What do airplane windows and ballpoint pens have in common?

Airplane Window by Heute

They both have a tiny hole on their side. Why? Well, pressure, of course.

If you’ve ever taken a window seat on an airplane you might have noticed that there is a tiny hole at the bottom of the window glass. Even though it is quite a small hole one can’t help but wonder what its purpose is. After all, if there is one thing you don’t want to see on a plane is a hole.

That hole, however, serves a very important purpose. As you might be aware, airplanes are pressurized to create a comfortable and safe environment for passengers and crew at high altitudes where air pressure and oxygen levels are too low for humans to survive. Otherwise, we would either freeze or pass out from the lack of oxygen. None of these options are ideal for passengers, let alone for the pilots and the rest of the crew.

However, the difference in air pressure between the outside and the inside of the aircraft creates tension between the glass panes of the aircraft’s windows and if left unchecked could cause the window to crack or even shatter. I cannot stress this enough, holes on an airplane are a big no-no.

The easiest way to fix this would be to not have windows at all. Unfortunately, that would make for a very unpleasant experience for the passengers and would also create a safety issue making it harder for passengers, crew, and potential rescuers to navigate their way in and out of an aircraft in case of a crash. This is where those tiny holes come in.

Called ‘bleed holes’ or ‘breather holes’ they are typically located in the middle layer of the three-layer aircraft window design, and their  purpose is to regulate pressure between the different glass panes and prevent fogging.

This hole allows the air pressure to equalize between the panes, stopping the outer glass from bearing the full brunt of the pressure changes as the airplane ascents and descends during flight, preventing it from shattering. By allowing air to circulate between the panes it also keeps moisture from accumulating and compromising visibility.

In case of an emergency landing, a regular window would most likely shatter due to the rapid changes in pressure as the plane quickly descends. This tiny hole prevents that from happening by keeping the window’s structural integrity even in the most extreme scenarios.

BIC Cristal Pen by Wikimedia Commons

Now that you have some grasp of why these holes are so important for an aircraft, you might be wondering why a ballpoint pen would also need one. After all, unless you are using it during an exam, it’s probably not going to find itself in many high pressure situations.

Although a regular ballpoint pen will probably not ever fly to a high altitude, there is still a difference in air pressure between the inside of the pen and the outside. The principle is the same as that of an airplane window. The small hole on its side is there to equalize the air pressure between the inside and the outside of the pen and to prevent the ink from leakage.

Ballpoint pens work by applying pressure to the tip of the pen which makes the ball rotate and the ink to come out through capillary action – the movement of a liquid within narrow spaces, such as a tube or a straw.

To put it simple, a liquid in a narrow tube like the one that a pen uses to store its ink will always be drawn upwards unless there’s a force preventing it.

This way, by keeping the pressure equalized, the hole on the side of the pen keeps the ink from leaking while the pen is not being used.

Bad habits die hard

It’s not just the pen itself that has a hole in it. The pen cap also has a hole on its top. This however has nothing to do with pressure but it does have to do with air, particularly with breathing.

Even if you don’t do it yourself you probably have at least one friend who likes to nibble on pen caps. You know. The one you never asked to borrow a pen from because they always looked gross and chewed on.

Because of your friend and of millions of other people like them, pen caps have a hole at the top so that if they ever happen to swallow and choke on it, the cap will not stop them from breathing, by allowing the air to pass through its top.

It’s literally a safety issue that prevents people with bad chewing habits from dying in a horrible manner. 

Aviatyrannis: Portugal’s very own Tyrannosaur… Maybe

Aviatyrannis, an illustration by Johan Egerkrans

Found in rocks dating back to the Late Jurassic period, this small theropod dinosaur might be the grandmother of the famous T. rex. However, new research is putting its classification into question.

Aviatyrannis was discovered by German paleontologist Oliver Rauhut in the year 2000 in Guimarota, a lignite coal mine in the district of Leiria, Portugal.

It was described in a paper published in 2003, and given the name Aviatyrannis jurassica, which aptly translates to ‘the tyrant's grandmother from the Jurassic’. It was a small theropod dinosaur, a term used to describe mostly meat eating predators like T. rex, Allosaurus, or Velociraptor, but also some dinosaurs with a more generalist diet like Gallimimus, Ornithomimus, or Deinocheirus, and even a branch of herbivores with long sharp claws like Therizinosaurus, one of the most recent additions to the cast of the Jurassic World franchise.

