I am a physicist - an atomic physicist and astrophysicist to be precise. As an atomic physicist I study the smallest building blocks of matter. As an astrophysicist I study the largest structures in the cosmos. Although I am paid to do this, my work is not so much a job as a way of life, and it defines my core convictions.

I believe that the physical world - which in reality is the only world there is - is governed by universal, immutable, and impersonal laws of nature.

Universal means that these laws apply everywhere and to everyone. No one is exempt from the laws of physics. You may get away with a traffic violation or income tax evasion, but try to defy the law of gravity and the consequences will be immediate and probably unpleasant. Immutable means these laws held sway since the universe came into existence over ten billion years ago. They have never been - and will never be - arbitrarily suspended or modified by the supernatural deities of the human imagination. Impersonal means these laws do not exist for the benefit or the detriment of humankind. They simply are.

I believe in the laws of physics not out of blind faith or submission to some priestly authority, but from personal experience. I see the predictable and reliable operation of physical laws every day in the laboratory, at home, in the mountains, by the sea, or wherever. And should the laws which currently seem valid to me ever fail to provide a correct, reproducible, and self-consistent description of the physical world, I would search for other physical laws rather than for a supernatural explanation, because, being a physicist, I believe the human mind is ultimately capable of comprehending the intricacies of nature.

Believing in the laws of physics gives me a realistic perspective of the place of human beings in the overall scheme of things - and this place is not an especially flattering one. One of the most amazing photographs I have ever seen was taken by the Hubble Space Telescope. The telescope had peered into deep space, revealing, not a void, but a cosmos teeming with galaxies, each one an island universe unto itself with tens of billions of stars. How cosmically insignificant, by comparison, is that infinitesimal blue speck on which all humankind travels around its own undistinguished sun.

Far from being the pinnacle of a special creation, we humans are but one of many kinds of organisms that evolved to share the living space on a fragile and finite planet among countless other suns and planets in the universe. Nothing "out there" is looking after our well-being; for that we must rely on our own good judgment. No supernatural agent exists to give meaning to our lives; the purpose of each person's existence must come from his or her own worthy objectives and actions. And if, through carelessness, greed, and stupidity, humans irretrievably damage the one place in the cosmos where they evolved and can live, then, like any other unfit species, they will go extinct.

For the sake of humanity's future, I hope many more than I also believe this.