P31???Are ghost ships real

One foggy morning in 1884, the British steamer "Rumney" crashed into the French ship "Frigorifique." Seeing their ship filling with water, the French crew climbed aboard the "Rumney." But as they sailed towards the nearest port, a silent form suddenly emerged from the fog: the abandoned "Frigorifique." It was too late to turn, and the impact was enough to sink the "Rumney." As the sailors scrambled into the lifeboats, the empty "Frigorifique" sailed back into the fog, having seemingly taken its revenge. In reality, the French sailors had left the engines running, and the "Frigorifique" sailed in a circle before striking the "Rumney" and finally sinking. But its story became one of the many tales of ghost ships, unmanned vessels that apparently sail themselves. And although they've influenced works like "Dracula" and "Pirates of the Caribbean," crewless ships aren't the product of ghostly spirits, just physics at work. One of the most famous ghost ships was the "Mary Celeste" found sailing the Atlantic in 1872 with no one aboard, water in its hold, and lifeboats missing. The discovery of its intact cargo and a captain's log that ended abruptly led to wild rumors and speculation. But the real culprits were two scientific phenomena: buoyancy and fluid dynamics. Here's how buoyancy works. An object placed in a liquid displaces a certain volume of fluid. The liquid in turn exerts an upward buoyant force equal to the weight of the fluid that's been displaced. This phenomenon is called Archimedes's Principle. Objects that are less dense than water, such as balsa wood, icebergs, and inflatable rafts always float. That's because the upward buoyant force is always stronger than the downward force of gravity. But for objects or ships to float when they're made of materials, like steel, that are denser than water, they must displace a volume of water larger than their weight. Normally, the water filling a ship's hull would increase its weight and cause it to sink - just what the "Mary Celeste's" crew feared when they abandoned ship. But the sailors didn't account for fluid dynamics. The water stopped flowing at the point of equilibrium, when it reached the same level as the hull. As it turned out, the weight of the water wasn't enough to sink the ship and the "Mary Celeste" was found a few days later while the unfortunate crew never made it to shore. Far stranger is the tale of "A. Ernest Mills," a schooner transporting salt, whose crew watched it sink to the sea floor following a collision. Yet four days later, it was spotted floating on the surface. The key to the mystery lay in the ship's heavy cargo of salt. The added weight of the water in the hull made the vessel sink, but as the salt dissolved in the water, the weight decreased enough that the force of gravity became less than the buoyant force and the ship floated back to the surface. But how do we explain the most enduring aspect of ghost ship legends: multiple sightings of the same ships hundreds of miles and several years apart? The answer lies in ocean currents, which are like invisible rivers flowing through the ocean. Factors, like temperature, salinity, wind, gravity, and the Coriolis effect from the Earth's rotation create a complex system of water movement. That applies both at the ocean's surface and deep below. Sailors have always known about currents, but their patterns weren't well known until recently. In fact, tracking abandoned ships was how scientists determined the shape and speed of the Atlantic Gyre, the Gulf Stream, and related currents in the first place. Beginning in 1883, the U.S. Hydrographic Office began collecting monthly data that included navigation hazards, like derelict ships, whose locations were reported by passing vessels. So abandoned ships may not be moved by ghost crews or supernatural curses, but they are a real and fascinating phenomenon born through the ocean and kept afloat by powerful, invisible, scientifically studied forces.

