Usefulness of vacua

Strive as they may, scientists have been unable to attain a vacuum wherein a cubic inch includes fewer molecules than there are people in the world. Even so they have succeeded in removing 99.99,999,999 per cent of the gas. In other words, only one of every 10,000,000,000 molecules remains; yet there are 40,000,000,000 molecules in every cubic inch; the population of the earth is estimated at less than 2,000,000,000.