A giant ‘singing’ cloud in space will help us to understand how star systems form

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The dark band is the Dark Doodad Nebula, a place where new stars and planets can form.
Flickr/cafuego, CC BY-SA

By Aris Tritsis, Australian National University

We know that the birthplaces of stars are large molecular clouds of gas and dust found in space.

But what exactly determines the number and kind of stars and planets that are formed in these clouds? How was our Solar system nursed and how did it emerge from such a cloud billions of year ago?

These are mysteries that have been puzzling astronomers for decades, but research published today in Science adds an extra dimension to our understanding.

A 3D approach

Knowledge of the 3-dimensional structure of these clouds would be an important leap in our understanding of how stars and planets are born.

Read more:
From pancakes to soccer balls, new study shows how galaxies change shape as they age

The physics responsible for the formation of stars is also responsible for shaping the clouds. But even with the most advanced telescopes in the world we can only see the two-dimensional projections of clouds on the plane of the sky.

Thankfully, there is a way around this problem. A recently discovered type of structure in molecular clouds, called striations, was found to form because of waves.

Here enters Musca, a molecular cloud that “sings”. Musca is an isolated cloud in the Southern sky, below the Southern Cross, that looks like a thin needle (see top image). It is hundreds of light years away and stretches about 27 light years across, with a depth of about 20 light years and width up to a fraction of a light year.

Musca is surrounded by ordered hair-like striations produced by trapped waves of gas and dust caused by the global vibrations of the cloud.

3D model of Musca molecular cloud.
Aris Tritsis, ANU, Author provided

Trapped waves act like a fingerprint – they are unique and can be used to identify the sizes of the boundaries that trapped them. Boundaries are naturally created at the edges of clouds where their physical properties change abruptly.

Just like a cello and a violin make very distinct sounds, clouds with different sizes and structures will vibrate in very different manners – they will “sing” different “songs”.

A ‘song’ in the cloud

By using this concept and calculating the frequencies seen in observations of Musca it was possible to measure for the first time the third dimension of the cloud, the one that extends along our line of sight.

The frequencies found in the observations were scaled to the frequency range of human hearing to produce the “song of Musca”.

A “singing” molecular cloud.

The results from this method were amazing. Despite the fact that Musca looks like a thin cylinder from Earth, the true size of its hidden dimension is not small at all. In fact, it is comparable to its largest visible dimension on the plane of the sky.

No longer a thin cylinder when the extra dimension is revealed (Aris Tritsis)

Musca is not actively forming stars. It will be millions of years before gravity can overcome all opposing forces that support the cloud.

Read more:
Signals from a spectacular neutron star merger that made gravitational waves are slowly fading away

As a result, with its structure now determined, Musca can be used as a prototype laboratory against which we can compare our models and study the early stages of star formation.

The ConversationWe can use Musca to better constraint our numerical models and learn about our own Solar system. It could help solve many mysteries. For example, could the ices found in comets have formed in clouds rather than at a later time during the life of our solar system?

Aris Tritsis, Postdoctoral Fellow, Australian National University

This article was originally published on The Conversation. Read the original article.

Experiment shows Einstein’s quantum ‘spooky action’ approaches the human scale

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An illustration of the two 20-micrometre-wide vibrating drumheads, each composed of trillions of atoms, in an entangled quantum state of motion.
Petja Hyttinen and Olli Hanhirova, ARKH Architects Ltd., Author provided

By Matt Woolley, UNSW

Quantum physics is often defined as the physics of the very small – think atoms, electrons and photons.

But we have managed to demonstrate one of the quirky features of quantum physics at a much larger scale. In a paper published today in Nature, we describe how we were able to create quantum entanglement of the motion of objects composed of many billions of atoms.

Entanglement is where two objects that may be separated by an arbitrary distance are somehow connected: a measurement on one object leads to a change in the results of measurements made on the other – what Albert Einstein called “spooky action at a distance”.