P32??Are naked mole rats the strangest mammals

What mammal has the social life of an insect, the cold-bloodedness of a reptile, and the metabolism of a plant? Bald and buck-toothed, naked mole rats may not be pretty, but they’re extraordinary. With a lifespan of 30 years, their peculiar traits have evolved over millions of years to make them uniquely suited to survive harsh conditions, especially long periods without oxygen. In the deserts of East Africa, naked mole rats feed on root vegetables. They dig for the roots with teeth that can move independently, like chopsticks. But even with these special teeth, a single naked mole rat doesn’t stand a chance of finding enough food; the roots are large and nutritious, but scattered far and wide. A large workforce has a much better chance, so naked mole rats live in colonies. Similar to ants, bees, and termites, they build giant nests. Housing up to 300 mole rats, these colonies feature complex underground tunnel systems, nest chambers, and community bathrooms. Also like insects, naked mole rats have a rigid social structure. The dominant female, the queen, and two to three males that she chooses, are the only naked mole rats in the colony who have babies. All the other naked mole rats, male and female, are either soldiers, who defend the colony from possible invaders, or workers. Teams of workers are dispatched to hunt for roots, and their harvest feeds the whole colony. Living in a colony helps naked mole rats find enough food, but when so many animals live in the same underground space, oxygen quickly runs out. Mammals need a lot of oxygen; we use it to make the energy that fuels everything from maintaining our body temperatures to our heartbeats to voluntary movements. Without oxygen, we quickly die. In fact, no other mammal could survive the oxygen depletion experienced in a naked mole rat colony. Naked mole rats can thrive in low oxygen in part because they’ve abandoned one of the body functions that requires the most oxygen: thermoregulation. Most mammals are warm-blooded, meaning they have to keep their body temperature consistent. Naked mole rats don’t get enough oxygen to do this. Instead, they’re the only mammals whose body temperature fluctuates with their environment, making them cold-blooded, like reptiles. They also have a special type of hemoglobin, the molecule in the blood that transports oxygen. Their hemoglobin is much stickier for oxygen than ours and can pick oxygen up even when it’s scarce. In response to a real oxygen emergency, naked mole rats enter a state of suspended animation. They stop moving, slow their breathing, and dramatically lower their heart rate. This greatly reduces the amount of energy, and therefore oxygen, they need. At the same time, they begin to metabolize fructose, like a plant. Fructose is a sugar that can be used to make energy without burning oxygen. Usually, mammals metabolize a different sugar called glucose that makes more energy than fructose, but glucose only works when oxygen’s available. Human brain and heart cells have some cellular machinery to use fructose, but not nearly as much as naked mole rats. Naked mole rats are, in fact, the only mammals known to have this ability. While we can hope humans won’t ever need to exclusively live in underground tunnels, there are many situations where we would benefit from needing less oxygen. During heart attacks and other medical emergencies, people often die or sustain debilitating organ damage from oxygen deprivation. Could we replicate the naked mole rat’s use of the fructose pathway for human health? It took millions of years of evolution to bring the behavior of an insect, the temperature regulation of a reptile, and the energy production of a plant together in one little mammal, but maybe, with enough study, we can replicate just a few of their wild adaptations.

