What is Gravity?
Gravity is one of the four fundamental forces that apply in our universe:
- Weak Nuclear Force
- Strong Nuclear Force
Gravity is the force exerted by anything that has mass. Even sub-atomic particles exert a gravitational pull on nearby objects. Isaac Newton proved that objects with a greater mass exert a stronger gravitational pull. Weirdly, however, gravit-y is pathetically weak!
“Weak!? But gravit-y holds planets in orbit around the Sun, and holds us on the Earth’s surface” Correct, but look at it this way – a tiny magnet can hold a paperclip against the gravitational pull of our planet. A newborn baby can defeat Earth’s gravit-y by lifting a block off the floor.
Gravity has undergone some modifications since Newton, with Einstein’s General Relativity providing an explanation of how gravit-y worked. Here is a helpful (although flawed) analogy:
- Space and time form a 2-D fabric analogous to a trampoline.
- Stars, and other objects of great mass, are like bowling balls sitting on the trampoline.
- Roll a ball bearing too close to the bowling ball and it will curve around it like a ball in a roulette wheel – this is a smaller mass being caught by the gravity of a greater mass.
Einstein stated that objects of mass bend and warp the fabric of space-time (bowling ball on trampoline). Large masses move in response to this curvature in space time; move too close to the curve and you are forced to move in a new direction. Matter tells space how to curve; curved space tells matter how to move. Gravity is thus the result of all the collective wrinkles in the fabric of the Universe.
Fast Fact: Even on Earth, gravity is not even. The Earth is not a perfect sphere, and its mass is distributed unevenly. This means that the strength of gravity can change slightly from place to place.