It has recently been pointed out, though, that ghost imaging doesn’t have to involve any quantum alchemy at all.
Sometimes, the light bouncing off the object and into the bucket is sent as a series of alternating crisscross patterns. Lighter parts represent greater photon emission; darker parts less so. The light intensity received by the bucket are then compared and contrasted with each other using a computer.
After some careful overlapping, the shadow image is built up, again without directly photographing the object, but this time without requiring any quantum entanglement. Instead, classical physics rules the roost.
In any case, ghost imaging has always required computers to compare and contrast the received mirrored photons to build up an image. This new paper indicates we can do this ourselves.
A University of Glasgow-led team found that, as expected, showing people the reflected crisscross patterns on a projector separately doesn’t give them any idea what the object is. However, showing all of the received patterns in quick succession, say, 200 of them in 0.02 seconds, causes them to blur together enough to create an image. In this case, it was one of Albert Einstein, because of course it was.
This represents the first time ghost imaging has been achieved without using any computational technology – and a brand-new way to probe the visual systems afforded to us by millions of years of evolution.