P33? ?Are spotty fruits and vegetables safe to eat

In 2010, $30 billion worth of fruits and vegetables were wasted by American retailers and shoppers in part because of cosmetic problems and perceived spoilage. That's a poor use of about 30% of the produce on the market, not to mention the water and energy required to grow and transport it, and the landfill space getting used up by rotting fruit. So what are those cosmetic problems? You've probably passed over a spotty apple in the grocery store, or accidentally sunk your thumb into a mushy patch on a tomato. These blemishes can doom produce to the trash can. But what are they anyway, and are they actually bad for you? Those spots are evidence of an epic battle between plants and microbes. Like humans, plants coexist with billions of fungi and bacteria. Some of these microbes are beneficial to the plant, suppressing disease and helping it extract nutrients. Others are pathogens, attacking the produce, still alive as it sits in a store display or your refrigerator and siphoning off molecules they can use themselves. The good news is they're almost never bad for you. These fungi and bacteria have spent millions of years developing strategies to overcome a plant's immune system. But healthy human immune systems are different enough that those strategies just don't work on us. So in a plant, what does this process look like? Microbes can reach plants in a number of ways, like getting splashed onto it during watering or fertilization. Under the right conditions, the microbes grow into large enough colonies to attack the waxy outer layer of fruit or leaves. Their target: the delicious sugars and nutrients inside. This type of pathogen often makes spots like this. A clump of bacteria drains the nutrients and color from the fruit's cells making that yellow halo. It then moves outward, leaving a black spot of dead cells in its wake. Each spot, which could contain hundreds of thousands of microbes is actually caused by a combination of microbial attack and the host defending itself. For example, this is the bacterial pathogen Pseudomonas syringae. Once on a tomato, it enters the fruit and leaves, multiplies in the space between the cells, and produces toxins and proteins that allow it to disrupt the plant's immune response. One toxin coronatine makes plants' stomata open up, allowing bacteria to enter more freely. Coronatine also activates pathways leading to chlorophyll degradation, which you can see as yellow spots. As the bacteria continue to feed and multiply, they start to kill off the plant cells. That explains spots, but what about mushy blemishes? Those are usually caused when the fruit is attacked by microbes after it's detached from the plant. If the plant is wounded during transport, necrotic fungi can infiltrate through the wound, kill the cells, absorb their nutrients, and leave your food looking mushy or brown. Those spots in particular can taste pretty bad. You're eating dead and decomposing tissue, after all. But you can usually salvage the rest of the fruit. The non-mushy spots, like the ones you typically see on apples or tomatoes, are just on the surface and don't usually affect flavor. Of course, microbes that do make us sick, like E. coli and salmonella, can hitch a ride on vegetables, too. But because they're not plant pathogens, they don't typically cause spots. They just hang out invisibly on the surface. So it's washing fruit and veggies, not avoiding the spotty ones, that will help you avoid getting sick. So the next time you're at the grocery store, don't be afraid to pick up funky-looking fruit. Some stores will even give you a discount. Wash them well and store them properly, as some produce like apples and cabbages will keep in the fridge for weeks. The spotty ones may not be eye candy, but they're safe and just as delicious.

P34? ?Are the illuminati real

The year was 1776. In Bavaria, new ideals of rationalism, religious freedom, and universal human rights competed with the Catholic church’s heavy influence over public affairs. Across the Atlantic, a new nation staked its claim for independence on the basis of these ideas. But back in Bavaria, law professor Adam Weishaupt’s attempts to teach secular philosophy continued to be frustrated. Weishaupt decided to spread his ideas through a secret society that would shine a light on the shortcomings of the Church’s ideology. He called his secret society the Illuminati. Weishaupt modelled aspects of his secret society off a group called the Freemasons. Originally an elite stoneworkers’ guild in the late Middle Ages, the Freemasons had gone from passing down the craft of masonry to more generally promoting ideals of knowledge and reason. Over time, they had grown into a semi-secret, exclusive order that included many wealthy and influential individuals, with elaborate, secret initiation rituals. Weishaupt created his parallel society while also joining the Freemasons and recruiting from their ranks. He adopted the code name Spartacus for himself, after the famed leader of the Roman slave revolt. Early members became the Illuminati’s ruling council, or Areopagus. One of these members, Baron Adolph Knigge, was also a freemason, and became an influential recruiter. With Knigge’s help, the Illuminati expanded their numbers, gained influence within several Masonic chapters, and incorporated Masonic rituals. By 1784, there were over 600 members, including influential scholars and politicians. As the Illuminati gained members, the American Revolution also gained momentum. Thomas Jefferson would later cite Weishaupt as an inspiration. European monarchs and clergy were fearful of similar revolts on their home soil. Meanwhile, the existence of the Illuminati had become an open secret. Both the Illuminati and the Freemasons drew exclusively from society’s wealthy elite, which meant they were constantly rubbing shoulders with members of the religious and political establishment. Many in the government and church believed that both groups were determined to undermine the people’s religious faith. But these groups didn’t necessarily oppose religion— they just believed it should be kept separate from governance. Still, the suspicious Bavarian government started keeping records of alleged members of the Illuminati. Just as Illuminati members begun to secure important positions in local governments and universities, a 1784 decree by Duke Karl Theodor of Bavaria banned all secret societies. While a public ban on something ostensibly secret might seem difficult to enforce, in this case it worked. Only nine years after its founding, the group dissolved, their records were seized, and Weishaupt forced into exile. The Illuminati would become more notorious in their afterlife than they had ever been in their brief existence. A decade later, in the aftermath of the French Revolution, conservative authors claimed the Illuminati had survived their banishment and orchestrated the overthrow of the monarchy. In the United States, preacher Jedidiah Morse promoted similar ideas of an Illuminati conspiracy against the government. But though the idea of a secret group orchestrating political upheaval is still alive and well today, there is no evidence that the Illuminati survived, reformed, or went underground. Their brief tenure is well-documented in Bavarian government records, the still-active Freemasons’s records, and particularly the overlap between these two sources, without a whisper since. In the spirit of rationalism the Illuminati embraced, one must conclude they no longer exist. But the ideas that spurred Weishaupt to found the illuminati still spread, becoming the basis for many Western governments today. These ideas didn’t start or end with the Illuminati— instead, it was one community that represented a wave of change that was already underway when it was founded and continued long after it ended.

