We make a vague assumption or approximation of large number. To be precise, we just unfocus on large number.
Let take an example: There is a surprising difference between a million and a billion. Let’s be clear: How long ago was a million second ago? Answer is 12 days. But how long ago was a billion second ago? The answer is 32 years ago.
There is a massive difference between 16 days and 32 years. Similarly, a trillion second ago was 32000 (exactly 31709.7919) years ago.
We just blur the large number.