Three blockbuster movies have addressed these questions in recent times: Deep Impact with Robert Duvall, Armageddon with Bruce Willis, and Don’t Look Up with Leonardo DiCaprio. These films fantasise that in the event of a planet-killing asteroid heading our way, NASA or some United Nations-coordinated space force could blow it up and save the planet. But what’s the reality?
Faced with such a situation, would we be sitting ducks, or could anything be done to prevent it just like in a movie (And in only one of those mentioned were we entirely successful)? Well, this would be a two-step process. The first step would be successfully deploying a nuclear warhead into an asteroid, and the second step would be to generate an explosion big enough to obliterate it.
We know step one is possible because NASA has successfully demonstrated proof of concept by launching and smashing a spacecraft into the asteroid Didymos as part of the Double Asteroid Redirection Test (DART). They were not attempting to blow it up, however. In fact, they ignored the nuclear explosion option altogether and elected to try the kamikaze approach to try and push it off course. DART seeks to develop a method to protect Earth in the case of an asteroid threat, which in this case involves shifting an asteroid’s orbit through kinetic impact, which they did successfully.
So, we know it’s possible to deploy a nuke into an asteroid belt, but would it generate an explosion big enough to obliterate it? Experts suggest that we could generate a nuclear explosion big enough to destroy a small asteroid, but not really one sure to pose an existential threat. It is asteroids larger than 6.2 miles across that are a concern, as they are considered extinction class and would destroy all life on Earth in the event of a collision. The issue here is that we don’t have nuclear bombs big enough to wipe out these mega-asteroids. A NASA report suggests that a nuke would most likely cause an asteroid of this size to fragment into several large pieces, which could still cause significant damage to our planet.
This brings us back to DART. While nuclear bombs could conceivably be used to destroy smaller asteroids, it’s likely that planetary defence strategists would look to deflect the course of planet-killing asteroids away using kinetic impact, as in the DART example. In any scenario, the goal would be course deflection.
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The Earth’s atmosphere is a complex and dynamic system in which a multitude of chemical, thermodynamic and fluid dynamic effects take place. It has undergone three major evolutionary changes since the formation of our planet: the early atmosphere, ocean formation and biological era. Without it, life would not exist, so it is imperative that we protect it to safeguard our future.
When the Earth was formed 4.5 billion years ago, there was no atmosphere. Volcanic activity formed the very first protective layer around our planet, through the release of gases such as carbon dioxide, methane, nitrogen and water vapour. As the planet began to cool 700 million years later, the water vapour condensed to form our oceans which in turn soaked up large amounts of carbon dioxide from the atmosphere. We finally entered the biological era of our atmosphere through the action of photosynthesis from bacteria and algae. This caused much of the atmospheric carbon dioxide to be converted into oxygen, creating the ozone layer and a supportive environment for life on Earth.
The chemical composition of our modern day atmosphere is vastly different to how it began. It is currently composed of 78% Nitrogen (the most abundant but inert gas), 21% oxygen (the part we need to breathe), 0.9% Argon, 0.04% carbon dioxide and 0.06% other gases. Ozone in the atmosphere helps to protect us by absorbing harmful UV rays while greenhouse gases help insulate the planet to keep it warm and able to sustain life. Human activity in the last 200 years through industrialisation, however, has had a profound effect on the atmosphere. With the burning of fossil fuels, deforestation and release of carbon dioxide back into the atmosphere, we have seen an increase in global warming.
Our atmosphere is broken down into five main layers. The lowest layer is known as the troposphere and is the layer we all live directly beneath. It contains most of our weather patterns and water vapour and extends around 10km high. Higher up lies the stratosphere, which contains most of the ozone that protects us from UV rays. Unlike the troposphere, the temperature rises in the stratosphere as the altitude increases; this reflects the increase of unabsorbed UV rays. The mesosphere is considered part of the middle atmosphere and contains gases that are still thick enough to slow down meteors heading towards earth. The thermosphere absorbs large amounts of solar radiation, causing ionisation of molecules and also plays an important part in radio wave reflection around the globe. The outer layer is called the exosphere and contains gases that are so sparse they rarely come into contact with each other.
Our atmosphere is vital to our planet and its delicate balance of gases enable the right conditions for life to thrive. It plays an important part in regulating the earth’s temperature, protects us from UV rays and facilitates global weather patterns and the water cycle. In the modern age of industrialisation, our atmosphere is now under threat and increased efforts are needed to move towards renewable energy sources and sustainable practices. Hopefully this article will have demonstrated further evidence and reason as to why the fight against climate change is so important. It is factual, undeniable, and if we are not more direct in our response, its break down is entirely inevitable.