P35??Are there universal expressions of emotion

The 40 or so muscles in the human face can be activated in different combinations to create thousands of expressions. But do these expressions look the same and communicate the same meaning around the world, regardless of culture? Is one person’s smile another’s grimace? Charles Darwin theorized that emotional expression was a common human feature. But he was in the minority. Until the mid-20th century, many researchers believed that the specific ways we show emotion were learned behaviors that varied across cultures. Personality theorist Silvan Tomkins was one of the few to insist otherwise. Tomkins claimed that certain affects— emotional states and their associated facial expressions— were universal. In the 1960s, psychologist Paul Ekman set about testing this theory by examining hundreds of hours of film footage of remote tribes isolated from the modern world. Ekman found the native peoples’ expressions to be not only familiar, but occurring in precisely the situations he would expect. Conversely, he ran tests with tribes who had no prior exposure to Western culture. They were able to correctly match photos of different facial expressions with stories designed to trigger particular feelings. Over the next few decades, further research has corroborated Darwin’s idea that some of our most important emotional expressions are in fact universal. The degrees of expression appropriate to a given situation can, however, vary greatly across cultures. For instance, researchers have studied facial expression in people who are born blind, hypothesizing that if expressions are universal, they would be displayed in the same way as sighted people. In one study, both blind and sighted athletes displayed the same expressions of emotion when winning or losing their matches. Further evidence can be found in our evolutionary relatives. Comparisons of facial expression between humans and non-human mammals have found similarities in the structure and movement of facial muscles. Chimpanzee laughter looks different from ours, but uses some of the same muscle movements. Back in the 60s, Ekman identified six core expressions. Anger is accompanied by lowered eyebrows drawn together, tense and narrowed eyes, and tight lips; disgust, by the lips pulled up and the nose crinkling. In fear, the upper white of the eyes are revealed as the eyebrows raise and the mouth stretches open, while surprise looks similar, but with rounded eyebrows and relaxed lips. Sadness is indicated by the inner corners of the eyebrows being drawn inwards and upwards, drooping eyes, and a downturned mouth. And of course there’s happiness: lips drawn up and back, and raised cheeks causing wrinkling around the eyes. More recently, researchers have proposed additional entries such as contempt, shame, and disapproval, but opinions vary on how distinct boundaries between these categories can be drawn. So if Ekman and other researchers are correct, what makes certain expressions universal? And why are they expressed in these particular ways? Scientists have a lot of theories rooted in our evolutionary history. One is that certain expressions are important for survival. Fear and surprise could signal to others an immediate danger. Studies of humans and some other primates have found that we pay more attention to faces that signal threats over neutral faces, particularly when we’re already on high alert. Expressions also could help improve group fitness by communicating our internal states to those around us. Sadness, for example, signals to the group that something’s wrong. There’s some evidence that expressions might be even more directly linked to our physiology. The fear expression, for instance, could directly improve survival in potentially dangerous situations by letting our eyes absorb more light and our lungs take in more air, preparing us to fight or flee. There’s still much research to be done in understanding emotional expression, particularly as we learn more about the inner workings of the brain. But if you ever find yourself among strangers in a strange land, a friendly smile could go a long way.

