Hanukkah Lights

By Robert Pollack | Issue Date: November 2012

Space. Photo: ENASA/JPL-CALTECH, D. Figer (Space Telescope Science Institute/Rochester Institute of Technology) and The Glimpse Legacy Team of E. Churchwell, B. Babler, M. Meade, and B. Whitney (University of Wisconsin), and R. Indebetouw (University of Virginia).The miracle of Hanukkah is light, more light than the world of Greek science of the day could imagine to be possible. The festival is celebrated each year in the month of least light and longest darkness, just at the end of the waning of the moon, as even more darkness surrounds us. Hanerot Hallelu are a hope, a prayer, and an offering of light, in the expectation of light coming back to us. And every year so far, light has come back, first with the dawn, then with the waxing of the new moon, then with the longer days of spring. Well and good.

But for some of us—the intellectual descendants of those of the Y’vanim who were the world’s first scientists—the gift of longer days each year is shadowed by the clarity with which we can explain it as one of the consequences of being on a planet that tilts on its axis of rotation as its moon rotates around it and as both planet and moon travel in an annual ellipse around our sun. Another even more radical diminishment of the miraculous lies in the picture of the universe we have through science.

The world of nature of which we and our sun are a part has its own beginning, about 13.7 billion years ago, in an instant at which both time and space began. As time has gone forward, the universe has expanded from that dimensionless point until today it is of unknown volume. At the same time as it has expanded, the material within space has been gathered into clumps, and clumps of clumps, by the force of gravity. Today our sun is one of 100 billion suns in the clump we call the Milky Way, our galaxy.

The problem with this picture is not that it is inaccurate so far, but that it is incomplete. Gravity is not strong enough to account for the clumping that has occurred, unless the universe is filled with a kind of matter that contributes its mass to gravity but that does not interact at all with the energy and atoms we are made of; we call this material “dark matter,” and there is much more of it in the universe than there is of the stuff we are made of.

Hanukkah at BJ. Photo: Belinda LaskyAnd that’s not even yet a complete picture: The universe is expanding too fast for it to have been flung out by an initial push. We call the energy that causes the universe to expand ever faster “dark energy.” The material we are made of and the forces that hold it together, including the material of our candles and the energy of the light they shed, are made up of only a small minority of the material and forces that permeate the universe.

More shadow: Light itself sets a cap on what we may know of the universe. The universe that we can know is a sphere 13.7 billion light years in radius in all directions from us; a light year is the distance light travels in a year, traveling at about 300,000 kilometers/second. Space may go on in all directions beyond this radius, but since nothing in nature travels faster than light, no information from beyond that radius can have reached us in the time since the universe began.

The lights of nature that we can and now do know, therefore, include not only our candles and our sun, but also the hundred billion suns of our galaxy and a similar number of similar suns in each of about a hundred billion other galaxies in the observable universe. More curious than any other fact of nature, our candles matter more than all those ten thousand billion billion suns: the lights they shed on Hanukkah are full of meaning.

Meanings are not in nature, except when we find them there.

Robert Pollack and his wife Amy have been members of BJ since 1994. He’s a Professor at Columbia University, and the Director of the Center for the Study of Science and Religion.