We now know gold on earth was created in space

Dr Irengbam Mohendra Singh *

Gold is the most sought-after element on Earth. Dr JJ Eldridge, of the University of Auckland, New Zealand, proclaimed: "We're all made of stardust, but gold, silver and platinum are made of neutron stardust" after the confirmation of the detection of gold in the Outer Space for the first time in August 2017. Scientists for a few decades had believed that gold came from outer space as meteorites that have struck the planet over billions of years. Now it's proven to be a scientific fact.

I have delayed writing this article as I wanted the youth in Manipur, who are interested in science, to familiarise themselves with astrophysical scientific vocabulary, which I introduced in previous columns.

The name GOLD is English, but it originates from Latin aurum meaning shining down. So its chemical symbol is 'Au'. Gold is one of the 94 naturally occurring elements, to which 24 synthetic elements are now added (total 118).

Gold is not formed on Earth like diamonds. Most of gold on Earth is located in its core, where its heavy properties caused it to shrink over time. Some volcanic eruptions were found to contain gold. Some gold is also found near the surface of the Earth as a result of relatively recent strikes of meteorites.

On August 17 2017, astronomers in the US picked up a signal from two neutron (collapsed) stars crashing together 130 million years ago. The findings were published in the journal, Nature, Astronomy and Science. The period is estimated to be when dinosaurs still roamed the Earth. Dinosaurs became extinct 65 million years ago, presumably after a huge meteorite crashed to Earth near the Gulf of Mexico.

The impact of the collision known as 'kilanova' (an explosion that is 1,000 times stronger than a 'supernova' – explosion when a star ends it life) was so powerful that it not only shook space, but sent ripples or 'gravitational waves' (see below) through the space-time fabric of the universe. After the ripples were detected on Earth, astronomers across the world, looked through their telescopes to the area of the space from which it originated. They picked up the tell-tale sign of infrared afterglow of light from the collision.

Inside that infrared glow of light, which was powered by extreme nuclear reactions, they detected typical chemical patterns of gold, silver and platinum by spectroscopy. It was first observed by Dr Joe Lyman, at the University of Warwick, UK, who was observing at the European Southern Observatory in Germany. He then alerted the scientific community.

Dr Lyman explains. In that kilanova, "heavy elements, such as gold, silver and platinum were created as cinders forged in the billion-degree [temperature] remnants of merging neutron stars. Neutron stars are created when giant stars die in spectacular burst of light called supernovas. As their cores collapse, protons and neutrons meld together to form neutrons ie small yet incredibly dense stars. It's so dense that a teaspoonful of neutron star would have a mass of billion tons.

According to astronomers, the two stars whose collision was detected in August, were as heavy as our Sun, yet only 6 miles (9.6 Km) across. They existed in a galaxy called NGC 4993. They approached each other over millions of years and revolved around each other with faster and faster speed. Eventually they spun around each other 500 times per second, until they crashed, forming either a large neutron star, or collapsing into a black hole [for much bigger stars].

Colliding stars can fuse light atomic nuclei to create heavier nuclei, but it's not clear how often such smashups occur and how much material they throw out. The space-time ripples created by the collision were observed by LIGO detectors in Washington and Louisiana, US. In Louisiana, the first discovery of 'gravitational waves' was made in September 2015, confirming Albert Einstein's prediction 100 years ago, and earning three pioneers of the project a Nobel Prize.

The confirmation of this first discovery of gravitational waves from the merger of two neutron stars has made history in astronomical science, following the discovery of gravitational waves from the merging of binary black holes by LIGO detectors in Louisiana, US, and VIRGO detectors located near Pisa in Italy.

Scientists consider this most momentous discovery in astrophysics very important as it will help them better understand the inner workings and emissions of neutron stars, as well as more fundamental physics such as Einstein's theory of general relativity and the expansions of the universe. Neutron stars are new in physics, discovered in 1967 as isolated pulsating stars.

Why gold is golden has been a mystery for a very long time. Even quantum mechanics didn't explain it until very recently. It's because of its atomic structure. The gold atom is so heavy and electrons moves so fast that you have now to include Einstein's theory of relativity into the mathematics of quantum mechanics. Unlike other metals that reflect light straight back, electrons in the gold slosh around a little, with the result that gold absorbs a bit of the blue spectrum of light, giving the light that is reflected back its distinctive gold colour.

Humans have always been fascinated by gold. It's rather curious why gold has been considered so valuable throughout men's history, beginning from Incas and Aztecs of South America, who used gold for religious ceremonies. Aztecs describe gold as "the sweat of the Sun". They dressed themselves in solid battle armour with gold to protect themselves, until they found that it was no match for the steel of the Spanish conquistadors.

In ancient Egypt, gold was precious though it wasn't the rarest metal and the most useful. Much later, ancient Greeks viewed gold as a social status. Gold however, was not always a showpiece material. Once, Napoleon served a state banquet on Aluminium plates as it was much more valuable than gold at that time.

The Bible mentions gold (Genesis 2:10-12). The Bible was 2,500 years old, by the time gold was discovered in Greece. In India, gold coins were introduced by foreign invaders, Kushans in 100 CE. In Manipur by Ningthou Chourajit Singh in 1803-1813 CE.

Though gold can in theory be found anywhere on earth, it's found only in the more geologically active parts of the planet, mostly by accident around stream beds where gold particles and nuggets were washed down from the hills and mountains. The erosive power of water is helpful in revealing places where gold deposits can be found. Because gold is vey malleable it's usually found in lumps or irregular masses – the nuggets.

Gold is in demand because it's beautiful and extremely rare, as it is collected in bits and pieces from all over the world and melted down together. It's very hard to extract. It has a low relatively melting point and therefore easy to turn into coins, ingots and jewellery. It does not tarnish like silver, nor does it react with other chemicals and thus doesn't corrode. It's non-toxic and doesn't cause eczema/dermatitis. It's so scarce that it's estimated if you collect all the gold from the world including bits used at contact points in solid state electronic devices like the mobile phones, you will have just one 20- metre cube.

Gold has been used as currencies in countries where it has been accepted as having some value. To standardise transactions in the world trade market, a "Gold Standard" was introduced by the Bank of England in 1694, so that a country's currency or paper money can be converted directly to a fixed amount of gold. A country with the gold standard system sets a fixed price for gold, and buys and sells gold at that price. This fixed price was used to determine the value of the currency.

There is no more gold standard now, since Britain stopped using it in 1931. The US followed suit in 1933, and the rest of the world in 1971, when President Nixon cut the dollar's tie to gold by serving notice that it will no longer cash in foreign-held dollars for gold bullion held at Fort Knox (cf. James Bond movie Gold finger). Vietnam war drained American resources.

It's now replaced by the term "fiat money". A "fiat" system by contrast, is a monetary system in which the value of money is not based in gold (fixed), but it's allowed to fluctuate dynamically against other currencies on the foreign exchange markets. So the value of fiat money is based simply on the fact that they are legal tender by way of government decree.

India is the greatest importer and consumer of gold as women use a lot of gold jewellery. India has about 700kg of gold smuggled into it everyday, mostly from Gulf countries (cf. Dev Anand film JaaL). The Bank of India has one of the largest stores of gold. Gold is now pouring in India since the government scrapped gold import restrictions in 2015.

In the international market "pure" gold means 24 karat (24K). Since gold is very soft and malleable, it's usually mixed with other metals, called alloys to increase its hardness eg 14k jewellery contains 14 parts of gold mixed throughout with 10 parts of one or more alloys. In Manipur we use 24k gold jewellery with a copper base.