Here’s How Space Megastructures Will Look, According to Neal Stephenson

Post 6867

Annalee Newitz

Here’s How Space Megastructures Will Look, According to Neal Stephenson

Here's How Space Megastructures Will Look, According to Neal Stephenson

Famed scifi author Neal Stephenson’s new novel Seveneves is out today, and one of the most exciting things about it is that it’s packed with realistic representations of space megastructures where humans live. We talked to Stephenson about his ideas, and have some exclusive art from Weta showing what they look like.

Mild spoilers for the book follow.

The premise of Seveneves is in the novel’s very first sentence (you can read the first chapter on Gizmodo here):

The moon blew up without warning and for no apparent reason. It was waxing, only one day short of full. The time was 05:03:12 UTC. Later it would be designated A+0.0.0, or simply Zero.

After Day Zero, which happens about a decade into our future, humanity discovers that it only has a few hundred day left to live before fragments of the Moon start bombarding the planet and turn it into a fiery hellscape. So the world’s governments, engineers, and an Elon Musk-esque space entrepreneur get together to try to turn the International Space Station into the centerpiece of a massive “swarm” of spacecraft that will hold a couple thousand humans and keep them safe for the next 5,000 years while the Moon carpet-bombs Earth.

Above, you can see what eventually happens to the Endurance, one of the spacecraft launched in the frantic years before what the characters call the “hard rain” of Moon fragments. It’s been joined to the old space station, radiation shielded with a massive chunk of ice chipped off of a nearby asteroid, and it’s basically running for its life out of the burning Earth’s gravity well.

Stephenson told me by phone from Seattle:

I wanted to create an interesting scifi universe that didn’t violate the laws of physics, and that means that you’re limited to staying inside the solar system. I also wanted to get away from the ship-centric style of science fiction. Star Trek is ship-centric and it’s all about the Enterprise — there are many other examples. What if we decided to get away from the obsession with ships and instead thought about big machines and structures that might be used to create a civilization inside the solar system?

Here's How Space Megastructures Will Look, According to Neal Stephenson

Above, you can see an illustration of the many kinds of craft that Earth launched to become the swarm that’s humanity’s new home. They need many small craft in order to make their habitat resilient and able to move fast — especially because they’re surrounded by the debris from the Moon exploding. So if a chunk of rock is hurtling toward them, the ships follow a complicated algorithm to spread apart and get out of the way.

At the core of the swarm is Izzy, the nickname for a future version of the ISS. Future asteroid miners have attached a metal-rich asteroid to her, and a roboticist aboard the craft is researching how to use her fleet of robots to mine it.

Because everybody is stuck in small groups in those “arklets” you see in the illustration above, they communicate mostly via the internet. And this results in a horrific social media war after humanity’s demise. I won’t spoil it for you, but suffice to say that when the last couple thousand people on Earth start trolling each other online, it gets really terrifying.

Stephenson says:

It’s common to observe that the style of discourse on social media doesn’t always represent what’s best in ourselves. So this is more of a contingent thing — it’s about having the wrong technology at the wrong time. Disastrous consequences emerge from it.

He also believes that space technology as we know it today was developed at the wrong time:

We developed space tech too early due to weird historical circumstances. Hitler wanted to bomb London so he put resources into rockets way ahead of they would have been built otherwise. Before the war they were just small experimental things. And then suddenly this bizarre situation came up where the only way that Hitler could bomb London was by building rockets. It wasn’t even a good military strategy, but he was crazy and had dictatorship so he got what he wanted.

So rockets are like this weird thing in tech history, and their development accelerated even more with A bomb being developed at the end of that war. Rockets were a great way to throw nukes around. So between Hitler and the U.S. and Soviets during the Cold War, a staggering amount of resources got thrown at rockets, over a span of a few decades. And all the smart people who work at Google today would have been building rockets back then.

The pendulum between information tech and space tech is swinging back the other direction, though. Stephenson adds:

In the last couple of decades, we’ve swung the other direction. We’ve dropped everything on the front of infrastructure and smart people are doing apps or what have you. It’s been two extreme swings of the pendulum. And now I think we’re coming back to reasonable middle ground. where Elon Musk — who made his fortune in information technology — is applying that money to building rockets.

