The Purpose of Science (Part I)

Posted by jns on June 27, 2005

About 10 or 12 years ago, when I was still a scientist producing science, I was working on an experiment that eventually flew on two Space Shuttle missions (in 1994, then 1996 — our project was called “Zeno”¹). We were working under the umbrella of “microgravity” research, research that wanted to exploit the very reduced gravity available while orbiting the Earth.² We were studying some general properties of fluids in very unusual thermodynamic states; when they were in these states, they were very susceptible to the effects of gravity, which supressed the effect we were trying to look at. “Turning down gravity” was our answer.
At any rate, our experiment was of the type often referred to as “pure science”; we were doing “science for science’s sake”. Of course, to us, the goal of the experiment was importantly related to questions about thermodynamics, critical phenomena, universality, the renormalization-group theory, and other things that we physicists got excited about but no one else had ever heard of.
I spent quite a bit of time working with the NASA Public-Affairs Office (at Marshall Space Flight Center, our home for mission operations, in Huntsville, AL) trying to find interesting things that they could say to the public-at-large about our project. We all took that goal — inviting the public to share our excitement — very seriously and worked hard at it, but it was a challenge to explain in a sound-bite why we were doing it all and why we were spending $20 million to do it.
I still think that elucidating science to interested non-scientists is an important thing to do. Generally, my feeling is that understanding full-blown concepts deserves more than bite-sized explanations, at least when there’s time, but there’s not always time.
The perennial question about any science experiment seems to be “what’s it good for”, that is, “what new product to make out life better are you working on”. It’s very frustrating to be asked over and over, when we felt that our work was important but that our distance from products on the shelf was rather large. We often felt that it was not the best question to ask.
I wanted to expound about the thrill of intellectual pursuit, the great adventure, exploring the unknown corners of the physical universe … but those weren’t the answers that were wanted. We could say some things about how it might lead to new, environmentally friendlier refrigerants, or help in industrial painting applications (both were true), but that seemed so trivializing.
I still don’t have the sound-bit answer. The best I’d been able to come up with then was a small parable, a metaphor for the place of science in a technology consumer’s life.

Think of technology as being a house that we all live in. The house of technology is built on a foundation of science. The foundation is made of many, many bricks. Each brick is a scientific idea, or scientific discovery, or the result of a scientific experiment. All the bricks fit together and make a solid foundation for the house of technology.
Perhaps, we think, all those bricks aren’t really necessary to hold up the house. Surely we could take some out and the house would still stand.
Undoubtedly this is true. Pull out some of the bricks. Choose some more and yank them out, too. For awhile the house is fine, but sooner or later trouble arrives. The house develops cracks in the walls, the floor shifts precariously, windows no longer open properly. Ultimately the house collapses, unable to stand without a solid foundation.
Which bricks are the most important ones? Who can say which bricks are supporting the house and which ones are not essential for holding the house up?
Technology is built on a solid foundation of science, a foundation that gets its strength from many, many interconnected bricks. Although individual bricks look individually unimportant, and any one or two might be removed with no apparent effect, all of them are needed to keep the foundation strong.

[Edited and updated from the orignal post of 4 April 2005.]
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¹There is a Zeno home page, which is very rudimentary. I put it together during the second Zeno mission in 1996. It was my first website, and the technology was still in the early stages, which explains why there was no website at the time of the first mission in 1994.
²“Microgravity” was meant literally as a measure: micro, 10^-6, times g, the acceleration due to gravity. One micro-g was about the level of residual accelerations in quiet orbit on the space shuttle, i.e., provided the astronauts weren’t exercising or bouncing (literally) off the walls. These tiny accelerationswere mostly caused by tidal forces on the shuttle itself, due to the fact that the spacecraft is large enough (an “extended body”, i.e., not a “point mass” without size) that different parts of the craft, being at slightly different distances from the center of the Earth, would prefer to orbit the Earth at slightly different velocities. Thus, the magnitude also depended slightly on the “attitude” of the Shuttle, whether it was moving with its nose in front of it (in the direction of the velocity vector) or pointed away from the center of the Earth (tail to the Earth); the latter was common, apparently because it was led to more stable orbits that required fewer firings of the retro-rockets to maintain. However, I’m no expert at orbital dynamics, which would nevertheless be an entirely different posting anyway.

Polling: “Margin of Error”

Posted by jns on June 24, 2005

This is not a particularly recent poll, although the assertion is still true. But that’s not the point.

The New York Times > Washington > New Poll Finds Bush Priorities Are Out of Step With Americans

The poll was conducted by telephone with 1,111 adults from Thursday through Monday. It has a margin of sampling error of plus or minus three percentage points.

Have you ever wondered where that “margin of error of + or – 3 % points” comes from, or why the weird number of people polled (which most people react to by thinking it’s much too small)?
The simple answer is simple. Follow along:

1. The sample size is 1,111
2. The square root of 1,111 is 33.33
3. 33.33 / 1111 = 0.03, or 3%

The answer is that simple. In random sampling from a uniform population, the best estimate of how good the average result is will be

+/- [sqrt(N) / N] = [1/sqrt(N)],

where N is the number of [statistically independent] samples.
The inverse works too. If you are told that the error is E%, then

N = 1 / (E/100)²

is the original sample size.
There is no mystery about this relationship between error and sample size in polls, and it is not what determines careful or “scientific” polling. It is simply an unvarying, mathematical result giving the best guess you can make about the error in an average calculated from random (i.e., statistically independent) samples taken from the larger population that one is trying to characterize.
The trick, of course, is in that bit about taking “random samples”. That’s the part that polling organizations work very hard at: to convince their customers that they (and they alone among their competitors) know how to take very good, very nearly “random samples” from any given population — all Americans, all likely Republican voters, all women under 18 who watch MTV, all men over 50 who eat chocolate ice cream at least twice a week, whatever group the poll’s sponsor is interested in.
All the work, or artistry (some would like to say “science”) goes into selecting the samples so that they will be randomly drawn from the population of interest; none of it goes into calculating the margin of error.
So now, when you hear a margin of error quoted, you can amaze all your friends by revealing the exact number of people who were asked the question, and sound amazingly clever.

Traditional Atomic Theory

Posted by jns on June 16, 2005

Reminding us that atoms were “just a theory” until the twentieth century when experiment finally established atomic reality (in some quantum mechanical sense yet to be understood fully):

But as late as 1894, when Robert Cecil, the third Marquis of Salisbury, chancellor of Oxford and former Prime Minister of England, catalogued the unfinished business of science in his presidential address to the British Association, whether atoms were real or only convenient and what structure they hid were still undecided issues:

“What the atom of each element is, whether it is a movement, or a thing, or a vortex, or a point having intertia, whether there is any limit to its divisibility, and, if so, how that limit is imposed, whether the long list of elements is final, or whether any of them have any common origin, all these questions remain surrounded by a darkness as profound as ever.”

[Richard Rhodes, The Making of the Atomic Bomb (Simon & Schuster, New York, 1986) p. 31.]

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^*Perhaps the idea of atoms is the oldest surviving scientific concept in that “just a theory” category — far older certainly than the continually changing, ever evolving “traditional marriage”.