While I was a college physics major, I came across the book Cosmology, by H. Bondi (Cambridge monographs on physics, 1961, 182 pp.). It looked intriguing! So I bought and read it. Today, when I pulled it out of my bookshelf, I noticed that the spine had faded from years of sunlight, but both front and back covers are still like new. I obviously haven’t had occasion to refer to it very much over time.
But there was one bit that never left me over the years. Bondi introduced me to Olbers’ paradox. As Bondi explained it, back in the 1820’s, Olbers was puzzled by the darkness of the night sky.
That was the feeling I had at the time. Actual shivers. An electricity, throughout my teenage/young adult brain and body. Spiritual music. Half a century later, I’ve never failed to experience this emotion each time Olbers has come to mind. Imagine…taking a mundane reality…every day the sun goes down, and then it gets dark…and having the awareness to ask “Why is that? What are the implications? What does that mean about the universe?” This is the kind of question every scientist dreams of formulating.
Nerd alert! If you’re interested, you can read more below…otherwise, skip down to the next horizontal line
The Wikipedia link above conveys this better than I can, but the argument goes something like this. If the universe is infinite, and when you consider volumes large enough, homogeneous (that is, each volume contains about the same number of stars, and they’re each about as bright as the sun, no matter how distant you go), then the entire sky (not just nighttime sky, but daytime sky as well) ought to be as bright as the disk of the sun. That is, really bright! [Oh…and really hot…as hot as the surface of the sun.]
Bondi fleshed out the logic in a way that to most of us is a little pointy-headed. The light reaching us from each star falls off as (1/r)2, where r is the distance of that star from us. But the volumes of concentric shells of radius r surrounding the Earth each contain a number of stars proportional to r2, so each concentric shell of equal thickness contributes equal brightness…and so on, out to infinity. This worked for me back in the 1960’s.
The Wikipedia discussion looks at it a simpler way. If the universe were homogeneous and infinite, then whichever direction we look, our field of vision should extend to the nearest star in that direction. The further out we go, the smaller the individual target, and the weaker the light from any one star, but the greater the number of them. The Wikipedia entry actually has a nice video clip of this.
Olbers was a medical doctor,. When it came to astronomy, he was only an amateur. The best explanation he could think of was that maybe the universe contained a lot of dust or some such material, which was absorbing the light from the distant stars. But it wasn’t long after Olbers before physicists developed the field of thermodynamics. When they applied this to Olbers’ paradox, they quickly realized that any such interstellar dust would itself start heating up…and eventually heat up to the point where it was as bright as the stars themselves. So that explanation didn’t work.
So, as Bondi pointed out, and this helped fire my youthful imagination, the dark nighttime sky implied that the universe might be finite, or so young that the light from the more distant stars has yet to reach us, or that the universe was expanding, etc. So many possibilities released by such a simple fact!
[Ah, scholarship. Turns out that more recent historical research suggests astronomers puzzled over the night sky long before Olbers. Today, one Thomas Digges, who lived in the 16th century, is credited with this insight. My apologies for perpetuating the error here, but the paradox still bears Olbers’ name.]
But all this made me curious. Were Olbers alive today, what would he find puzzling?
You might have fun coming up with your own answer, but here’s mine. You may find it whimsical, but let’s run with it.
Olbers would find it amazing that society today is spending no more than 0.1% of World Domestic Product (WDP) on the study of the Earth as a resource, a victim, and a threat – a mere $40B/year out of $60T.of economic activity overall, as described in the April 7th post.
To him, that wouldn’t seem very bright.
Maybe, he’d come up with the following candidate list of explanations (you might have others).
1. We can’t afford to spend any more. This is ludicrous on the face of it. World expenditures on ice cream each year? Comparable. U.S. expenditures on pets are $50B. World outlays for cosmetics? $170B/year. Sponsorship of sports events worldwide? Over $30B/year. International tourism? Over $700B/year. This is not an argument for adjusting these figures. [I like ice cream!] But it should be clear there’s more than enough money around to learn more about the Earth and what it might be cooking up for us next.
2. We have the money, but nowhere to spend it. To be a bit more precise, the marginal utility of additional investment in observing systems, in modeling capacity, in research, in science-based services, in education of professionals to carry out this work, doesn’t justify the expense. If we invested much more, we wouldn’t learn anything additional, or we wouldn’t extend the time horizon or the accuracy of our forecasts, or we wouldn’t improve the communication of those forecasts to users. The equipment isn’t available; the experts aren’t there to use it.
This interpretation? Also highly unlikely. The scientists and engineers I know have plenty of ideas, volumes of proposals and plans and ideas, if only the funds and commitment were available. They know how we could extend global coverage of our observations, especially over inaccessible and hitherto mysterious parts of the Earth – the polar regions, the deserts and rainforests, the mountain ranges, the deep ocean, the planetary interior. They also have plenty of thoughts on how to couple atmospheric, oceanic, and land-surface models, how to make better seasonal-inter-annual outlooks down to smaller regions and more specific locales, how to extend the range of hurricane forecasts and tornado watches, how to detect drought in the early stages, how to predict earthquakes. The list is endless. And a lot of this stuff looks valuable. Very valuable.
3. Higher levels of expenditure haven’t seemed necessary in the past. Maybe now we’re getting warm. Ever since we’ve been relative newcomers to the planet, we’ve found resources available for the taking. Grain? You didn’t have to plant it; you could pluck wild oats, wheat, barley, rice… Fruits and nuts? Hanging from every tree. Why raise livestock when fish and game were plentiful? Wood for fire? All over the place. When that ran out? There were these seams of coal, right on the surface. Oil? It was oozing to the surface too. If the planet posed a threat…say drought set in, or flooding, you could pick up your tent and move. You could argue that the planet has proved such a cornucopia and life so good we’ve been pretty much having a party this past hundred thousand years or so. We’ve only done a little Earth science because we’ve been curious. It’s only relatively recently in human experience that we’ve had to fret about crop yield worldwide, or drill miles below the surface to reach oil, etc.
But today, our situation might be considered more problematic. Population growth and social change are making a hash of these happy-go-lucky approaches to the Earth as resource, victim, and threat. Margins are declining, hazards pose increasing threats, and the environment, ecosystems, and biodiversity are in decline.
4. We lack a compelling cost-benefit/value-of-information argument. This explanation resonates as well. [We discussed this as early as August 18 and again on August 25.] Absent an analytical foundation for making such investments, we’re condemned to a strategy (if you can glorify it by calling it that) of spending this year what we spent last year, after making minor adjustments for inflation and then maybe subtracting some because the federal deficit has grown, swollen by entitlements, defense spending, and other costs difficult to manage. Costs are easy to measure, but benefits more difficult, especially the components that are hard to monetize, such as the value of ecosystem services, and the national security implications of our ignorance.
Though a government shutdown has just been narrowly averted here in the United States, or delayed a few days, we’ve seen how dangerous it is to lack such cost-benefit analyses. Their absence made it possible for politicians to debate budgets for DoE, NOAA, USGS, EPA, USDA, and other departments and agencies on what might be considered theological grounds, rather than on the merits.
Our community urgently needs to build its capacity for observing the Earth and predicting what it will do next. But our greatest need is a robust business case for such work, as opposed to appeals to emotion or back-of-the-envelope calculations.
We need to bring light to what has thus far been a dark place.