Question: What does the electromagnetic force play a major role in?
About the article "Electromagnetism", section "Abstract".

Candidate passages:
Electromagnetism, or the electromagnetic force is one of the four fundamental interactions in nature, the other three being the strong interaction, the weak interaction, and gravitation.
This force is described by electromagnetic fields, and has innumerable physical instances including the interaction of electrically charged particles and the interaction of uncharged magnetic force fields with electrical conductors.
The word "electromagnetism" is a compound form of two Greek terms, ἢλεκτρον, "ēlektron", "amber", and μαγνήτης, "magnetic", from "magnítis líthos" (μαγνήτης λίθος), which means "magnesian stone", a type of iron ore.
The science of electromagnetic phenomena is defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as elements of one phenomenon.
During the quark epoch, the electroweak force split into the electromagnetic and weak force.
The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life.
Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter.
Electrons are bound by electromagnetic wave mechanics into orbitals around atomic nuclei to form atoms, which are the building blocks of molecules.
This governs the processes involved in chemistry, which arise from interactions between the electrons of neighboring atoms, which are in turn determined by the interaction between electromagnetic force and the momentum of the electrons.
There are numerous mathematical descriptions of the electromagnetic field.
In classical electrodynamics, electric fields are described as electric potential and electric current in Ohm's law, magnetic fields are associated with electromagnetic induction and magnetism, and Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, in particular the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.
Although individuals who report electromagnetic hypersensitivity believe that electromagnetic fields from common electrical devices trigger or exacerbate their symptoms, it has not been established that these fields play any role in the cause of these symptoms.
Exposures are to intensity levels below those generally accepted to cause physiological effects, and the diverse physiological effects reported are not what would be expected from high intensity electromagnetic fields.
Sufferers and their support groups are convinced of a causal relationship with electromagnetic fields, but presently the scientific literature does not support such a link.
Some professionals consider electromagnetic hypersensitivity to be a physical condition with an unclear cause, while others suggest that some aspects may be psychological.
Reviews have suggested that psychological mechanisms may play a role in causing or exacerbating EHS symptoms.
Research has also shown neurophysiological differences between sensitive individuals and controls.
This may reflect either a psychophysiological stress response to participating in the study or a more general imbalance in autonomic nervous system regulation.
In 2005, a systematic review looked at the results of 31 experiments testing the role of electromagnetic fields in causing ES.
Each of these experiments exposed people who reported electromagnetic hypersensitivity to genuine and sham electromagnetic fields under single- or double-blind conditions.
The review concluded that: The symptoms described by 'electromagnetic hypersensitivity' sufferers can be severe and are sometimes disabling.
However, it has proved difficult to show under blind conditions that exposure to electromagnetic fields can trigger these symptoms.
This suggests that 'electromagnetic hypersensitivity' is unrelated to the presence of electromagnetic fields, although more research into this phenomenon is required.
Seven studies were found which did report an association, while 24 could not find any association with electromagnetic fields.
However, of the seven positive studies, two could not be replicated even by the original authors, three had serious methodological shortcomings, and the final two presented contradictory results.
Since then, several more double-blind experiments have been published, each of which has suggested that people who report electromagnetic hypersensitivity are unable to detect the presence of electromagnetic fields and are as likely to report ill health following a sham exposure, as they are following exposure to genuine electromagnetic fields.
One of the studies which Rubin et al.
reviewed, known as the Essex study, received some criticism for its methodology and analysis, and the authors responded in full to these initial criticisms.
The authors noted that their study says nothing about the long-term effects of exposure to electromagnetic fields, but those affected generally claimed to respond to the fields within a few minutes.
In January, 2010 Rubin et al.
published a follow up to their original review which included 15 experiments done since the last original review, bringing the totals up to 46 double-blind experiments and 1175 individuals with claimed hypersensitivity.
The study confirmed the results of the original, claiming "no robust evidence could be found" to support the hypothesis that electromagnetic exposure causes EHS.
The review also found that the studies included did support the role of the nocebo effect in triggering acute symptoms in those with EHS.
In 2008, another systematic review reached the same conclusion as Rubin et al.
