Universe

The universe is the whole spacetime continuum in which we exist, together with all the energy and matter within it. Attempts to understand the universe in this sense, on the largest possible scales, are made in cosmology, a science that has grown from physics and astronomy. During the second half of the 20th century, the development of observational cosmology, also called physical cosmology, led to a split in the meaning of the word universe, between observational cosmologists and theoretical cosmologists; where the former (usually) abandon the hope of observing the whole spacetime continuum, the latter retain this hope, attempting to find the most reasonable speculations for modeling the whole of spacetime, despite the extreme difficulty in imagining any empirical constraints on these speculations and the risk of declining into metaphysics.

External links

• Richard Powell: An Atlas of the Universe - a series of images at various scales, with explanations.
• Cosmos - an Illustrated Dimensional Journey from microcosmos to macrocosmos
• Age of the Universe at Space.Com
• My So-Called Universe by Jim Holt, on various arguments for and against an infinite Universe and parallel universes
• Parallel Universes by Max Tegmark
• eXplore the Universe by Moving Planets
• Why Does Anything Exist?
• Logarithmic Maps of the Universe
• Seti@Home - the Search for Extraterrestrial Intelligence