The List: Five Physics Lessons for Obama

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Terrorism

Conventional wisdom: A nuclear attack is the biggest terrorist threat we face.

The hard science: Making a nuclear bomb is excruciatingly difficult. North Korean leader Kim Jong Il spent billions making onestarving his people in the processand even his bomb fizzled. When it was tested in 2006, it released the energy equivalent of about half the jet fuel of each of the planes that crashed into the World Trade Center towers.

But even if a nuclear bomb fizzles, cant it spread deadly radioactivity? And what about a dirty bomb, a smaller weapon specifically designed to do just that? This threat is also mostly exaggerated. In reality, a dirty bomb would leave very few immediate casualties. Thats because radioactivity, once spread after an explosion, drops below the threshold for radiation illness. A dirty bomb might not even cause an observable increase in cancer rates. Perhaps thats why alQaeda instructed Chicago gang member Jos Padilla to abandon his goal of making a dirty bomb and told him instead to blow up apartment buildings using natural gaswhich would have a greater chance of killing a large number of people. What is most scary is that al Qaeda seems to understand this fact better than many politicians.

Message for Obama: Many people may worry most about the drama of nuclear terrorism, but as 9/11 showed, its far easier for terrorists to inflict massive damage with commercially available explosives such as jet fuel or gasoline.

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Energy

Conventional wisdom: Big oil companies are behind our addiction to fossil fuels. If we could break their grip, we would have energy from other sources, such as hydrogen and high-tech batteries.

The hard science: Our gasoline addiction is based in large part on physics and chemistry: Gasoline contains, pound for pound, 15 times more energy than TNT.

But doesnt hydrogen have even more energy? Yes, per pound, but not per gallon. Thats because a pound of hydrogen takes up a lot more space than gasoline. Even as a liquidits densest formit has only one fourth as much energy per gallon as gasoline. And that liquid has to be kept at a very inconvenient -253degrees Celsius (-423 degrees Fahrenheit). Moreover, hydrogen is not a source of energy, because we cant mine it; we have to manufacture it either by electrolysis (running an electric current through water to get the H2 from H2O) or from natural gas. Hydrogen is only a means of transporting energy, not an energy source in its own right.

What about high-quality batteriesthe kind used in cellphones and laptops? These batteries contain only 1 percent of the energy of their equal weight in gasoline. You can recharge them cheaply, but current batteries typically die after 1,000 charges. If you include the cost of replacement, then they are far more expensive to use than gasoline, though a bit less harmful to our atmosphere.

Message for Obama: The biggest source of clean, cheap energy is energy not used. And conservation doesnt have to be uncomfortable. Tell people they can turn up their thermostats to any temperature they like, but encourage them to make sure there is some good (and it can be cheap) insulation in the walls of their homes.

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Nuclear Energy

Conventional wisdom: Nuclear power would be great if only we could figure out how to get rid of the horrific waste. Plutonium lasts 24,000 years. There is absolutely no way we can keep that waste safe for such a ridiculously long time.

The hard science: Yes, plutonium has a half-life of 24,000 years, but it is so insoluble in groundwater that most experts agree it is easy to store safely. Additionally, plutonium can be reprocessed for use as fuel in reactorsthats what France does. The real worry about nuclear waste is the other radioactive elements involved in the process.

How bad is this other waste? The U.S. government has put fantastic restrictions on allowed levels of nuclear leakage. Nevadas Yucca Mountain nuclear waste storage facility, for example, is required to demonstrate that people living downstream, and drinking all their water from underground wells, will not get more than 15millirems of radiation exposure each year from leakage. To put that number in perspective, those same people will get an average of 350millirems per year from nature and typical medical procedures.

Its true that after 300 years, nuclear waste is still about 100 times more radioactive than the original uranium that was removed from the earth. But even this isnt as scary as it sounds. If the waste is stored underground in such a way that theres only a 10 percent chance that 10 percent of it will leakwhich should be more than doablethe risk will be no worse than if we had never mined the uranium in the first place.

Message for Obama: Politicians believe the problem with nuclear waste is technical in nature. The scientists and engineers believe the problem is political. Mr. Obama, you need to explain the numbers to the public, because you are probably the only person in the United States who can convince citizens that nuclear waste storage really is a solved problem.

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Space

Conventional wisdom: Sending humans into space is indispensable. Astronauts saved the United States hundreds of millions of dollars by repairing the Hubble Space Telescope. Astronauts were essential during the Apollo missions to the moon.

The hard science: Manned space flight might be a great adventure, but dont fool yourself into thinking that the presence of humans helps advance science. The greatest scientific achievements of the space program have been the unmanned missions to the planets and the use of remotely controlled instruments to measure the cosmos. All of our greatest space science has come from robots. Yes, Hubble was fixed by humans, but building a telescope that was safe for humans to repair was actually far more expensive than just building a spare one that could have been launched if things went wrong.

Most scientists roll their eyes when NASA talks about the need for human astronauts. Numerous missions have been delayed (and made substantially more expensive) when NASA decided they had to be launched with the space shuttle instead of cheaper unmanned rockets. NASAs circular rationale: to justify the cost of the shuttle.

Message for Obama: Explain to the public that putting humans in space is not only very dangerous; it usually slows the advance of science. If the public just wants the adventure, then let them know that that is the real purpose.

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Global Warming

Conventional wisdom: Because the United States is responsible for about one fourth of the excess carbon dioxide that drives the greenhouse effect, the key to solving the problem is for America to go green.

The hard science: Yes, it is true that the United States is responsible for one fourth of past global warming. However, U.S. emissions are growing relatively slowly today.

So why are we so worried? Its the rapidly growing greenhouse gas emissions of the developing world. China has already surpassed the United States in annual emissions. Its economy has been growing at 10 percent per year (pessimists think the recent economic crash may slow it to 8 percent), but its carbon dioxide emissions are growing 12 to 13 percent per year. Soon it will far outpace the United States as a contributor to global warming. The rest of the developing world is following.

Some say the United States needs to set an example. But it already has: Once a country is wealthy, it can afford to cut back on carbon dioxide. Unfortunately, by the time China is as wealthy as the United States, the world will very likely be 5 to 7 degrees Fahrenheit warmer.

Message for Obama: If we want to stop global warming, then our focus must be on the developing world. Wealthy countries could start by financing clean coal in China. For $50 billion per year, we could at least make sure that new coal plants in China are capable of sequestering carbon dioxide. Sending that kind of money to China would have been a tough sell during the election, but now that the campaign is over, it is time to come cleanabout getting cleanto the American people.