Ask the Expert at Decoded Science

Mercury fillings are a controversial dental amalgam: studies have consistently shown to release levels of mercury below toxic levels, but what about the particles that result from dental work?

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The Question: If the Earth is rotating on its axis and also revolving around the Sun, why don’t we feel any motion?

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How would an EMP affect our Nuclear Power Plants? An EMP, or electromagnetic pulse, can be a potential threat to the United States and the world, that we are not prepared for. It can occur when a high-altitude nuclear weapon is detonated, or through severe space weather such as a solar flare or Coronal Mass Ejection. Even a lightening strike can produce an electromagnetic pulse, and interrupt transmission of power. Although non-scheduled outages from power surges are usually transitory, the affect on power generation presents an unacceptable risk. The loss of supply not only cripples the end user but the generator of the power, as well. So, what happens when the transmission lines can not accept power from the producers, and how do the plants shut down under a station blackout condition? An EMP’s affect on the successful shutdown of a nuclear power plant must have consequences, so what are they? Power Transmission and EMP An EMP is caused by a high-intensity burst of electromagnetic energy and a rapid acceleration of charged particles. Through this burst, gamma rays collide with particles to produce free electrons which produce current (E1). It is this current that would destroy electronic equipment on Earth [...]

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The Question: Will 2012 be the year of the solar storm? Stories about “Solar Max” and electric gadget-frying-levels of solar flares are running high in the rumor mill. What is the truth about the solar maximum and solar storms in 2012? The short answer is: 2012 is will probably not be the “Year of the Solar Storm.” The level of solar storms will actually not be particularly high during 2012. It is not, however, possible to be 100% certain, because predicting solar storms, as with predicting weather on Earth, is difficult and therefore subject to being occasionally wrong. What Are Solar Storms? Astronomers have been studying sunspots since Galileo discovered them with his new telescope in the early seventeenth century. The solar magnetic activity, which causes sunspots, also causes a variety other magnetic activity loosely described as solar storms. Solar flares are one of these manifestations of solar magnetic activity; a small region of the Sun brightens for a short time and releases a significant amount of energy. Coronal Mass Ejections (CMEs) are another example of solar storm activity that affects Earth. When the material shot from the Sun in a CME strikes Earth, it interacts with Earth’s magnetic field [...]

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Question: “What are the arsenic, lead, etc., limits for water and wastewater treatment products?” Wastewater treatment produces purified drinking water and less-stringently processed water used for a number of purposes. Whether or not the treatment products are used for drinking, the amount of toxins allowed in the final product is regulated by the Environmental Protection Agency. In order to answer this question from a Decoded Science reader, we describe here the sources of these pollutants and the current U.S. legislation regarding drinking water and the discharge of wastewater. Arsenic: Sources and Effect on the Health Arsenic (As) is an element used for several human activities. It is a very poisonous element; prolonged exposure to it or ingestion of small amounts can cause long term effects, such as cancer. In nature, As is present in the form of various minerals, such as arsenpyirite (FeAsS) and lollyngite (FeAs2). Leaks of these minerals into ground waters can cause contamination. Arsenic is used in several industries and/or agricultural processes; for many years it has been used, for instance, as a wood preservative. More recent applications are in the field of electronics, as arsenic-based compounds such as gallium arsenide (GaAs) are used as semiconductors. The [...]

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The Question: “Why do you feel colder when the air is humid? I understand why higher humidity, which suppresses evaporation cooling, makes you feel warmer at normal temperatures. But people keep telling me opposite is true when it gets near freezing or below. I am not buying this. All other things being equal (same wind, no rain, dry clothes, etc.) I suspect moisture in the air will always make one feel warmer, even at 20 degrees. Help me settle this argument.” Limiting Case Experimental Answer In science, the ultimate arbitrator for answering questions is experiment rather than theoretical arguments. Physicists also often use the limiting case to gain insight into a particular situation. The limiting case of high humidity is 100% humidity, which means its raining. Anyone who has ever been caught in a cold rain while wearing inadequate clothing knows that 100% humidity during cool weather makes us feel much colder than if it were dry at the same temperature. This experiment strongly suggests, but does not prove, that high humidity (dampness) during cold weather makes us feel even colder. The same mechanisms that make people feel colder during a cold rain contribute to making cold damp weather feel [...]

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Question: “Every year, I pull out my Christmas ornaments, and find that the majority of strands of lights don’t work anymore. Why do Christmas lights only last one year?” To answer this question, we describe the most common types of Christmas lights, and what can cause their failure. Lights Made with Incandescent Bulbs The most common Christmas lights are the traditional strings of lights made with incandescent bulbs. In the incandescent bulb there is a metallic filament, usually made of tungsten (W) connected to the electric circuit. When there is an electric current going through the filament, this becomes hotter and hotter; consequently it starts glowing and generates light. There are several other parts in the bulbs, the most important being: The contact wires, which connect the tungsten filament to the electric circuit; A case or envelope, to protect the filament.  As the bulb can get very hot (more than 200oC), the case has to be made of a material resistant to high temperature, such as glass. The case is filled with an inert gas, such as argon. Why Incandescent Light Bulbs Can Fail Generally if a light bulb fails, it is because the filament becomes too hot, and burns. [...]

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Petroleum fuels the world. From ocean-based rigs to new developments in the oil sands, petroleum also fuels local and global controversy about the ways in which we extract and use fossil fuels. To many, oil extraction brings to mind an ecstatic oilman, gleefully watching as free-flowing oil gushes from the ground. While some oil flows freely, bitumen is more prosaic. It doesn’t flow well unless it is diluted with other hydrocarbons. This slow, sandy petroleum product is also known as tar, since bitumen is a slow, molasses-like substance. This is what makes up the oil sands. How Did the Tar Sands Form? Like other petroleum products, the tar sands began a long, long time ago. Once, an ocean covered the Canadian province of Alberta. Tiny creatures lived in the ocean sands. When these creatures died, the heat of the ocean and years of silt accumulation turned them into oil. Today, the oil sands cover over 87,000 square miles of Alberta’s Athabasca, Cold Lake and Peace River regions. After Saudi Arabia, the oil sands may be the largest oil reserve in the world. Environmental Impacts of Oil Sands Development Why are ancient ocean creatures so controversial? Oil sands are relatively difficult [...]

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I was recently asked by a reader, ” Does the time change mean we have more daylight?” Unfortunately, the answer is no – the term, “Daylight Savings Time” is the cause of much misunderstanding. It’s often thought that putting the clocks forward an hour in spring and turning them back an hour in autumn actually gives us “more daylight.” In fact what it does is provide longer daylight hours in the morning (when we turn the clocks back) or in the evening (when we move the clocks forward.) The amount of daylight reaching any point on the earth over any 24-hour period varies according to the position of the earth relative to the sun – not by government changes to the clocks. For example, on 5 November, 2011, sunrise in New York is at 0730 (7:30 AM) and sunset is at 1748 (5:48 PM.) On the 6th of November, when the clocks have been put back an hour, sunset is at 0632 (6:30 AM) and sunset set is at 1647 (4:47 PM.) However, the amount of daylight (subject to three minutes of seasonal shortening) remains the same. Daylight savings time is a purely artificial construct which affects how humans choose [...]

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