With an estimated length of 1 meter (3.3 ft) and a body mass of 4 kg (8.8 lb) it wouldn’t be much larger than a medium size dog. However, Rauhut believes that the holotype specimen he described was only a juvenile, meaning Aviatyrannis could potentially reach a larger size.

A holotype is a single type specimen upon which the description and name of a new species is based. In this case, Aviatyrannis’ holotype is named IPFUB Gui Th 1 and consists of an ilium, the bone that makes up the upper portion of the hip bone and pelvis, only ninety millimeters long (3.54 inches).

Oliver Rauhut also referred two other bones to this species, a partial right ilium, and a right ischium, another hip bone, that belonged to slightly larger individuals, along with sixteen isolated teeth.

Found in the Alcobaça Formation, a geological formation that dates back to about 155 million years ago, this would put Aviatyrannis as one of the oldest tyrannosaurs ever found. Currently, the oldest known ancestor of the mighty T. rex is Proceratosaurus, a three meter (9.8 ft) long dinosaur found in the UK, that lived about 166 million years ago.

However, a 2023 paper by a group of Japanese researchers led by Soki Hattori had a closer look at Aviatyrannis’ holotype and reclassified it as an ornithomimosaur.

This team of paleontologists noted that this dinosaur’s ilium was strikingly similar to that of the recently described Tyrannomimus, a deinocheirid. Even though a more detailed study is needed, the authors argue that Aviatyrannis could be the earliest known ornithomimosaur and even possibly the earliest known deinocheirid.

Although not close as famous as Tyrannosaurs, Deinocheirids were a particular family of theropod dinosaurs. The most well-known was Deinocheirus, an unusual looking dinosaur that could grow to be 11 meters (36 ft) long, and weighing 6.5 metric tons (7.2 short tons).

If you’re familiar with the documentary series Prehistoric Planet, Deinocheirus makes an appearance in one episode, bathing in a swamp and, well, relieving himself to put it kindly.

Deinocheirus as portrayed in Apple TV’s Prehistoric Planet Episode ‘Freshwater’

It might not be as glamorous, but being the earliest known deinocheirid is in and of itself an interesting feat for such a small dinosaur found in the most unlikely of places.

Living among Giants

155 million years ago, during the Late Jurassic period, the region now known as Portugal was a lot different than it is today. Portugal was part of the northern margin of the supercontinent Laurasia, near the Tethys Ocean that would later become the Atlantic.

It had a warm tropical to subtropical climate with lush forests and shallow seas covering coastal areas.

Aviatyrannis lived alongside large meat eating dinosaurs like Allosaurus, and Ceratosaurus, giant sauropods like Lusotitan, Dinheirosaurus, and Lourinhasaurus, and even the thagomizer wielding Stegosaurus.  

It shared its environment with various species of fish, amphibians, turtles, lizards, and mammals. In the skies it would not be uncommon to spot the occasional pterosaur, like Rhamphorhynchus.

Much is yet to be known about Aviatyrannis but regardless of where it fell in the dinosaur family tree it already earned its place as one of the most intriguing creatures of Jurassic Portugal.

Perovskite Solar Cells are ushering in a new age in sustainable energy

A field of solar panels by Michael Pointner

It might still be too early to tell, but this new technology is giving silicon solar cells a run for their money.

In 2025 the highest certified efficiency for a single-junction perovskite solar cell is 26.7%. To put this into perspective, a regular solar cell has an efficiency rate between 15 and 22%.This may not seem like much but it’s enough to put a significant dent in your energy bill.

As solar panels have become cheaper more and more countries, companies, and individuals are looking at solar power as a sustainable and accessible energy solution. It’s even likely that you or someone you know has already installed a couple of solar panels on their roof.

However, not all solar panels are the same, and in recent years, perovskite solar panels have gained a lot of momentum for their remarkable efficiency, low production costs, and versatility. 

While a typical residential solar power set up can produce somewhere between 20 and 25 kwh of energy on a clear summer day, the same set up using perovskite solar panels can produce about 37.5 kwh. This amounts to a 50% increase in energy output, enough to power a single family home for a little over a day.

In this article, we will dive into the science behind perovskite solar panels, their advantages, challenges, and the potential they hold for revolutionizing the future of solar energy.