Here's How Space Megastructures Will Look, According to Neal Stephenson

In Seveneves, the offspring of the people who make it into space eventually figure out how to live there permanently. And they build massive cities out of the Moon’s debris, forming a ring of habitats around Earth. They travel between these cities by riding on “the Eye” (pictured above), which is a city in the shape of a wheel — and the cities of the ring pass through it, docking briefly so that people can get on and off. There’s actually a whole city built inside a chain on the inner ring of the Eye, which is called Chainhattan.

Stephenson said:

There’s been plenty of work for many decades about things like O’Neill [cylinders], built with in situ materials. I wanted to know — what if you made a machine that flew back and forth to connect each of these habitats in turn. There are certain parts of the world like the Philippines where everybody is on an island, so ferries become incredibly important. So then I started figuring out how you could make a device that would sit up there and have the ability to connect with different habitats at different times.

Plus, he wanted to connect the Eye with Earth. So he imagined a mobile space elevator hanging down from its outer ring, with a city called the Cradle serving as a counterweight in the atmosphere:

If you work on physics it requires a system of counterweights to traverse around the ring. It seemed to make sense to run a tether down to the surface and have a space elevator on the tether. It hangs lose in atmosphere and it’s effectively a city on the end of a rope. It gets dragged through clouds and it can be set down in certain locations.

Here's How Space Megastructures Will Look, According to Neal Stephenson

There’s nothing better than reading about space megastructures that you want to visit. Well, visiting them would be even better. But for now, we can at least read Seveneves and feast our eyes on these incredible illustrations of the space cities of tomorrow.

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The World’s Oldest Stone Tools Were Not Made By Humans

Post 6866

Sarah Zhang

The World’s Oldest Stone Tools Were Not Made By Humans

The World's Oldest Stone Tools Were Not Made By Humans

Archeologists working in Kenya have discovered the world’s oldest stone tools. At 3.3 million years, they’re 700,000 years older than what were previously the most ancient stone tools ever discovered. In fact, they’re even older than humans.

Since io9 wrote about the discovery presented at a conference in April, the archeological team has published a paper in Nature with a bevy of new photos. These humble rocks may not look particularly exciting to the untrained eye. But to archeologists, these are clearly tools: anvils, sharp-edged flakes, and hammers. All told, researchers found 149 stone artifacts at a site in northern Kenya.

The World's Oldest Stone Tools Were Not Made By Humans

The tools were likely made with rudimentary techniques, as Smithsonian explains:

Further analysis of the markings on the tools and attempts to replicate their production suggests two possible ways: The toolmaker might have set the stone on a flat rock and chipped away at it with a hammer rock. Or, the toolmaker could have held the stone with two hands and hit it against the flat base rock.

But it’s really their age that’s surprising. Carbon isotope dating puts them before the emergence of Homo genus 2.8 million years ago. The discovery means scientists will have to rethink the current narrative of brain evolution in early hominins. Who actually made the tools is unknown. One suspect is Kenyanthropus platyops, first discovered in, yes, Kenya in 1999.

At Gizmodo, we’re usually dedicated to bringing the latest and greatest in tech. But here are technology’s humble origins. Behold, the world’s oldest known tools.

[Nature via Smithsonian]

The World's Oldest Stone Tools Were Not Made By Humans

The World's Oldest Stone Tools Were Not Made By Humans

The World's Oldest Stone Tools Were Not Made By Humans

Image credits: MPK-WTAP

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The Wrong Drug Reaction Could Literally Make Your Skin Peel Off

Post 6865

Esther Inglis-Arkell

The Wrong Drug Reaction Could Literally Make Your Skin Peel Off

The Wrong Drug Reaction Could Literally Make Your Skin Peel Off

Good morning, and get ready to get a bad case of internal shivers! This morning’s body horror is provided by toxic epidermal necrolysis, which can be induced by… so many things. So many things.

Toxic epidermal necrolysis begins when angry red patches erupt on the skin on your face. And your chest. Also your genitals. The patches spread and grow until they form a connected painful, blistering expanse of skin that covers much of your torso. Eventually, your skin dies while still covering your body. Once it’s dead, there’s nothing holding it there, so it comes off in huge sheets.

