This article was based originally on a series of lectures, and is intended for readers who, while interested in natural sciences, have no previous training in theoretical physics and yet are familiar to a certain extent with physical ideas. In conformity with the express wish of the Verband deutscher Elektrotechniker, a under whose auspices the lectures were given, a short history of atomic physics, as well as a general review of contemporary knowledge of atomic and nuclear structure, are included here as an introduction. Obviously, a thorough understanding of nuclear physics cannot be gained from a short survey of this nature, but it may at least succeed in providing a basis for an understanding of the lectures on nuclear physics which follow. In my treatment of nuclear physics, I have departed somewhat from the method followed by other popular books on the subject, inasmuch as I have at- tempted to begin my discourse with the theory of the processes and reactions with-in the atom, and to discuss practical applications in conclusion only. At the same time, it was essential to make the theory intelligible without resort to mathematics, with the aid of illustrative models and by citing as analogies certain more widely known related phenomena. Nuclear physics lends itself to such a treatment more than many other branches of physical science. However, this method obviously has its natural limitations, and for a more profound understanding of the entire complex of relationships, a mathematical presentation of the subject is, of course, essential. For a thorough study of nuclear physics in this sense, there are many excellent books available. In the present volume, the technical apparatus of nuclear physics is discussed in the seventh chapter only; the eighth, and last, chapter presents a survey of the practical applications achieved up to the present time. Since the publication, during the war, of the first edition of this book, reports have been published on the great progress in the field of nuclear physics, and especially on those technical developments relating to the atomic nucleus which had till then been restricted to the secret laboratories of the belligerent nations. These new developments are described, in general outline, in the last chapter of this book, where the practical applications of nuclear physics are discussed. Furthermore, those discoveries which were made or published after the war only, are dealt with in the text elsewhere. The present English edition, appearing some time after the German one, may be of interest in connection with the history and the principles of nuclear physics rather than with respect to its recent development. Since the writing of the book and even since its last revision in 1948 an enormous development of nuclear physics has taken place, in its principles as well as in technical applications. There- fore some of the content of the book may now be commonplace to many readers, some parts are definitely out of date, since new discoveries have changed the picture. In a new edition the shell structure of the nucleus should play a central rôle, since it has simplified our knowledge of the nucleus considerably through the work of Mayer-Göppert, Haxel, Jensen and Suess. In dealing with the nuclear forces one should mention all the new types of mesons that have been found in recent years and their modes of interaction. But it would probably be entirely impossible to give an account of the present state of nuclear physics in a short work. Therefore this book may still serve as an introduction to a field, the knowledge of which would require much more extended studies.

Novel: Nuclear Physics and Nuclear Data Science
Novel: Nuclear Physics and Nuclear Data Science

