reference to a time adjustment.
m=f/a=E/c²
I think....
don’t know but it works even in space
Not on large scales. It requires a paradox factory to hide all its imperfections.
Well put.
Your equation has gravitas.
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