![](http://upload.wikimedia.org/wikipedia/en/math/d/5/d/d5d38569c12e04088ee6e9085fc190f7.png)
In the PBS science program Cosmos: A Personal Voyage, Episode 9: "The Lives of the Stars", astronomer and television personality Carl Sagan estimated that writing a googolplex in standard form (i.e., "10,000,000,000...") would be physically impossible, since doing so would require more space than the known universe provides.
An average book of 60 cubic inches can be printed
with 5 ×10 5 zeroes (5 characters per word, 10 words per line, 25 lines per page, 400 pages), or
8.3 ×10 3 zeros per cubic inch. The observable (i.e.
past light cone) universe contains 6 ×10 83 cubic
inches ( 4 /3 × π × (14 ×10 9 light years in inches) 3 ). This math implies that if the universe is stuffed with paper printed with 0s, it could contain only
5.3 ×10 87 zeros—far short of a googol of zeros. In
fact there are only about 2.5 ×10 89 elementary particles in the observable universe, so even if one were to use an elementary particle to represent each digit, one would run out of particles well before reaching a googol of digits.
Consider printing the digits of a googolplex in unreadable, one-point font (0.353 mm per digit). It
would take about 3.5 ×10 96 metres to write a googolplex in one-point font. The observable
universe is estimated to be 8.80 ×10 26 meters,or
93 billion light-years, in diameter, [2] so the distance required to write the necessary zeroes is
4.0 ×10 69 times as long as the estimated universe.