How could someone write a history of time? And how could that person possibly make it brief? Time is a dimension; it is the fabric of reality. Writing a history of time would be like trying to write a history of up, or the history of green.

But when I read “A Brief History of Time,” Stephen Hawking’s popular-science touchstone, at some point in middle school, it felt more accessible than I expected. It described how we know what we know, and in doing so, it taught me the rules of the universe. I found those rules had profound implications. The book introduced me to the idea that science is a search for meaning amid complexity, and for the answer to why the universe — and everything else — came to exist.

Depending on your thoughts about the afterlife, Hawking is no longer among us. He died March 14 at his home in Cambridge, England. He was 76.

Hawking’s theories are among the most celebrated discoveries in modern physics, and defy simple explanation even among his peers. But to me and millions of others who read his books, he was a wonderfully approachable teacher. Because of Hawking, I came to see physics as the foundation and pinnacle of science and philosophy.

In his book, I learned that we actually know quite a lot about how we got here. About 13.8 billion years ago, at a point of infinite density, the universe began in what we call the Big Bang, and is still flying outward today. We have no idea why this happened, or what set it off.

Through Hawking’s book, I also learned about how all this might come to an end. The book was my introduction to entropy, a law of thermodynamics that says, basically, things even out in the end. And further, that this is the way things are supposed to be. The attempt to instill order from chaos is one of the foundational projects of human society, and certainly one of our greatest sources of trouble. Yet disorder is the natural way of the universe; entropy always increases.

I also learned that nothing can escape entropy — not even black holes. This was one of Hawking’s great insights, and it is one of the most important discoveries in the history of modern physics. Like the philosophical notion of entropy, it has profound meaning for us all.

Black holes are so named because they are bottomless gaping maws of destruction from which not even light can escape. Except when it can! Hawking realized that black holes, by warping spacetime, apparently leak out a form of radiation. This will eventually cause them to dry up and evaporate. Even black holes have a thermodynamically limited lifespan, it appears. They will fade away. The sun will fade away. Eventually, everything fades away.

Hawking wrote an equation that explains this black hole radiation, which is now named for him. It set the cornerstone of four decades of efforts to come up with a grand unified theory, a way to reconcile thermodynamics, gravity and quantum mechanics (though we still haven’t worked it out).

Through Hawking and Albert Einstein, I also learned that perspective is the key to knowing the universe. According to quantum theory, pairs of particles throughout the universe are constantly bubbling in and out of existence, and becoming many different manifestations of things at any given time and place. These are called “virtual particles.”

Hawking realized that at a black hole’s jaws — a special, weird location called the event horizon — these virtual particle pairs can be split apart. When this happens, the black hole swallows one and not the other. They become no longer virtual, but a definite thing. The black hole acts as the decider of their fates, if you will. At least, this is how it would appear to an observer on the outside of the black hole. So, whether or not a particle is really here, like here here, in time and space, literally depends on how you look at it. Reality depends on your perspective.

These discoveries made Hawking famous, as did his debilitating ALS and his sense of humor, temper and ego. He was the most recognizable scientist since Einstein, and a prominent figure in popular culture.

He was not uncontroversial. Hawking often inspired, sometimes even fomented, controversy in the highest echelons of science, even as he sold millions of books and enthralled multitudes with his simplified and witty explanations. He famously made public wagers with other physicists and gloated when he finally won. He was a complicated — some would say flawed — parent and spouse. He worried candidly and publicly about contacting aliens, and about artificial intelligence. He boycotted a science conference in Israel at the behest of Palestinian researchers.

Yet he is one of the rare Western public intellectuals whom almost everyone could respect in some way regardless of politics. I tried to think of someone else who could fill the void he leaves — brilliant scientist, philosopher, writer, engaging speaker, teacher, advocate for government-subsidized health care and champion of people with disabilities — and I couldn’t.

It’s been a long time since I read my parents’ paperback copy of “A Brief History of Time.” But the ideas Hawking presented in it have stayed with me. Things fall apart, and it’s okay. We have limited time in this universe, so make the most of it. Try to see things from others’ point of view, because doing so will enable you to construct a more meaningful existence.

Stephen Hawking served as my tutor for these physics laws-turned-life-lessons. I will miss him.