Sunday, January 20, 2008

SCIENCE- The Scientific Method in Action (part III)

So we pick up the story where we left off...

The ancient Greeks had surmised that everything in the world was made up of elementary substances and that those elementary substances were comprised of tiny particles surrounded by interstitial spaces. It took two thousand years but eventually people were able to show that this natural philosophy was an actual verifiable fact. But the question remained as to what these primary particles were and how they worked to form the universe.

By 1799 Joseph Louis Proust had formulated the Law of Definite Proportions. While working with copper carbonate he found that no matter how much of each of the raw materials he started with, they would only combine in certain proportions to form that compound- 5 parts copper, 4 parts oxygen, and one part carbon by weight. This lent further credence to the theory that everything was made up of tiny indivisible units. If the ratios had ever changed then that might mean part of an atom was being used in the compound. But that never happened. So it seems that Democritus’ idea that atoms could not be broken down any farther was right. (There are exceptions but we’re only dealing with chemical means of disassociating compounds.)

Still, you couldn’t see these teeny little particles, you had to infer their existence in a sort of indirect way, so not everybody was convinced. Another Frenchman named Claude Louis Berthollet said that he had done experiments that showed compounds forming in varying proportions. So what was going on? Was somebody lying? Perhaps they were just mistaken. After all, scientists are only human and are just as capable of making mistakes or unconsciously skewing their data to verify their presuppositions as anyone. It would take a Swede, Jons Jakob Berzelius, to carry out a series of experiments that in the end would verify Proust’s observations to the rest of the chemical community. But as yet no one had formulated a theory of why this happened and what the nature of these tiny particles was.

So enter John Dalton. Dalton was the gifted son of a Quaker weaver. He decided he wanted to be either a doctor or lawyer (The dreams of weaver’s sons haven’t changed so much, have they?) but that was pretty unlikely. Not for the usual reasons (or maybe exactly for the usual reasons) but because Dalton’s family were desenters. Back then that didn’t mean that they refused to go to war, it meant that they thought the government had no right deciding what religion everyone should be. Instead they thought that it was up to the individual and his conscience when it came to the questions of their relationship to the almighty and the government had no right to intercede. In a world where it was common that government established a religion that all citizens were obligated to follow the tenants of that religion, this was both heresy and treason. So John Dalton’s beliefs about individual determination kept him from pursuing his chosen career path. He wound up teaching at a desenter university and published papers on weather, the nature of heat and light, colorblindness (A paper so influential about an ailment from which he suffered that for quite a while color blindness was called Daltonism. And which it turned out that he was almost completely wrong about.), and grammar.

He was also interested in gasses and was familiar with the work of Lavoisier and Proust. Dalton knew that you could make compound gasses with differing amounts of the same primary gasses. For instance you might combine three parts carbon with four parts oxygen (again, by weight) and get one compound gas, or you might combine three parts carbon with eight parts oxygen and get a different compound with radically different properties. However he did verify that the proportions remained constant throughout the reactions. He figured that if you accounted for the different particulate weights of each this would mean that each atom of carbon was combining with one atom of oxygen in the first example and two in the second. (As to the difference one atom of oxygen makes, the second compound is what you exhale and the first is what kills you if you leave the car running in a closed garage!) He even took to calling these particles atoms just as Democritus had. And in 1803 he published both a paper, which called this the Law of Multiple Proportions, and a rudimentary list of elements and their atomic weights. But he didn’t stop there. In 1808 Dalton took all the evidence for atomism that he knew and tied it all together in a book called The New System of Chemical Philosophy. In it he stated that each element was made up of distinct atoms, that each atom of a given element was the same as every other atom of that element, that each element’s atoms had a distinct weight, that these atoms could not be broken down or created by chemical means, and that these atoms combined with other atoms in regular proportions to form compounds. This was pretty much atomic theory as we understand it today.

Of course Dalton got a few things wrong. He believed that the simplest compounds were always in a 1:1 ratio, which caused him to underestimate the atomic weight of oxygen by half. That’s the way a theory in science works. It’s a framework for understanding all the data available about a certain group of phenomena. It doesn’t have to be right in every facet, but it does have to explain why observed phenomena are happening, be useful in making predictions about further phenomena that have not as yet been observed, and not be contradicted by any other observable phenomena.

