* * *
"Well?" Timothy smiled when they met again.
"If we believe Democritus, then in water all the atoms are much closer together than in steam, so if we boil water in an enclosed space, we get much more pressure, and if you did that, you could make it push a lever and lift something."
"Anything else?"
"You'll think this stupid, but if you put your fire and steam on a chariot, you could do away with the horse!"
"Why would I think that stupid? What's wrong with what you're saying?"
"The chariot would burn, and the weight of everything would be so great it probably wouldn't move anyway."
"They're good thoughts," Timothy said. "Now, let us return to Democritus and his theory that everything is made up of atoms that are continually moving around in a void. The hotter the stuff, the faster the atoms must be going. What do you say to that?"
"It would confirm the theory that coldness is the absence of hotness, however I haven't ever seen an atom and I can't see a void, almost by definition, but that doesn't mean they don't exist."
"The issue is difficult" Timothy agreed. "Democritus believed atoms were eternal, and never came to be nor passed away, but are combined to form things, and these combinations can come to be and pass away. Aristotle did not believe in atoms, but he did believe there was a substratum from which all things came to be and perhaps return to, and in some ways Aristotle's substratum is difficult to separate from Democritus' atoms. Also Aristotle was clear that it is very easy to refute arguments that prove the existence of the void, but he is equally clear that people who try to prove the void does not exist merely demonstrate their erroneous logic."
"Presumably there are arguments for such a void?"
"One argument is motion itself. If something moves, and there is no void, it must move to where something else is, in which case there would be two things in the same place, which is impossible, therefore there is a void. Comment."
"There is a town square," Gaius replied, after some time. "It is full of people. But I can get through because people will move aside."
"An excellent point. In fact that is similar to one made by the great Aristotle himself!" Timothy beamed. "Another reason for the void lies in fresh white ashes."
"They are full of void?"
"That is the argument," Timothy said. "If I take such ashes and add water, the volume of the ashes stays the same, but the weight is that of ashes plus water. The water has gone into the ashes, presumably into the void. Comment."
"Perhaps air has come out," Gaius offered. "It weighs almost nothing, and we know it requires space and if it can open doors, it should be able to keep bits of ash apart. Also. ."
"Also?" Timothy was again puzzled. He was now beginning to recognize the look on Gaius' face as he headed into new territory.
"If we think ice, water and steam are made from the same atoms, then I guess in ice the atoms are hanging onto each other firmly; in water they are hanging on, but they can swap links, and in steam, they are moving too fast and don't really grasp each other at all."
"Very good!" Timothy nodded. "So, is there or is there not a void?"
"Yes, there is," Gaius said slowly. "If steam has the same number of atoms as water, and it occupies a lot more space, there must be void between the atoms. Also, if there is not, according to what I did with water there cannot be eternal motion. I refer to the void not as a thing, but rather as the absence of a thing."
"That is a good argument," Timothy nodded. "Now, atoms? An argument against atoms is that basically, everything that is in motion eventually falls. Heavier things fall faster, but sooner or later, everything falls, no matter how light."
"Until they hit the ground," Gaius offered, "then they stop and. ."
"And?" Timothy smiled.
"According to you, Aristotle said that everything, no matter how light, fell to the centre?"
"Correct." Timothy was puzzled. Why was that objectionable?
"In which case," Gaius said very slowly, "air will fall too. But you said it rises?"
"You can see it rises," Timothy smiled. "Tip a jar over into water, tilt it, and watch the air come out."
"With a force lifting them equal to the weight of the water displaced," Gaius said triumphantly. When Timothy looked puzzled, he smiled, and added, "According to the great Archimedes, anyway."
"That is quite logical," Timothy agreed. He stared at Gaius in surprise. Once again he had not expected a fresh conclusion.
"So the Moon could move in a void!" Gaius insisted. "The layer of air may merely be at the top of the heap on Earth."
"From which you would consider this evidence supporting Aristarchus?"
"Well, yes."
"Persistent, if nothing else," Timothy nodded, "but since it is logic I am trying to get into your head, persistence has its merits. Anyway, let us consider two consequences of atoms. The first was due to Epicurus. He reasoned that if atoms were continually moving in the void, and if the properties of everything depended on how the atoms were joined together, and on the sun's light, and a number of other things, much of which we do not know, there is no need for Gods. Accordingly, there are no Gods. Comment?"
"Many of us Romans find the Gods to be more of a convenience than a necessity," Gaius replied, then suddenly felt apprehensive. He had effectively denied Athene. He paused, and continued, ". . but that's not an answer, is it?"
"No. It isn't."
"There's no answer, then!" Gaius said in an irritated way.
"Apparently, not from you."
"And what's that supposed to mean? How's that argument supposed to help know whether there's a God?" Gaius said, waving an arm in desperation.
"And I don't suppose you would stop to think that that might be an answer?" Timothy said, evenly. "Suppose the argument does not follow? Suppose the logic is not there?"
"That's what I said! But it doesn't help decide whether there's a God."
"That's not the issue. What I am trying to do is to get you to use logic, to find fault in arguments, so that wherever you go, if a problem is given to you, your mind can cut through the irrelevancies and see things for what they are, or, as our example with the map, to see what is not there."
"Then my answer," Gaius said, "is that atoms and Gods are not connected logically, therefore the first part of the argument is silly. As I said, even if the first part happened to be true, and Gods are not required, it does not follow that they are not there. Equally, this argument does not mean that they are."
* * *
"Now, there is a really strange aberration in physics, namely Lucretius. The aberration is that he is Roman and who had something constructive to say. Comment?"
"I have no idea what he said," Gaius replied, "but the fact he's Roman doesn't make him wrong," Gaius looked almost challenging, then a thought struck him, "or right, for that matter."
"A nice addition," Timothy said caustically. "Lucretius said that atoms form some groupings that are immutable. One such grouping is in living things, for example, sparrows have a sparrow grouping, which means all sparrow eggs give sparrows with the same brown markings in the same place, and this immutable grouping is a fixed joining of a lot of atoms. Comment?"
"I presume the comment about a lot of atoms comes from the fact that if a grouping makes sparrows, and another makes gulls, and another makes fish, there must be a huge variation of groupings, so it makes sense that there are a lot of atoms in the grouping," Gaius said, "and if sparrows are the same as they used to be, I suppose it means the groupings are immutable."