Thursday, June 01, 2006

Fuel Economy

by Charles Bartlett (Class of '06)

It is a well-known fact that the world has a limited supply of oil. Oil is used in a multitude of ways, but its most lucrative application is in the automotive industry due to its vast amount of stored energy. The oils used in the auto industry are usually derived from petroleum, and much of the world’s petroleum supply exists under some of the most politically instable and fanatical areas of the world. Finally, the emissions from oil and gasoline, which is also derived from petroleum, once the two are used to their potential in the internal combustion engine have been shown to have damaging effects on the earth’s atmosphere and ozone layer.

Do to these problems, some people have long been calling for an alternative to the use of oil and gasoline in the internal combustion engine, or for a different engine all together. This argument gained a lot of strength in the 1990s, due to all of the media coverage that global warming received. As much of the world’s oil supply is located in the Middle East, political and military uncertainty in the region further increases the demand for alternative power. In the last year or so, this demand has become even stronger due to the sharp spike in gasoline sales.

Currently, some promising alternatives to gasoline are the hybridization of gasoline engines to include electric power, and the use of either ethanol or hydrogen as fuel. Gas-electric hybrids have already been released on the automotive market. These cars use both electricity and gasoline or diesel fuel, and the result is much better gas mileage. Though there are many designs, the most common is that used in the Toyota Prius. When the car is at cruising speed, or at any other point when the car only needs a small thrust, the internal combustion part of the motor spins a generator, which either recharges the battery, or powers the electrical apparatus that propels the car. Other charging of the battery occurs during regenerative braking, where the braking system of the car captures some of the kinetic energy that would usually be lost to heat in normal cars. When the battery has been charged sufficiently, the car is able to switch to its electrical means of propulsion, and is thereby able to save immense amounts of fuel.Another promising alternative is the use of ethanol as a fuel. Brazil is leading the way in the use of ethanol, and produces its ethanol from sugarcane. The country recently announced that it no longer depends on Middle Eastern oil for its fuel. The United States is also pursuing the use of ethanol. The U.S. has long been a great producer of corn, and it will hopefully use much of its corn crop in the future to produce ethanol. The engines that use ethanol in the future will most likely be FlexFuel engines that can run on gasoline, ethanol, or any combination of the two.

Though the future of automotive fuel is still in question, the alternatives to gasoline and oilmake for safe and efficient driving in the future.

Black Hole Information Lost Forever? Not Quite, According to String Theory

by Sam Wass (Class of '06)

One of the most intriguing conclusions found by string theory, the proposed “theory of everything” which unifies the four fundamental forces (gravity, electromagnetism, strong nuclear force, weak nuclear force), regards one of the universe’s most bizarre objects: black holes. String theory applied to black holes suggests that black holes do not necessarily lose all of the information of the objects sucked inside of them. This resolves one of the greatest problems in modern physics, called the information paradox. Classical equations stipulated that the end result of a black hole was always the same, regardless of the matter put into it. However, this violates quantum mechanics, because it stipulates that processes must be traceable.

Black holes are one solution to Einstein’s equations of general relativity. They are the remnants of stars so massive that they collapsed in on themselves after their supernova, a massive explosion of a dying star. These bizarre objects have zero volume and infinite density, and are completely described by their electrical charge, angular momentum, and mass. It was long thought that information sucked into a black hole was lost forever, but string theory suggests that this may not be the case at all.

String theory, as its name indicates, suggests that the universe is composed of tiny “strings”, which are extremely small loops of energy. They vibrate in different ways, in very much the same was as a musical string would be plucked, and these different vibrations produce the different particles that science observes. Because of Einstein’s mass/energy equivalent (E=mc^2), the string at lower energies represent the least massive particles, while strings at high energies represent more massive particles.

If string theory is applied to black holes, then the singularity, or center of the black hole where the laws of physics do not apply, does not become so indescribable anymore. String theorists describe the singularity as a large mesh of strings, rather than a point in space. This mesh, or “fuzzball” as it is often called, would become very stretchy as it becomes more massive in order to create a supermassive object like a black hole. Scientists who tested the diameter of a black hole that would be produced using this method found that their answer closely approximated the diameter of classical equations.

If this postulate is correct, then information about the objects sucked into the black hole can be stored inside, and then reemitted via Hawking radiation, which happens when the black hole radiates its mass in the form of small particles. Until the application of string theory to black holes, it was believed that a black hole would destroy any information stored inside it. In order to justify this loss of information, quantum mechanics, the rules that govern the universe at its smallest scales, was thought to break down in black holes. However, the application of string theory shows that information stored in black holes is not lost, if string theory is proven to be correct.


New Scientist, “Hawking Cracks Black Hole Paradox” by Jenny Hogan

“Physics, M-Theory, and Black Holes"

"Information Paradox Solved? If So, Black Holes Are “Fuzzballs”"