Here is one of those things you make every effort not to think about: paper money and coins go hand to hand, passing from person to person and as a result are really, really dirty stuff. 

The use of paper currency has lost much of of its proeminence due to plastic currency and other digital payment methods, but it is still required on certain situations.

The idea here is to devise a currency that, somehow, remains germ-free after use. 

On the same line of this idea, we could build a desinfecting machine that could help to keep money safe, instead of a disease vector. What technology to employ to sterilize money, that would no damage the bills? 

I know that are people around the world working to make these machines real. 

I'm a bit fascinated with gold. Not only it has fantastic physical and chemical properties but it also shines in a particular way under light, well, it is hard to explain.

So as many people before me every now and then I try to come up with a way to get gold out of seawater. 

In this idea, you would use an X-Ray source to produce rays that when interacting with gold ions, would produce a distinct signature, that you could pick up with a sensor. 

Imagine a flow of seawater, whenever this signature is detected, you open up an aperture and sucks the seawater with gold out of the stream. 

The idea is to repeat this process for a long time, ever concentrating the gold, until it is concentrated enough to be recovered by other traditional methods. 

This is an incredibly naive and ambitious project.

Study how memories are formed in the brain, until you find a way to produce a memory forming drug. Then you would map memories from individuals who dedicated their lifes to be proficient in a skill or part of the human knowledge. 

Finally you would commercialize vials of skills and knowledge: "Calculus 101" or "Business Intelligence 101" and so on. 

Honestly it worries me from time to time that we will reach a point where the human lifespan will not be enough to reach frontier knowledge.

I considered once, that when you place magnets with same poles close to each other, in unconfortable positions, you are storing energy. 

The idea is to pick up many tiny magnets, and place them in these positions in a container. Then you drip glue to them, holding them in place. This arranging and gluing is meant to be done by a machine.

Now the real issue, that I haven't worked completely, is releasing this energy in a controlled form. I though that you could melt the glue in a flame. You keep feeding the flame with this magnet bar, moving forward. The magnets would be set free, violently, and would collide with a rotating wheel, that would capture their motion.

There is a great change the overall efficiency would be really low.

Imagine that inside a turbine blade there are tiny little channels. These channels transport a fluid that solidifies in contact with air or water, depending on where the blade operates. This fluid is is the same material that is used to coat the blade in the first place. When the blade is damaged, the channels are exposed and the fluid leaks, covering the damage part and restoring it. 

Now, I don't think that other types of blades, sharped blades, would actually retain their sharpness if such channels were used there, but I honestly don't know.   

This is not an idea, but a problem. It is the single most important problem that Mankind has ever faced.

How can you transverse light-years of distance?

Solar sails, hybernation, artificial wormholes, FTL drives?

Our future lies in the stars.

There is a capacitor, hooked up to a DC power source. Now what happens of you take part of the wire that goes from the source to the capacitor, and put a section of it inside the capacitor places, where the field is going?

Would the electrons get a "kick"? 

How does that work, they are producing the very field that speeds them up?

Imagine that there is an alien communication system, all around the galaxy, passing through us at this very moment. 

How would it be? 

How would you tap into it?

Inside a warehouse there are all sorts of crates. You can imagine this idea in a harbor crammed with containers too. These boxes are identified by tags that are read by flying drones, via cameras and pattern recognition software. These drones hover around and maintain a list of everything that is on the warehouse and their locations, updating the inventory as these items are moved.

Initially I thought this was going to be a good way to find my glasses at home, but soon realize my cat wouldn't allow it.

This idea is somehow similar to my idea of putting a magnet on the tip of a spring. 

Now, what happens if you pass electricity through a normal metalic spring, and then put it to oscillate?