Holography

Holography is a technique for creating records (holograms) of the light scattered by an object. Holograms are interpreted by the observer as looking at a three-dimensional object through a two-dimensional window. Unlike photography (which creates two-dimensional projections) and stereography (which uses binocular vision to create an illusion of seeing a 3D scene in the brain), holography does not represent the object from a fixed viewpoint, but from a range of possible viewpoints — looking at a hologram from different angles will give different views of its contents, as if the viewer were looking from different angles at a real object.

Crank magnetism
In fiction, "holograms" usually refer to three-dimensional images projected into thin air. So, in popular culture, any kind of 3D projection technology, real or imagined, is going to be called a "hologram".

Holograms, being weird, are often the subject of different kinds of science woo that usually ascribes to them special, magical properties. The situation is similar to the one with crystals, which lends weight to the hypothesis that humans and magpies are closely related.

The Moon is a hologram!
There is also the strange claim that the Universe is a hologram, known as the Holographic Principle and some have even taken the time to debunk this claim. A somewhat similar, but recently popular, claim borrows a page from the Moon hoaxers, but takes it further and more literally by claiming that the Moon is a hologram.

In 2013, YouTube user Crrow777 started posting videos which he claims show proof that the Moon is a hologram. Crrow claims “lunar waves” (supposedly power glitches in an artificial electrical system) demonstrate that the Moon is a hologram. Crrow says three other individuals privy to classified information were able to confirm his suspicions, as well as unnamed "Russian scientists".

Problems with the theory
Sure, it gives hope to believers in a Moon landing hoax, but...


 * If there's no Moon to exert gravitational pull, why are there tides on Earth?
 * Radio signals are reliably bounced off the Moon. Holograms can't reflect radio transmissions.
 * The Moon emits measurable gamma ray radiation. Holograms don't.
 * The Moon has been observed on Earth since antiquity. Surely aliens (or whoever is responsible) would have occasional equipment failures that attract Earthly notice.
 * If someone is technologically advanced enough to create and maintain a large-scale illusion of a moon, WHY would they need to? They could simply do whatever they want (colonization, invasion, etc.) right out in the open without fear of resistance.