P36? ?Are we living in a simulation

We live in a vast universe, on a small wet planet, where billions of years ago single-celled life forms evolved from the same elements as all non-living material around them, proliferating and radiating into an incredible ray of complex life forms. All of this— living and inanimate, microscopic and cosmic— is governed by mathematical laws with apparently arbitrary constants. And this opens up a question: If the universe is completely governed by these laws, couldn’t a powerful enough computer simulate it exactly? Could our reality actually be an incredibly detailed simulation set in place by a much more advanced civilization? This idea may sound like science fiction, but it has been the subject of serious inquiry. Philosopher Nick Bostrom advanced a compelling argument that we’re likely living in a simulation, and some scientists also think it’s a possibility. These scientists have started thinking about experimental tests to find out whether our universe is a simulation. They are hypothesizing about what the constraints of the simulation might be, and how those constraints could lead to detectable signs in the world. So where might we look for those glitches? One idea is that as a simulation runs, it might accumulate errors over time. To correct for these errors the simulators could adjust the constants in the laws of nature. These shifts could be tiny— for instance, certain constants we’ve measured with accuracies of parts per million have stayed steady for decades, so any drift would have to be on an even smaller scale. But as we gain more precision in our measurements of these constants, we might detect slight changes over time. Another possible place to look comes from the concept that finite computing power, no matter how huge, can’t simulate infinities. If space and time are continuous, then even a tiny piece of the universe has infinite points and becomes impossible to simulate with finite computing power. So a simulation would have to represent space and time in very small pieces. These would be almost incomprehensibly tiny. But we might be able to search for them by using certain subatomic particles as probes. The basic principle is this: the smaller something is, the more sensitive it will be to disruption— think of hitting a pothole on a skateboard versus in a truck. Any unit in space-time would be so small that most things would travel through it without disruption— not just objects large enough to be visible to the naked eye, but also molecules, atoms, and even electrons and most of the other subatomic particles we’ve discovered. If we do discover a tiny unit in space-time or a shifting constant in a natural law, would that prove the universe is a simulation? No— it would only be the first of many steps. There could be other explanations for each of those findings. And a lot more evidence would be needed to establish the simulation hypothesis as a working theory of nature. However many tests we design, we’re limited by some assumptions they all share. Our current understanding of the natural world on the quantum level breaks down at what’s known as the planck scale. If the unit of space-time is on this scale, we wouldn’t be able to look for it with our current scientific understanding. There’s still a wide range of things that are smaller than what’s currently observable but larger than the planck scale to investigate. Similarly, shifts in the constants of natural laws could occur so slowly that they would only be observable over the lifetime of the universe. So they could exist even if we don’t detect them over centuries or millennia of measurements. We're also biased towards thinking that our universe’s simulator, if it exists, makes calculations the same way we do, with similar computational limitations. Really, we have no way of knowing what an alien civilization’s constraints and methods would be— but we have to start somewhere. It may never be possible to prove conclusively that the universe either is, or isn’t, a simulation, but we’ll always be pushing science and technology forward in pursuit of the question: what is the nature of reality?