Read more:
Star Wars’ last Jedi may use the Force of quantum science

Entanglement has been demonstrated for microscopic-scale systems, such as those involving photons, ions and electron spins. But a number of challenges remained before we could demonstrate entanglement on a larger scale.

Before I look at how we solved some of those challenges we need to understand a bit more about quantum physics.

The size of things

Does size really matter in quantum physics? Well, kind of. There is, in fact, nothing in the formulation of quantum mechanics that mandates that it should apply only to the very small.

What then really matters in determining whether an object will behave according to the strange rules of quantum physics, or according to the familiar rules of classical physics?

There are perhaps two ingredients required for the observation of quantum behaviour in an object.

The first is isolation. The world outside is full of sound and fury, such as other matter and radiation. If the object can find a way to isolate itself from this fury, it can evolve according to the simple rules of quantum mechanics.

An object that cannot isolate itself from the fury will find that the richness of quantum dynamics cannot be accessed. So its motion will be well described by the familiar rules of classical physics.

A thrown ball will follow a well-defined trajectory; it will not spread out as one might expect from quantum physics. A rolling stone will go up a hill until the supply of the energy of motion it had at the bottom of the hill is exhausted; it cannot possibly emerge on the other side of the hill as it might according to the rules of quantum tunnelling.

The second ingredient is frequency, the rate at which a confined object vibrates. The emergence of quantum behaviour typically requires that the energy associated with the object (which is related to its frequency of vibration) exceeds the energy associated with the object’s environment (which is related to its temperature).

Even if an object is well isolated from its environment, it will not be perfectly isolated, so the properties of the object’s environment still matter.

Consider light. Photons of light interact only weakly with other photons, so that if we consider light propagating in near vacuum we have a well-isolated system. That’s the first ingredient.

What about frequency? Well, the electric and magnetic fields associated with visible light go up and down around 6×1014 times per second.

In this case, the energy associated with a photon of light vastly exceeds the energy scale of the likely thermal environment. One can tell a similar story for the electronic levels of isolated atoms. Thus very small objects are more likely to possess the ingredients required for the observation of quantum phenomena.

Scale things up a bit

Let’s go bigger and more tangible. Instead of thinking about the electromagnetic fields of light or the electronic levels of an atom, how about the motion of a macroscopic, massive object? Can we make and observe such an object behave according to the rules of quantum physics?

The answer, as we report today, is yes.

In an experiment, performed recently in the laboratory of Professor Mika Sillanpää at Aalto University in Finland, we set up two microfabricated vibrating circular membranes, like drumheads.

Each was about the width of a human hair and we were able to measure them in a state that exhibited the quantum property of entanglement.

The two drumheads were brought into an entangled state through careful driving of a superconducting electrical circuit to which both were coupled.

While these drumheads may seem small on the human scale, they are huge on the atomic scale – each drumhead is composed of trillions of atoms.

These drumheads are the largest objects to be prepared in an entangled state, and this experiment is perhaps the closest approach to a literal implementation of the famous thought experiment of Einstein, Podolsky and Rosen that first studied the phenomenon that became known as entanglement back in 1935.

Why we did it

So why should we take the trouble to demonstrate quantum physics with massive, macroscopic objects? There are two answers: one fundamental and one applied.

On the fundamental side, this demonstration gives us greater confidence that the laws of quantum physics do indeed apply to large objects.

But will this continue to hold true as the size and mass of the objects in such experiments is increased? We don’t know.

Read more:
Physicists use Einstein’s ‘spooky’ entanglement to invent super-sensitive gravitational wave detector

Tabletop experiments with massive objects bring forth the possibility that such a question might one day be answered.

On the applied side, one may ask: what could mechanical quantum systems offer in this electronic age? But mechanical systems are more common than many people realise.

The humble quartz oscillator remains a crucial technology for clocks. Surfaces are imaged using the atomic force microscope, essentially a suspended cantilever that deflects light. Gravitational waves are observed by monitoring the motion of suspended mirrors using laser light.

