Gravity, electromagnetism, strong & weak nuclear forces?

Question

can they be observed(or their effects) separetely?

photon mediates the em force gluon mediates the strong force z,w+,w- are responsible for the weak interaction

and the gravaton (or whatever it is called) isn't known.

does each of the 4 have a positive and negative? how is it believed gravity is the one out( not testable as the other)?

is there no possibility of a strong and weak gravity?

can magnetism be weak and electricity strong ? and how exactly do you give someone 10 points?

Answer 1

is this your homework?  or are you just curious to know all this?

Answer 2

Many questions. I'll try to answer in general terms because if I knew for sure, I'd be in Stockholm to receive my Nobel Prize! :-)

Four forces are observed. It doesn't mean that there aren't any other but ... that's what we have, so far.

The idea to unify them is an old newtonian dream. If we could explain everything by an equation, we could predict the future.

Alas, Quantum uncertainity seems to say that it is an impossible dream. Still, if we could unify all the forces and understand how they appeared right after the Big Bang.

Apparently, all forces can be unified with enough temperature and pressure ... except gravity. That's the odd ball in the game and the very mysterious one. First, it is extremely weak compared to the three others. Then Quantum and Relativity don't really agree to what it is. Einstein meant that gravity was nothing else than the actual bending of the spacetime web. Quantum sees it as a force, though. String theory imagine that gravity is the only thing that goes through string membranes, a.k.a. branes. In its most exotic form, there are 'parallel' universes where only gravity affect each other.

A graviton is another Quantum hypotetical particle without mass. Dark matter and dark energy are also hypotetical stuff that should explain why galaxies hold together and why the universe expands.

But we must draw a line between what is fact and theory. Interestingly enough, Relativity is called a theory. But the spacetime distortion is something we are now able to measure and verify in many different ways. The Big Bang, on the other hand, is - and will probably remain for a long time - a theory. Yes, everything points toward the fact that, at one time in the past, all matter, energy, space and time were together. But we have no proof.