Although gravity may seem to be a force overcome with strength for keeping the world orbiting around the sun or drawing massive bodies close to one another, it is actually quite feeble. Every day we walk, jump and easily circumvent gravities pull. One way to show how weak gravity is is by putting a paper clip on a counter top and using a magnet to pull the paper clip through the air and up onto the magnet. Even a small magnets electromagnetic force can easily circumvent gravity. Think about the strong force of atoms.http://physics.bu.edu/cc104/proton_repel.gif
The strong force holds protons and neutrons together with so much force that when we use unstable atoms to give protons the energy they need to escape strong force’s grasp we get an atom bomb. The electromagnetic force means that like charges repel. So ++ and -- repel. The strong force is what keeps the protons in the nucleus.
Why though is gravity so weak? String theory states that all matter is made up of tiny vibrating strings. A more recent development in string theory was that our universe is many strings conjoined and connected to make one huge, moving membrane. This addition to string theory became known as membrane theory, or M theory. Well, thanks to string theory we know that there are eleven dimensions in the universe. Some are so small that they are trillionths of millimeters across.
Image of many conjoined strings in a large rippling membrane
Some scientists had a thought that gravity was being diluted into all of these dimensions. But others thought that maybe gravity wasn’t being diluted within our universe, maybe gravity was leaking into our universe. In a parallel membrane, or universe, gravity would be as strong as the other forces, but by the time it reached us it would be a fraction of what it used to be. Physicists started to get behind this idea and did the math to prove that parallel universes were leaking gravity into our own and they found that the math worked. Scientists were finding more and more parallel membranes which were taking on many different shapes and sizes.
The universes rush around, filled with energy. The membranes will often collide with considerable force and since they are made of the tiny strings that are vibrating, they membranes could collide at different places and at different times, rippling into one another violently. This would release tremendous amounts of energy in a big bang. The tiny strings would be ripped out of the membrane and shot into the empty universe and the strings would want to come back together. When they did meet again, they created matter. The ripples of the membranes that hit at different points at different times give explanation to clumps of matter in the universe. If the membranes didn’t ripple and were flat, all matter in the universe would be clumped together from the start. Thanks to the ripples the matter was spread out just right. Another phenomenon that may have happened during the collision is that forces from one universe may leak into the other very rapidly. Therefore, gravity from another universe may have spilled into ours.
Image shows rippling membranes about to collide
There could be universes out there that have laws that are nothing like the laws of physics of our own universe. There is an infinite number of parallel universes which means that there is an infinite number of universes that can support inelegant life. So, there could be parallel universes out there that are exactly the same as ours, the only difference being, you are not there.
(I apologize to all of my readers for having a bad picture to word ratio in this post. There are not many pictures that portray Membranes well because it is a relatively new theory and is hard to put into picture form.)