While quantum control of mechanical systems conceivably offers an advantage in each of these scenarios, mechanical systems offer another advantage: they move, and so they couple to both microwaves and light.

While the processing power of a future quantum computer might rely on microwaves in a low-temperature laboratory environment, quantum communications systems require light propagating through optical fibres or free space.

Mechanical systems can act as intermediaries between these worlds and thereby contribute to the realisation of a quantum internet.

The ConversationWhile it is hard to say exactly where these experiments might ultimately lead, it is clear that the era of massive quantum machines has arrived, and is here to stay.

Matt Woolley, Senior Lecturer in Electrical Engineering, UNSW

This article was originally published on The Conversation. Read the original article.

Space weather threatens high-tech life

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A coronal mass ejection erupts from the sun in 2012.

By Roger Dube, Rochester Institute of Technology

Shortly after 4 a.m. on a crisp, cloudless September morning in 1859, the sky above what is currently Colorado erupted in bright red and green colors. Fooled by the brightness into thinking it was an early dawn, gold-rush miners in the mountainous region of what was then called the Kansas Territory woke up and started making breakfast. What happened in more developed regions was even more disorienting, and carries a warning for the wired high-tech world of the 21st century.

As the sky lit up over the nighttime side of the Earth, telegraph systems worldwide went berserk, clacking nonsense code and emitting large sparks that ignited fires in nearby piles of paper tape. Telegraph operators suffered electrical burns. Even disconnecting the telegraph units from their power sources didn’t stop the frenzy, because the transmission wires themselves were carrying huge electrical currents. Modern technology had just been humbled by a fierce space weather storm that had arrived from the sun, the largest ever recorded – and more than twice as powerful as a storm nine years earlier, which had itself been the largest in known history.

My seven years of research on predicting solar storms, combined with my decades using GPS satellite signals under various solar storm conditions, indicate that today’s even more sensitive electronics and satellites would be devastated should an event of that magnitude occur again. In 2008, a panel of experts commissioned by the National Academy of Sciences issued a detailed report with a sobering conclusion: The world would be thrown back to the life of the early 1800s, and it would take years – or even a decade – to recover from an event that large.

A solar explosion

Space weather storms have happened since the birth of the solar system, and have hit Earth many times, both before and after that massive event in 1859, which was named the Carrington event after a British astronomer who recorded his observations of the sun at the time. They’re caused by huge electromagnetic explosions on the surface of the sun, called coronal mass ejections. Each explosion sends billions of protons and electrons, in a superheated ball of plasma, out into the solar system.

About 1 in every 20 coronal mass ejections heads in a direction that intersects Earth’s orbit. Around three days later, our planet experiences what is called a space weather storm or a geomagnetic storm.

While these events are described using terms like “weather” and “storm,” they do not affect whether it’s rainy or sunny, hot or cold, or other aspects of what it’s like outdoors on any given day. Their effects are not meteorological, but only electromagnetic.

Aurorae are signs of a geomagnetic storm.
NASA/Terry Zaperach

Hitting Earth

When the coronal mass ejection arrives at Earth, the charged particles collide with air molecules in the upper atmosphere, generating heat and light called aurora.

Also, as happens anytime moving electrical charges encounter a magnetic field, the interaction creates a spontaneous electrical current in any conductor that’s available. If the plasma ball is big enough, its interaction with Earth’s magnetic field can induce large currents on long wires on the ground, like the one that overloaded telegraph circuits in 1859.


On March 13, 1989, a storm only about one-fifth as strong as the Carrington event hit Earth. It induced a large surge of current in the long power lines of the Hydro-Quebec power grid, causing physical damage to transmission equipment and leaving 6 million people without power for nine hours. Another storm-induced power surge destroyed a large transformer at a New Jersey nuclear plant. Even though a spare transformer was nearby, it still took six months to remove and replace the melted unit. Some people worried that the bright auroral lights meant nuclear war had broken out.