Bitcoin, blockchains, and cryptocurrencies are fascinating to me because there are so many elements to understand. This multidisciplinary nature is one of the reasons I, and so many others, love the industry — it is easy to get sucked into the rabbit hole, and as you try to understand each element, every answer begets more questions. The journey starts with ‘What is Bitcoin?’ but the explanations and answers come from the disciplines of economics, law, computer science, finance, civil society, his- tory, geopolitics, and more. You could create a pretty comprehensive high school curriculum around Bitcoin and have plenty of material to spare. And this is the very reason why it is so hard to explain. This book is an attempt to cover the basics. It is aimed at the thinking person but assumes that the reader doesn’t have a detailed background in the various disciplines mentioned previously. Different people will find different parts interesting. I try to use analogies where I think they help explain some concepts, but be gentle with me: all analogies break down if stretched too far. And although I have tried to be accurate, there will still be oversimplifications, errors and omissions. What is true today may not be tomorrow: the pace of change is rapid. I am the first to admit that there are limits to my own technical expertise. Nevertheless, I hope that every reader comes away learning something new. Bitcoin¹ and Ether are two of the better-known cryptocurrencies or coins (note that the coin on the Ethereum network is called Ether, though is often mis- named in the media as ‘Ethereum’). These are assets or items of value that exist digitally, not physically, and are created by software. They have no issuer as such. No person, company, or entity backs these, and there are no terms of service or guarantees associated with them. Like physical gold, cryptocurrencies simply exist, and are created or destroyed according to the rules articulated in the code that creates and governs them. If you own some cryptocurrency, and we’ll see what that actually means later, it is your asset that you control. It has value, and can be exchanged for other cryptocurrencies, US dollars, or other global sovereign (or fiat) currencies. Its value is determined with- in marketplaces called exchanges where buyers and sellers come together to trade at mutually agreed prices. As well as ‘coins,’ units of cryptocurrencies may be described as digital assets. That is, unique data items whose ownership can be passed from account to ac- count. These accounts are technically called addresses, and we will explore what addresses are later. When these digital assets move from one account to another they are all recorded on their respective transaction databases known, because of some unique shared characteristics which we will look into later, as blockchains. Just to confuse everybody, some digital assets are described as tokens, as in ‘Is it a cryptocurrency or a token?’. Cryptocurrencies and tokens are both types of cryptographically secured digital assets, sometimes known as cryptoassets. These tokens have different characteristics from cryptocurrencies and from each other. Tokens can be fungible (one token being more or less replaceable by another), or non-fungible (where each token represents something unique). Unlike cryptocurrencies, these newer tokens are usually issued by known issuers who stand behind them, and the tokens can represent legal agreements (like financial assets), physical assets (like gold), or future access to products and services. Where the underlying item is an asset you could think of the token as a digital version of a cloakroom ticket, issued by a cloakroom clerk and redeemable for your coat. Indeed, these tokens are sometimes called DDRs — Digital Depository Receipts. Where the underlying item is an agreement, product or service, you can think of the token as something like a concert ticket issued by a con- cert organiser and redeemable for entry to a concert at a later date. To give some real examples, there are tokens that represent everything from gold bullion sitting in a vault somewhere², through to tokens representing unique ‘CryptoKitties’ — collectable digital cats with specific visual attributes determined by their ‘DNA’ code. What do all of these coins and tokens have in common? All transactions related to them, including their creation, destruction, changes of ownership, and other logic or future obligations, are recorded on blockchains: replicated data- bases that act as the ultimate books and records — the ‘golden source’ that represents the universal understanding of the current status of all units of the digital asset. Bitcoin’s blockchain is an ever-growing list of every Bitcoin transaction that has ever happened, right from the creation of the very first Bitcoin on 3 January 2009, through to the most recent transfer or payment from one account to an- other. Ethereum’s blockchain is a list of transactions involving the cryptocurrency Ether, a multitude of other tokens (including those representing CryptoKitties) and other related data, all of which is recorded on Ethereum. Different blockchains have different characteristics, so much so that nowadays it is almost impossible to make a general statement about ‘blockchain’ without being wrong for some particular example. Some blockchains, like the well- known Bitcoin and Ethereum chains, are public, or permission-less, meaning that their list of transactions can be written to by anyone, with no gatekeepers to ap- prove or reject parties who want to create blocks or participate in bookkeeping. Self-identification is not a requirement to create blocks or validate transactions. Other blockchains can be private or permissioned, in that there is a controlling party who allows participants to read or write to them. And finally, we need to distinguish between protocols, code, software, transaction data, coins, and blockchains. Bitcoin is a bunch of protocols: rules that define and characterise Bitcoin itself — what it is, how ownership is represented and recorded, what constitutes a valid transaction, how new participants can join the network of operators, how participants should behave if they want to be kept up to date with the latest transactions, and so on. These protocols, or rules, can be described in English or any other human language, but are best articulated in computer code, which in turn can be compiled into software — Bitcoin software — that enacts those protocols, i.e. makes them operate. When the software is run, Bitcoin coins are generated and can be sent from one account to another. These actions are recorded as transaction data, and this transaction data is bundled into bundles or blocks, and linked together to form the Bitcoin blockchain. So, to recap, Bitcoin protocols are written out as Bitcoin code which is run as Bitcoin software which creates Bitcoin transactions containing data about Bit- coin coins recorded on Bitcoin’s blockchain. Got it? Good. Not all other cryptocurrencies or tokens work this way, but it is as good a basis as any to start the journey. Some people think of Bitcoin as the next evolution of money — it is described as a (crypto) currency after all. So we need to understand a little more about money. What is money? Has it always been the same? How successful has money been? Are some forms of money better than others? Can the nature of money ever change, or is what we have going to be the same for evermore? Do cryptocurrencies sit easily alongside today’s money, fulfilling a niche or purpose that existing forms of money cannot serve, or are cryptocurrencies competitors to today’s money that threaten the status quo of state-issued currency? This book should give you a good well-rounded education into the basics of bitcoins and blockchains and assumes no specific starting expertise. We start by defining and understanding the nature of money. Then we dive into digital money and how value is really transferred around the world. We then explore a few key concepts from a branch of mathematics called cryptography, so that we can then move to cryptocurrencies themselves. In the cryptocurrencies sec- tion, we dive into the Bitcoin and Ethereum networks, and the Bitcoin and Ether digital tokens — what they are, how to buy, store, and sell them, how to explore their blockchains, and the risks in managing them, including the unique challenges in moving this new digital money around the world. Finally, we discuss the types of blockchain technology that are being explored by banks and big businesses to join up their databases and do more efficient business. Although I have my personal biases and interests, throughout the book I try to maintain a neutral position on the cryptocurrencies, tokens, and blockchain platforms. I try not to neither over-sell them nor be overly critical. I leave it up to readers to conclude for themselves whether these technologies are a trend or a fad, useful or useless, good or bad.

