Caloric and Catastrophism (scientific theories we got utterly wrong)

In the previous article about once compelling but now defunct scientific theories, I wanted to show that the topic is more than just a trifle of passing interest, where we marvel at humanity’s former nescience and feel ever more superior for our own sophisticated scientific worldview (which is, admittedly, somewhat satisfying).

Knowledge of our past blunders is also remarkably illuminating. First of all, this knowledge provides us with a much more detailed and therefore more accurate understanding of how the picture of science unfolded.

In school, we are presented with impressively fleshed-out theories and models that give us the impression that science is only ever elegant; that scientists are in the business of perfection. Yet in reality, our modern theories were only revealed through centuries of clumsy trial and error.

At first blush, the subject appears thoroughly intimidating to us mere mortals: how could we – prone as we are to making mistakes, and struggling to understand the modern theories – ever hope to contribute something to the field, or indeed, to understand it in any great depth?

I suspect that this perception of science is never fully dispelled in most people, and so they leave school with a notion that science is something ‘other’; something done by scientists – those Gods of genius like Einstein and Newton. They miss the fact that science is, and always has been the project of ordinary people, with an intense curiosity to understand – people who make mistakes, and who plod only slowly and inelegantly towards an understanding of how the world works.

Contemporary theories were hard-won, and so an understanding of the intellectual battles (with and among ourselves) that got us there, is essential to understanding science itself.

Caloric Theory

In addition to all of the above, learning about superseded scientific models also reveals something interesting about the very nature of what a theory, or ‘model’ actually is.

Consider the model of Caloric theory – a now abandoned theory of heat that was popular in 18th century scientific circles.

It postulates that there is a type of matter – a weightless gas called caloric, which is self-repellant, and which explains the phenomenon of heat.

The ‘model’ is a mental (and mathematical) picture, that we can hold in our heads, or jot down on paper – in this case, of a peculiar substance which repels itself, much like magnets aligned with their north poles towards each other.

From this simple model we ask the question: ‘if this were really true, what kind of things would we observe?’ And thus we apply the model to phenomena in the real world.

The success of the model comes from the fact that, from some relatively simple starting principles (i.e. self-repelling particles), it is able to explain a wide variety of observations.

For example, caloric theory perfectly explains why heat moves from hot objects to cold ones. A hot cup of tea (which contains a high concentration of caloric, giving it its ‘hotness’) in a cold room will gradually cool down, because the caloric in the tea repels itself, thus eventually leaving the cup and mingling with the air in the room.

The theory also explains thermal expansion – the increase in volume when you heat something up – since you are adding more material (in the form of caloric) to the system as you do so.

So when we place a thermometer in someone’s mouth, what happens is that the high concentration of caloric in their body moves – by a kind of self-driven diffusion – outwards, and some is absorbed into the thermometer. The mercury in the thermometer expands (since it absorbs caloric), to a level that is proportional to the amount of caloric in the person’s body (presumably at the point where the influx of caloric into the thermometer equals the outflux from the thermometer to the environment).

You’ll notice that this simple model of caloric is capable of great feats of explanation. But it can only survive as long as it continues to serve as an adequate explanation for every heat-related phenomenon we observe. And unfortunately for the caloric theorists, it was unable to do so.

Specifically, it could not account for the rise in temperature that resulted from mechanical work.

The physicist Benjamin Thompson conducted experiments in which he repeatedly bored holes into a piece of metal, and found that the amount of heat generated did not diminish over time.

That neat little caloric model floating tenuously in one’s head is unable to contend with this observation – since, according to that model, the amount of caloric stored in the metal should decrease after repeated boring, thus the measured temperature should decrease over time.

Only the kinetic theory of heat (in which temperature is taken to be a measure of the average kinetic energy of the particles in a substance) survives contact with Thompson’s experiment.*1

This is yet another example of the mercilessness of the scientific method: if you have a particular theory, or model, it must survive contact with every single phenomenon we observe. If it does not, then the model is wrong – or at least, in need of alteration.

Catastrophism

 It is mighty fortunate that we have the scientific method; so many of our models of how the world works would otherwise be terribly inaccurate, since they would have been generated solely by our biased and parochial imaginations.

Catastrophism is another example of this. Catastrophism is an early geological theory which posits that earth’s landscape was formed primarily by a succession of sudden and catastrophic events, such as eruptions, floods and earthquakes.

In this model, mountains were formed over a relatively short period of time, having been thrust up from the bowels of the earth in a single cataclysmic movement.

This is in contrast to the currently accepted theory of ‘uniformitarianism’, in which earth’s geological featues are thought to have been formed only gradually*2, with mountains rising slowly, but ineluctably.

Now, catastrophism was appealing to us humans for a couple of reasons. First of all, for the accordance it has with religious scripture, since it preserves the notion that earth might be only 10,000 years old.

But even without the motivation of specific religious dogmas, the theory would probably still have gained preeminence. We humans, with our ephemeral lives of eighty-odd years simply do not readily notice the tiny, gradual changes to our environment. They occur so inchmeal that we assume the earth is more-or-less static. Only through careful measurement do we see that mountains are actually growing, and that the processes of erosion are gradually sculpting cliffs and rocks into the contoured edifices we observe.

On the other hand, we do occasionally observe volcanic eruptions, and violent earthquakes that wreak utter destruction on the land, so it’s no wonder we would exclusively attribute the shape of earth’s landscape to such events.

Again, it was the scientific method that saved us from our own shortcomings. As a model, catastrophism doesn’t stack up to the accumulated evidence, whereas the theory of uniformitarianism, with its principle that “the present is the key to the past” works perfectly, upon careful observation and analysis.

Conclusion

These theories are a mere fragment from the mass grave of busted theories that science leaves behind. They help to reveal the reality of science: that it is conducted by a bunch of shortsighted but well-meaning primates. But they also reveal that, remarkably, this doesn’t matter a great deal.

Science is a process that is largely independent of those who operate it. It is a self-correcting machine that ensures that it is not necessarily the theories we like that prevail, but those that are true. And for those of us that like theories because they’re true – we have good reason to love science a great deal.

 

 


*1 In reality, while Thompson’s experiment was indeed indicative of the inaccuracy of caloric theory, the theory only gradually fell out of favour, as the principles of conservation of energy, and kinetic heat were elaborated and clarified over time.

*2 With the exception of occasional catastrophic events, which do in fact alter the landscape.

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