A recent news item about lead from a Roman shipwreck has struck a deep chord in academia, and perhaps beyond. The matter at hand pits archaeologists, seeking to preserve a critical artefact of ancient society, against physicists, who are hoping to utilize evidence that might reveal information about a period much further back in time. The historians are looking to explain the workings of Roman shipping; the scientists want to know more about the Big Bang. Analysis of the leaden anchors and ingots used for ballast, preserved for thousands of years underwater, might be useful for inquiry into either of these times long past.
Writing in the journal Rosetta Elena Perez Alvaro, a doctoral candidate at the University of Birmingham, sets the matter up thus:
On 14 th May 2011 a 2000- year- old shipwreck’s cargo was used as a source for experiments in particle physics. Italy’s new neutrino detector, CUORE (Cryogenic Underground Observatory for Rare Events), at the Italian National Institute of Nuclear Physics, received from the National Archaeological Museum of Cagliari in Sardinia 120 archaeological lead bricks from a ship, which was built more than 2,000 years ago and recovered from the sea 20 years ago on the coast of Sardinia. This ‘ Roman lead ’ – mainly found in the anchors of sunken ships – was used because of its low radioactivity: for, being underwater for 2,000 years, the very low original radioactivity was reduced approximately 100,000 times.
Why should physicists want to analyze such well-preserved ancient lead? It is no small matter they are searching for, rest assured. Scientists are able to account for only 17% of the materials that make up the universe. “The understanding of the origin of the remaining 83% of the matter present in the universe remains an open question in the field of Cosmology,” Perez Alvaro writes.
This mystery substance is known popularly as “dark matter,” and it is very hard to detect. “Important as dark matter is thought to be in the cosmos,” Wikipedia reports, “direct evidence of its existence and a concrete understanding of its nature have remained elusive.” As I understand it, the difficulty of detecting dark matter has to do with its not being a common substance found on earth: scientists are searching in a haystack for a never-before-seen needle, one that would, very likely, alter its composition upon coming into contact with radiation.
Shielding against radiation is the critical part of detecting dark matter, and so laboratories for this sort of analysis are established far underground. One such lab is run by the University of Minnesota in the Soudan Underground Mine; another is the Gran Sasso National Laboratory in central Italy. Each is involved in the series of experiments called Cryogenic Dark Matter Search (CDMS). Locating uncontaminated material for analysis is a huge part of the research, and this is where the shipwrecked Roman anchors come into the picture. As Perez Alvano states,
Recently, ancient Roman lead recovered from the bottom of the Mediterranean Sea has been studied in detail and demonstrates extremely low levels of intrinsic radioactive emissions. Moreover, its conservation underwater prevented the lead from being radioactively activated by cosmic rays, thus further improving its properties.
As you know if you have ever been X-rayed at the dentist’s office and seen technicians wearing lead-lined cloaks, lead–Pb, plumbum in Latin–is a heavy metal highly resistant to radioactivity. Lead ingots and anchors from shipwrecks, preserved for millenia under the sea, are apparently unique in offering truly positive results about the existence of dark matter. The hope, of course, is to uncover more information about the universe’s origin, plumbing its depths, as it were.
These particular pieces of ancient lead had been bought by CDMS researchers from a French company called Lemer Pax, who had salvaged it from a Roman ship off the French coast, according to livescience. The wreck is in fact significant– found near Madrague de Giens, evidence of the ship’s construction has been used to confirm the shape and proportions of a ship on a contemporary mosaic from Tunisia (right).
The problem, of course, is that looters of archaeological sites are always on the lookout for items that will sell, and if there is a new market among physicists for ancient lead, it is reasonable to expect there will be a rise in pilfering. “It’s another example of something from a shipwreck that has value and will encourage an approach to shipwrecks that won’t be available for careful meticulous study,” says James Delgado, director of maritime heritage at the National Oceanic and Atmospheric Administration, on the livescience website. “Science and archaeology go out of the window in the quest for profits.”Perhaps the most important Roman anchor found in recent years proves the point. On April 24, 2005–the same day that Pope Benedict XVI was celebrating his first mass as Pope–a large lead anchor-stock was discovered off the coast of Malta. Inscribed on the so-called “the Benedict anchor” were the name of the gods, ISIS and SARAPIS, indicating an Egyptian origin for the ship from which the anchor had come. Immediately the question was raised: could the anchor have come from the grain ship St. Paul had been sailing on from Alexandria which ran aground at Malta, as recorded by Luke in Acts, chapters 27-28?
As Luke writes,
…we came to Myra in Lycia. There the centurion found an Alexandrian ship bound for Italy and put us on board. … Paul advised them, 1saying, ‘Sirs, I can see that the voyage will be with danger and much heavy loss, not only of the cargo and the ship, but also of our lives.’ … When neither sun nor stars appeared for many days, and no small tempest raged, all hope of our being saved was at last abandoned.
Paul is source of strength to the sailors, however, and they fight the storm for two weeks:
When the fourteenth night had come, as we were drifting across the sea of Adria, about midnight the sailors suspected that they were nearing land. So they took soundings and found twenty fathoms; a little farther on they took soundings again and found fifteen fathoms. Fearing that we might run on the rocks, they let down four anchors from the stern and prayed for day to come. … In the morning they did not recognize the land, but they noticed a bay with a beach, on which they planned to run the ship ashore, if they could. So they cast off the anchors and left them in the sea.
Eventually, Paul and the others jump overboard and make for the land, which, they discover, is the island of Malta. As you can imagine, marine archaeologists have ever after been in search of any of the very anchors tossed from Paul’s ship, and in 2005, they may very well have found one, though we will probably never know for sure.
Still, we know that, for Paul, the image of the anchor was an important one: We have this hope, a sure and steadfast anchor of the soul, a hope that enters the inner shrine behind the curtain, as he writes in the letter to the Hebews (6:19). Some will realize that this quotation informs the imagery of the Rhode Island state seal. Perhaps it is interesting to note in this connection that, only a few months ago, Brown University reported the first hopeful results of its Large Underground Xenon (LUX) experiment, the most sensitive dark matter detector in the world, located not in its native Rhode Island, but in an underground laboratory in South Dakota–under a town called Lead.
Postscript, February 10, 2014. I did not know about this before, but the shipwreck of St. Paul is commemorated every year in Malta on February 10th as the festival of San Pawl Nawfragu, at the Collegiate Parish Church of St Paul’s Shipwreck in Valletta. A video of the festival is below: