1. Which are older, the atoms in the body of an elderly person or those in the body of a baby?
2. World population grows each year. Does this mean that the mass of Earth increases each year?
3. Are there really atoms that were once a part of Albert Einstein incorporated in the brains of all the members of your family?
1. The age of the atoms in both is the same. Most of the atoms were manufactured in stars that exploded before the solar system came into existence.
2. The greater number of people increases the mass of Earth by zero. The atoms that make up our bodies are the same atoms that were here before we were born—we are but dust, and unto dust we shall return. The material that makes up human cells is a rearrangement of material already present. The atoms that make up a baby forming in its mother’s womb are supplied by
the food the mother eats. And those atoms originated in stars—some of them in far-away galaxies. (Interestingly, the mass of Earth does increase by the incidence of roughly 40,000 tons of interplanetary dust each year, but not by the birth and survival of more people.)
3. Quite so, and of Oprah Winfrey, too. However, these atoms are combined differently than they were previously. If you experience one of those days when you feel like you’ll never amount to anything, take comfort in the thought that many
of the atoms that now constitute your body will live forever in the bodies of all the people on Earth who are yet to be. Our atoms are immortal.