But really, it begins earlier, when you take one of a hundred different kinds of medications. These medications are safe. They’ve been approved. For some reason, though, your body just fails to metabolize them. Instead it shifts what it apparently considers to be horrifically toxic chemicals to the epidermis, and sheds the epidermis.

The Wrong Drug Reaction Could Literally Make Your Skin Peel Off

The epidermis is only the outer layer of your skin. You’re not just vein and muscle underneath it. However, the epidermis is the primary barrier that keeps infection out of your body. People who develop toxic epidermal necrolysis are at incredibly high risk for lethal sepsis.

Fortunately, this condition is one-in-a-million, but it leaves people hospitalized for weeks, and has a 25% mortality rate. What’s truly scary is the range of drugs that cause it. The list of drugs known to occasionally do this includes corticosteroids routinely used to treat inflammation, and antibiotics, including good old penicillin. If your body decides it can’t deal with any of these, it might just shed your skin to get rid of them. At which point you can’t do anything but get skin grafts, stay in a sterile environment, and never take those drugs again.

Image: The Scream.

[Source: The Hypochondriac’s Pocket Guide To Horrible Diseases You Probably Already Have]

Sleep Paralysis: Causes, Symptoms & Treatment

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Sleep Paralysis: Causes, Symptoms & Treatment

Sleep paralysis is the inability to move or speak immediately after waking up. This can be an exceptionally scary time for those afflicted with this weird phenomenon, but despite former beliefs, the feeling of paralysis is not caused by supernatural beings.


During rapid eye movement (REM) sleep the brain has vivid dreams, while the muscles of the body are essentially turned off. While sleeping, the muscles are unable to move so that the person won’t be able to act out dreams with their body. Sleep paralysis happens when a person wakes up before REM is finished. The person will be conscious, but the body’s ability to move hasn’t been turned back on yet.

Several things can bring on episodes of sleep paralysis. For example, sleep deprivation, some medications and some sleep disorders, such as sleep apnea are triggers. Also, sleep paralysis is commonly seen in patients with narcolepsy, said Dr. Shelby Harris, director of Behavioral Sleep Medicine at the Sleep-Wake Disorders Center at the Montefiore Health System in the Bronx, New York.

According to a study in 2011 by Pennsylvania State University, 7.6 percent of the general population has problems with sleep paralysis. People with mental disorders such as anxiety and depression are more likely to experience sleep paralysis. According to the study, 31.9 percent of those with mental disorders experienced episodes.


Those afflicted with sleep paralysis are often unable to move their bodies or speak immediately after waking up. This can last one to two minutes, according to the Mayo Clinic. People experiencing sleep paralysis may also feel a weight on their chest or a choking feeling.

In the past, it was believed that demons caused sleep paralysis by holding people down or sitting on their chest. This was often due to hallucinations, which are a common symptom during sleep paralysis because the brain is still in a dream state. People have reported seeing ghosts, demons and other strange apparitions while experiencing paralysis.

Prevention and treatment

For most people, there is no treatment for sleep paralysis. The key is prevention and the treatment of any underlying causes.

After one episode of sleep paralysis, it may not be necessary to get a doctor’s appointment right away. “If you have rare episodes of sleep paralysis, but haven’t been seen by a sleep specialist, make sure your sleep hygiene is solid. For example, sleep paralysis can be a sign that you’re sleep deprived,” Harris told Live Science. Harris suggested that those experiencing sleep paralysis should make sure to get enough sleep on a regular basis, avoid alcohol, nicotine and drugs all night, starting three hours before bedtime. They should also limit caffeine after 2 p.m. and keep electronics out of the bedroom.

“If these things don’t help, and you’re having episodes that are becoming somewhat more frequent, see a sleep specialist to see if there’s any underlying medical disorder that might be causing the sleep paralysis,” Harris said.

According to the UK National Health System (NHS), sleep paralysis is not dangerous, though those experiencing extreme sleep paralysis may be prescribed a short course of antidepressant medication, such as clomipramine.

During the attack it is important to stay calm and realize that it will pass soon. “There’s not much you can do during an attack besides say to yourself, ‘This is only temporary. It will pass very shortly and I will be able to move soon,'” Harris said. “This really only works if you’ve had an episode or two before and know what to expect. These attacks can be quite scary to experience, especially if you’ve never had one before.”