And in October 2003, a rapid series of solar storms affected Earth. Collectively called the Halloween solar storm, this series caused surges that threatened the North American power grid. Its effects on satellites made GPS navigation erratic and interrupted communications connections during the peak of the storm.

Larger storms will have wider effects, cause more damage and take longer to recover from.

Wide-reaching effects

Geomagnetic storms attack the lifeblood of modern technology: electricity. A space weather storm typically lasts for two or three days, during which the entire planet is subjected to powerful electromagnetic forces. The National Academy of Sciences study concluded that an especially massive storm would damage and shut town power grids and communications networks worldwide.

Electricity, shown in the upper right, is integrated into every aspect of modern life.
Federal Communications Commission

After the storm passed, there would be no simple way to restore power. Manufacturing plants that build replacements for burned-out lines or power transformers would have no electricity themselves. Trucks needed to deliver raw materials and finished equipment wouldn’t be able to fuel up, either: Gas pumps run on electricity. And what pumps were running would soon dry up, because electricity also runs the machinery that extracts oil from the ground and refines it into usable fuel.

With transportation stalled, food wouldn’t get from farms to stores. Even systems that seem non-technological, like public water supplies, would shut down: Their pumps and purification systems need electricity. People in developed countries would find themselves with no running water, no sewage systems, no refrigerated food, and no way to get any food or other necessities transported from far away. People in places with more basic economies would also be without needed supplies from afar.

It could take between four and 10 years to repair all the damage. In the meantime, people would need to grow their own food, find and carry and purify water, and cook meals over fires.

Some systems would continue to operate, of course: bicycles, horse-drawn carriages and sailing ships. But another type of equipment that would keep working provides a clue to preventing this type of disaster: Electric cars would continue to work, but only in places where there were solar panels and wind turbines to recharge them.

Preparing and protecting

Geomagnetic storms would affect those small-scale installations far less than grid-scale systems. It’s a basic principle of electricity and magnetism that the longer a wire that’s exposed to a moving magnetic field, the larger the current that’s induced in that wire.

In 1859, the telegraph system was so profoundly affected because it had wires stretching from city to city across the U.S. Those very long wires had to handle enormous amounts of energy all at once, and failed. Today, there are long runs of wires connecting power generators to consumers – such as from Niagara Falls to New York City – that would be similarly susceptible to large induced currents.

The only way to reduce vulnerability to geomagnetic storms is to substantially revamp the power grid. Now, it is a vast web of wires that effectively spans continents. Governments, businesses and communities need to work together to split it into much smaller components, each serving a town or perhaps even a neighborhood – or an individual house. These “microgrids” can be connected to each other, but should have protections built in to allow them to be disconnected quickly when a storm approaches. That way, the length of wires affected by the storm will be shorter, reducing the potential for damage.

A family using solar panels and batteries for storage and an electric car to get around would likely find its water supply, natural gas or internet service disrupted. But their freedom to travel, and to use electric lights to work after dark, would provide a much better chance at survival.

When will the next storm hit?

People should start preparing today. It’s impossible to know when a major storm will hit next: The most we’ll get is a three-day warning when something happens on the surface of the sun. It’s really only a matter of time before there is another one like the Carrington event.

Solar astrophysicists are also studying the sun to identify any events or conditions that might herald a coronal mass ejection. They’re collecting enormous amounts of data about the sun and using computer analysis to try to connect that information to geomagnetic storms on Earth. This work is underway and will become more refined over time. The research has not yet yielded a reliable prediction of a coming solar storm before an ejection occurs, but it improves each year.

The ConversationIn my view, the safest course of action involves developing microgrids based on renewable energy. That would not only improve people’s quality of life around the planet right now, but also provide the best opportunity to maintain that lifestyle when adverse events happen.

