In 1936 van Stockum solved the Einstein equations for the gravitational field of a rapidly rotating infinite cylinder. It is shown that such a field violates causality, in the sense that it allows a closed timelike line to connect any two events in spacetime. This suggests that a finite rotating cylinder would also act as a time machine.
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L’âge des cavernes


森林浴
Shinrin-Yoku

The growing interest in environmental stress has been accompanied by a rapid accumulation of evidence indicating that environment can elicit substantial stress in people living in urban environments [1]. Furthermore, it is broadly conceived that the natural environment can enhance human health [2]. There have been several questionnaire studies on the psychological effects of forest environments. A previous study found an enhancement of positive emotions among subjects who were shown pictures of natural environments [3–6]. Moreover, other studies have also found that forest environments improve the psychological wellbeing of people [7–12].
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Neko no Myōjutsu

“Truth is, surfing is like a martial art. ”
– Kelly Slater

The Swordsman and the Cat – Issai Chozan, 1727

There was once a swordsman called Shōken, who was very much annoyed by a furious rat in his house. The rat was bold enough to come out of its hiding place even in the daytime, doing all kinds of mischief. Shōken made his pet cat go after it, but she was not its equal, and being bitten by it, she ran away screaming.
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