Additional resources

Editor’s Recommendations

Exercise Fuels Mental ‘Time Travel’

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Exercise Fuels Mental ‘Time Travel’

Wendy Suzuki is a Professor of Neural Science and Psychology at New York University (NYU)’s Center for Neural Science. A popular speaker, she is a regular presenter at the World Science Festival and TEDx, and is frequently interviewed on television and in print for her expertise regarding the effects of exercise on brain function. Her first book, “Healthy Brain, Happy Life” (Dey Street Books, 2015), is now available. Suzuki contributed this article to Live Science’s Expert Voices: Op-Ed & Insights.

In my late 30s, when I first began to exercise regularly, I experienced firsthand the profound effects that exercise can have on both my body and my brain. In fact, these observations completely changed my motivation for going to the gym. It started during a river rafting trip on the mighty Cotahuasi river in Peru, in one of the deepest valleys in the world. On that trip I realized that, although I was healthy, I was not nearly as strong as my fellow river rafters: There were 16-year-olds on the trip who could lift more than I could, and there were 60-year-olds who had more stamina than I did. I knew I had to do something about it.

When I got back, I marched to the nearest gym, got myself a trainer and started building a regular and rigorous exercise routine. I started slowly at first, but I’m happy to say I am still exercising regularly today, almost 10 years later. As I made a gradual yet profound change in my exercise routine, I began to notice an equally profound change in both my body and my brain. I noticed not only clear improvements in my strength, stamina and overall cardiovascular fitness, but also strikingimprovements in my mood, memory, attention — as well as other things that were more difficult to name, at first. I felt like a poster child for all of those positive brain effects reported so frequently by the press.

Exercise improves mood, memory and attention

As a professor of neuroscience with an active research lab, I specialize in the study of the hippocampus, a brain structure critical for long-term memory, so I was particularly interested in how exercise affected my memory. I noticed the cognitive benefits of exercising especially when I was writing grants, and found it much easier to remember and integrate related findings from different journal articles.

In fact, as reviewed in a 2013 article published in Trends in Cognitive Science, we know a lot about the memory functions of the hippocampus, as well as the effects of exercise on the hippocampus, mainly through studies with rodents. We also know, from a series of key studies published throughout the 1990s, that the hippocampus is one of only two brain areas where new brain cells are born in adults — a process known as adult hippocampal neurogenesis.

Experiments with rodents have shown that exercise (in the form of activity on a running wheel) significantly enhances the rate at which new hippocampal cells are born. In addition, a growing number of studies have shown that, compared to sedentary rats, rats that exercise and experience exercise-enhanced hippocampal neurogenesis show better memory performance on a range of different tasks. The striking improvements I saw in my own mood and memory inspired me to want to understand if the same brain changes that researchers had seen in rodents with exercise were also happening in my brain.

I was so fascinated with this question that I shifted my entire research focus from the study of memory in the hippocampus to the effects of exercise on brain functions in people. (I tell the story of how this personal transformation made me change the research direction in my lab, and the science behind it, in my new book Healthy Brain Happy Life.)  [‘Healthy Brain, Happy Life’ (US, 2015): Book Excerpt]

Can exercise also improve creativity? 

As I increased my regular exercise routine, even more astonishing than the improvements in my mood, attention and memory was what seemed to be a newfound spark of creativity.

For example, I found myself coming up with “out of the box” neuroscience courses to teach, I started exploring new hobbies like writing and singing, and started exploring new professional collaborations with artists, musicians and dancers.

In observing that exercise was enhancing not only my memory but also my creativity, I started to explore that connection. It turns out that this observation is consistent with a new discovery related to the functions of the hippocampus. [Delayed Gratification – How the Hippocampus Helps Us Hold Off (Op-Ed)]

More than 50 years of research has clearly linked the hippocampus to episodic memory — that is, memory for the details of the events in our lives. Recent studies have started to provide striking evidence that the hippocampus is also important for what neuropsychologists call “future thinking,” otherwise known as imagination.

The hippocampus, the past and the future

In the 1980s, influential Estonian-Canadian memory expert Endel Tulving described remembering personal experiences as “mental time travel,” involving both the past and the future. While the vast majority of studies done since Tulving proposed this idea have focused on memory — mental time travel to the past — recent findings suggest that the same brain areas are involved in mental time travel to the future, or future imagination.

