Perovskite is offering new hope for versatile and efficient solar cells to meet our future energy needs.

The energy needs of the world could all, in principle, be fulfilled by one single source -- the sun. There are challenges in making this a reality, however: affordability first, and finding a way to capture this energy efficiently to turn it into electricity.

Recently, a new material known as perovskite has seen the light of day and within just a few years it has started rivaling the efficiency of traditional photovoltaic solar cells, which currently maxes out at roughly 20 percent. This is the amount of solar energy that gets converted into electricity and the higher this is, the more we meet our energy needs. Over 80 percent of today's photovoltaics are made from crystalline silicon, but the high expense of both their production and installation means we are in need of alternatives.

Perovskite is a mineral found in the Earth's mantle, named after Russian mineralogist Lev Perovski. Since 2009, it has caught the attention of researchers across the globe, including those at Oxford University and the Federal Institute of Technology in Lausanne (EPFL).

Graetzel discovered how perovskite works and he's helping develop new solar cells as well as potential ways to add on to existing ones: "You can put perovskite on top of traditional silicon cells to make them more efficient," he says. "This is not an expensive process and can become an attractive application for mainstream solar panels."

Stability tests are still needed as this magical material is sensitive to water and high temperatures: "This is all being examined now. I'm optimistic and sure this can be tackled. It's an exciting time".

Perovskite solar cells may be the ones to watch, but the search for the most efficient, affordable and usable form of solar energy is a diverse battlefield.

Mental exercise in blindness reflects the reality of our universe

Take a look around you, and in your mind's eye, randomly wipe out all but a small fraction of what you can see. Pretend the vast rest of reality is there but invisible.

You'd probably like a device that helps you see much more of it.

Scientists working at CERN, the European Organization for Nuclear Research, have made some progress in that direction with the Alpha Magnetic Spectrometer (AMS), which has been riding aboard the International Space Station since 2011.

Physicists believe that mental exercise in blindness reflects the reality of our universe, only about 4% of which manifests as the kind of matter and energy we can perceive.

More than 70% consists of so-called dark energy, physicists say, and more than 20% is dark matter, neither of which humans can directly detect so far.

But scientists feel certain it must exist, partly because of the gravity it exerts on the visible universe.

What makes some people capable of amazing perseverance?

In September 2013, at age 64, distance swimmer Diana Nyad achieved a goal she’d been chasing for more than 35 years: 

She swam from Cuba to Florida, 110 miles, without a shark cage to protect her. During the 53-hour swim, she paddled through swarms of venomous box jellyfish and vomited repeatedly from swallowing saltwater. 

Her entire body trembled from the cold. But she forged on, resolute in her determination to complete one stroke after another. 

A good breeze

It might not be something you think much about, but a well-ventilated room is important for your health. “There’s a lot of studies that have been done over the last 20-30 years that say people who work or study in naturally ventilated buildings perform better,” says Ben Hughes, a Lecturer in Building Physics from the University of Leeds. Free-flowing air removes dust and dirt as well as reducing the amount of CO2 and excess moisture in your immediate atmosphere and makes for a much more pleasant environment. “As air passes over your skin it gives you a sensation of being comfortable,” says Ben.

But moving air also removes heat, so a well-ventilated building needs good heating – and that comes at a price. Most commercial buildings use mechanical heating ventilation and air conditioning (HVAC) systems to control the temperature and airflow in a room. But “depending on where in the world you are, between 40-60% of a building’s energy consumption is from the HVAC systems,” says Ben.

One way to tackle this intensive energy use is to design and build super-economical airtight houses. This is the idea behind the Passivhaus standard; a house that doesn’t need heating but relies instead on heat from the people living in the house and items such as the cooker and lights. 

So designers are now taking inspiration from the old way of ventilating houses and buildings, so-called natural ventilation.

A bolt of lightning has enough energy to toast 100,000 slices of bread.

It's an awful lot of toast, but then a typical lightning bolt isn't short on energy with over five billion Joules. This means that one typical strike could power a 1000 Watt, two slice toaster for 84,000 minutes in which time you could make around 100,000 slices of toast.

Thunderstorms are an amazing natural spectacle, but even more amazing is the fact that we still don't totally understand the processes which create lightning. What we do know is that lightning is a discharge of the static electricity that builds up in clouds in certain weather conditions.

You've probably noticed that thunderstorms often happen on summer afternoons when the ground is warm and the air is humid. As the warm, humid air rises and meets cooler conditions higher up, water condenses out of the air to form clouds. The condensed water droplets then start to fall and collide with the warm air that is still rising.

All these little collisions give the water droplets a charge and for some, as yet unknown, reason the positively charged droplets find their way to the top of the cloud whilst the negatively charged droplets fall to the bottom.

This separation of charge creates an electric field within the cloud which grows stronger as the charges build up and induces a positive charge in the ground directly below the cloud. Zigzagged.
Air is normally a very good electrical insulator, but when the electric field becomes strong enough it ionises the air, separating it into negative and positive ions, and producing a conductive path between the cloud and ground. But the ionisation of the air isn't uniform and zigzagged "step leaders" start to appear from the cloud following the various conductive paths. At the same time positive streamers start reaching up from the ground, waiting for the step leaders to connect to them. Once a complete path is formed, there's a deafening crack and the lightning reaches the ground.

With five billion Joules of electrical energy being discharged, the surrounding air becomes hotter than the surface of the Sun. We see this as a white flash and hear it as rumbles of thunder as the air rapidly expands.

Why We Yawn?

Researchers are starting to unravel the mystery surrounding one of the most common behaviors: the yawn. 

WSJ’s Jonathan Rockoff and evolutionary psychologist Dr. Andrew Gallup explain new studies suggesting it’s a way of keeping your brain sharp. Science has disproved the theory that it’s the body’s way of sending oxygen to your brain when deprived. Says Rockoff, one of the leading theories is that yawning is a “cranial air conditioner.” 

In times of stress and anxiety, we experience a slight rise in brain temperature. So the body steps in to cool it off.