P37? Are we running out of clean water

From space, our planet appears to be more ocean than Earth. But despite the water covering 71% of the planet’s surface, more than half the world’s population endures extreme water scarcity for at least one month a year. And current estimates predict that by 2040, up to 20 more countries could be experiencing water shortages. Taken together, these bleak statistics raise a startling question: are we running out of clean water? Well yes, and no. At a planetary scale, Earth can’t run out of freshwater thanks to the water cycle, a system that continuously produces and recycles water, morphing it from vapour, to liquid, to ice as it circulates around the globe. So this isn’t really a question of how much water there is, but of how much of it is accessible to us. 97% of earth’s liquid is saltwater, too loaded with minerals for humans to drink or use in agriculture. Of the remaining 3% of potentially usable freshwater, more than two-thirds is frozen in ice caps and glaciers. That leaves less than 1% available for sustaining all life on Earth, spread across our planet in rivers, lakes, underground aquifers, ground ice and permafrost. It’s these sources of water that are being rapidly depleted by humans, but slowly replenished by rain and snowfall. And this limited supply isn’t distributed evenly around the globe. Diverse climates and geography provide some regions with more rainfall and natural water sources, while other areas have geographic features that make transporting water much more difficult. And supplying the infrastructure and energy it would take to move water across these regions is extremely expensive. In many of these water-poor areas, as well as some with greater access to water, humanity is guzzling up the local water supply faster than it can be replenished. And when more quickly renewed sources can’t meet the demand, we start pumping it out of our finite underground reserves. Of Earth’s 37 major underground reservoirs, 21 are on track to be irreversibly emptied. So while it’s true that our planet isn’t actually losing water, we are depleting the water sources we rely on at an unsustainable pace. This might seem surprising – after all, on average, people only drink about two liters of water a day. But water plays a hidden role in our daily lives, and in that same 24 hours, most people will actually consume an estimated 3000 liters of water. In fact, household water – which we use to drink, cook, and clean – accounts for only 3.6% of humanity’s water consumption. Another 4.4% goes to the wide range of factories which make the products we buy each day. But the remaining 92% of our water consumption is all spent on a single industry: agriculture. Our farms drain the equivalent of 3.3 billion Olympic-sized swimming pools every year, all of it swallowed up by crops and livestock to feed Earth’s growing population. Agriculture currently covers 37% of Earth’s land area, posing the biggest threat to our regional water supplies. And yet, it’s also a necessity. So how do we limit agriculture’s thirst while still feeding those who rely on it? Farmers are already finding ingenious ways to reduce their impact, like using special irrigation techniques to grow “more crop per drop”, and breeding new crops that are less thirsty. Other industries are following suit, adopting production processes that reuse and recycle water. On a personal level, reducing food waste is the first step to reducing water use, since one-third of the food that leaves farms is currently wasted or thrown away. You might also want to consider eating less water-intensive foods like shelled nuts and red meat. Adopting a vegetarian lifestyle could reduce up to one third of your water footprint. Our planet may never run out of water, but it doesn’t have to for individuals to go thirsty. Solving this local problem requires a global solution, and small day-to-day decisions can affect reservoirs around the world.

P38? Are you a body with a mind or a mind with a body

Look at your hand. How do you know it's really yours? It seems obvious, unless you've experienced the rubber hand illusion. In this experiment, a dummy hand is placed in front of you and your real hand is hidden behind a screen. Both are simultaneously stroked with a paint brush. No matter how much you remind yourself the dummy hand isn't yours, you eventually start to feel like it is, and inevitably flinch when it's threatened with a knife. That may just be a temporary trick, but it speaks to a larger truth: our bodies, the physical, biological parts of us, and our minds, the thinking, conscious aspects, have a complicated, tangled relationship. Which one primarily defines you or your self? Are you a physical body that only experiences thoughts and emotions as a result of biochemical interactions in the brain? That would be a body with a mind. Or is there some non-physical part of you that's pulling the strings but could live outside of your biological body? That would be a mind with a body. That takes us to an old question of whether the body and mind are two separate things. In a famous thought experiment, 16th-century philosopher René Descartes pointed out that even if all our physical sensations were just a hallucinatory dream, our mind and thoughts would still be there. That, for him, was the ultimate proof of our existence. And it led him to conclude that the conscious mind is something separate from the material body that forms the core of our identity. The notion of a non-physical consciousness echoes the belief of many religions in an immaterial soul for which the body is only a temporary shell. If we accept this, another problem emerges. How can a non-physical mind have any interaction with the physical body? If the mind has no shape, weight, or motion, how can it move your muscles? Or if we assume it can, why can your mind only move your body and not others? Some thinkers have found creative ways to get around this dilemma. For example, the French priest and philosopher Nicolas Malebranche claimed that when we think about reaching for a fork, it's actually god who moves our hand. Another priest philosopher named George Berkeley concluded that the material world is an illusion, existing only as mental perceptions. This question of mind versus body isn't just the domain of philosophers. With the development of psychology and neuroscience, scientists have weighed in, as well. Many modern scientists reject the idea that there's any distinction between the mind and body. Neuroscience suggests that our bodies, along with their physical senses, are deeply integrated with the activity in our brains to form what we call consciousness. From the day we're born, our mental development is formed through our body's interaction with the external world. Every sight, sound, and touch create new maps and representations in the brain that eventually become responsible for regulating our experience of self. And we have other senses, besides the typical five, such as the sense of balance and a sense of the relative location of our body parts. The rubber hand illusion, and similar virtual reality experiments, show that our senses can easily mislead us in our judgment of self. They also suggest that our bodies and external sensations are inseparable from our subjective consciousness. If this is true, then perhaps Descartes' experiment was mistaken from the start. After all, if we close our eyes in a silent room, the feeling of having a body isn't something we can just imagine away. This question of mind and body becomes particularly interesting at a time when we're considering future technologies, such as neural prosthetics and wearable robots that could become extended parts of our bodies. Or the slightly more radical idea of mind uploading, which dangles the possibility of immortal life without a body by transferring a human consciousness into a computer. If the body is deeply mapped in the brain, then by extending our sense of self to new wearable devices, our brains may eventually adapt to a restructured version with new sensory representations. Or perhaps uploading our consciousness into a computer might not even be possible unless we can also simulate a body capable of delivering physical sensations. The idea that our bodies are part of our consciousness and vice versa also isn't new. It's found extensively in Buddhist thought, as well as the writings of philosophers from Heidegger to Aristotle. But for now, we're still left with the open question of what exactly our self is. Are we a mind equipped with a physical body as Descartes suggested? Or a complex organism that's gained consciousness over millions of years of evolution thanks to a bigger brain and more neurons than our distant ancestors? Or something else entirely that no one's yet dreamt up?

