Matrioshka Brains

Matrioshka Brains (MB)1 are megascale computers constructed out of microelectronic and/or nanoscale components.  MB may be constructed as shells around a star (internally powered Matrioshka Brains: IPMB) or may be constructed independently of a star if large amounts of power are harvested from stars in other locations and beamed to the MB (externally powered Matrioshka Brains: EPMB).  A third variant, (self-powered Matrioshka Brains: SPMB) which generates power via controlled n...

 The Physics of Fusion

The basic physics of thermonuclear energy is seductively simple. Fission produces energy by atomic fracture, fusion by tiny acts of atomic union. Every atom contains at least one proton, and all protons are positively charged, which means that they repel one another, like identical ends of a magnet. As protons are forced closer together, their electromagnetic opposition grows stronger. If electromagnetism were the only force in nature, the universe might exist only as single-proton hydrogen a...

 tokamak

It is called a tokamak—old Soviet shorthand for a more precise and geometrical name, toroidalnaya kamera s aksialnym magnitnym polem, or “toroidal chamber with an axial magnetic field.” Sakharov’s rough sketch depicted a doughnut-shaped vacuum chamber, or torus, ringed with electromagnets, and that is how iter’s core will look, too, once it is completed. In myriad ways, the project is a fragment of the Cold War stranded in the present day. Sakharov had predicted that a reactor base...

 The ITER Project

Years from now—maybe in a decade, maybe sooner—if all goes according to plan, the most complex machine ever built will be switched on in an Alpine forest in the South of France. The machine, called the International Thermonuclear Experimental Reactor, or iter, will stand a hundred feet tall, and it will weigh twenty-three thousand tons—more than twice the weight of the Eiffel Tower. At its core, densely packed high-precision equipment will encase a cavernous vacuum chamber, in which a s...

 The Delicate Balance of the Forces of the Universe

the universe would be a vastly different place if the properties of the matter and force particles were even moderately changed. For example, the existence of the stable nuclei forming the hundred or so elements of the periodic table hinges delicately on the ratio between the strengths of the strong and electromagnetic forces. The protons crammed together in atomic nuclei all repel one another electromagnetically; the strong force acting among their constituent quarks, thankfully, overcomes t...