Dalton’s unverified assumption about simple compounds didn’t invalidate his theory. And it’s a good thing because the evidence that this was wrong was already available. Several years earlier a British chemist named William Nicholson had passed electricity through water and found that by doing so he could disassociate the component parts into hydrogen and oxygen. Funny thing was that he got twice as much hydrogen by volume as he did oxygen. Now because we already know Boyle’s law we can infer that if you have twice as much volume at the same temperature and pressure then you must have twice as much stuff (twice as many atoms). Dalton knew about all this but he had a strong belief in the basic simplicity of the universe and that blinded him to what was really going on. Oddly it’s not that uncommon for a scientist who makes a great leap in logic to be incapable of taking the next step in the process. After revolutionizing science’s understanding space, time, gravity, and light, Einstein was unable to wrap his head around quantum mechanics for some time. (This is what prompted his famous “God does not play at dice” quote.) It would eventually take our old friend Jon Berzelius to do the experiments and work out the actual atomic weight of oxygen correctly. He also worked out the atomic weights of a great number of other elements and concluded that each element had a unique atomic weight and that every atom of an element had the same atomic weight. He published his findings in 1828 and, of course, even that wasn’t the whole story because he was unaware of isotopes that are instances where an element has a slightly different atomic weight.

Of course, the story doesn’t even end there. The story of science never ends because there is always something new to discover about the universe. Some ideas are even dismissed or not noticed. Not because they aren’t right, just because that is the way human beings do things. For instance (in this instance), an Italian chemist named Amadeo Avogadro hypothesized that any given volume of a any gas (at the same temperature and pressure) would have the same number of molecules in 1811. (A hypothesis is an educated guess based on observations which is advanced to see if is has actual rigorous validity when scrutinized.) And while it may seem that while Berzelius made use of this idea in doing his experiments, he probably didn’t actually realize it because his table of atomic weights is wrong in places. In fact, nobody paid much attention to it until almost fifty years later when, in 1858, another Italian, Stanislao Canizzaro, rediscovered Avogrdro’s work and corrected the numbers for several atomic weights. He became famous when he explained Avogrdro’s Hypothesis (as it would forever be known) in a big convention of chemists from all over Europe that was held in 1860. This would lead Jean-Servais Stas to publish an even better list of atomic weights and that would prompt Dmitri Ivanovich Mendeleev to spend hours with little cards in front of him with everything he knew about every element written on them. Mendeleev arranged them this way and that way, trying to see some way that they fell into groups that would explain the character of each element and associate that character with their atomic properties. After weeks of trial and error it came to him. And the final arrangement would result in what we now call the Periodic Table- the big poster that hangs to this day in the front of virtually every chemistry class on the planet. Mendeleev’s arrangement of elements had holes in it where there were spaces for elements that he didn’t even know of at the time, but it would predict the characteristics of those elements so well that it assisted the scientists looking for them to know what they were looking for.

So, learning about atoms and molecules we see that the process of science is self correcting and methodical. We start with an idea- that the universe is made up of tiny bits of a few basic substances. That these bits combine to make complex compounds. That those tiny bits are surrounded by mostly empty space. That they follow certain rules in how they combine and that even though they are each distinct, the compounds they form can have novel properties, different from what any of the components exhibit by themselves. That the universe is structured and orderly and there is no supernatural intervention required for it to function. Along the way we discard incorrect ideas through experimentation and observation. We come to understand that elemental components are not infinitely reducible. Later we realize that elements combine the way they do because of their sub-atomic structure. And we use that knowledge to infer even greater truths about the structure of the universe and everything in it, including ourselves, based on that knowledge. And we gain greater control over our surroundings by applying that knowledge to increase our technology.

None of this answers the basic questions about human existence. It simply lets us know that if the universe is an artifact that it was made on a plan that we are able to comprehend. As Einstein said, “The most amazing thing about the universe is that we can understand it at all.” Science can have no opinion on whether this is because the basic structure of the universe is so simple that even our primate brains can comprehend it, because we are the product of a universe developing sentience to enable it to understand itself, or because we have a link to the creator who set this universal machine in motion. Those are questions for religion or philosophy. Science is for figuring out how the universe works and nothing does a better job.


salvage said...

If I may suggest a sequel to this fascinating piece, how about something on the g-block?

If I ever had a rap band that's what I'd call it by the way.

memphisto said...

What a great idea! Especially since I just finished Half Life 2 on the PS3 (been clearing my head with Gotham 4 all morning). We may have to work up to islands of stability however since I really wanted the science articles to be shorter and at a high school level. When I taught in college I found out that while college students may be able to regurgitate the facts in the book, often they didn't really understand the big picture. I'm trying to give a little perspective on things. For instance, my next planned article is on the renal system, titled What Do You Call the White Stuff on Top of Chicken Shit?
Large stable molecules will be coming, though.