Ah yes now this thread i really like! E very brief and simple explanation of the 4 forces:
These forces are the second basis for the universe. Every fundamental particle in the universe affects the movement of every other particle. It can either attract or push it with one or more of the 4 forces that physics knows today. Two of these forces we are very familiar with i.e. gravity and magnetism, the other two, the nuclear forces only apply to the world of atoms and such particles.
If you let an object go it will fall to the ground, supposedly the earths gravity attracts it but in reality every particle in the object is attracted by every particle on earth and vice versa. The small object naturally moves more than earth because it has less of these particles, but ofc the earth moves too. (apr. 1/ 10^22 mm if i remember correctly).
Gravity is the force keeping us on this planet and if we wanted to escape that pull we would have to travel at 11 km/s =~= 40 000 km/h. Our planet stays in the orbit of the sun because of that same force, the sun is pulled by our galaxy, gravity here holds billions of stars together, even though the speed of our sun around the center of the galaxy is apr. 250 km/s.
Even if gravity does all that its still the weakest of the 4 forces by far. It only seems powerful because it reaches far and affects everything. The two nuclear forces, even if they are much stronger, only work between particles which are very close, protons and neutrons in an atom core for example. Electromagnetic force too is much stronger than gravity and has a long range as well. If you want to see how much stronger than gravity it is than rub a stick
and use it to lift pieces of paper. Electromagnetism in that small amount does that even though every particle on earth is pulling those pieces of paper.
The firs rule about electtromagnetism is that opposites attract. So the positive proton attracts the negative electron but two protons will push one another. This attraction is what holds the electrons in their orbits. To compare the relative forces of gravity and emagnetism we would have to separate the particles (say protons which will push one another) in atoms on lets say our planet and the moon, in that case the moon would blast off because of the force of the push.
Emagnetism also forces electric force forces the electrons to move along the wire. In metal electrons aren't fixed onto their atoms and the weak electric force - voltage - causes them to move. In a wire there is always the same amount of protons and electrons so its always neutral. The flow of electrons of course transports energy .
The moving electrons also produce the magnetic force. Here too are 2 poles + and - or N and S and again opposites attract. But its different from electricity because it can never exist on its own. It cant exist in only a form of a single pole. If you cut a magnet in half it will polarize into N and S again. Then there are the electromagnet and the generator but i wont go into that ... The electrons make up a circular electric current, so every atom is a little electromagnet on its own with a N and S pole. The circulation of electrons in atoms in most atoms tries to eaven out and become neutral with some exceptions like Fe.
Electricity and magnetism are really just a different manifestation of the same fundamental force -> electromagnetism.
The last two, strong and weak nuclear forces are just as important. The strong n force hold together the quarks, this force is enormous, considering how in the atom core there are many protons (+) stuck together. We can see this power in the H bomb where new cores are formed. There is also the fusion of H, that also happens in the sun.
The weak nuclwar force is the most ''mysterious'' since it is hidden behind the more powerful magnetic and even more powerful strong force. Most of the effects of this force are shown to us during reactions and not on the actual movement i.e. push/pull of particles. A free neutron for example is very hard to meintain for long and than it forms a proton an electron and an antineutrino (antimatter eq of a neutrino). We could say the weak force is the most important because it regulates the first stages of H fusion in stars, they would never emit light if it wasnt for that or would just explode as soon as they were born.
Weak force however could only be the other side of emagnetism. Just like once separate magnetism proved to be another manifestation of emagnetism. We hope to soon unify 3 forces and maybe prove that they are different manifestations of one force and than only gravity will pose a problem.
but to answer your q extremely simply, yes the gravity of earth is strong (only because a very high number of particles are pulling you) but still gravity is the weakest, try building a lets say, nuke of the same size and number of particles and you will see just how weak gravity is
_____ _______ -> Algalon, Cambridge, UK ... hope u enjoyed reading it
sorry for any typos i didnt read it back
P.S. the string theory is beautiful, most who dont study physics cant understand its complexity, it involves extreme mathematics. science has changed a lot, at the beginning most ppl could understand new achievents in science but today only a few ppl in every field can understand it so im pretty sure most ppl here cant comment on the string theory well enough to do it justice
