Gravity's Force Keeps us Grounded

Did you know that the force of gravity travels at the speed of light?

Gravity is the invisible glue that pulls us down to the ground. It was first discovered and named by Isaac Newton in the 17th century. Since this time, many scientists, and researchers have theorized about gravity. In 1937, for example, physicist Paul Dirac suggested that gravity itself might actually be changing very slowly over time.

If gravity were to weaken over time, the Earth would just look like a lump of nothing in space. Further, new planets that formed would resemble giant, misshapen asteroids. Gravity would simply not be strong enough to pull them into spheres like the Earth. If this were the case, there would also be fewer stars; the pressure in star-forming clouds would cause the stars to burn.

If gravity were to become stronger over time however, Earth would look like a very smooth asteroid floating around in space. The increased pressure inside of the Sun would make it burn much hotter and faster, and it would actually die a lot sooner than is expected now.

Remember, gravity that is not too weak or too strong helps us keep our feet on the ground. Let's all be thankful that --at least for now-- Dirac's theory doesn't seem to be true.

[Source: Secrets of The Universe]