The United Nations has declared 2025 the Year of Quantum Science and Technology to mark the 100th anniversary of our foundational model of the atomic world, quantum mechanics. This model is the most precise predictive description we have in all of science. Its theoretical calculations are verified by experiments to 9 or 10 decimal places. This level of understanding makes the modern world – from cell phones and cameras to solar panels and electric cars -- possible. But it also provides a unique set of tools with which to explore space and time.I have a passion for sharing the enriched view of the world that science provides. Thus, most of my five decades of teaching have been spent offering science courses designed for non-science majors. From an initial meander from my astrophysical roots into paleoclimatology – the reconstruction of past climates from the atomic record – my interest spread to the many other applications of atomic physics, chemistry, biology, and geology that reveal the past through techniques that clever people have devised over the last half century. Thus, this book.By measuring the pattern of light from a primordial galaxy 13 billion light-years away, we can see that the Carbon atoms there are identical to the Carbon atoms in my fingernail. By determining the ratio of the different flavors of Carbon atoms in ancient bones, we can chart the spread of maize agriculture from the highlands of Mexico to New England 5000 years later. From the same sort of ratio in the neuronal DNA in a human brain, we can establish that new nerve cells are being formed in our memory center throughout our lives. Simply counting atoms provides all these insights and many more.