The first clear evidence in support of the role of the hippocampus in imagination came from a report published in 2007 in the Proceedings of the National Academy of Sciences. That study examined patients with selective damage to the hippocampus. Patients with hippocampal damage and people of the same age and education level who did not have damage to the hippocampus were asked to imagine something new that did not contain memories of past events.

When they were asked to imagine a scene in which they were lying on a white, sandy beach in a tropical location, one of the patients with hippocampal damage, who had never visited a tropical beach, said, “As for seeing, I can’t really, apart from just sky. I can hear the sound of seagulls and of the sea…. Um… that’s about it…..”

By contrast, when study participants without hippocampal damage were asked the same question, they provided great detail about the surrounding landscape, the temperature, what they imagined they were drinking and the activities on the fishing boat passing by. These findings, supported by similar results from other studies published in 2011 in the Journal of Neuroscience and in 2010 in the journal Neurocase suggest that damage to the hippocampus produces impairments in the ability to imagine future events, in addition to the hippocampus’s critical role in remembering past events.

As reviewed in 2007 in an article published in Nature Reviews Neuroscience, key insights have also come from neuroimaging studies in humans in which researchers monitor the patterns of brain activation while subjects are asked to remember a personal experience from their past or imagine a plausible event in their future. Study participants might be cued by a noun for both of these conditions (e.g., “mountain” or “cat”).

Those studies show that remembering episodic memories from the past as well as imagining future scenarios engage the same widespread network of brain areas, including not only the hippocampus and some of the surrounding structures in the brain’s temporal lobe, but also the medial prefrontal cortex and regions toward the back of the brain, including the precuneus and the retrosplenial cortices.

Those neuroimaging results provide new insight into the widespread network of brain structures, including the hippocampus, which is involved in both recalling personal episodic memories from the past and constructing or imagining possible scenarios in the future.

A sense of place

My favorite evidence supporting the idea that the hippocampus is involved in imagining future events doesn’t come from studying people, but rather rodents. One of the most striking patterns of neural activity in the rodent hippocampus is in their hippocampal place cells. Their discovery, by John O’Keefe of University College, London, was recognized with the 2014 Nobel Prize in physiology or medicine.

Place cells respond with brief bursts of electrical activity, called action potentials or spikes, whenever the rat is in a particular location in its environment. The part of the environment where a place cell fires is called the cell’s place field. When the rat is running down a particular alleyway or arm on a maze, instruments can record groups of place cells that fire in sequence as the rat runs through its particular place fields.

When imaged between bouts of running (either when the rat is just being still or sleeping), the rat’s hippocampus actually replays those same spatial trajectories from the same sequences of place cells that were active when the rat was running. This phenomenon is called hippocampal replay. The replay typically happens at a much faster speed than the original sequence. However, the pattern is the same, and replay is thought to be involved in the strengthening spatial memory.

But recent evidence provided a new and unexpected twist to hippocampal activity. In 2011 a study published in the journal Nature, showed that rodent hippocampal cells not only exhibit replay of spatial information from past events, but if you closely examine hippocampal activity during those rest periods, you also see patterns of activity that predict some of the patterns of activity that will be experienced in the future. Note that I’m not talking about the neural basis of ESP but rather the hippocampal network seems to be projecting or “playing” future possible spatial scenarios based on its past experience, some of which actually occur.

This study identified this phenomenon by first recording the activity of hippocampal cells as rats became familiar with one part (Part A) of a spatial maze where lots of place cells and replay events were active. During the exploration of Part A, there was also a part of the maze that was blocked off, and the rats never experienced the other part (Part B). When the rats finally saw Part B of the maze, the experimenters discovered that some place-cell activity seen in the rest period, before Part B was ever revealed, actually predicted the pattern of activity seen when the rat was able to explore Part B of the maze.

This phenomenon is called hippocampal preplay and suggests the hippocampus is not only replaying spatial events it had experienced before (memory), but also seems to be playing out possible scenarios that could occur some time in the future (imagination). Those hippocampal preplay events are based on knowledge of the current environment and form a framework for future neural signals representing those future events.