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When you look at the vast, arid landscape of the Sahara desert, you may find it hard to believe that this was once a lush, green space full of grasses, trees and lakes. Yet this is likely the case. It has been called the North African Humid Period, and occurred around 12,000 years ago during the late Pleistocene and Holocene geological epochs.
There is good paleoclimatological evidence to suggest that over the last 3,000,000 years, there have been 230 of these North African Humid Periods (NAHPs), indicating that the Sahara region alternates between arid phases (as present) and humid phases, which are full of rivers, vegetation and lakes. According to an article in Nature Magazine online, these NAHPs are governed by a phenomenon known as the Procession Cycle, which is when a wobble occurs in the orientation of the Earth’s axis of rotation. Thereafter, you might imagine the planet as a slightly off-centre spinning top. This off-centre rotation continues for a period of around 25,000 years. Procession is an additional form of planetary motion to the more well-known daily rotation and annual revolution cycle of the Earth. It is caused by the gravitational tidal force of the Sun and Moon acting on our planet’s equatorial bulge. There is a good visual of this rotational phenomenon here on Wikipedia.
The wobble itself is known as an Axial Procession, and it makes seasonal contrasts more extreme in one hemisphere and less extreme in the other. Not only does the procession cycle govern the seasonal contrasts, it determines temperature and precipitation variance between seasons. During the periods of increased Boreal Summer Insolation (when solar radiation hits the Earth’s northern hemisphere between March and September), the African Monsoon systems are intensified. It is these precipitation-rich phases of the procession cycle that underpin the North African Humid Periods.
This article in the Geographical explains how the most recent incarnation of the dry version of the Sahara came about. Around 12,000 years ago, the end of the ice age led to a wetter climate in the region, possibly due to low-pressure areas forming over collapsing ice-sheets in the north. But, once these ice sheets melted, the Northern Sahara region dried out. However, monsoon conditions in the South meant that the Southern Sahara region was wetter. But, eventually this monsoon retreated south (as part of the procession cycle) and the entire Sahara region become desert. This is the incarnation of the Sahara you see today.
When will this cycle end, then? Well, not for a while. Experts predict that the Sahara will revert back to that lush green alternative state in about 10,000 years.
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Mars, with its cold and barren landscape, may seem inhospitable to life as we know it, but it might once have been teeming with life. I mean, the Sahara desert wasn’t always a desert. Just 2,500 years ago, during the African Humid Period, it was lush green and covered in grass, trees, and lakes. Is it so hard to believe that 2,000,000 years ago the desert-like Mars might have also been teaming with life?
Astrobiologists, those involved in the study of the origin and evolution of off-world life, have in recent years attempted to answer this question with the help of technological and off-world scientific rovers that traverse and study the geological makeup of Mars. One of the key pieces of evidence supporting the idea of past life on Mars is the presence of huge craters — called bench-and-nose formations — which are thought to have once been habitable rivers. These were discovered by NASA’s Curiosity Mars rover and the scientists who analysed its data, using numerical models that simulated thousands of years of erosion.
In 2020, the continuing search for signs of past life on Mars led to the deployment of advanced robotic missions like NASA’s Perseverance rover (The image above is a photo of the surface taken by the rover. Its helicopter component can also be spotted in flight on the right of the shot). With its cutting-edge instruments, the goal of Perseverance is to explore and examine the ancient lake-bed of Jezero Crater, where scientists believe that the then-warm and wet conditions may have been conducive to life billions of years ago.
One of Perseverance’s primary objectives is to collect rock samples that may preserve traces of ancient microbial life. These samples will be stored and eventually returned to Earth, where the extraterrestrial rocks can be analysed in laboratories equipped with sophisticated instruments capable of detecting any such fossilised biomolecules.
In addition to these physical searches overground, in 2021 scientists (writing in the peer-reviewed journal Astro Biology), studied Martian meteorites and revealed that rocks below the planet’s surface could produce the same kinds of chemical energy that allow for subterranean life on Earth. Again, this was a fascinating but tentative conclusion, drawn from circumstantial evidence just like previous rover studies. So, while we can’t say definitively that there was once life on Mars, the case for it is getting much more compelling.
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The subject of quantum computing remains largely confined to the realm of exclusive coffee table discussions among theoretical physicists like Fernando Brandao and Oskar Painter. This suggests that the topic of quantum computing may fly way over the average person’s head, fascinating as it is. One of the best ways to shed light on this esoteric subject is to compare it with classical computing, and then outline the underlying quantum principles in a more relatable, albeit cursory way.
