The scale is 10 × × log 10 ⁡ ⁡ { t } where { t } is the time since the Big Bang expressed in years. For example, 10 billion years after the Big Bang (3.8 billion years ago) is 10 × × log 10 ⁡ ⁡ { 10 , 000 , 000 , 000 } = 10 × × 10 = 100 .