What is Perovskite?

Perovskite can actually mean two things: a mineral and a crystal structure. The mineral perovskite, also known as calcium titanium oxide (a bit of a mouthful), was discovered in the Ural Mountains in Russia, by Gustav Rose, a German mineralogist, in 1839.

However, the thing that made perovskite stand out wasn’t the mineral itself but its crystal and chemical structure. Here’s a quick chemistry lesson: The general chemical formula for perovskite materials is ABX₃, where 'A' and 'B' are cations of different sizes, and 'X' is an anion that bonds to both cations.

Even though perovskite itself is a very common mineral found in nature, perovskite solar panels don’t use it. Instead they rely on hybrid organic-inorganic lead or tin halide based compounds such as Methylammonium Lead Iodide (MAPbI3) and Formamidinium Lead Iodide (FAPbI3).

These materials have unique optoelectronic properties that make them highly efficient at converting sunlight into electricity.

What makes perovskite solar panels so efficient?

The working principle behind perovskite solar panels is similar to that of other photovoltaic technologies. When sunlight strikes the perovskite layer, it excites electrons, creating electron-hole pairs. These are then separated and collected at the electrodes, generating an electric current. The efficiency of this process is influenced by the quality of the perovskite material, the architecture of the solar cell, and how different layers interact between them.

So, basically, when we talk about efficiency in solar panels, we are referring to their ability to convert sunlight into electricity. Perovskite materials excel in this regard due to their high absorption coefficient, which means they can absorb a significant amount of sunlight even in thin layers. This allows perovskite solar panels to be much thinner and lighter than traditional silicon-based solar panels.

Which means you can have a more efficient solar panel, with lower production costs, that can not only be used on rooftops, but also in windows, balconies, cars and other vehicles, and also in small or even wearable devices.

Imagine having a small solar powered lightweight energy unit that you can take with you when you go camping to power your devices. This technology could also be used to power remote or impoverished areas with no access to the energy grid, by a fraction of the cost of a regular solar panel.

But this isn’t all that a perovskite solar panel can do. Perovskite materials can also be easily tuned by varying their chemical composition, this means you can optimize these materials for different light conditions and applications. For instance, you can design perovskite solar panels to absorb a broader range of the light spectrum to increase their overall energy efficiency.

You can also combine perovskite solar cells with other photovoltaic materials, such as silicon, to create a tandem solar cell. These tandem cells can achieve higher efficiencies by capturing a wider range of the light spectrum.

Perovskite-silicon tandem cells have already demonstrated efficiencies well above 29%, surpassing the theoretical limit of single-junction silicon solar cells.

What about any downsides?

You may, however, be asking yourself, if perovskite solar panels are so great, why aren’t they being rolled out everywhere.

Well, in spite of their many advantages, perovskite solar panels still face several challenges that need to be addressed before they can be widely adopted.

One of the main concerns with perovskite solar panels is their long-term stability. Perovskite materials are sensitive to environmental factors such as moisture, oxygen, and UV light, which can degrade their performance over time. Researchers are actively working on developing more stable perovskite formulations and encapsulation techniques to protect the cells from these issues.

Another problem is that most perovskite materials contain lead, which we all know can be toxic. However, while the amount of lead used in perovskite solar panels is relatively small, it might still have an impact on public health and the environment, if they’re not properly disposed of and or recycled. To resolve this issue, efforts are underway to develop lead-free perovskite materials, such as those based on tin or other non-toxic elements.

Since this is a new technology, most of the data we have on its performance has come from testing in controlled laboratory settings. This means that scaling up perovskite solar panels for commercial use might not yet be viable. Issues such as uniformity, reproducibility, and the development of large-scale manufacturing processes need to be addressed to ensure consistent performance and reliability.

Perovskite solar cells have also reported efficiency losses associated with charge recombination, interface defects, and other factors that require more research to mitigate these issues and to improve their overall performance.

As we confront the pressing challenges of climate change and energy sustainability, perovskite solar cells emerge as a beacon of hope. Their unique properties and advantages could help unlock a new era of renewable energy, making solar power more efficient, accessible, and versatile than ever before.

As researchers continue to innovate and perfect this technology, we may soon find ourselves living in a world where access to clean, renewable energy is not just a long-term goal but a daily reality thanks, in part, to the remarkable capabilities of perovskite materials.