Geomagnetic archaeology 地磁考古

Geomagnetic archaeology 地磁考古

Earth’s magneticfield illuminates biblical history

第一段：

When sennacherib, King of Assyria, sent his army to the kingdom of Judah in 701BC, and had it destroy the city of Lachish, 43km south-west of Jerusalem, he was doing his bit for science as well. As Yoav Vaknin of Tel Aviv University told this year’s meeting of the American Geophysical Union, held in New Orleans and online, residual magnetism in the burnt-down buildings is helping archaeologists to date other finds in the area. It also helps geophysicists to chart the ups and downs of terrestrial magnetism.

公元前701年，亚述王西拿基立出兵攻打犹大王国，摧毁了耶路撒冷西南43公里的拉吉城，这也是他为科学所做的贡献。正如以色列特拉维夫大学的Yoav Vaknin教授今年在新奥尔良举行的美国地球物理联盟会议上所说的那样，被烧毁的建筑物中的残余磁力正在帮助考古学家确定该地区其他发现的年代。它还可以帮助地球物理学家绘制地磁的起伏图。

第二段：

Mr Vaknin’s work at Lachish is the most recent of a series of studies he has performed that were enabled by arsonous ancient kings. The first examined a building destroyed when Jerusalem was burned by Babylonian troops in 586BC. According to the biblical Book of Kings, this happened “in the fifth month, on the seventh day of the month, which was the nineteenth year of King Nebuchadnezzar, King of Babylon”.

瓦克宁在拉吉什的工作是他在古代国王纵火的情况下所进行的一系列研究的最新成果。第一组研究了公元前586年耶路撒冷被巴比伦军队烧毁时的一座建筑。根据圣经《列王记》，这件事发生在“五月，该月的第七天，也就是巴比伦王尼布甲尼撒十九年”。

第三段：

Mr Vaknin says that date is considered reliable by biblical scholars. So he and his colleagues were able to pinpoint the moment when this building, the remains of which were found under a car park, was destroyed. Those remains included pieces of the polished upper floor and the burnt wooden beams that once supported it.

瓦克宁先生说，圣经学者认为这个日期是可靠的。所以他和他的同事们能够确定这座建筑的残骸在停车场下被摧毁的确切时间。这些残骸包括抛光的上层地板的碎片和曾经支撑它的烧焦的木梁。

第四段：

The fire’s heat would have erased any magnetism in the minerals of this floor. Earth’s magnetic field then left its mark as those minerals cooled, magnetising them anew. Assuming the fragments have not moved since then, the alignments of their magnetic fields will point in the direction of Earth’s field as it was on that fateful day.

火的热量会抹去地板上矿物的磁性。随着这些矿物冷却，地球磁场留下了它的印记，重新磁化它们。假设这些碎片从那时起就没有移动过，它们的磁场就会指向地球磁场的方向，就像那灾难性的一天一样。

第五段：

Looking for magnetic alignments in this way was well understood when Mr Vaknin began his investigation. But he and his colleagues also did an experiment. They heated samples of the fallen floor in their laboratory and exposed them to a magnetic field as they cooled down, thus repeating what had happened when the edifice was destroyed. By comparing the resultant magnetisation with the original one, and knowing the strength of the field they had themselves applied, they were able to estimate the strength of Earth's magnetic field on the day of the sack.

当瓦克宁先生开始他的研究时，以这种方式寻找磁场排列是很容易理解的。但他和他的同事们还做了一个实验。他们在实验室里加热掉下来的地板样本，并在它们冷却时将它们暴露在磁场中，从而重复了大厦被摧毁时发生的事情。通过将合成的磁化强度与原来的磁化强度进行比较，并了解他们自己施加的磁场强度，他们就能够估算出在洗劫当天地球的磁场强度。

第六段：

They have now repeated this approach at other sites, leading to well-dated reconstructions of the magnetic fields connected with the sackings of Gath, Kinneret, Bethsaida and Ekronin, as well as Lachish and Jerusalem, courtesy of military campaigns by Aramean, Assyrian and Babylonian kings. The dates range from about 830BC to exactly 586BC.

现在，他们在其他地点重复了这种方法，导致了与迦特、Kinneret、Bethsaida和Ekronin，以及拉吉和耶路撒冷被洗劫有关的磁场的年代久远的重建，这些都是由于亚兰、亚述和巴比伦国王的军事行动。日期从公元前830年到公元前586年。

第七段：

That is more or less the maximum span for which this approach is feasible. Written accounts of earlier invasions, in the Bible and other texts, are thought insufficiently reliable. And after the Babylonians came the Persians, who were, as Mr Vaknin observes, “kind enough not to destroy cities”.

这或多或少是这种方法可行的最大跨度。《圣经》和其他文本中关于早期入侵的书面记载被认为不够可靠。巴比伦人之后是波斯人，正如瓦克宁所言，波斯人“非常善良，不会摧毁城市”。

第八段：

It is, though, an extremely useful span, for it coincides with a hiatus in the archaeological record called the Hallstatt plateau. This “plateau” is a flat stretch of the calibration curve used for a technique called radiocarbon dating. It is a period, from 400-800BC, when, for reasons not entirely clear, radiocarbon dating breaks down.

然而，这是一个非常有用的时间段，因为它正好与考古记录中被称为哈尔斯塔特高原的一个空白期相吻合。这个“平台”是一种被称为放射性碳年代测定法的校准曲线的平坦延伸。这是公元前400-800年的一个时期，由于不完全清楚的原因，放射性碳定年法被打破了。

第九段：

Samples from the time of the plateau have hitherto been undatable within that four-century span. This might now change. Radiocarbon dating relies on measuring the amount of 14C, an unstable isotope of carbon, in organic materials such as wood. Thanks to the ingenuity of Mr Vaknin and his colleagues, and the ruthlessness of ancient kings, the magnetisation of inorganic materials that have been exposed to heat, such as shards of pottery from cooking vessels, offers an alternative.

迄今为止，高原时期的样本还无法确定这四个世纪的时间跨度。这种情况现在可能会改变。放射性碳年代测定法依赖于测量有机材料(如木材)中碳的一种不稳定同位素——14C的含量。多亏了瓦克宁先生和他的同事们的聪明才智，以及古代国王们的冷酷无情，诸如烹饪器皿上的陶瓷碎片等暴露在高温下的无机材料被磁化，提供了另一种选择。

第十段：

Mr Vaknin’s data points are also valuable for geophysicists who want to understand how movements in Earth’s core change the planet’s magnetic field. The period Mr Vaknin studies was one in which this field was usually about 50% stronger than it is today, and for short periods was double today’s strength.

对于想要了解地核运动如何改变地球磁场的地球物理学家来说，瓦克宁先生的数据点也很有价值。在瓦克宁研究的时期，这一领域通常比现在强50%，而且在短期内是现在的两倍。

第十一段：

As to Lachish, history did not forget it. Sennacherib celebrated victory by ordering huge alabaster reliefs of his victory (one of which is depicted above) to decorate his palace in Assyria’s capital, Nineveh. They are now in the British Museum.

至于拉吉，历史没有忘记它。西拿基立下令用巨大的雪花石膏浮雕来装饰他在亚述首都尼尼微的宫殿，以此来庆祝胜利。它们现在收藏在大英博物馆。