Bitcoin and Cryptocurrencies to the Real World — Blockchain Technology
Bitcoin and Cryptocurrencies to the Real World — Blockchain Technology

Earth’s core is the very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly-solid mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). Planet Earth is older than the core. When Earth was formed about 4.5 billion years ago, it was a uniform ball of hot rock. Radioactive decay and leftover heat from planetary formation (the collision, accretion, and compression of space rocks) caused the ball to get even hotter. Eventually, after about 500 million years, our young planet’s temperature heated to the melting point of iron — about 1,538° Celsius (2,800° Fahrenheit). This pivotal moment in Earth’s history is called the iron catastrophe. The iron catastrophe allowed greater, more rapid movement of Earth’s molten, rocky material. Relatively buoyant material, such as silicates, water, and even air, stayed close to the planet’s exterior. These materials became the early mantle and crust. Droplets of iron, nickel, and other heavy metals gravitated to the center of Earth, becoming the early core. This important process is called planetary differentiation. Earth’s core is the furnace of the geothermal gradient. The geothermal gradient measures the increase of heat and pressure in Earth’s interior. The geothermal gradient is about 25° Celsius per kilometer of depth (1° Fahrenheit per 70 feet). The primary contributors to heat in the core are the decay of radioactive elements, leftover heat from planetary formation, and heat released as the liquid outer core solidifies near its boundary with the inner core. Unlike the mineral-rich crust and mantle, the core is made almost entirely of metal — specifically, iron and nickel. The shorthand used for the core’s iron-nickel alloys is simply the elements’ chemical symbols — NiFe. Elements that dissolve in iron, called siderophiles, are also found in the core. Because these elements are found much more rarely on Earth’s crust, many siderophiles are classified as “precious metals.” Siderophile elements include gold, platinum, and cobalt. Another key element in Earth’s core is sulfur — in fact 90% of the sulfur on Earth is found in the core. The confirmed discovery of such vast amounts of sulfur helped explain a geologic mystery: If the core was primarily NiFe, why wasn’t it heavier? Geoscientists speculated that lighter elements such as oxygen or silicon might have been present. The abundance of sulfur, another relatively light element, explained the conundrum. Although we know that the core is the hottest part of our planet, its precise temperatures are difficult to determine. The fluctuating temperatures in the core depend on pressure, the rotation of the Earth, and the varying composition of core elements. In general, temperatures range from about 4,400° Celsius (7,952° Fahrenheit) to about 6,000° Celsius (10,800° Fahrenheit). The core is made of two layers: the outer core, which borders the mantle, and the inner core. The boundary separating these regions is called the Bullen discontinuity. Outer Core The outer core, about 2,200 kilometers (1,367 miles) thick, is mostly composed of liquid iron and nickel. The NiFe alloy of the outer core is very hot, between 4,500° and 5,500° Celsius (8,132° and 9,932° Fahrenheit). The liquid metal of the outer core has very low viscosity, meaning it is easily deformed and malleable. It is the site of violent convection. The churning metal of the outer core creates and sustains Earth’s magnetic field. The hottest part of the core is actually the Bullen discontinuity, where temperatures reach 6,000° Celsius (10,800° Fahrenheit) — as hot as the surface of the sun. Inner Core The inner core is a hot, dense ball of (mostly) iron. It has a radius of about 1,220 kilometers (758 miles). Temperature in the inner core is about 5,200° Celsius (9,392° Fahrenheit). The pressure is nearly 3.6 million atmosphere (atm). The temperature of the inner core is far above the melting point of iron. However, unlike the outer core, the inner core is not liquid or even molten. The inner core’s intense pressure — the entire rest of the planet and its atmosphere — prevents the iron from melting. The pressure and density are simply too great for the iron atoms to move into a liquid state. Because of this unusual set of circumstances, some geophysicists prefer to interpret the inner core not as a solid, but as a plasma behaving as a solid. The liquid outer core separates the inner core from the rest of the Earth, and as a result, the inner core rotates a little differently than the rest of the planet. It rotates eastward, like the surface, but it’s a little faster, making an extra rotation about every 1,000 years. Geoscientists think that the iron crystals in the inner core are arranged in an “hcp” (hexagonal close-packed) pattern. The crystals align north-south, along with Earth’s axis of rotation and magnetic field. The orientation of the crystal structure means that seismic waves — the most reliable way to study the core — travel faster when going north-south than when going east-west. Seismic waves travel four seconds faster pole-to-pole than through the Equator. Growth in the Inner CoreAs the entire Earth slowly cools, the inner core grows by about a millimeter every year. The inner core grows as bits of the liquid outer core solidify or crystallize. Another word for this is “freezing,” although it’s important to remember that iron’s freezing point more than 1,000° Celsius (1,832° Fahrenheit). The growth of the inner core is not uniform. It occurs in lumps and bunches, and is influenced by activity in the mantle. Growth is more concentrated around subduction zones — regions where tectonic plates are slipping from the lithosphere into the mantle, thousands of kilometers above the core. Subducted plates draw heat from the core and cool the surrounding area, causing increased instances of solidification. Growth is less concentrated around “superplumes” or LLSVPs. These ballooning masses of superheated mantle rock likely influence “hot spot” volcanism in the lithosphere, and contribute to a more liquid outer core. The core will never “freeze over.” The crystallization process is very slow, and the constant radioactive