Editor’s Recommendations

‘Healthy Brain, Happy Life’ (US, 2015): Book Excerpt

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‘Healthy Brain, Happy Life’ (US, 2015): Book Excerpt

Wendy Suzuki is a professor of Neural Science and Psychology at New York University (NYU)’s Center for Neural Science. She is a regular presenter at the World Science Festival and TEDx, and is frequently interviewed on television and in print for her expertise regarding the effects of exercise on brain function. Her first book, “Healthy Brain, Happy Life” (Dey Street Books, 2015), is now available. Suzuki contributed this article to Live Science’s Expert Voices: Op-Ed & Insights.

The following is an excerpt from “Healthy Brain, Happy Life” (Dey Street Books, 2015), Reprinted with permission from Dey Street Books, Copyright © 2015 by Wendy Suzuki. For more about Suzuki’s research, read her essay, “‘Mental Time Travel’ and the Effects of Exercise on the Brain.”


Discovering a Workout With a Message

During one of my regular evening sessions at the gym when I had already attained most of my weight-loss goal, the list of possible classes caught my eye. I had a choice that evening between a cardio boot camp class and another class that I had never heard of called intenSati — with no explanation for what intenSati meant. I was not feeling all that energetic, and the cardio boot camp class just sounded too hard. So that’s how I ended up walking into my first intenSati class. Little did I know that this class was not only harder than cardio boot camp but would be the catalyst for upping the level of my workouts, improving my mood and my outlook on life, and eventually even shifting my neuroscience research.

At the beginning of that class, the instructor, Patricia Moreno, the woman who created this class, told us that the term intenSati, comes from the combination of two words. Inten comes from the word intention. Sati is a Pali word (a language from India) that means “awareness or mindfulness.” She told us that the goal of the practice of intenSati is to bring an awareness/mindfulness to our own intentions. She explained that we were going to be doing different movements from kickboxing, dance, yoga and the martial arts, all the time shouting positive affirmations along with each move. I was not so sure about the shouting part, but Moreno was a completely riveting instructor so I stayed to experience this intriguing new class for myself.

That first class felt like an explosion of movements. Moreno started off showing us a simple yet energetic movement, such as alternating left and right punches. Once we got the movement down, she would then give us the affirmations that we would shout out along with that move. For example, with the punches, we said out loud, “I am strong now!” This move was called Strong. Each move had a specific name. We would do the first movement for a while, and then she would add a movement/affirmation combo, until we had strung fifteen or twenty different movements and affirmations together. Each particular set of affirmation/movement combos was written as a series with a specific message. The message was one of empowerment: The power of your mind, the power of positive action, the power of your body, and the power of positive thoughts over negative ones. It was a workout with a message.

Moreno told us that what we declare with our voices is powerful. And that when we start incorporating these powerful affirmations into our thoughts — that is, when we start to think and believe them — they become even more powerful still.

When we pushed our arms up in the air in an alternating fashion with our palms open and our fingers spread wide, we shouted, “Yes! Yes! Yes! Yes!”

When we punched up and down, we shouted, “I believe I will succeed!”

When we threw uppercut punches with alternating hands, we shouted, “I am inspired now!”

It was a workout for my body and my brain. Asking your brain to remember arm and foot work combinations, as well as affirmations to shout out, is asking your brain to work! There are also the words of the affirmations that the instructor is telling you, which you are also trying to remember — even before she says them. So your memory is also put to the test in an intenSati class.

Of course, I didn’t appreciate all of the brain–body connections being made by intenSati after just one class. I was trying hard just to keep up and remember the movements — never mind remembering the affirmations at the same time! And it was hard. Shouting those affirmations while doing all the moves made you more out of breath than just doing the movements alone and upped the level of the workout considerably. I was also definitely a little shy at first about shouting out the affirmations. But there were plenty of regulars in class that night shouting with abandon, and once I managed to get the movements down, I got caught up in the fun and started shouting along with everyone else.

Have you heard people say that people won’t remember what you say, only how you made them feel? I can’t remember the exact affirmations that I said that night in class, but I do remember how I felt: totally empowered, energized, and enlivened — in a brand-new way. And I could not wait to come back for the next class.

