The Electric Universe (EU) hypothesis is a theory that states that electricity is the force behind many natural and astrophysical events. It posits that the Sun and stars are powered by electricity, and that cosmic occurrences are electrical in nature. Furthermore, it also believes that the universe is a vast, electrical organism that is full of other phenomena such as masses, holes and relationships waiting to be discovered.
Some of the claims that proponents of the EU hypothesis have included:
Einstein's postulates (ie. that the laws of physics have the same form in all inertial reference frames; that light propagates through empty space with a definite speed independent of the speed of the observer (or source); and that in the limit of low speeds, the gravity formalism should agree with Newtonian gravity) are wrong
General relativity (GR) is wrong
The universe is not expanding
The electric force travels faster than the speed of light with near-infinite velocity
Gravity has two poles like a bar magnet; ie. dipole gravity
A plenum of neutrinos forms an all-pervasive aether
Planets give birth to comets
Stars do not shine because of internal nuclear fusion caused by gravitational collapse; instead, they are anodes for galactic discharge currents
Impact craters on Venus, Mars and the Moon are not caused by impacts, but by electrical discharges. This also applies to formations such as the Valles Marineris (a massive canyon on Mars) and the Grand Canyon on Earth.
The Sun is negatively charged, and the solar wind is positively charged - the two systems forming a giant capacitor
EU proponents from the Thunderbolts Project claim to have predicted the natures of Pluto and Comet 67P more accurately than NASA or the ESA.
Notable proponents of the EU hypothesis include Nikola Tesla (1856-1943), Immanuel Velikovsky (1895-1979) and Wallace Thornhill.
There are two groups of EU advocates. One group believe that the EU hypothesis is a legitimate, revolutionary scientific theory, and that the rest of the scientific community are ignoring them, either out of ignorance or deliberately for more sinister reasons. Some of this group are also Flat Earthers, who are looking for an alternate scientific explanation for gravity.
The second group of EU advocates include Young Earth Creationists, and some of the more fringe theorists of climate change denial.
Many of the claims made by EU proponents are unsubstantiated by scientific observations. Comets, for example, have been studied for decades, including the landing of the Rosetta spacecraft on the comet 67P, and these studies have shown that they are not in any way "electric". There has never also been any evidence to substantiate the EU claim that stars are powered by energy sources at the centre of galaxies.
There is also photographic and video proof of the formation of impact craters by meteor impacts and not from "electrical discharges".
The EU hypothesis has never been supported by any "reputable" scientific studies, nor has it ever appeared in any peer-reviewed scientific journals. Despite this, there is still an annual Electric Universe conference that covers many topics besides the EU hypothesis (such as mythology, homeopathy and dipole gravity). The International Science Foundation, an EU group, also claims to have donated $2,200,000 USD to fund the SAFIRE Project, which is a laboratory experiment to test EU claims about the nature of the Sun. It should be noted, however, that there is no independent analysis of the SAFIRE Project and it has not appeared in any publications.
Sources:
Electric Universe Theory: The Science, Models and Controversy (Gaia)
Electric Universe (RationalWiki)