One thing I have thought about recently:
Many types of alarms are based on detecting movement. This one is not!
It’s very simple and effective. Just seal the “gold room” air-tight, and let the pressure inside be lower or higher than the outside air pressure.
As soon as a door/ventilation/window/mouse hole gets opened, the pressure sensors get triggered.
It’s that simple!
Not all inventions need to be complex to work 
So, some of you may know, some of you may not.
Ice bullets have been around for some time now. Well, actually not really “ice bullets” - what has been used till now was ice shell around the actual bullet, which was preventing it from being “market” by the gun, thus givin up the shooter or the source of the gun, or.. etc.
Ice bullets are not perfect because they actually leave a metal trace - their “inside” bullet.
I have come around a way to prevent that.
Meet the real bullet - with no metal parts. Just ice. Totally untraceable.
Just mix 15% of wood dust with 85% water. Freeze. Use. This mixture will prevent the bullet from melting on the way to it’s target. It will make the ice 10 times stronger. And will do it’s job.
I don’t care if somebody steals this - unlike many others, I would rather be happy of seeing this real than dying keeping it under my bed…
So, getting to the point:
Hotels could service their clients by using little RFID chips - attach them to a customer’s hand bracelet, and this way store their purchases at the bar, track who is client and who is just visiting the hotel, call customers by name when approaching them in the restaurant, and so on and so on - the opportunities are endless.
RFIDs can be scanned from a distance - especially the ones with batteries with them. The ones which are not scanned, are not part of this discussion - they are not as “user friendly” as the ones needed to serve clients who do not want to be asked for their IDs all the time, for example.
A guest enters the hotel, presents his ID once and gives his credit card details. He is then given an RFID bracelet and forgets about being asked to identify or look for money until he leaves the hotel - the SPA, pools, bars, restaurants - all are open for him. He feels like he paid for ALL INCLUSIVE service - when in fact he pays for what he uses. Yet, this is so friendly for him, that he is ready to consume, consume, consume!
I don’t care if somebody steals this - unlike many others, I would rather be happy of seeing this real than dying keeping it under my bed…
So, getting to the point:
To take a picture of everyone on a crowded street, and possibly track a suspect, you would need either more cameras, or a camera with unbelievably high resolution. Neither has been yet created in the size, suitable for the size of a hidden camera.
However, if you pack 10 small cameras in a box, with powerful lenses and really fast turning engines, you get what you need - swift, momentary identification of everybody, at any moment moving in sight of the cameras.
One camera needs just part of a second to take a picture, especially if you have optical zoom - the size of the picture needed is very very small - much smaller than the ones needed to take a picture of a whole street.
So imagine 10 cameras in a box, taking 20 pictures per second - or in other words, single camera being able to identify 20 people per second!
Each small camera will be able to move quickly, guided by software to picture only human faces. It will not waste pixels for filming concrete or cars - just faces. With the advancement of technology (and optics already at perfection), if we combine these we could focus a single IR camera with small enough beam to film only an eye, thus making possible mass iris detection and surveillance. This is literally impossible with the current cameras on the streets.