How the Greeks Knew the Earth was a Sphere

‘As long ago as 340 BC the Greek philosopher Aristotle, in his book On the Heavens,
was able to put forward two good arguments for believing that the earth was a round sphere rather than a Hat plate. First, he realized that eclipses of the moon were caused by the earth coming between the sun and the moon. The earth’s shadow on the moon was always round, which would be true only if the earth was spherical. If the earth had been a flat disk, the shadow would have been elongated and elliptical, unless the eclipse always occurred at a time when the sun was directly under the center of the disk. Second, the Greeks knew from their travels that the North Star appeared lower in the sky when viewed in the south than it did in more northerly regions. (Since the North Star lies over the North Pole, it appears to be directly above an observer at the North Pole, but to someone looking from the equator, it appears to lie just at the horizon. From the difference in the apparent position of the North Star in Egypt and Greece, Aristotle even quoted an estimate that the distance around the earth was 400,000 stadia. It is not known exactly what length a stadium was, but it may have been about 200 yards, which would make Aristotle’s estimate about twice the currently accepted figure. The Greeks even had a third argument that the earth must be round, for why else does one first see the sails of a ship coming over the horizon, and only later see the hull?’

– Hawking. S. (1998) A Brief History of Time New York, United States: Bantam Books p. 2

Conversations: Arrogant Scientists?

Helena
As many critics of religion have pointed out, the notion of a creator poses an immediate problem of an infinite regress. If God created the universe, what created God?

Galene
The God of most monotheists is believed to be an uncreated entity.

Sappho
To say that God, by definition, is uncreated simply begs the question. The truth is that no one knows how or why the universe came into being. It is not clear that we can even speak coherently about the creation of the universe, given that such an event can be conceived only with reference to time, and here we are talking about the birth of space-time itself.

Helena
The physicist Stephen Hawking, for instance, pictures space-time as a four dimensional, closed manifold, without beginning or end (much like the surface of a sphere). Having said that, any intellectually honest person will admit that he does not know why the universe exists. Scientists, of course, readily admit their ignorance on this point. Religious believers do not.

On the Trouble of Existing

“Why does the Universe go to all the trouble of existing?”

– Stephen Hawking

Spaghettification

Spaghettification is the process by which any object would be stretched and ripped apart by gravitational forces on falling into a black hole. Essentially, when a particle draws too close to the source of the powerful gravitational field, it is stretched into long thin shapes, like pasta.

The term was coined by Stephen Hawking in his book, A Brief History of Time, where he likened this process to spaghetti. Much like other aspects of the black hole theory and model, this effect of drawing too close to a black hole remains untested, unobserved and unproven, and relates to areas of physics that remain largely unexplored, namely the concept of a force so powerful that no matter what components make up a piece of matter, it will be stretched further than is deemed by many to be within the realms of physical plausibility.

“Sure, black holes can kill us, and in a variety of interesting and gruesome ways. But, all in all, we may owe our very existence to them.” ― Phil Plait

Arrogant Scientists?

‘As many critics of religion have pointed out, the notion of a creator poses an immediate problem of an infinite regress. If God created the universe, what created God? To say that God, by definition, is uncreated simply begs the question. Any being capable of creating a complex world promises to be very complex himself. As the biologist Richard Dawkins has observed repeatedly, the only natural process we know of that could produce a being capable of designing things is evolution.

The truth is that no one knows how or why the universe came into being. It is not clear that we can even speak coherently about the creation of the universe, given that such an event can be conceived only with reference to time, and here we are talking about the birth of space-time itself.[5]

[5] The physicist Stephen Hawking, for instance, pictures space-time as a four dimensional, closed manifold, without beginning or end (much like the surface of a sphere).

Any intellectually honest person will admit that he does not know why the universe exists. Scientists, of course, readily admit their ignorance on this point. Religious believers do not. One of the monumental ironies of religious discourse can be appreciated in the frequency with which people of faith praise themselves for their humility, while condemning scientists and other non-believers for their intellectual arrogance. There is, in fact, no worldview more reprehensible in its arrogance than that of a religious believer: the creator of the universe takes an interest in me, approves of me, loves me, and will reward me after death; my current beliefs, drawn from scripture, will remain the best statement of the truth until the end of the world; everyone who disagrees with me will spend eternity in hell. …

An average Christian, in an average church, listening to an average Sunday sermon has achieved a level of arrogance simply unimaginable in scientific discourse—and there have been some extraordinarily arrogant scientists.

