 In the PBS science program "", , astronomer and television personality Carl Sagan estimated that writing a googolplex in full decimal form (i.e., "10,000,000,000...") would be physically impossible, since doing so would require more space than is available in the known universe.One googol is presumed to be greater than the number of atoms in the observable universe, which has been estimated to be approximately 1078.Thus, in the physical world, it is difficult to give examples of numbers that compare to the vastly greater googolplex.