For example, this Caltech article explains that both quantum and classical computers — yes the one you are currently using — tend to have microchips, circuits, and logic gates. Algorithms written by programmers, and increasingly by AI, control the operations using binary code and ones and zeros in both classical and quantum computing. Furthermore, both quantum and classical machines employ physical objects to encode binary data. However, this is where the similarities end.
While the computer you are reading this on encodes data in two states, either on or off (binary digits), Quantum computers have taken a significant quantum leap forward. They use quantum bits (or qubits) and process data differently. While today’s computers process using ones and zeros, a qubit can be a superposition of one and zero simultaneously until its state is measured. Also, these states of multiple qubits can be quantum mechanically entangled. Superposition and entanglement are what give quantum computers powerful capabilities extending beyond that of classical computing.
While the potential of quantum computing is indeed profound, the full extent of its impact on modern computing capabilities remains uncertain. Quantum computers have existed in a nascent and experimental form for roughly a decade and are not yet utilised in industry or for practical everyday tasks. For now, classical computing reigns supreme.
However, quantum computing made an important experimental breakthrough in 2019 when it completed a calculation in a fraction of the time a classical computer would have required. While this is considered proof of principle it will be years before quantum computers will be solving practical problems like this in the everyday, or grace the desks of everyday users!
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Have you ever looked up at the sky and marvelled at aeroplanes, defying gravity and soaring through the clouds? We take the wonder of flight for granted much of the time, unless, of course, we are flying through heavy turbulence. But, behind the seemingly effortless motion of these aircraft lies a complex interplay of four forces: lift, weight, thrust and drag, that enable them to take off, manoeuvre and stay aloft.
Lift is the aerodynamic force that must be generated to overcome the weight of an aircraft, allowing it to take off and rise. It is generated primarily by the wings of the aircraft as it moves through the air. The shape of the wings, known as aerofoils, creates a pressure difference between the upper and lower surfaces. This pressure difference results in an upward force, lifting the aircraft against the pull of gravity. Tilting the wing upwards deflects the air downward, creating more lift, and is used to help the plane climb, and vice versa!
Weight is the gravitational force exerted on an aircraft due to its mass. It acts downward towards the centre of the Earth and is equal to the mass of the aircraft multiplied by the acceleration due to gravity (F=mg). For an aircraft to achieve flight, the lift generated by its wings must equal or exceed its weight.
Thrust is the force that propels an aircraft forward through the air. It is generated by engines or propulsion systems such as propellers or jet turbines which expel air or gases and generate thrust that overcomes drag (defined next), causing the aircraft to accelerate and maintain its speed.
Drag is the aerodynamic force that opposes the motion of an aircraft through the air. It is caused by the friction between the aircraft’s surfaces and the air molecules it encounters.
These four forces combine to create and maintain flight in two stages. Firstly, during takeoff, the thrust provided by the engines accelerates the aircraft, allowing it to reach a speed at which lift generated by the wings exceeds the aircraft’s weight, enabling it to ascend into the sky. Then, when a plane is in steady, level flight, the four forces of flight are in a state of equilibrium. The lift generated by the wings balances the weight of the aircraft, while thrust overcomes drag to maintain forward motion.
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To mark British Science Week, from the 8th to the 17th of March, let’s shine a light on some of the greatest contemporary British minds in Science, Technology, Engineering and Maths (or STEM, for short).
Sue Black is a Professor of Computer Science at Durham University. An outspoken and active social media campaigner, Sue led a campaign to save Bletchley Park and is one of the most influential women in tech. An advocate for equality, diversity, and inclusion, particularly for women in computing, she founded BSCWomen, an online network for women in tech, and #techmums, a social enterprise which empowers mothers and their families through technology. In the 2016 New Year Honours, Sue received an OBE for services to technology.
Timothy Berners-Lee is a computer scientist and software engineer who is most famous for inventing Hypertext Transfer Protocol, or HTTP, and the World Wide Web. He also created the first internet browser, the HTML language, and the URL system, and in 1991 was named one of the 100 Most Important People of the 20th Century by Time Magazine. In 2004, Timothy was knighted by Queen Elizabeth II for his pioneering work, and he now works as Professor of Computer Science at the University of Oxford. He is also a professor emeritus at the renowned Massachusetts Institute of Technology (Often referred to as MIT).
