## Wednesday, August 05, 2015 ... /////

A proper hologram – as invented by Dennis Gábor – uses the interference of light waves, depends on the exact knowledge of the wavelength, and completely rearranges the information about the 3D image into an unreadable interference pattern.

A mathematically similar rearrangement of the higher-dimensional information into an interference pattern is exploited by Nature in quantum gravity – which is why we talk about the holographic principle that governs all consistent quantum theories of gravity (at least in some backgrounds).

For a while, I tended to believe that Microsoft Hololens (to be released in 2016) is a true holography. But the 4-days-old video above – which has already collected 5 million views – strengthens my opinion that Hololens won't be about true holography but something more ordinary that only looks like holography.

The 2-minute video above shows you how you may create your own moving holograms – objects moving and dancing on the horizontal display of your smartphone. You need a pen, paper, a ruler, and you cut a truncated pyramid from a DVD plastic case.

The pen and paper are only needed to make a pyramid of the right size, with the appropriate angles. Once your pyramid is ready, you are expected to open an appropriate demo video in your video player, e.g. this one from 2014:

A playlist with 93 HOLHO demo videos is available – if you don't know what to do with the rest of the summer.

You may see that this video contains no inteference patterns. Nothing in your smartphone really emits nice monochromatic light (am I wrong?) so it is not a genuine hologram. But it looks cool, anyway.

The four images in the video above are reflected into real images that exist somewhere in the middle of the pyramid. Well, I think it's obvious that the object can't be "truly" three-dimensional – at most, one may get the objects dancing on 4 vertical planes that differ from the plane of the smartphone's display – but it looks like a three-dimensional object.

I am looking for skillful TRF readers to create their "hologram projector" and share their experience.

Am I correct that the images we see "flying inside the pyramids" simply exist at the same vertical planes that you would get if the pyramid were made of a reflective mirror (the reflection would be off the external faces of the pyramid)? If I understand it well, the only reason why this HOLHO looks more hologram-like is that the CD plastic case is only partially reflective or semi-transparent – so the mirror image is juxtaposed with the scenery of your room around. Or do I misunderstand what's going on?

If these images look really cool, someone should quickly mass produce lots of these pyramids. ;-)

My guess is that some straightforward reflections are the core of the amazing "seven-dimensional" (?) holograms in Dubai and the Holo-Gauze, too. Holotronica.com seems to combine reflections with the bicolor 3D glasses.