Nav: Home

Ancient jars found in Judea reveal earth's magnetic field is fluctuating, not diminishing

February 14, 2017

Albert Einstein considered the origin of the Earth's magnetic field one of the five most important unsolved problems in physics. The weakening of the geomagnetic field, which extends from the planet's core into outer space and was first recorded 180 years ago, has raised concern by some for the welfare of the biosphere.

But a new study published in PNAS from Tel Aviv University, Hebrew University of Jerusalem, and University of California San Diego researchers finds there is no reason for alarm: The Earth's geomagnetic field has been undulating for thousands of years. Data obtained from the analysis of well-dated Judean jar handles provide information on changes in the strength of the geomagnetic field between the 8th and 2nd centuries BCE, indicating a fluctuating field that peaked during the 8th century BCE.

"The field strength of the 8th century BCE corroborates previous observations of our group, first published in 2009, of an unusually strong field in the early Iron Age. We call it the 'Iron Age Spike,' and it is the strongest field recorded in the last 100,000 years," says Dr. Erez Ben-Yosef of TAU's Institute of Archaeology, the study's lead investigator. "This new finding puts the recent decline in the field's strength into context. Apparently, this is not a unique phenomenon -- the field has often weakened and recovered over the last millennia."

Additional researchers included Prof. Oded Lipschits and Michael Millman of TAU, Dr. Ron Shaar of Hebrew University, and Prof. Lisa Tauxe of UC San Diego.

Delving into the inner structure of the planet

"We can gain a clearer picture of the planet and its inner structure by better understanding proxies like the magnetic field, which reaches more than 1,800 miles deep into the liquid part of the Earth's outer core," Dr. Ben-Yosef observes.

The new research is based on a set of 67 ancient, heat-impacted Judean ceramic storage jar handles, which bear royal stamp impressions from the 8th to 2nd century BCE, providing accurate age estimates.

"The period spanned by the jars allowed us to procure data on the Earth's magnetic field during that time -- the Iron Age through the Hellenistic Period in Judea," says Dr. Ben-Yosef. "The typology of the stamp impressions, which correspond to changes in the political entities ruling this area, provides excellent age estimates for the firing of these artifacts."

To accurately measure the geomagnetic intensity, the researchers conducted experiments at the Paleomagnetic Laboratory of Scripps Institution of Oceanography (SIO), University of California San Diego, using laboratory-built paleomagnetic ovens and a superconducting magnetometer.

"Ceramics, baked clay, burned mud bricks, copper slag -- almost anything that was heated and then cooled can become a recorder of the components of the magnetic field at the time of the event," said Dr. Ben-Yosef. "Ceramics have tiny minerals -- magnetic 'recorders' -- that save information about the magnetic field of the time the clay was in the kiln. The behavior of the magnetic field in the past can be studied by examining archaeological artifacts or geological material that were heated then cooled, such as lava."

Advanced dating method

Observed changes in the geomagnetic field can, in turn, be used as an advanced dating method complementary to the radiocarbon dating, according to Dr. Ben-Yosef. "The improved Levantine archaeomagnetic record can be used to date pottery and other heat-impacted archaeological materials whose date is unknown.

"Both archaeologists and Earth scientists benefit from this. The new data can improve geophysical models -- core-mantle interactions, cosmogenic processes and more -- as well as provide an excellent, accurate dating reference for archaeological artefacts," says Dr. Ben-Yosef.

The researchers are currently working on enhancing the archaeomagnetic database for the Levant, one of the most archaeologically-rich regions on the planet, to better understand the geomagnetic field and establish a robust dating reference.
-end-
Tel Aviv University (TAU) is inherently linked to the cultural, scientific and entrepreneurial mecca it represents. It is one of the world's most dynamic research centers and Israel's most distinguished learning environment. Its unique-in-Israel multidisciplinary environment is highly coveted by young researchers and scholars returning to Israel from post-docs and junior faculty positions in the US.

American Friends of Tel Aviv University (AFTAU) enthusiastically and industriously pursues the advancement of TAU in the US, raising money, awareness and influence through international alliances that are vital to the future of this already impressive institution.

American Friends of Tel Aviv University

Related Magnetic Field Articles:

Understanding stars: How tornado-shaped flow in a dynamo strengthens the magnetic field
A new simulation based on the von-Kármán-Sodium (VKS) dynamo experiment takes a closer look at how the liquid vortex created by the device generates a magnetic field.
'Quartz' crystals at the Earth's core power its magnetic field
Scientists at the Earth-Life Science Institute at the Tokyo Institute of Technology report in Nature (Fen.
Brightest neutron star yet has a multipolar magnetic field
Scientists have identified a neutron star that is consuming material so fast it emits more x-rays than any other.
Confirmation of Wendelstein 7-X magnetic field
Physicist Sam Lazerson of the US Department of Energy's Princeton Plasma Physics Laboratory has teamed with German scientists to confirm that the Wendelstein 7-X fusion energy device called a stellarator in Greifswald, Germany, produces high-quality magnetic fields that are consistent with their complex design.
High-precision magnetic field sensing
Scientists have developed a highly sensitive sensor to detect tiny changes in strong magnetic fields.
Brilliant burst in space reveals universe's magnetic field
Scientists have detected the brightest fast burst of radio waves in space to date -- locating the source of the event with more precision than previous efforts.
Optical magnetic field sensor can detect signals from the nervous system
The human body is controlled by electrical impulses in the brain, the heart and nervous system.
What did Earth's ancient magnetic field look like?
New work from Carnegie's Peter Driscoll suggests Earth's ancient magnetic field was significantly different than the present day field, originating from several poles rather than the familiar two.
Just what sustains Earth's magnetic field anyway?
Earth's magnetic field shields us from deadly cosmic radiation, and without it, life as we know it could not exist here.
Ironing out the mystery of Earth's magnetic field
The Earth's magnetic field has been existing for at least 3.4 billion years thanks to the low heat conduction capability of iron in the planet's core.

Related Magnetic Field Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".