As old as recorded history, there have been people who described the universe as infinite. Born near the year 100 B.C. the philosopher Lucretius argued that space can never end, for what would happen, he asked, if you throw a dart at the outer edge of the universe. "Wherever you may place the ultimate limit of things, I will ask you: 'Well then, what does happen to the dart?' The universe has nothing outside to limit it", said Lucretius. We know today that space is curved, and so the present universe can be finite if it is closed into a circle of some kind, but the point Lucretius made still holds true. There are no walls or edges where space suddenly ends.
It is interesting to imagine how Lucretius envisioned the universe from his poetic writing. In his book entitled, The Nature of the Universe, he writes:
- If all the space in the universe were shut in and confined on every side by definite boundaries, the supply of matter would already have accumulated by its own weight at the bottom, and nothing could happen under the dome of the sky -- indeed, there would be no sky and no sunlight, since all the available matter would have settled down and would be lying in a heap for all eternity. As it is, no rest is given to the atoms, because there is no bottom where they can accumulate and take up their abode.
Lucretius viewed the infinite as endless and boundless, but he always described it as having a consistent reality of space, time, and atoms. He made the age old mistake of defining atoms as separate things in an independent space. Albert Einstein would one day show that space, time, and matter are interdependent, but you may have noticed that he recognized the universe has no bottom or top, long before anyone knew anything about outer space in a scientific way. It was his ability to reason out such rules with argument, and his belief that such rules formed some basic eternal reality, that gave Lucretius his place in history. In another passage Lucretius writes:
- Things go on happening all the time through ceaseless movement in every direction; and atoms of matter bouncing up from below are supplied out of the infinite. There is therefore a limitless abyss of space, such that even the dazzling flashes of the lightning cannot traverse in their course, racing through an interminable tract of time, nor can they even shorten the distance still to be covered. So vast is the scope that lies open to things far and wide without limit in any dimension.
The most famous quote from Lucretius was, "Nothing can be created out of nothing." He deduced this from carefully observing his environment, noticing that plants died without rain, that things needed time to grow and required raw materials. He wrote, "Surely because each thing requires for its birth a particular material which determines what can be produced. It must therefore be admitted that nothing can be make out of nothing, because everything must be generated from a seed before it can merge into the unresisting air."
Lucretius in my mind is a great example of how science often fails to acknowledge its heritage with philosophers. I have never heard Lucretius given credit for developing the First Law of Thermodynamics, which states that energy is neither created nor destroyed, yet he was arguably the first to state the first law, deriving it simply from intuitive reasoning and observing his environment.
- The second great principal is this: nature resolves everything into its component atoms and never reduces anything to nothing. If anything were perishable in all its parts, anything might perish all of a sudden and vanish from sight.
From the principle that elementary things are never destroyed, or something never becomes nothing, Lucretius recognized that the universe must exist some way in a forever time. He wrote:
- If throughout this bygone eternity there have persisted bodies from which the universe has been perpetually renewed, they must certainly be possessed of immortality.
His cosmology was rather complete considering he lived two thousand years ago. He derived the second law also, which states that a system moves from an ordered to a disordered state, stating that all things eventually return to their constituent parts, writing "nature repairs one thing from another, and allows nothing to be born without the aid of another's death. He even had his own version of the anthropic principle.
- Certainly atoms did not post themselves purposefully in due order by an act of intelligence, nor did they stipulate what movements each should perform. As they have been rushing everlastingly throughout all space in their myriad's, undergoing a myriad of changes under the disturbing impact of collisions, they have experienced every variety of movement and conjunction till they have fallen into the particular pattern by which this world of ours is constituted.