The Universe is 13.82 billion years old, give or take 20 million years. This was established from precise measurements of the cosmic microwave background (CMB) - the afterglow of the "big bang" that pervades all space.
This understanding was one of the great innovations of our era. But the medieval period is notable for its own innovations, not least of which were universities, capitalism, banking, concepts of individual freedoms, property rights, political constitutions and emerging empirical science. All notions of the "dark ages" as a meaningful description of the era are now abandoned.
The "dark ages" also refers to the first 380,000 years after the big bang before light (and the CMB) could pass through space.
These, and countless other insights, are agreed upon through reasoned and open-minded discourse. Invective and ridicule never played a part in establishing truth. Neither did a show of hands or a straw poll. And Bob's-your-uncle straw-man arguments never improved understanding either - nor can they in deciding the crucial issues of life, religion and destiny.
I am at a meeting of some 10,000 physicists in Baltimore, Maryland. In earlier years at this meeting some of these great insights of cosmology gained common assent through respectful debate and careful attention to evidence. That is the model for all truth-seeking.
Maryland was once a slave state, though it remained with the Union.
This year is the 150th anniversary of Lincoln's 1863 Emancipation Proclamation, freeing slaves not just in Maryland but across the US. But did this remove for all time the curse of slavery?
Buried for millennia under the desert sands of Mesopotamia is a chronicle of ancient human commerce, science and discourse. Some half million clay tablets have been found in the ruins of Babylon, Sippar, Ur, Calah and Nineveh that record every imaginable aspect of public and private life. Many now reside in the British Museum.
My interest in these clay tablets lies partly in the extensive astronomical records that they contain and partly in their relevance to validating the Biblical historical record.
Today with the assistance of astronomical computer simulation packages, which can take us back in time and place, we can check these records in great detail. They are, of course, very accurate.
One example is "The Babylonian Astronomical Diaries" - a comprehensive record of 1000 years of astronomical observation. What is so interesting is that after an event is described one often finds the statement "I did not see it". This was because the event occurred below the horizon or, on other occasions, it was concealed by cloud cover. And yet the eclipse, conjunction or comet motion is described in detail. How come?
Well, the Babylonians could accurately calculate what was coming up and they trusted their calculations as a complete and reliable proxy for eyes and instruments.
Virtual reality is as old as rational humanity.
What, you may wonder, has this to do with slavery, dark ages and human decency?
Well, these astronomical diaries were not just scientific records. They also recorded the weather, religious rites, exchange rates and commodity values - including the ever shifting cost of slaves. By linking these costs back to the value of silver, the cost of a slave at any time can be translated to today's dollar value. The result is astonishing and bleak.
In ancient Ur, the Biblical city of Abraham's origin, slaves could be bought for $130 in 2000BC. From then on the going rate just went on rising. In old Babylon in 1780BC it was $216, in Ugarit in 1400BC it was $325, in Assyria in 800BC it was $540, rising to $1242 in the Persian Empire around 530BC.
Moving on in time, and out of Mesopotamia, in Imperial Rome in 79AD uneducated slaves fetched a price of around $2700 while just prior to emancipation in the US slaves sold at around $35,000 each.
Just to be clear, that this is not simply reflecting currency inflation over 4000 years, all these figures are converted to today's NZ dollars. Physicists will plot such data on what is called a logarithmic plot.
It forms a straight line. This means the value of slaves rose exponentially over four millennia - without deviation.
Now here is the tragedy of our times. Extrapolating this exponential plot forward to the present one might expect that if, God forbid, we still had legal slavery, the individual value of slaves would now be somewhere around $50,000.
In fact, slavery is officially banned in every nation but it nonetheless continues unabated.
One million children are exploited annually by the global commercial sex trade and of an estimated $35 billion in annual profits from human trafficking half is generated in industrialised nations.
It is estimated that there are more slaves now than at any other time in history. And here is the shocking thing: the average going rate around the globe is less than $100. We have to turn the clocks back 4000 years to ancient Ur to find a time when human lives were so devalued.
This leads in turn to a callous brutality.
If a modern slave becomes ill it is not considered worthwhile to assist them to recover. They are often simply disposed of. For countless millions the dark ages are right here and now.
Humankind is capable of the highest ideals and accomplishments, whether the subtle calculations of astronomy or cosmology, or the unwavering moral leadership of a president such as Lincoln. But we are also capable of the most base conduct. And modern slavery, where fellow humanity is an all-time, low-priced commodity in gross oversupply, is a monstrous cancer on the face of our species.
This is not just a Third World problem. Its seeds are to be found in our own homes and cities across this nation.
Dr Jeff Tallon, CNZM, is a physicist specialising in superconductivity. He was jointly awarded the inaugural Prime Minister's Science Prize for outstanding achievement in science.
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