Roger Dube, Research Professor of Imaging Science, Rochester Institute of Technology

This article was originally published on The Conversation. Read the original article.

How to fight Insectageddon with a garden of native plants

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A giant swallowtail butterfly feeds from the flower of an alternate-leaved dogwood.
(Nina Zitani), Author provided

by Nina M. Zitani, Western University

People across North America love to garden, yet the vast majority of garden plants are non-native species.

Day-lilies, peonies, roses, chrysanthemums and butterfly bushes, just to name a few, are all non-natives. They evolved in far-away places such as Europe and Asia and people transported them to North America.

With Insectageddon — the great insect die-off — upon us, it’s time to rethink our gardens.

Habitat destruction is the primary cause of the decline in biodiversity. Around the world, wildlife habitat has been destroyed by a variety of human activities such as residential and commercial development, agriculture and mining operations.

But gardeners can help to reverse the trend in biodiversity loss by creating backyard habitat, and native plants are the key.

Gardening with native plants has a long history in North America, but it remains under the radar of mainstream gardening. It’s time we embraced our native plants and the biodiversity that comes with them.

Our feathered — and furry — friends will thank us for it.

And if you’re an insect hater, now might be a good time to rethink that attitude.

Many insects are picky eaters

It was hot and steamy in the Costa Rican tropical forest. I was looking for caterpillars — the cute, wiggly, multi-legged and often furry larval stages of moths and butterflies.

As a graduate student at the University of Wyoming, I wasn’t studying caterpillars per se, but looking for new insect species. My job was to search for parasitoid wasps — minute, non-stinging wasps that spend their immature stage living inside caterpillars.

I collected the caterpillars in plastic bags along with the fresh green leaves they were feeding on, and brought them back to the field station for rearing.

But before I knew it, I was headed back into the forest. The caterpillars were leaf-eating machines and needed fresh leaves often. But I couldn’t just go into the forest and grab some leaves. I had to find the exact plant species the caterpillars were eating, or they would starve and die.

And that’s how I learned that caterpillars, most of them anyway, are picky eaters.

The caterpillar of the giant swallowtail butterfly feeds on the leaves of hoptree.
(Nina Zitani), Author provided

Neatly tucked away in the scientific literature, you’ll find the fascinating story of plant-animal co-evolution that began millions of years ago during the Mesozoic Era. There are many outcomes of that co-evolution, such as pollination, seed dispersal and the close relationship caterpillars (and other plant-feeders) have with their food plants.

Today, flowering plants produce toxic chemicals in their leaves to deter animals from eating them. But some animals, namely caterpillars, have adapted to eat the plant leaves — toxins and all.

So if you’re interested in creating wildlife habitat in your backyard, then you’re going to need the favourite food plants of insects. Insects will then thrive in your garden — as will the many larger animals that depend on insects for food.

What is a native plant?

To better understand the concept of a native species, consider common milkweed and its relative, the dog-strangling vine.

Both are members of the milkweed family and found today in North America. Common milkweed is a native plant — it evolved in North America thousands of years ago, along with some other animals, including the monarch butterfly and the milkweed tussock moth. Today it is vital to the survival of those species.

But dog-strangling vine is a non-native plant from Europe that was introduced to North America by settlers in the 1800s. Monarch caterpillars and other native milkweed specialists that hatch on dog-strangling vine die because they can’t eat it.

To make matters worse, dog-strangling vine has become an invasive species, forming dense colonies that displace native plants and their associated animals, contributing to biodiversity loss.

(No, it does not strangle dogs, by the way.)

Planting for the birds

Birds (and other larger animals) depend on bugs. “Nearly all terrestrial birds rear their young on insects, not seeds or berries,” writes Doug Tallamy in his book Bringing Nature Home.

A simple way to think of it is this: Native plants maintain natural ecosystem food webs, whereas non-native plants don’t. Native plants will attract and support healthy insect populations in your garden, which will provide essential food for birds and other animals.

