Magnetism is the ability of a material to be attracted by a magnet. It also include the ability for some material to act like a magnet. No doubt youve handled refrigerator magnets. You can see some in Figure 1.28. You probably know they stick to a metal refrigerator. This is what holds your homework up. Maybe your little sisters drawings are hung on the fridge in this manner. Do magnets stick to all materials? Of course not. You have probably checked and they do not stick to other surfaces. They do not stick to wooden doors or glass windows. Wood and glass are not attracted to a magnet. Obviously, only certain materials are attracted to magnets.

What do magnets not stick to?

To make certain the U.S. was aware of the danger, in July 1939, a few months before the beginning of World War II in Europe, Szilard and Wigner visited Einstein to explain the possibility of atomic bombs, which Einstein, a pacifist, said he had never considered. He was asked to lend his support by writing a letter, with Szilard, to President Roosevelt, recommending the U.S. pay attention and engage in its own nuclear weapons research. A secret German facility, apparently the largest of the Third Reich, covering 75 acres in an underground complex, was being re-excavated in Austria in December 2014 and may have been planned for use in nuclear research and development. The letter is believed to be "arguably the key stimulus for the U.S. adoption of serious investigations into nuclear weapons on the eve of the U.S. entry into World War II". In addition to the letter, Einstein used his connections with the Belgian Royal Family and the Belgian queen mother to get access with a personal envoy to the White House's Oval Office. President Roosevelt could not take the risk of allowing Hitler to possess atomic bombs first. As a result of Einstein's letter and his meetings with Roosevelt, the U.S. entered the "race" to develop the bomb, drawing on its "immense material, financial, and scientific resources" to initiate the Manhattan Project. It became the only country to successfully develop an atomic bomb during World War II. For Einstein, "war was a disease ... [and] he called for resistance to war." By signing the letter to Roosevelt he went against his pacifist principles. In 1954, a year before his death, Einstein said to his old friend, Linus Pauling, "I made one great mistake in my life--when I signed the letter to President Roosevelt recommending that atom bombs be made; but there was some justification--the danger that the Germans would make them ..."

How many years before Einstein's death did he begin the quest toward creating a nuclear weapon?

(CNN) -- Beyond skateboards, Silicon Valley and hippies, California has a trendsetting streak of a different kind. The state has been first to pass major public health initiatives that have spread throughout the country. California was first to require smog checks for clean air, pass anti-tobacco initiatives and bike helmets laws. While these laws were met with skepticism and ridicule, they've often become standard practice in other states. The Golden State was first to ban smoking in workplaces, bars and restaurants in 1998. Now similar rules exist throughout the country. Some advocates tout the state as a forward-thinking vanguard in which its health and safety laws are routinely emulated by other states. "There have been progressive legislations in tobacco, environment and obesity prevention," said Mark Horton, a lecturer at the University of California Berkeley School of Public Health. "In some respect, the rest of the country looks to California as a laboratory for moving forward with those various types of initiatives." But some critics liken the Golden State to a nanny state. California has 151,002 health and safety laws. "It never ends," said Laer Pearce, who works in public affairs in Orange County. "Every year, several hundred bills come through and dozens of them tell us how to live our lives." Starting in January, 760 new California laws went into effect -- for example, the importing of shark fins is prohibited, student athletes are required to have medical clearance after suffering a head injury, teens are banned from using tanning booths and the sale of caffeinated beer is forbidden. There's a perception that California has "more folks who are health-oriented and more health-minded," said Horton, former director of the California Department of Public Health. It's not just workout fanatics hanging out at Muscle Beach, Sierra Club members hiking mountains or the uber-health-conscious touting organic foods. Californians in general tend to have healthier habits, ranking 10th for physical activity, fourth for healthy blood pressure and fifth for a diet high in fruits and vegetables compared with other states, according to America's Health Rankings.
What are a few public health initiatives that California passed?