A 2005 report by the UK Health Protection Agency concluded that electromagnetic hypersensitivity needs to be considered in ways other than its etiology; that is, the suffering is real, even if the underlying cause is not thought to be related to electromagnetic fields.
They also wrote that considering only whether electromagnetic radiation was a causative factor was not meeting the needs of sufferers, although continued research on etiology was essential.
In 2002, some controversy over the causal relationship was demonstrated by the Freiburger Appeal, a petition originated by the German environmental medical lobby group IGUMED, which stated that "we can see a clear temporal and spatial correlation between the appearance of disease and exposure to pulsed high-frequency microwave radiation", and demanding radical restrictions on mobile phone use.
To address some of these concerns, and others, Hocking advised in a 2006 WHO proceedings that the test type and duration should be tailored to the individual, and that washout times are needed to prevent a carry-over effect of previous exposure.
However, in 2005 the World Health Organization concluded that there is no known scientific basis for the belief that electromagnetic hypersensitivity is caused by exposure to electromagnetic fields. 
The Heisenberg uncertainty principle does not allow a particle to exist in a state in which the particle is simultaneously at a fixed location, say the origin of coordinates, and has also zero momentum.
Instead the particle has a range of momentum and spread in location attributable to quantum fluctuations; if confined, it has a zero-point energy.
An uncertainty principle applies to all quantum mechanical operators that do not commute.
In particular, it applies also to the electromagnetic field.
A digression follows to flesh out the role of commutators for the electromagnetic field.
Because of the non-commutation of field variables, the variances of the fields cannot be zero, although their averages are zero.
The electromagnetic field has therefore a zero-point energy, and a lowest quantum state.
The interaction of an excited atom with this lowest quantum state of the electromagnetic field is what leads to spontaneous emission, the transition of an excited atom to a state of lower energy by emission of a photon even when no external perturbation of the atom is present. 
Electromagnetic propulsion (EMP), is the principle of accelerating an object by the utilization of a flowing electrical current and magnetic fields.
The electrical current is used to either create an opposing magnetic field, or to charge a fluid, which can then be repelled.
It is well known that when a current flows through a conductor in a magnetic field, an electromagnetic force known as a Lorentz force, pushes the conductor in a direction perpendicular to the conductor and the magnetic field.
This repulsing force is what causes propulsion in a system designed to take advantage of the phenomenon.
The term electromagnetic propulsion (EMP) can be described by its individual components: electromagnetic- using electricity to create a magnetic field (electromagnetism), and propulsion- the process of propelling something.
One key difference between EMP and propulsion achieved by electric motors is that the electrical energy used for EMP is not used to produce rotational energy for motion; though both use magnetic fields and a flowing electrical current.
The science of electromagnetic propulsion does not have origins with any one individual and has applications in many different fields.
The thought of using magnets for propulsion continues to this day and has been dreamed of since at least 1897 when John Munro published his fictional story "A Trip to Venus".
Current applications can be seen in maglev trains and military railguns.
Other applications that remain not widely used or still in development include ion thruster for low orbiting satellites and magnetohydrodynamic drive for ships and submarines.
Ray guns are now being developed in the University of Electromagnets and Electro-technology in California.  
  Quantum chromodynamics: What are the phases of strongly interacting matter, and what roles do they play in the cosmos?
What is the internal landscape of the nucleons?
What does QCD predict for the properties of strongly interacting matter?
What governs the transition of quarks and gluons into pions and nucleons?
What is the role of gluons and gluon self-interactions in nucleons and nuclei?
What determines the key features of QCD, and what is their relation to the nature of gravity and spacetime?
Do glueballs exist?
Do gluons acquire mass dynamically despite having a zero rest mass, within hadrons?
Does QCD truly lack CP-violations?
Nuclei and Nuclear astrophysics: What is the nature of the nuclear force that binds protons and neutrons into stable nuclei and rare isotopes?
What is the origin of simple patterns in complex nuclei?
What is the nature of exotic excitations in nuclei at the frontiers of stability and their role in stellar processes?
What is the nature of neutron stars and dense nuclear matter?
What is the origin of the elements in the cosmos?
What are the nuclear reactions that drive stars and stellar explosions?