When both ends are fixed, this represents a string trapped in same volume; so, such a string is a component of a subatomic particle. A string with one fixed end and one free end should represent a string stretching out from the particle; these strings cover subatomic particles. This type of string can create a string vortex when its free end spins, causing a force that drags in the stem ends of other vortexes. This force is the quantum electric force; and from it arise subatomic particles covered with positive and negative electric charges. These strings may join to create a quantum short circuit between the positive and negative quanta, represented as the quantum strong nuclear force.
Closed strings stop spinning; instead, the string circles or rotates around an axis through the "hub" of the space enclosed by the string, something like a wheel. They can thereby apply force on other rotating strings. These strings produce the quantum magnetic force. Looped strings cannot cover the surfaces of regular particles like string vortexes can. Still, particles consisting of a collection of the looped strings exist. Thus, we have also magnetic particles.
Scattered strings have both ends free and can adjust to the needs of neighboring strings, and thus serve to manifest electric and magnetic field lines. This type of string works alone; it is not a part of any particle, nor is it a string traveling in space.
Strings are packed inside the volumes of subatomic particles, and are under pressure that comes from the closed surface. Still, these strings can move inside the volumes of their subatomic particles, as was discovered by CERN. The moving strings inside the volume of subatomic particles gives them the physical property we call mass. This means that the strings inside the volume of the subatomic particles have momentum, and therefore can interact with other strings having momentum when they penetrate subatomic particles.
Free strings in motion have linear momentum. They travel at light speed, c, and can have two wave patterns: They can propagate longitudinally or transversely. Thus, two kinds of far-reaching forces exist. Strings vibrating longitudinally like springs, and traveling at c, are gravitons. They interact with strings trapped inside subatomic particles, generating gravity. Transverse strings moving at c interact with other strings, due to spatial geometry, lending their momenta to wherever they land. The linear momentum pushes away the other strings they collide with, so this repulsion must also be a physical reality in space. The angular momentum of this string pattern can also be exploited. Since strings travel at c, they may quickly transfer the information that is "written" on them (frequency and amplitude). We use this kind of string to broadcast information.
To get the full account of particles and forces, we need to discuss the mutual habit of the electric force and the magnetic force to be at cross directions, producing the electromotive force. There also exists a far-reaching force caused by assembled looped strings; this is the magnetic force, produced by the magnetic particle, the neutrino. The neutrino travels at c, and thus has a linear momentum, and can travel through most matter without being impeded due to its magnetism. However, when the neutrino enters matter, where electrons create a circuit coil, then the neutrino may interfere with matter via the magnetism created by the circuit. So, as the neutrino propagates through this coil (as a magnetic "bullet" through cannon's barrel tube), there is a magnetic interaction having an effect such that the neutrino pulls the coil toward the source of the neutrinos, and the coil pulls neutrinos inside the coil, and thus inside matter. Therefore, the Universe experiences the other attractive force caused by these particles when they penetrate matter having electron coils in its inner structure.
The Standard Model (SM) of particle and forces attempts to be the prime SM of physics. Physicists who promulgate it attempt to explain this by saying it must be based on strict materialism. Since these physicists try to present the architect of the Standard Model as String Theory, the term "string" must relate to real materials. However, their String Theory just demonstrates the mathematics of a string. Quantum Mechanics comes to present a particle as a quantum energy packet, as to be in an ampoule. This quantum is neither created nor destroyed. Then Quantum Field Theory has particles emerging from "energy bank" called an "energy field." No quantum particles can exist in isolation because they are components of fields. To extract a particle from a field, you need to give energy to the field energy to be excited. It however means to have a new quantum of energy to produce the quantum (particle). Thus, you have circular flow of energy. This means their view of particles is not materialistic. From the very beginning, SM loses legitimacy, since these theorists have come to the conclusion the fundamental item of existence is an invisible field, particles just demonstrate the existence of fields. This is simply magical thinking.
Since the fundamental particle of any string theory must be a string with the intrinsic property of vibration, they present oscillation as the building blocks of the Universe. Different fundamental particles of the SM are just different versions of "condensed wavefunctions", thus not ampoules of energy but waves.
Far-traveling quanta propagate as string loops or open strings or point particles. Traveling loops are not physically observed; what are observed are waves, composed of open strings. Physicists work mostly with transverse waves of propagating quanta, and assign them electromagnetic properties. They have just one far-reaching force carried by quanta: the electromagnetic force.
In their physics, interactions of traveling quanta are not solved in accordance with the physical theory of collisions; rather, the quantumologists speak of some exchange force in quantum electrodynamics produced by exchange particles. They see this force in Feynman diagrams of mathematical statistics and probability. They solve their proposed exchange of gluons between quarks by creating a new branch of physics called quantum chromodynamics.
Gravity is explained by the General Theory of Relativity as a warping of space rather than by any carrier of gravitational quanta. The General Theory of Relativity ignores the existence of refraction, which slows the speed of light in nature, and works instead with the bending of light caused by the bending fabric of space. It seems strange to the quantumologists that gravity affects the parts of a clock, and therefore they needed to introduce a new theory to explain gravitational time -- General Relativity.