There are thousands of native, or wild, North American pollinator species, including approximately 4,000 native bees and about 700 native butterflies, not to mention other pollinating insects such as moths, flies and beetles.

The leaves of native plants provide the food for caterpillars. The flowers of native plants provide food — pollen and nectar — for the pollinators.

When we consider the entire life cycle of insects, the essential role of native plants becomes clear.

A caterpillar and a bumblebee on native Carolina rose.
(Nina Zitani), Author provided

And let’s not forget the non-native honey bee, one of the few domesticated insect species. Although the honey bee is not wildlife, it does pollinate some crops and produces honey. It too will find plenty of food in a native plant garden.

Small gardens, big impact

My family kicked off our native garden by planting a single common milkweed plant into our tiny urban garden. The following summer it bloomed, and when a monarch butterfly landed on it, we were hooked.

When we moved to a larger property years later, we decided to create a monumental garden full of biodiversity.

We travelled for hours to purchase plants from nurseries that specialized in locally sourced native plants. Over several years, we planted more than 100 native species, including two kinds of milkweed, nannyberry, daisies of all sorts, multiple kinds of roses, dogwoods, elderberry and more.

We also planted hoptree (Ptelea trifoliata, a Citrus relative), the food plant for the caterpillar of the giant swallowtail, North America’s largest butterfly.

A monarch butterfly gathers nectar on a native daisy commonly called cup plant.
(Nina Zitani)

You don’t need to have a huge garden to support wildlife. Start small, and plant just one native plant. Butterfly milkweed is a great choice, but there are thousands of native species to choose from. Starting small is better than not starting at all.

It’s easy to get started. The Nature Conservancy of Canada publishes the “Native Gardening 101” guide. The USDA Plants Database has species range maps for all of North America and allows you to search on common names of plants such as butterfly milkweed. The Ontario Invasive Plant Council’s “Grow Me Instead” guide includes many native plant options.

Nature Needs Half is a growing conservation movement. A reasonable end goal might be to devote half of your garden to native plants.

A year after we planted the hoptree, we spotted a giant swallowtail butterfly laying eggs on its leaves. Several days later we found the caterpillars eating the leaves, and we celebrated.

The ConversationBut not for long — we had gardening to do!

Nina M. Zitani, Assistant Professor of Biology, part-time, Western University

This article was originally published on The Conversation. Read the original article.

How we recreated a lost African city with laser technology

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LiDAR, was used to “redraw” the remains of the city, along the lower western slopes of the Suikerbosrand hills near Johannesburg.
Karim Sadr

By Karim Sadr, University of the Witwatersrand

There are lost cities all over the world. Some, like the remains of Mayan cities hidden beneath a thick canopy of rainforest in Mesoamerica, are found with the help of laser lights.

Now the same technology which located those Mayan cities has been used to rediscover a southern African city that was occupied from the 15th century until about 200 years ago. This technology, called LiDAR, was used to “redraw” the remains of the city, along the lower western slopes of the Suikerbosrand hills near Johannesburg.

It is one of several large settlements occupied by Tswana-speakers that dotted the northern parts of South Africa for generations before the first European travellers encountered them in the early years of the nineteenth century. In the 1820s all these Tswana city states collapsed in what became known as the Difeqane civil wars. Some had never been documented in writing and their oral histories had gone unrecorded.

Four or five decades ago, several ancient Tswana ruins in and around the Suikerbosrand hills, about 60 kilometres south of Johannesburg, had been excavated by archaeologists from the University of the Witwatersrand. But from ground level and on aerial photos the full extent of this settlement could not be appreciated because vegetation hides many of the ruins.

But LiDAR, which uses laser light, allowed my students and I to create images of the landscape and virtually strip away the vegetation. This permits unimpeded aerial views of the ancient buildings and monuments.

We have given the city a generic placeholder name for now – SKBR. We hope an appropriate Tswana name can eventually be adopted.

