How holograms work
Laser light is much purer than ordinary light. In ordinary light the waves are random, jumbled up and run along like schoolchildren racing down a corridor when the bell rings for home time. But in a laser beam the light waves are coherent; they all travel precisely in step, like soldiers marching on parade.
When a laser beam is split up in two to make a hologram, the light waves in each beam continue to travel in identical steps. But while one of the beams, the reference beam, is directed unencumbered onto a recording medium, the other, the object beam, is first directed at the object, and then redirected onto the recording medium. Since the object beam was disturbed by reflecting off the outer surface of the object, when the two beams are recombined in the photographic plate, they intersect and interfere with each other, and the interference pattern they create is a virtual image of the object. That image is burned permanently by the beams into the photographic plate, and the hologram becomes a permanent record of what something looks like seen from any angle.
Since every point in the hologram catches light waves from every point in the object, wherever you look at the hologram you see exactly every point as if you had been looking at the real object, and as you move your head around, the holographic image appears to change just as the image of a real object changes. That is why holograms appear to be three-dimensional.
And this is really neat, if you break a hologram into tiny pieces, you can still see in any of the pieces the entire object; smash a glass hologram of a cup into bits and you can still see the entire cup in any of the bits! Each piece of a hologram contains a particular perspective of the image, but it includes the entire object. 
In the words of the Norwegian intellectual Jostein Gaarder in “Sophie’s World”: If a hologram “depicts a car, for example, and the hologram is fragmented, we will see a picture of the whole car even though we only have the part of the hologram that showed the bumper. This is because the whole subject is present in every tiny part. In a sense, our bodies are built up in the same way. If I loosen a skin cell from my finger, the nucleus will contain not only the characteristics of my skin; the same cell will also reveal what kind of eyes I have, the color of my hair, the number and type of my fingers, and so on. Every cell of the human body carries a blueprint of the way all the other cells are constructed. So there is ‘something of everything’ in every single cell. The whole exists in each tiny part.” 
We are like a hologram. We imprint each and every cell we create in our bodies with the same blueprint that not only contains precise instructions on how to grow and develop our specific organism, but also commands them to comply with a set of universal properties … Become, Self-organize, Bond, Self-generate, Adapt, Self-perpetuate, Transform … while at the same time endowing them with a degree of freedom to affect and be affected by their internal and external environments.
Our Universe is like a hologram. It imprints each and every one of its creations, you and me included, with the same blueprint that not only contains precise instructions on how to grow and develop in specific environments, but that also commands us to comply with a set of universal properties … Become, Self-organize, Bond, Self-generate, Adapt, Self-perpetuate, Transform … while at the same time endowing us with a degree of freedom to affect and be affected by our internal and external environments. This is the blueprint of Creation: Every moment we create something eminently new and something eminently old. This is how, as you and I constantly re-create ourselves upon the lessons of our primal inheritance, our Universe re-creates itself. This kind of interrelatedness is about impossible for us to comprehend under a Paradigm based on our separation from Nature. But amazingly enough, over two thousand years ago, the Greek philosopher Anaxagoras [500-428 BC] already saw the interrelatedness of everything: “There is something of everything in everything”. This is the key to a better understanding of what we are: Because every one of us is imprinted with the same universal blueprint, the whole magnificent mystery can be glimpsed at by understanding ourselves. Answers to the mystery of the Universe are contained within us.
 Abstracted from “How holograms work” at: http://www.explainthatstuff.com/holograms.htm And “When a piece is a whole” from http://hyperphysics.phy-astr.gsu.edu/hbase/optmod/holog.html#c4
 Highlights mine
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