Why won't holograms be like in the Hollywood?

AI generated free-space hologram image

Hologram technology has featured as a visual effect element in countless popular culture works over the past decade, such as Star Wars, Avatar, Iron Man and many silimal entertainment productions. And naturally, many people believe that three-dimensional projections that can float freely in the air without

any static projection surface and that can be walked through are exist in reality. However, unfortunately, even by 2025, Hollywood-style free-air holograms have not yet been invented beyond Volumetric Displays, which provide images through optical illusions with glass barriers. In this article, I will explain why Hollywood-style 'Free-Space Holograms' are not entirely possible.

Free-space holograms can easily reflect light emitted from a projector onto a point at any desired depth and distance, shaping it into complex forms and moving it around, but achieving this fully within the framework of the laws of physics is quite difficult. Air is not a sufficiently dense medium for light to scatter, and in a non-specialised vacuum environment, light cannot find a surface to reflect off. Technologies presented as holograms in the reality are actually systems based on optical illusions, such as OLED panels, reflective screens, and thin mist screens, and none of them are true 'holograms'. Among these technologies, the system closest to being a free-space hologram is a laser technology called 'Aerial Plasma Display'. This system can create single-colour, fairly simple, touch-sensitive flying shapes by drawing with sparks, using micro-explosions created by ionising small air pockets with lasers that have very high peak power. However, for this system to produce holograms as detailed and colourful as those seen in films, air molecules must be repeatedly stimulated and ionised every millisecond, which requires astronomical amounts of energy and could lead to dangerous consequences, such as filling a room with lightning. Therefore, it can be said that this system is not a viable method.

Apart from this, it is conceivable that a hologram effect similar to that seen in films could be created indirectly, by projecting onto a micro-particle or gas environment such as dust or vapour, and this is already an existing method. For this purpose, the vapour or dust used for projection is made into a straight flow and can create images that appear to be suspended in the air using projectors or lasers. However, this still falls short of the desired Hollywood level, because the projected image cannot create a true 3D volume as it is reflected onto the gas or dust medium as a surface, disappears when viewed from the side or from behind, and lacks depth.

In order to create true holograms, a technology is required that can illuminate millions of points in the air at the desired depth, colour and resolution in a completely free, safe and silent manner, and that can calculate and control each of these points. At present, we can say that optical technology at this level will not be possible in the near future, at least, due to its energy requirements, computational complexity, and uncertainties regarding light reflection.