Harnessing the Power of the Brain – Body Connection

What was so different about this workout? Remember, I was already in good if not great shape by the time I wandered into this class. I was really starting to feel great about both my overall cardiovascular and muscular strength as well as the outside package after I lost the weight. I loved going to the gym and had already made it a regular part of my life. I was already feeling great and energized and was sure that my workouts helped me through those stress-filled years as I was applying for tenure, but intenSati brought something brand new into my life. I would not have been able to articulate it at first, but I now realize that this workout was so special because it brought the power of the brain–body connection to life for me more powerfully than I had ever felt it before.

The first thing I noticed was that I pushed myself during those workouts more than I had in any other class I was taking. Why? It was the power of those positive affirmations and actually speaking them out loud that seemed to flip a switch in me. It was the difference between doing a class and getting a good, sweat-inducing workout and really feeling strong because I was declaring I was strong or empowered or confident or a million other positive affirmations we used in that class. I was pushing myself even harder be- cause I started to really believe I was strong. And I started to really feel that strength, embodying it not just during class but also long after class ended, when I went back into the real world.

But this is where the power of the brain–body connection comes into play. This connection refers to the idea that the body has a powerful influence on our brain functions and conversely that the brain has a powerful influence over how our bodies feel and work and heal. While I had been going to the gym for some time, and I definitely felt much more fit and energized and happy, I really started to appreciate the true power of the brain–body connection only with this new class. And the first thing I noticed was how strongly this workout (body) boosted my mood (brain).

From a neurobiological perspective, we know the most about the brain basis of mood from situations in which mood is altered — namely from the study of depression, one of the most common psychiatric conditions in first-world countries like the United States.

From studies of abnormal mood states, we know mood is determined by a widespread and interconnected group of brain structures together with interconnected levels of a set of well-studied neurotransmitters and growth factors. We talked about the role of the hippocampus in memory, and recent studies have shown that its normal functioning is also involved in mood. In addition, the amygdala, important for processing and responding to emotional stimuli, and the prefrontal cortex are both implicated in regulating our mood states. Furthermore, two other systems, which I describe in greater detail in later chapters — the autonomic nervous system including the hypothalamus (Chapter 7) and the reward circuit (Chapter 8) — are involved in regulating our mood. We also know that the appropriate levels of particular neurotransmitters are important for regulating mood.

An influential theory of depression is that it is caused by a depletion of a category of neurotransmitters called monoamines. These include serotonin, whose low levels most of us associate with depression, but lowered levels of norepinephrine, another neurotransmitter, as well as dopamine are found in the brains of patients with depression. Therefore, the studies suggest that if you boost the levels of these neurotransmitters, you can boost mood.

Well, little did I know but I was getting a triple whammy of mood-boosting power with the intenSati workout. First, many studies have shown that not only does aerobic exercise improve measures of mood in subjects both with depression and without but that exercise boosts levels of the three key monoamines we know play a key role in mood: serotonin, noradrenaline and dopamine.

Besides these classic mood-associated neurotransmitters, exercise also increases levels of endorphins in the brain. Endorphin literally means “endogenous (made in the body) morphine.” It is a kind of morphine that has the ability to dull pain and provide feelings of euphoria. Endorphins are secreted by the brain’s pituitary gland into the blood, where they can affect cells throughout the brain that have specific receptors for them. Because endorphins are secreted into the bloodstream, they are categorized as a hormone; neurotransmitters, on the other hand, are released at synapses from the axon of the cells that synthesize them.

While most of us assume that endorphins are responsible for all or most of the high associated with some forms of exercise, the story is not as clear as all that. In fact, for many years there was a huge controversy in the neuroscience community (invisible to the popular press) over whether endorphins had anything to do at all with the so-called runner’s high. This was because, while there was good evidence that the level of endorphins increased in the peripheral bloodstream (that is, the bloodstream that courses through the body), it was not clear if exercise changed the level of endorphins in the brain, which is where they had to be working to produce the runner’s high. Only recently has a group in Germany provided evidence that running does activate the endorphin system in human brains and that the more profound the reported runner’s high, the stronger the activation. So neuroscience shows that a range of different neurotransmitters associated with mood and/or euphoria are increased with exercise and are likely causing at least part of the party mood caused by exercise.