Maggie Aderin-Pocock is a space scientist, educator, and communicator. Throughout her career, she has worked on some of the most prestigious projects at some of the UK’s top universities and is currently an honorary research associate within the Department of Physics and Astronomy at University College London and Chancellor at the University of Leicester. She is also a presenter of the TV show The Sky at Night and does much outreach work to engage young people in science. Her academic work now focuses on building instruments and equipment to aid the fight against climate change. Maggie received an MBE for services to science education in 2009 – an honour that was upgraded to OBE in this year’s New Year Honours.
Donald Palmer is an Associate Professor of Immunology at the Royal Veterinary College where his current research interests focus on the ageing of the immune system. After completing his PhD at King’s College London, he took post-doctoral fellowship positions at Cancer Research UK and Imperial College where he carried out research on lymphocyte development. Donald is also a co-founder of the Reach Society – an initiative to inspire, encourage and motivate young people, particularly young Black men and boys, to achieve their full potential.
Roma Agrawal is a structural engineer who is most known for her work on The Shard in London. Born in Mumbai, she completed her undergraduate degree in physics at the University of Oxford and gained an MSc in structural engineering from Imperial College London. She has gained several awards for her work, including the Institute of Structural Engineers’ Structural Engineer of the Year’ award in 2011 and, more recently, the Royal Academy of Engineering’s ‘Rooke Award for Public Promotion of Engineering’. She is an active public speaker and advocate for diversity and inclusion within STEM.
Saiful Islam is Professor of Materials Modelling at the University of Oxford. He gained a chemistry degree and PhD from University College London and his research interests focus on gaining a deeper understanding of the processes that exist within energy materials, particularly batteries. As well as numerous academic awards and honours, Saiful holds a Guinness World Record for the highest voltage lemon battery (usually a low powered, simple battery used for the purposes of education).
To learn about more successful British scientists, visit the Inspiring Scientists website.
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The Earth, as you can imagine, has a complex geological structure. It has a central core encased within the Earth’s mantle, which in turn is surrounded by the Earth’s crust. Across these layers, elements (those you might find in the periodic table) are randomly distributed within different rocks and materials. These elements exist in varying quantities and combinations, forming specific chemical compounds that have unique compositions. These compounds are known as minerals.
Humans inhabit the outer part of the Earth, the crust, composed of common elements we know well, such as silicon, aluminum, iron, calcium, potassium, and magnesium, in some kind of oxidised form. Other elements from the periodic table are much rarer in the crust and exist within particular minerals in very specific areas.
According to the Natural History Museum, the rarest elements in the Earth’s crust are the platinum group metals (existing up to 3000 km below the surface) and include palladium (Pd), platinum (Pt), rhodium (Rh), osmium (Os), and iridium (Ir). They exist in concentrations of around 0.0002 parts per million by weight! Their most common use is as an autocatalyst, and platinum is also used in jewellery. These metals are so important in the industrial world that they are valued at more than twice the price of gold.
Other rare elements of note include Neptunium, which is a precursor in plutonium production and used in (MeV) devices that detect high-energy neutrons. Curium, Americium, and Californium are so rare that scientists aren’t even sure if trace amounts exist naturally. They come into existence as byproducts of nuclear plants and are used for power sources in pacemakers, particle X-ray spectrometers, smoke detectors, nuclear reactors, neutron moisture gauges, and cancer treatment.
Astatine probably tops the charts as the rarest element, with only 1 gram thought to be present on Earth at any given time, and only 0.05 micrograms have even been created. This will most likely be used in nuclear medicine and targeted alpha-particle therapy. Others like Berkelium, Francium, Protactinium, and Organesson exist in similarly minuscule amounts but are not thought to have any practical use.
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Although hard of hearing, Thomas Alva Edison was the epitome of the inventor genius whose lack of managerial abilities led him to undertake inventive challenges that others at the time dismissed. His role as a machine shop operator set the foundation for his career, nurturing the skills he needed to develop his printing telegraphs, telephone carbon button transmitter, phonograph, alkaline storage battery and of course the electric lightbulb.
Born in America in 1847, Edison – or ‘Al’ as he was known as a boy – was home-schooled by his mother and showed a strong interest in the way mechanical mechanisms worked. He had his first taste of entrepreneurship selling newspapers to train passengers. Unfortunately, he lost most of his hearing at the age of twelve, although he himself saw this as an advantage in being able to focus on his work.
