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The question of the origin of water on Earth has been a puzzle since long. The standard scenario that comets have deposited water here over eons has many loopholes, and some recent results have put a question mark on this. Instead, asteroids have become the favorite candidates for ferrying the water. At the same time, other discoveries seem to hint towards a large reservoir of water inside Earth.
Gravitational waves have been detected in the centenary year of Einstein’s formulation of general theory of relativity that predicts these waves. It has been heralded as a landmark discovery, since it not only confirms various predictions of the theory, but also opens up a new window of observing the universe. I will discuss a few basic characteristics of gravitational waves in this article, and a...
The article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Although Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine structure constant he introduced has remained as an important parameter in the field of atomic structure.
Soon after the discovery of the cosmic background radiation, Zeldovich and Sunyaev proposed that hot gas in galaxy clusters should cast a faint shadow because of the interaction between energetic electrons and the radiation photons. Sunayev-Zeldovich effect is now routinely observed, and it has become an important tool for studying the history of the universe.
Gamma ray bursts — which are first detected in energetic gamma rays and which then glow in X-ray, visible and radio wavelengths — are the result of the biggest explosions in the universe. Astronomers wonder what causes these violent events, and some of their ideas are discussed in this article.
Soon after the discovery that we live in a separate galaxy and that there are many other galaxies in the universe, Hubble designed a classification scheme of galaxies based on their appearances. It was such a robust scheme that it continues to be one of the basic tools of modern astronomy, and motivates astronomers to look for connections between different types of galaxies.
Cosmic rays are energetic particles that zoom through space and occasionally enter our atmosphere. They are believed to be produced by violent astronomical events in and outside our Galaxy. Study of these particles provides a glimpse into the fascinating world of high energy physics.
Part 11 of the article discussed the discovery and observed properties of cosmic ray particles. These energetic particles are produced during violent astronomical events. We discuss possible sources of cosmic rays detected on Earth in this article. Supernovae explosions of dying stars are believed to produce cosmic rays with low energy. The detection of ultra-high energy cosmic rays is however difficult...
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