decay of Earth’s interior slows it even further. Scientists estimate it would take about 91 billion years for the core to completely solidify — but the sun will burn out in a fraction of that time (about 5 billion years). Core HemispheresJust like the lithosphere, the inner core is divided into eastern and western hemispheres. These hemispheres don’t melt evenly, and have distinct crystalline structures. The western hemisphere seems to be crystallizing more quickly than the eastern hemisphere. In fact, the eastern hemisphere of the inner core may actually be melting. Inner Inner CoreGeoscientists recently discovered that the inner core itself has a core — the inner inner core. This strange feature differs from the inner core in much the same way the inner core differs from the outer core. Scientists think that a radical geologic change about 500 million years ago caused this inner inner core to develop. The crystals of the inner inner core are oriented east-west instead of north-south. This orientation is not aligned with either Earth’s rotational axis or magnetic field. Scientists think the iron crystals may even have a completely different structure (not hcp), or exist at a different phase. Magnetism Earth’s magnetic field is created in the swirling outer core. Magnetism in the outer core is about 50 times stronger than it is on the surface. It might be easy to think that Earth’s magnetism is caused by the big ball of solid iron in the middle. But in the inner core, the temperature is so high the magnetism of iron is altered. Once this temperature, called the Curie point, is reached, the atoms of a substance can no longer align to a magnetic point. Dynamo TheorySome geoscientists describe the outer core as Earth’s “geodynamo.” For a planet to have a geodynamo, it must rotate, it must have a fluid medium in its interior, the fluid must be able to conduct electricity, and it must have an internal energy supply that drives convection in the liquid. Variations in rotation, conductivity, and heat impact the magnetic field of a geodynamo. Mars, for instance, has a totally solid core and a weak magnetic field. Venus has a liquid core, but rotates too slowly to churn significant convection currents. It, too, has a weak magnetic field. Jupiter, on the other hand, has a liquid core that is constantly swirling due to the planet’s rapid rotation. Earth is the “Goldilocks” geodynamo. It rotates steadily, at a brisk 1,675 kilometers per hour (1,040 miles per hour) at the Equator. Coriolis forces, an artifact of Earth’s rotation, cause convection currents to be spiral. The liquid iron in the outer core is an excellent electrical conductor, and creates the electrical currents that drive the magnetic field. The energy supply that drives convection in the outer core is provided as droplets of liquid iron freeze onto the solid inner core. Solidification releases heat energy. This heat, in turn, makes the remaining liquid iron more buoyant. Warmer liquids spiral upward, while cooler solids spiral downward under intense pressure: convection. Earth’s Magnetic FieldEarth’s magnetic field is crucial to life on our planet. It protects the planet from the charged particles of the solar wind. Without the shield of the magnetic field, the solar wind would strip Earth’s atmosphere of the ozone layer that protects life from harmful ultraviolet radiation. Although Earth’s magnetic field is generally stable, it fluctuates constantly. As the liquid outer core moves, for instance, it can change the location of the magnetic North and South Poles. The magnetic North Pole moves up to 64 kilometers (40 miles) every year. Fluctuations in the core can cause Earth’s magnetic field to change even more dramatically. Geomagnetic pole reversals, for instance, happen about every 200,000 to 300,000 years. Geomagnetic pole reversals are just what they sound like: a change in the planet’s magnetic poles, so that the magnetic North and South Poles are reversed. These “pole flips” are not catastrophic — scientists have noted no real changes in plant or animal life, glacial activity, or volcanic eruptions during previous geomagnetic pole reversals. Studying the Core Geoscientists cannot study the core directly. All information about the core has come from sophisticated reading of seismic data, analysis of meteorites, lab experiments with temperature and pressure, and computer modeling. Most core research has been conducted by measuring seismic waves, the shock waves released by earthquakes at or near the surface. The velocity and frequency of seismic body waves changes with pressure, temperature, and rock composition. In fact, seismic waves helped geoscientists identify the structure of the core itself. In the late 19th century, scientists noted a “shadow zone” deep in the Earth, where a type of body wave called an s-wave either stopped entirely or was altered. S-waves are unable to transmit through fluids or gases. The sudden “shadow” where s-waves disappeared indicated that Earth had a liquid layer. In the 20th century, geoscientists discovered an increase in the velocity of p-waves, another type of body wave, at about 5,150 kilometers (3,200 miles) below the surface. The increase in velocity corresponded to a change from a liquid or molten medium to a solid. This proved the existence of a solid inner core. Meteorites, space rocks that crash to Earth, also provide clues about Earth’s core. Most meteorites are fragments of asteroids, rocky bodies that orbit the sun between Mars and Jupiter. Asteroids formed about the same time, and from about the same material, as Earth. By studying iron-rich chondrite meteorites, geoscientists can get a peek into the early formation of our solar system and Earth’s early core. In the lab, the most valuable tool for studying forces and reactions at the core is the diamond anvil cell. Diamond anvil cells use the hardest substance on Earth (diamonds) to simulate the incredibly high pressure at the core. The device uses an x-ray laser to simulate the core’s temperature. The laser is beamed through two diamonds squeezing a sample between them. Complex computer modeling has also allowed scientists to study the core. In the 1990s, for instance, modeling beautifully illustrated the geodynamo — complete with pole flips.