Over 99 percent of the species that ever walked, flew, or slithered upon this earth are now extinct. This fact alone appears to rule out intelligent design. When we look at the natural world, we see extraordinary complexity, but we do not see optimal design. We see redundancy, regressions, and unnecessary complications; we see bewildering inefficiencies that result in suffering and death. We see flightless birds and snakes with pelvises. We see species of fish, salamanders, and crustaceans that have nonfunctional eyes, because they continued to evolve in darkness for millions of years. We see whales that produce teeth during fetal development, only to reabsorb them as adults. Such features of our world are utterly mysterious if God created all species of life on earth “intelligently”; none of them are perplexing in light of evolution.’

– Harris. S. 2006. Letter To A Christian Nation p. 24

Turtles All The Way Down

A jocular expression of the infinite regress problem in cosmology posed by the unmoved mover paradox – a philosophical concept described by Aristotle as a primary cause or mover of all the motion in the universe. As is implicit in the name, the unmoved mover is not moved by any prior action. Aristotle argues, in Book 8 of the Physics Book 12 of the Metaphysics: “there must be an immortal, unchanging being, ultimately responsible for all wholeness and orderliness in the sensible world.”

“Turtles all the way down” is a phrase that was popularized by Stephen Hawking in 1988. The turtle metaphor in the anecdote represents a popular notion of a so-called primitive cosmological myth, the flat earth supported on the back of a World Turtle. A person who believes the Earth rests on a giant turtle can thereby also deny the existence of the universe.

A Florida Box Turtle or Terrapene Carolina Bauri

A comparable metaphor describing the circular cause and consequence for the same problem is the chicken and egg problem – which came first? Another metaphor addressing the problem of this infinite regression (as the turtles would imply), albeit not in a cosmological context, is Quis custodiet ipsos custodes? – a phrase coined by the Roman poet Juvenus which is often translated as “Who watches the watchmen?” The same problem in epistemology is known as the Münchhausen Trilemma.

The Trilemma was named after Baron Münchhausen, who allegedly pulled himself (and the horse he was sitting on) out of a swamp by his own hair. This Trilemma is a philosophical term coined to stress the purported impossibility to prove any truth even in the fields of logic and mathematics. If we ask of any knowledge: “How do I know that it’s true?”, we may provide proof; yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen Trilemma is that we have only three options when providing proof in this situation:

• The circular argument, in which theory and proof support each other (i.e. we repeat ourselves at some point) “Only an untrustworthy person would run for office. The fact that politicians are untrustworthy is proof of this.”
• The regressive argument, in which each proof requires a further proof ad infinitum (i.e. we just keep giving proofs, presumably forever) “A is proven by B, which is proven C, which proven by D etcetera ad infinitum.”
• The axiomatic argument, which rests on accepted precepts (i.e. we reach some bedrock assumption or certainty) “A. Baron Münchhausen exists, B. Baron Münchhausen has got hairs on his head etcetera.”

The first two methods of reasoning are fundamentally weak, and because the Greek sceptics advocated deep questioning of all accepted values and refused to accept (unconditional axiomatic) proofs of the third sort. The trilemma, then, is the decision among these three equally unsatisfying options.

Back to turtles. The most widely known version of the Turtles All The Way Down story appears in Stephen Hawking’s 1988 book A Brief History of Time, which starts:

A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the centre of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: “What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.” The scientist gave a superior smile before replying, “What is the tortoise standing on?” “You’re very clever, young man, very clever,” said the old lady. “But it’s turtles all the way down!”

Hawking’s suggested connection to Russell may be due to Russell’s 1927 lecture Why I Am Not a Christian. In it, while discounting the First Cause argument intended to be a proof of God’s existence, Russell comments (with an argument not relevant to modern Hindu beliefs):

If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument. It is exactly of the same nature as the Hindu’s view, that the world rested upon an elephant and the elephant rested upon a tortoise; and when they said, “How about the tortoise?” the Indian said, “Suppose we change the subject.”

There is an allusion to the story in David Hume’s Dialogues Concerning Natural Religion (published in 1779):

How can we satisfy ourselves without going on in infinitum? And, after all, what satisfaction is there in that infinite progression? Let us remember the story of the Indian philosopher and his elephant. It was never more applicable than to the present subject. If the material world rests upon a similar ideal world, this ideal world must rest upon some other; and so on, without end. It were better, therefore, never to look beyond the present material world.

Philosophical allusion to the story goes back at least as far as John Locke. In his 1690 tract An Essay Concerning Human Understanding, Locke compares one who would say that properties inhere in “substance” to the Indian who said the world was on an elephant which was on a tortoise “but being again pressed to know what gave support to the broad-backed tortoise, replied — something, he knew not what.”

The fact is the world does not rest on elephants, turtles or any other animal for that matter. However, the reasoning and philosophical attempts to prove a possibility of there being a giant tortoise on which the earth can rest are fascinating. Just as fascinating as the cultures out of which these beliefs have emerged.

To quote comedian Rich Hall: “This is why America has a space program.”

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