Bringing the city to life

Judging by the dated architectural styles that were common at SKBR, it’s estimated that the builders of the stone walled structures occupied this area from the fifteenth century AD until the second half of the 1800s.

The evidence we gathered suggests that SKBR was certainly large enough to be called a city. The ancient Mesopotamian city of Ur was less than 2km in diameter while SKBR is nearly 10km long and about 2km wide.

The ancient homesteads at Suikerbosrand are shown against an aerial photograph from 1961. The two rectangles show the footprint of the LiDAR imagery.
Karim Sadr

It is difficult to estimate the size of its population. Between 750 and 850 homesteads have been counted at SKBR, but it’s hard to tell how many of these were inhabited at the same time, so we cannot easily estimate the city’s population at its peak.

Given what we know about more recent Tswana settlements, each homestead would have housed an extended family with, at the least, the (male) head of the homestead, one or more wives and their children.

Many features of the built environment at SKBR seem to signal the wealth and status of the homesteads or suburbs that they are associated with. For example, parallel pairs of rock alignments mark sections of passageways in several different parts of the city.

South African archaeologist Professor Revil Mason, who has carried out a great deal of research on stone walled ruins around Johannesburg, called these features cattle drives, built to funnel the beasts along certain routes through the city.

If these were cattle drives the width and location of these passageways would have signalled the livestock wealth of the ward or homestead that constructed them, even when the cattle were not present.

In the central sector of SKBR there are two very large stone walled enclosures, with a combined area of just under 10, 000 square meters. They may have been kraals and if so they could have held nearly a thousand head of cattle.

Monuments to wealth

Among the largest features of the built environment at SKBR are artificial mounds composed of masses of ash from cattle dung fires, mixed with bones of livestock and broken pottery vessels. All this material appears to have been deliberately piled up at the entrance to the larger homesteads.

These are the remains of feasts and the ash heaps’ size publicised the particular homestead’s generosity and wealth. The use of refuse dumps as landmarks of wealth and power is known from other parts of the world, like India, as well. Even the contemporary gold mine dumps of Johannesburg can be seen in this light.

Other monuments to wealth and power at SKBR include a large number of short and squat stone towers – on average 1.8 – 2.5 metres tall and about 5 metres wide at their base. The homesteads with the most stone towers tend to also have unusually large ash heaps at their entrance. The practical function of the towers isn’t known yet: they may have been the bases for grain bins, or they may mark burials of important people.

It will take another decade or two of field work to fully understand the birth, development and ultimate demise of this African city. This will be done through additional coverage with LiDAR, intensive ground surveys as well as excavations in selected localities.

The ConversationIdeally, the descendants of those who built and inhabited this city should be involved in future research at this site. Some of my postgraduate students are already in contact with representatives of the Bakwena branch of the Tswana who claim parts of the landscape to the south of Johannesburg. We hope that they will actively become involved in our research project.

Karim Sadr, Professor Geography, Archaeology and Environmental Studies, University of the Witwatersrand

This article was originally published on The Conversation. Read the original article.

Building a ‘second nature’ into our cities: wildness, art and biophilic design

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The plantings of New York’s High Line Park were inspired by plants that had naturally colonised the disused railway viaduct.
Beyond my Ken/Wikipedia, CC BY-SA

Jordan Lacey, RMIT University

Biophilic design is beginning to boom. Witness its recent incorporation into the Melbourne Metro project and Sydney’s award-winning One Central Park, Chippendale. Given the increasing popularity of this urban design technique, it’s time to take a closer look at the meaning of nature and its introduction into our cities.

Read more:
Why ‘green cities’ need to become a deeply lived experience


Nature is good for our mental well-being, numerous scientific studies tell us. This flood of research begins in 1984 with E.O. Wilson’s biophilia hypothesis, in which he hypothesises a gene that necessities our love of life and life-like processes. However, a genetic basis for biophilia has not been identified, and the value of a genetic argument for our attraction to nature has been questioned.

