Quick Read

The observable universe is everything from which light or another signal has had time to reach us; it is not necessarily the edge of the whole universe.

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Its comoving diameter is about 93 billion light-years—larger than light-speed times the universe's age because space expanded while light travelled.

In Depth

The boundary follows from a cosmological model and expansion parameters. It is an observational horizon, not a physical wall.

Scale measurement

9.3E10 ly · boundary

Quick facts

  • Its edge is an observational horizon.
  • It need not be the edge of the whole universe.
  • Its value is cosmology-dependent.

Related objects

Sources and review