Gravity is the weakest natural force.
Gravity is a force that makes things fall to the ground.
Gravity is a force that holds planets in orbit around stars and keeps stars from flying apart.
Gravity also keeps galaxies together, despite their high speed of rotation or expansion away from each other.
The electromagnetic force is much stronger than gravity.
The electromagnetic force is much stronger than gravity. It is a short range force, which means that it can only act over very small distances. It also acts at close to the speed of light, but because it's so strong you don't notice its effects until you get right next to another object. The electromagnetic force holds atoms together and makes them what they are (without electromagnetism, there would be no chemistry). It's measured in coulombs—the unit used for electric charge—and is 1038 times stronger than gravity! Gravitational forces come into play when one object gets close enough to another to feel them on Earth or any other place with mass."
The strong nuclear force and the weak nuclear force are short range.
The strong nuclear force holds together the protons and neutrons in an atom's nucleus. It also is responsible for binding quarks together to make hadrons, such as mesons and baryons (like protons or neutrons).
The weak nuclear force causes radioactive decay, which means that an unstable atomic nucleus will spontaneously change into a more stable one. This happens when the nucleus emits some sort of particle that carries away energy from it. The most familiar type of radioactive decay involves beta particles (electrons) being emitted from an unstable nucleus.
The strong nuclear force ties particles together to form protons and neutrons.
The strong force is a type of force that holds together the atomic nucleus, as well as all particles made up of quarks. It is the strongest of the four fundamental forces and has a short range.
In nuclear physics, it is responsible for holding together protons and neutrons to form atomic nuclei, which accounts for most of an atom's mass. The strong force also acts on other particles containing quarks and gluons (such as mesons), but at shorter distances.
Gravity becomes a 'superforce' at very low temperatures.
At the scale of atoms, gravity is a negligible force compared to the other three fundamental forces. However, at very low temperatures, quantum mechanics predicts that the weak nuclear force and electromagnetic force become equal in strength. At even lower temperatures, all four forces become equal in strength (this is called "Fermi-liquidity").
While this may seem like a strange prediction from quantum mechanics (where everything seems to be random), there's an elegant way of understanding this phenomenon using symmetry groups and supersymmetry theory: The strong nuclear force and weak nuclear force are two separate manifestations of one underlying superforce — referred to as SU(3)XSU(2)YU(1). In some sense, they're just different ways of describing the same thing; like how humans have five fingers but also have toes which are basically just tiny versions of their fingers.
If all of the four forces could be unified, they would become one large superforce that may have been what occurred at the beginning of time.
One of the greatest unsolved mysteries in physics today is the unification of all four fundamental forces. At present, these are electromagnetism, strong nuclear force (which binds together quarks to form protons and neutrons), weak nuclear force (responsible for radioactive decay), and gravity. If the two quantum fields that make up electromagnetic force could be combined with one quantum field that makes up strong nuclear force, we might end up with a single unified theory.
The problem is that looking at these disparate fields as separate entities only reveals so much about how they interact with each other; in order to truly understand their relationship we would have to look at them as part of a larger framework. According to this hypothesis, there existed at some point in time a superforce—a single grand unifying theory—that encompassed all four forces but which has since broken apart into what we currently see today: electromagnetism on Earth, strong nuclear force within atoms, weak nuclear force in stars like our Sun and other massive bodies throughout space (such as black holes), and finally gravitational pull between galaxies themselves."