What is a hologram?

"Your appearance now is what we call residual self-image, it's the mental projection of your digital self.
What is real? How do you define real?

If you're talking about what you feel, you can smell, you can taste and see, then real is simply electrical signals interpreted by your brain[...]

Welcome to the desert of the real"




Now that you decided to dip your toes into the tricky concept of holography there's no better way than this short dialog between the two pillars of the Matrix series Morpheus and Neo.

And like not being enough of 3D paradigm cracks all of a sudden:

Boom! Elon Musk states after thinking a lot about living in a simulation that "Games are indistinguishable from reality"

With all these being said let's get to the definition of a hologram: 

A hologram is a recording in a two- or three-dimensional medium of the interference pattern formed when a point source of light (the reference beam) of fixed wavelength encounters light of the same fixed wavelength arriving from an object (the object beam). When the hologram is illuminated by the reference beam alone, the diffraction pattern recreates the wave fronts of light from the original object. Thus, the viewer sees an image indistinguishable from the original object.

There we go, understanding holograms starts with the famous double slit experiment but this is for next time.