Age of the universe instance of time interval
Explanation
The Lambda-CDM concordance model describes the evolution of the universe from a very uniform, hot, dense primordial state to its present state over a span of about 13.77 billion years of cosmological time. This model is well understood theoretically and strongly supported by recent high-precision astronomical observations such as WMAP. In contrast, theories of the origin of the primordial state remain very speculative.
If one extrapolates the Lambda-CDM model backward from the earliest well-understood state, it quickly (within a small fraction of a second) reaches a singularity. This is known as the "initial singularity" or the "Big Bang singularity". This singularity is not understood as having a physical significance in the usual sense, but it is convenient to quote times measured "since the Big Bang" even though they do not correspond to a time that can actually be physically measured.
Though the universe might in theory have a longer history, the International Astronomical Union presently uses the term "age of the universe" to mean the duration of the Lambda-CDM expansion, or equivalently, the time elapsed within the currently observable universe since the Big Bang.Observational limits
Since the universe must be at least as old as the oldest things in it, there are a number of observations that put a lower limit on the age of the universe; these include
type of example of manifestation of representation of