In Praise Of Lasers

The military parade in China this week brought attention to lasers as defensive weapons but I think this would also be the best route to nuclear fusion.

Light actually exerts force. The force is electrical in nature, since light is electromagnetic and negatively charged electrons are the outermost part of atoms. But electromagnetic waves take the form of a sine wave and the waves are out-of-step, meaning that their peaks and troughs strike the object at different times, as well as being of all different wavelengths. The result is that the force is dissipated.

The principle of a laser is to generate light of one fixed wavelength and aligned so that the waves are all in step with each other. When this is done the beam will exert force and will not spread with distance, as light usually does.

THE REACTOR MENTALITY 

A much-awaited development is power from nuclear fusion. Fission, meaning to split atoms, has long been a source of power but no one has yet made fusion, meaning to fuse atoms together, into a practical source of power. 

If only fusion could be made to work, it holds tremendous promise. Fission only works with the very expensive and rare 235 isotope of uranium or the man-made plutonium. Fusion can work with any atoms, lighter atoms are easier to fuse together. Unlike fission, fusion produces no radioactive wastes. Fusion would produce far more energy per mass than fission.

It's certainly not that fusion can't be done. The sun and stars actually operate by fusion. A star is born when enough matter comes together for it's mutual gravity to overcome the electron repulsion between atoms and fuse lighter atoms into heavier ones. The new heavier atom contains less internal energy than the lighter atoms that were fused together to form it. The excess energy is released as radiation and that is why stars shine. The sun is now in the process of fusing four hydrogen atoms into one helium atom. 

Fission, the splitting of atoms that we use now, is actually a secondary nuclear process. All stars operate by fusion and, as time goes by, successively heavier elements are fused together. This releases more energy per time and upsets the star's equilibrium between the inward force of gravity and the outer force of the energy that is released. The sun will eventually swell into a "red giant", but the largest stars will explode from the center in a supernova. A tremendous amount of energy is released by the supernova and this fuses atoms together into heavier atoms that wouldn't ordinarily exist, as the ordinary fusion process only goes as far as iron. 

That is why iron and lighter elements are exponentially more common than heavier elements. This is where the uranium comes from that we use for fission. The energy we obtain is energy that originated in the supernova of the large star that preceded the sun. Some of these heavier elements are less-than-stable and gradually emit particles or radiation to reach a more stable state. These emissions are known as radioactivity.

The trouble with making fusion into a practical energy source is actually the tremendous amount of energy that it releases. This energy fuses more atoms, which releases more energy, so that the process is self-sustaining. But since it is energetic enough to fuse atoms together, that means no material made of atoms can contain the process. The only way to contain it is by a magnetic field, but this is very challenging and requires completely new technology. 

There is another way to fuse atoms together, and that is by lasers. I think that we would be better off taking this route to fusion power. It will be wonderful if the magnetic field containment is ever perfected and made practical. But who knows how long that is going to take? In the meantime we can proceed along the laser route.

I think we have the mentality of what a fusion reactor should be, that it should be along the lines of the existing fission reactors. But how about some thinking outside the box? What about an ordinary car engine? The same concept could apply to a fusion reactor. Energy is released in a chamber as lasers, mounted in the walls, fuse atoms together. Some of the energy is rerouted to power the lasers, and the rest is useful energy. This is in the same way that energy released by combustion is rerouted to drive the pistons.

LASER DEFENSE 

The wars that are underway are both proving grounds for ballistic missiles and drones. These missiles and drones will be everywhere. There are defensive missiles that can shoot them down. The trouble is that the defensive missiles tend to cost a lot more than the missiles and drones that they shoot down. A drone might cost a thousand dollars while the missile that shoots it down costs a million dollars.

Research into laser defense is already underway and that is definitely the best way to be secure from missiles and drones.