Milan is one of Europes most polluted cities and that puts Leonardo da Vincis The Last Supper at risk. The painting has been on the wall of a dining hall in Milans Santa Maria Delle Grazie monastery for more than 500 years. Particulates in the air fr

发表于:2019-01-08 / 阅读(70) / 评论(0) 分类 Scientific American(十二)月

Particles can come into being and be gone again in as little as 0.000000000000000000000001 second (10-24). Even the most sluggish of unstable particles hang around for no more than 0.0000001 second (10-7). 粒子可以在短达0.000 000 000 000 000 0

发表于:2019-02-17 / 阅读(67) / 评论(0) 分类 万物简史

CERN, the European Organization for Nuclear Research, is like a little city. Straddling the border of France and Switzerland, it employs three thousand people and occupies a site that is measured in square miles. CERN boasts a string of magnets that

发表于:2019-02-17 / 阅读(67) / 评论(0) 分类 万物简史

The intention of the collider was to let scientists probe the ultimate nature of matter, as it is always put, by re-creating as nearly as possible the conditions in the universe during its first ten thousand billionths of a second. The plan was to fl

发表于:2019-02-17 / 阅读(79) / 评论(0) 分类 万物简史

Particle physics, in short, is a hugely expensive enterprisebut it is a productive one. Today the particle count is well over 150, with a further 100 or so suspected, but unfortunately, in the words of Richard Feynman, it is very difficult to underst

发表于:2019-02-17 / 阅读(47) / 评论(0) 分类 万物简史

It is all, as you can see, just a little unwieldy, but it is the simplest model that can explain all that happens in the world of particles. Most particle physicists feel, as Leon Lederman remarked in a 1985 PBS documentary, that the Standard Model l

发表于:2019-02-17 / 阅读(49) / 评论(0) 分类 万物简史

Einstein disliked that, too. He devoted the rest of his life to searching for a way to tie up these loose ends by finding a grand unified theory, and always failed. From time to time he thought he had it, but it always unraveled on him in the end. As

发表于:2019-02-17 / 阅读(56) / 评论(0) 分类 万物简史

Quantum theory is very worthy of regard, he observed politely, but he really didnt like it. God doesnt play dice, he said. Or at least that is how it is nearly always rendered. The actual quote was: It seems hard to sneak a look at Gods cards. But th

发表于:2019-02-17 / 阅读(53) / 评论(0) 分类 万物简史

Remarkably, the phenomenon was proved in 1997 when physicists at the University of Geneva sent photons seven miles in opposite directions and demonstrated that interfering with one provoked an instantaneous response in the other. 令人惊叹的是,这

发表于:2019-02-17 / 阅读(47) / 评论(0) 分类 万物简史

It seemed as if there was no end of strangeness. For the first time, as James Trefil has put it, scientists had encountered an area of the universe that our brains just arent wired to understand. Or as Feynman expressed it, things on a small scale be

发表于:2019-02-17 / 阅读(68) / 评论(0) 分类 万物简史

Finally, in 1926, Heisenberg came up with a celebrated compromise, producing a new discipline that came to be known as quantum mechanics. At the heart of it was Heisenberg's Uncertainty Principle, which states that the electron is a particle but a pa

发表于:2019-02-17 / 阅读(58) / 评论(0) 分类 万物简史

At least the names for the two main possible culprits are entertaining: they are said to be either WIMPs (for Weakly Interacting Massive Particles, which is to say specks of invisible matter left over from the Big Bang) or MACHOs (for MAssive Compact

发表于:2019-02-25 / 阅读(89) / 评论(0) 分类 万物简史

In 1910, Rutherford (assisted by his student Hans Geiger, who would later invent the radiation detector that bears his name) fired ionized helium atoms, or alpha particles, at a sheet of gold foil. To Rutherford's astonishment, some of the particles

发表于:2019-03-10 / 阅读(166) / 评论(0) 分类 万物简史