Travel to the Earth Centre (Core-Nucleus) Operation
Travel to the Earth Centre (Core-Nucleus) Operation

This year’s COP24 annual UN climate conference concluded late on Saturday evening in Katowice, Poland, after two weeks of tension-filled talks. Nearly 23,000 delegates descended on the coal-tinged city with a deadline for hashing out the Paris Agreement “rulebook”, which is the operating manual needed for when the global deal enters into force in 2020. This was mostly agreed, starting a new international climate regime under which all countries will have to report their emissions — and progress in cutting them — every two years from 2024. But as countries wrestled with the “four-dimensional spaghetti” of competing priorities — as one delegate put it to Carbon Brief — they clashed over how to recognise the Intergovernmental Panel on Climate Change (IPCC) special report on 1.5C and whether to clearly signal the need for greater ambition to stay below this temperature limit. The final outcome included hints at the need for more ambitious climate pledges before 2020, leaving many NGOs disappointed at the lack of more forceful language. Meanwhile, new research released at the COP showed global emissions were going up, not down. With tension mounting across the fortnight of the talks, UN secretary-general António Guterres had to visit the COP several times to force progress. Despite settling on large parts of the Paris rulebook, countries failed to agree the rules for voluntary market mechanisms, pushing part of the process onto next year’s COP25 in Chile. The raison d’etre for the COP-24 Protocol on wind energy engineering is discussed with a focus on our changing climate and the buildup of atmospheric carbon dioxide;

Conference of Climate Change COP-24 Protocol and Renewable Energy Explained
Conference of Climate Change COP-24 Protocol and Renewable Energy Explained
Dr Francesco Dergano

Dr Francesco Dergano

Founder and Chief Executive Officer (CEO) of SkyDataSol