What is the most powerful type of explosion in the Universe?

There are two answers to this question. Scientists say the ultimate explosion was the Big Bang. This is the explosion thought to have given rise to the visible Universe. The concept comes from Albert Einstein's equations: The Universe is expanding. So if you trace time backwards, you would see that the Universe gets more and more compact. At the moment of the Big Bang, when time as we comprehend it began, all matter and energy was confined within a speck smaller than an atom.

The Big Bang is the most powerful explosion known, but it was a one-shot deal. The most powerful recurring explosions are gamma-ray bursts. These are quite common. Satellites detect these bursts at a rate higher than once a day. Gamma-ray bursts are a mystery, but it is becoming clear that they likely mark the birth of a black hole. This means that every day, somewhere, a new black hole is created.

Gamma-ray bursts are about 100 times more powerful than a type of star explosion called a supernova. Yet these bursts themselves might be from exploding stars. One theory is that supernovae are stars about 10 times more massive than our Sun. When they explode, they leave behind a dense core called a neutron star. Gamma-ray bursts might be from so-called hypernovae, bigger than supernovae; and when these explode, they leave a black hole behind. Another theory is that gamma-ray bursts arise from a merger of two neutron stars. Both theories might be correct.

Gamma-ray bursts are a mystery because they are so random and fleeting. They appear from any direction in the sky and last only for a few seconds. A long burst is about 60 seconds; the shortest are just a few milliseconds. Scientists have a hard time turning their telescopes to catch them before they fade forever.

Later this year scientists will launch an international satellite called Swift, which was assembled at NASA Goddard. Swift, as the name implies, will detect gamma-ray bursts and swiftly turn its instruments to study the bursts in-depth before they fade, even the shortest ones. We just may solve the mystery of the most powerful explosions in the Universe by this time next year. Stay tuned.

This week's question is provided by Christopher Wanjek. Mr. Wanjek is a science writer supporting the Beyond Einstein initiative, a roadmap to understand the forces of nature beyond General Relativity and Quantum Mechanics through the study of the Universe from the Big Bang to black holes.