The four-dimensional universe
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The four-dimensional universe book
Some boys and girls find it very difficult to learn which is their right and which their left hand. Likewise, when they begin writing, some confuse their p's and q's, or their b's and d's. Kant had the brilliant insight that children are right to be confused. In a strange space that had four spatial dimensions in addition to time, a left hand could be 'rotated' into a right hand. A left hand could thus be fitted into a right hand glove simply by flipping it around. The incongruency of the letters depends on the overall shape of the space. There was tremendous surprise in 1956 when two physicists, Tsung-Dao Lee and Chen Ning Yang, showed that incongruent counterparts play a role in fundamental physics. They studied very fragile subatomic particles, which can be produced by physicists but quickly decay and fall apart. Some of these particles come in pairs of incongruent counterparts.