So basically, the government has to detect these bundles and bundles of cash kept under the bed, over the ceiling, behind the toilet seat, in basements, cars seats and where not. One thing we can be sure of - that it is hidden very innovatively.
Now detection requires eye sight, which essentially requires light to reflect from those bundles of notes and get absorbed in the eyes of IT sleuths. The first problem is the covering material. It can be anything including roof, covering polythene, house walls, etc. They all make things opaque for. So we can't use visible light, infrared light, ultraviolet light, millimeter wavelength microwaves for black money detection in cash form. However, if we go one step ahead the radio waves used by mobiles and wifi used by our devices can go through these walls. No matter how deep a basement you are in, you still get network connectivity. So we need some kind of modeling that allows us to project and make an imagery of the radio waves.
This is where "The Dark Knight" strikes. You remember this scene -
The concept is to use mobile devices and turn them into high-frequency generator. This should then allow you to plot / trace the whole country - city by city - block by block - in and out. India, as a country has definitely managed to achieve decent mobile penetration. Don't have any person or company as a watchdog on this. It will unnecessarily go into tangles of law and privacy. A better approach will be to have the live imagery feed further equipped with AI bots to automatically detect huge stacks of cash. Alas, the technology is not yet there and a little futuristic. But it would have helped the Modi government immensely during these times of upheaval where the government wants to clean the system as much as possible from the evils of black money.
Is there anyone who would care to venture in getting high-frequency generator right?