P39? ?At what moment are you dead

For as far back as we can trace our existence, humans have been fascinated with death and resurrection. Nearly every religion in the world has some interpretation of them, and from our earliest myths to the latest cinematic blockbusters, the dead keep coming back. But is resurrection really possible? And what is the actual difference between a living creature and a dead body, anyway? To understand what death is, we need to understand what life is. One ancient theory was an idea called vitalism, which claimed that living things were unique because they were filled with a special substance, or energy, that was the essence of life. Whether it was called qi, lifeblood, or humors, the belief in such an essence was common throughout the world, and still persists in the stories of creatures who can somehow drain life from others, or some form of magical sources that can replenish it. Vitalism began to fade in the Western world following the Scientific Revolution in the 17th century. René Descartes advanced the notion that the human body was essentially no different from any other machine, brought to life by a divinely created soul located in the brain's pineal gland. And in 1907, Dr. Duncan McDougall even claimed that the soul had mass, weighing patients immediately before and after death in an attempt to prove it. Though his experiments were discredited, much like the rest of vitalism, traces of his theory still come up in popular culture. But where do all these discredited theories leave us? What we now know is that life is not contained in some magical substance or spark, but within the ongoing biological processes themselves. And to understand these processes, we need to zoom down to the level of our individual cells. Inside each of these cells, chemical reactions are constantly occurring, powered by the glucose and oxygen that our bodies convert into the energy-carrying molecule known as ATP. Cells use this energy for everything from repair to growth to reproduction. Not only does it take a lot of energy to make the necessary molecules, but it takes even more to get them where they need to be. The universal phenomenon of entropy means that molecules will tend towards diffusing randomly, moving from areas of high concentration to low concentration, or even breaking apart into smaller molecules and atoms. So cells must constantly keep entropy in check by using energy to maintain their molecules in the very complicated formations necessary for biological functions to occur. The breaking down of these arrangements when the entire cell succumbs to entropy is what eventually results in death. This is the reason organisms can't be simply sparked back to life once they've already died. We can pump air into someone's lungs, but it won't do much good if the many other processes involved in the respiratory cycle are no longer functioning. Similarly, the electric shock from a defibrillator doesn't jump-start an inanimate heart, but resynchronizes the muscle cells in an abnormally beating heart so they regain their normal rhythm. This can prevent a person from dying, but it won't raise a dead body, or a monster sewn together from dead bodies. So it would seem that all our various medical miracles can delay or prevent death but not reverse it. But that's not as simple as it sounds because constant advancements in technology and medicine have resulted in diagnoses such as coma, describing potentially reversible conditions, under which people would have previously been considered dead. In the future, the point of no return may be pushed even further. Some animals are known to extend their lifespans or survive extreme conditions by slowing down their biological processes to the point where they are virtually paused. And research into cryonics hopes to achieve the same by freezing dying people and reviving them later when newer technology is able to help them. See, if the cells are frozen, there's very little molecular movement, and diffusion practically stops. Even if all of a person's cellular processes had already broken down, this could still conceivably be reversed by a swarm of nanobots, moving all the molecules back to their proper positions, and injecting all of the cells with ATP at the same time, presumably causing the body to simply pick up where it left off. So if we think of life not as some magical spark, but a state of incredibly complex, self-perpetuating organization, death is just the process of increasing entropy that destroys this fragile balance. And the point at which someone is completely dead turns out not to be a fixed constant, but simply a matter of how much of this entropy we're currently capable of reversing.

