Presentation on theme: "The Accelerating Universe Walid J. Azzam Department of Physics College of Science University of Bahrain."— Presentation transcript:
The Accelerating Universe Walid J. Azzam Department of Physics College of Science University of Bahrain
Outline A Little Cosmology Supernovae – the tool The Accelerating Universe The Nobel Prize
Historical Perspective of Cosmology
The Official Story Modern Cosmology Assumptions: 1- Homogeneity 2- Isotropy 3- Universality of the Laws of Physics Cosmological Principle
Big Bang Theory The Universe “exploded” from a singularity of infinite density, about 13.7 billion years ago, and has been expanding ever since.
Any Evidence, Sir? Doppler shift of the spectral lines of galaxies. Percentage of H and He (and trace elements). Cosmic Background Radiation
Will the Universe Expand Forever? We need to compare the current density (matter + energy) to the critical density. > c ( 0 > 1) : expansion will stop; this will be followed by contraction = c ( 0 = 1) : expansion stops asymtotically at infinity < c ( 0 < 1) : expansion continues
Supernovae Historical Supernovae Types Remnants Use in Cosmology
Historical SNe SN 1006 Around April 30. Read by its light at night. Faded after 1 yr. Seen in: Egypt, Iraq, Europe, China, Japan. Visible in daylight.
SN 1054 July 4, “guest star”. China, Japan, Korea, and Arabic medical textbook. Visible by daylight.