Physics

How to Defy the Laws of Gravity



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Is it possible to defy the laws of gravity?  Ever since Isaac Newton was hit in the head by an apple falling from the tree above him, people have wondered about the natural laws that we know rule the universe.  Why do things fall from trees, and onto people's heads, too?

Newton's three laws of motion led to an understanding of gravity here on Earth: When things go up, they must come down, in layman's terms.  We know now that each object in a two-particle system exerts an equal and opposite force on the other object, which is equal to a gravitational constant times the two masses, all over the distance between the particles squared.  

The reason that the apple falls to the earth is a matter of the relationship between force, mass, and acceleration: since the two forces are equal, the earth's large mass causes it to have a very small acceleration towards the apple, and the apple's very small mass gives it a comparatively large acceleration towards the earth.

But that doesn't get to the heart of the issue: can humans actually defy gravity?  The answer, in short, as confirmed experimentally all over the earth and in outer space as well, is no.  Theoretically, all particles exert a force on all other particles in the universe, no matter how small.  The magnitude of all other gravitational forces besides the Earth on an apple, though, are so small that they are often ignored.

If one's definition of defying gravity is simply breaking free from the Earth's atmosphere and floating in space, then yes, people have done it on the many space missions over the years.  However, the fact that they are floating in weightless conditions does not mean that they are really defying gravity.  It simply can't be done with what we know now.

Defying gravity seems like it could be a test of human cunning, resourcefulness, and ingenuity.  With the recent discovery of the Higgs Boson, researchers are trying to figure how how particles have mass.  Could it be, since mass and gravity are linked, that the Higgs Boson could hold answers about what causes gravitational fields?  In coming years, scientists hope to learn more about gravity and mass through their study of the particle.

Defying gravity, while as far as we know to be impossible, remains a human dream and inspiration.  Who hasn't looked at the stars in the night sky and wished that they could fly away, to see the wonders of the universe?

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