Five must-read stories from the past week include the world’s smallest integrated optical switch, which operates at level of individual atoms; developing the technology needed to build next-gen HPC systems; an automatic bug-repair system that fixes 10x as many errors; cracking an infamous soviet cold war cipher; and solving the impossible problem of how many ways you can arrange 128 tennis balls.

**How Many Ways Can You Arrange 128 Tennis Balls? Impossible Problem Solved**

A bewildering physics problem has been solved in a study which provides a mathematical basis for understanding issues ranging from predicting formation of deserts, to making AI more efficient. A team developed a computer program that can answer this mind-bending puzzle: Imagine that you have 128 soft spheres, a bit like tennis balls. You can pack them together in any number of ways. How many different arrangements are possible?

**Cold War Russian Cipher may Finally be Solved **

The Soviet VIC cipher used in the early 1950s, long known for being complex and secure, may not be as impossible to crack as initially assumed. Cracking the infamous Soviet VIC cipher is possible if one understands the enciphering algorithm. If one does not know the algorithm, the cipher indeed lives up to its reputation, and becomes nearly impossible to decipher.

**Recognizing Correct Code: Automatic Bug-repair System Fixes 10x as Many Errors **

Researchers have developed a machine-learning system that can comb through repairs to open-source computer programs and learn their general properties, in order to produce new repairs for a different set of programs. The researchers tested their system on a set of programming errors, culled from real open-source applications, that had been compiled to evaluate automatic bug-repair systems.

**How Do You Fit 10 Million Computers into a Single Supercomputer? **

The ExaNeSt Consortium working to develop the technology needed to build next-generation high performance computing systems. These systems achieve performance in the range of 1 ExaFLOPS = 1018 FLOPS. The project states that “HPC is, today, a tool of capital importance in the hands of humankind.” As such, it is developing and prototyping solutions for some of the crucial problems on the path to production of exascale-level supercomputers.

**World’s Smallest Integrated Optical Switch Operates at Level of Individual Atoms**

Researchers have created the world’s smallest integrated optical switch. Applying a small voltage causes an atom to relocate, turning the switch on or off. The quantity of data exchanged via communications networks is growing at a breathtaking rate. The volume of data for wired and mobile communications is increasing by 23 and 57 percent respectively every year. This means that network components must constantly be made more efficient.