More stars than we thought?

A new study of the light from distant galaxies suggests astronomers might have underestimated the number of stars in the universe.

Astronomers typically extrapolate from what they know (or think they know) about the Milky Way to paint a picture of the rest of the universe. The Milky Way contains a certain proportion of "dwarf stars" relative to the number of stars similar to the Sun. Astronomers assumed this proportion held for other galaxies as well, and went on to calculate the stellar populations for those galaxies on the basis of their extrapolations. However, a different method of analyzing galaxies' stellar components, one that relies on the total light spectrum from each galaxy, suggests that the proportion of dwarf stars in some other galaxies is higher than that of the Milky Way, in some cases by an order of magnitude.

That discrepancy could have a significant effect on our understanding of the universe since it could mean astronomers have been underestimating the total mass attributable to stars. If cosmologists are still struggling with the need for previously unimaginable quantities of "dark matter" to account for the observed gravitational influence of mass throughout the universe, this underestimation of aggregate stellar mass might mitigate that struggle. (I say "if" because my layman's knowledge of cosmology is at least a decade out of date.)

It needs to be said, though, that these findings are preliminary and have not, as far as I know, been corroborated by others.

At a metalevel, thinking about how science actually progresses, news like this is a mixed blessing. If you think scientists need to show science is self-correcting, this is welcome news. If, on the other hand, you're concerned that pseudo-scientists and anti-scientific activists will seize on this as evidence that "science doesn't know everything," this isn't such a wonderful development.

Myself, I've never had a problem with the idea that "science doesn't know everything": that's what makes it such a worthwhile pursuit. However, a lot of people are looking for certainty these days. You would think the modern world would have disabused them of the notion that there are certainties these days (except for those perennials death and taxes), but there it is. Religion can offer certainties, or at least some religions can, but a lot of people -- especially in the U.S. -- want religion to stand in science's stead for some questions, or even all questions. That kind of thinking alarms me. Chilly though it can get, I stand naked before the cosmos, and I (and many others) have no desire to be enfolded within the suffocating embrace of religious belief, no matter how warm it makes others feel.

For those who wonder what else there's left to discover, this story should remind them that much of astronomy and cosmology rests on reasonable but sometimes untested assumptions. I've no doubt humanity has tasted the merest morsel of the universe's banquet of knowledge. and we will be feasting on it for as long as we exist as a species.