Edison began his career right when the telegraph industry began to build momentum. He took advantage of the opportunity to learn railroad telegraphy and used his skills to work as an apprentice telegraph operator. The system initially transmitted messages through dots and dashes although as the telegraphy receiver technology evolved to use sound, Edison’s lack of hearing led to a severe disadvantage. He focused on his inventions instead and through experimentation, designed the quadruplex – a telegraph capable of sending four messages at once through the same wire. Earning a reputation as a savvy businessman, he sold his invention to the highest bidder.
Edison realised he needed a dedicated place to focus on his inventions. With the help of his father, he built his famous ‘invention factory’ laboratory in Menlo Park. It was here that Edison employed some of the top inventors and mechanics work for him, such as Nikola Tesla. Realising his own shortcomings in his mathematical and scientific approaches, his hired associates complemented his work, bringing with them academic expertise. It was while experimenting for the automatic telegraph that Edison discovered that the conductivity of carbon changed under different pressures. This led him to design the carbon button transmitter which significantly improved the audibility of the telephone.
Edison’s work on the telephone led to the idea that sound, such as a person’s voice, could be transcribed as indentations or ‘phonography’ onto a tin foil surface which could be later played back later. Although its initial launch was met with scepticism, the phonograph quickly became a revelation and made Thomas Edison a household name, earning him the title of ‘The Wizard of Menlo Park’. Later, Edison made many adjustments and upgrades to the phonograph to make it a commercially viable and profitable venture. He pursued the idea of linking the phonograph to a zoetrope – a pre-film animation device that gave the illusion of moving images – but syncing the two together proved difficult and instead film production moved into the silent movie era.
Thomas Edison wasn’t the first to invent the incandescent electric lightbulb, but he was the first to make it commercially viable and available to the masses, with the help of Tesla’s AC system. His goal was to take the existing design and make the bulb burn longer and more reliably. He established the Edison Electric Light Company, and with the help of financial backing, developed a variety of vacuum lightbulbs, experimenting with the filament; from platinum, carbon and eventually carbonised bamboo fibre that could last over 1200 hours. It was his modifications that made the lightbulb publicly accessible for the first time.
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The Doppler effect is likely something you’ve experienced, even if you’ve never heard of it. Perhaps you noticed the sirens of an ambulance change pitch as it passed you by. The Doppler Effect was named after the Austrian physicist Christian Doppler, who first described the phenomenon in 1842 and is most widely associated with sound waves although the principle applies to all wave forms such as light and radio waves.
It has played a significant part in many scientific areas such as astronomy and medicine and has even been used as evidence for explaining the big bang theory and expansion of the universe.
All forms of waves have a particular frequency, which is the number of waves reaching an observer over a given time. It’s this frequency that determines the pitch of a sound. In technical terms, this effect happens because of the perceived alteration in frequency and wavelength of a wave, brought about by the relative motion between the wave source and the observer.
Taking the case of sound waves from an ambulance moving towards you, waves emitted in front of the vehicle are compressed, increasing the frequency which in turn increases the pitch of the sound. As the ambulance passes you by the waves expand and the frequency drops, leading to a lower pitch. As the passengers on the ambulance are travelling at the same speed as the sirens, they hear the sound at it’s true, unaltered pitch.
You may have seen police using speed guns to track the velocity of vehicles or the tracking system that measures the speed of a served tennis ball. Both systems work in the same way, using specialised radar equipment to send out a narrow stream of radio waves. Some of these waves bounce back off the ball/vehicle and are received back by the emitter. A computer system then calculates the velocity of the object by working out the time between the pulses sent out and the pulses received.
This same principle has played a revolutionary role in astronomy, where the study of changes in light frequency by celestial objects has helped to determine their speed of travel as well as their chemical compositions. Meteorologists use the Doppler effect to predict future weather patterns and track their changes through Doppler radar systems which analyse shifts in the frequency of electromagnetic pulses.
The Doppler effect has also allowed major advancements within the field of medicine, such as the introduction of ultrasound technology. During ultrasound scans, a small device emits high-frequency sound waves that are far beyond our normal audio range. They reflect off different parts of the body and are picked up by the probe and turned into a visual image. This way, parents can see an image of their unborn baby, while a surgeon can see a visual aid while navigating an internal procedure.
Doctors are also able to measure blood flow through a patient’s blood vessels with the use of a specialised Doppler ultrasound. By focusing the sound waves on the red blood cells, doctors can determine the existence of blood clots, heart defects or blocked arteries.
The Doppler effect continues to inspire scientific research and further technological advancements will increase its effectiveness in everyday usage. It is likely to play a future role in collision avoidance systems in autonomous vehicles, wireless communications and space exploration.
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