More recently, theorists have broadened the definition of biophilia to encompass the benefits of human-nature interaction. And it seems governments and industry are listening. Cities everywhere are embracing the change.

Read more:
Biophilic urbanism: how rooftop gardening soothes souls


I’ve spoken to numerous city dwellers over the years who tell me they find nature unsettling, if not terrifying. It’s mainly the isolation and silence they find overwhelming, particularly if they have spent their life in densely populated cities such as New York or Hong Kong. This sensation is captured by the term biophobia, a fear of nature.

While biophilia theorists acknowledge biophobia, it is rare to find this reflected in the work of biophilic designers whose work risks downplaying the complex ways in which we experience nature. After all, the feel-good message of biophilia is an easy sell. But if we can both love and fear nature we should ask ourselves: what is the source of these powerful emotional responses? And is the introduction of biota and abiota the only way we can elicit such experiences?

Art and nature

The philosopher Henri Lefebvre called the city a “second nature”. Given that every aspect of our cities, including ourselves, originated in what we refer to as nature this makes perfect sense. More obscurely, Lefebvre writes that in the creation of second nature we should produce “urban space, both as a product and as a work, in the sense in which art created works”.

To understand this we must consider the question: how does art make works? We might say that every artwork is unique in its making – no two artworks (assuming we don’t consider reproductions to be artworks) are the same. Similarly, nature’s creations are distinct: no two snowflakes are the same, every dawn is different etc.

In the creation of a second nature, Lefebvre challenges us to produce cities just as art produces work, so that our built environment might be as diverse as nature. Therefore, the production of a second nature is as much the responsibility of art as it is of design and architecture. If we are to create urban spaces rich in creative expression, then we should embrace this insight as much as possible.

There is scope for art in the expression of wildness.

A challenge to the creation of a second nature is to contend with the rules, regulations and controls of city bureaucracies that struggle to make room for creativity. Under these conditions, nature as introduced by biophilic designers is more likely to be applied as a functional agent, manicured and arranged, utilised for the production of more efficient workers and stress-free urban dwellers. But is it the purpose of nature to service such functional needs?

Read more:
Green for wellbeing – science tells us how to design urban spaces that heal us

Celebrating wildness

Wildness – a derivative of wilderness – is a term familiar to biophilia theorists. For instance, Timothy Beatley talks about the wildness of nature bursting through the cracks of the urban. New York’s High Line self-seeded landscape is a rare celebration of such growth, usually considered unkempt areas of the urban. Even Wilson, an epitome of scientific reductionism and mechanistic thought, speaks of a “spirit” interwoven between nature and ourselves, which must be preserved.

So, what is this spirit, this wildness we crave when we speak of nature? I would speculate that this wildness, or spirit, celebrated by biophilic theorists is the very same experience that sometimes terrifies our city dweller. It is the uncontrollable force of nature – always striving to exist, enabling it to appear everywhere and stirring our senses into states of wonder and awe.

In the creation of second nature, we should acknowledge that art has an equally powerful role to play in producing wildness. For instance, well-executed public art can be a source of wonder, imagination, contemplation and transformation. These are all experiences valued by biophilic practitioners.

The Serpentine Gallery Pavilion in London integrates elements of public art and nature.
Groume/flickr, CC BY-SA

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Towards second nature

We should encourage the growth of biophilic design in our cities. But if the nature we desire is, in fact, its expression as untamed wildness, then we should turn to art as much as we do to the elements of the natural world when designing and building our cities. Emerging infrastructure projects should consider the role of artists in directing human experience towards an urban wildness, which celebrates the creativity of nature.

The ConversationLet’s build cities that celebrate the wild, not just efficiency and productivity.

Jordan Lacey, Research Fellow, Architecture & Design, RMIT University

This article was originally published on The Conversation. Read the original article.