P40? ?Attack of the killer algae

We've all seen the movies where a monster, created by a scientist in a laboratory, escapes to wreak havoc on the outside world. But what if the monster was not some giant rampaging beast, destroying a city, but just a tiny amount of seaweed with the potential to disrupt entire coastal ecosystems? This is the story of Caulerpa taxifolia, originally a naturally occurring seaweed native to tropical waters. In the 1980s, one strain was found to thrive in colder environments. This trait, combined with its beautiful, bright green color and ability to grow quickly without maintenance made it ideal for aquariums, which it helped keep clean by consuming nutrients and chemicals in the water. Further selective breeding made it even heartier, and soon it was used in aquariums around the world. But it was not long before a sample of this aquarium-developed super algae turned up in the Mediterranean Sea near the famed Oceanographic Museum of Monaco. The marine biologist who found it believed that the museum had accidentally realeased it into the ocean along with aquarium waters, while museum directors claimed it had be carried into the area by ocean currents. Regardless of how it ended up there, the non-native Caulerpa multiplied rapidly, having no natural predators due to releasing a toxin that keeps fish away. And like some mythical monster, even a tiny piece that broke off could grow into a whole new colony. Through water currents and contact with boat anchors and fishing lines, it fragmented and spread throughout Mediterranean coastal cities covering coral reefs. So what was the result of this invasion? Well, it depends on who you ask. Many scientists warned that the spread of Caulerpa reduces biodiversity by crowding out native species of seaweed that are eaten by fish, with the biologist who first discovered its presence dubbing it Killer Algae. Other studies instead claim that the algae actually had a beneficial effect by consuming chemical pollutants -- one reason the aquariums strain was developed. But the disruption of a natural ecosystem by an introduced foreign species can have unpredictable and uncontrollable effects that may not be immediately visible. So when Culerpa taxifolia was discovered at Carlsbad's Agua Hedionda Lagoon, near San Diego in the year 2000, having most likely come from the dumping of home aquarium water into a connecting storm drain, it was decided to stop it before it spread. Tarps were placed over the Culerpa colonies and chlorine injected inside. Although this method killed all other marine life trapped under the tarps, it did succeed in eradicating the algae and native eelgrass was able to emerge in its place. By responding quickly, authorities in California were able to prevent Culerpa from propagating. But another occurrence of the strain, in the coastal wetlands of southeast Australia, was left unchecked and allowed to spread. And unfortunately, a tarp cannot cover the Mediterranean Sea or the Australian coast. Invasive species are not a new problem, and can indeed occur naturally. But when such species are the results of human directed selective breeding or genetic modification and then released into the natural environment, their effect on ecosystems can be far more radical and irreversible. With the proliferation of new technologies and multiple threats to the environment, it is more important than ever for scientists to monitor and evaluate the risks and dangers, and for the rest of us to remember that what starts in our backyard can effect ecosystems half a world away.