The second mood-boosting whammy from intenSati comes from the spoken affirmations that are such a prominent part of this workout. A relatively large body of psychology experiments has shown that self-affirmations like the ones we were shouting to the rooftops in class help buffer people from a whole variety of different stressors, including peer-based classroom stress, rumination associated with negative feedback, and stress associated with social evaluation. One recent study reported that positive self-affirmations significantly improved mood in people with high self-esteem. We don’t know the brain and neurochemical changes associated with self-affirmations, but the behavioral evidence is quite clear that positive affirmations boost mood.

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What Is the First Law of Thermodynamics?

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What Is the First Law of Thermodynamics?

The First Law of Thermodynamics states that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of conservation of energy. This means that heat energy cannot be created or destroyed. It can, however, be transferred from one location to another and converted to and from other forms of energy.

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. In particular, it describes how thermal energy is converted to and from other forms of energy and how it affects matter. The fundamental principles of thermodynamics are expressed in four laws.

“The First Law says that the internal energy of a system has to be equal to the work that is being done on the system, plus or minus the heat that flows in or out of the system and any other work that is done on the system,” said Saibal Mitra, a professor of physics at Missouri State University. “So, it’s a restatement of conservation of energy.”

Mitra continued, “The change in internal energy of a system is the sum of all the energy inputs and outputs to and from the system similarly to how all the deposits and withdrawals you make determine the changes in your bank balance.” This is expressed mathematically as: ΔU = Q – W, where ΔU is the change in the internal energy, Q is the heat added to the system, and W is the work done by the system.


Scientists in the late 18th and early 19th centuries adhered to caloric theory, first proposed by Antoine Lavoisier in 1783, and further bolstered by the work of Sadi Carnot in 1824, according to the American Physical Society. Caloric theory treated heat as a kind of fluid that naturally flowed from hot to cold regions, much as water flows from high to low places. When this caloric fluid flowed from a hot to a cold region, it could be converted to kinetic energy and made to do work much as falling water could drive a water wheel. It wasn’t until Rudolph Clausius published “The Mechanical Theory of Heat” in 1879 that caloric theory was finally put to rest.

Thermodynamic systems

Energy can be divided into two parts, according to David McKee, a professor of physics at Missouri Southern State University. One is our human-scale macroscopic contribution, such as a piston moving and pushing on a system of gas. Conversely, things happen at a very tiny scale where we can’t keep track of the individual contributions.

McKee explains, “When I put two samples of metal up against each other, and the atoms are rattling around at the boundary, and two atoms bounce into each other, and one of the comes off faster than the other, I can’t keep track of it. It happens on a very small time scale and a very small distance, and it happens many, many times per second. So, we just divide all energy transfer into two groups: the stuff we’re going to keep track of, and the stuff we’re not going to keep track of. The latter of these is what we call heat.”

Thermodynamic systems are generally regarded as being open, closed or isolated. According to the University of California, Davis, an open system freely exchanges energy and matter with its surroundings; a closed system exchanges energy but not matter with its surroundings; and an isolated system does not exchange energy or matter with its surroundings. For example, a pot of boiling soup receives energy from the stove, radiates heat from the pan, and emits matter in the form of steam, which also carries away heat energy. This would be an open system. If we put a tight lid on the pot, it would still radiate heat energy, but it would no longer emit matter in the form of steam. This would be a closed system. However, if we were to pour the soup into a perfectly insulated thermos bottle and seal the lid, there would be no energy or matter going into or out of the system. This would be an isolated system.

In practice, however, perfectly isolated systems cannot exist. All systems transfer energy to their environment through radiation no matter how well insulated they are. The soup in the thermos will only stay hot for a few hours and will reach room temperature by the following day. In another example, white dwarf stars, the hot remnants of burned-out stars that no longer produce energy, can be insulated by light-years of near perfect vacuum in interstellar space, yet they will eventually cool down from several tens of thousands of degrees to near absolute zero due to energy loss through radiation. Although this process takes longer than the present age of the universe, there’s no stopping it.

Heat engines

The most common practical application of the First Law is the heat engine. Heat engines convert thermal energy into mechanical energy and vice versa. Most heat engines fall into the category of open systems. The basic principle of a heat engine exploits the relationships among heat, volume and pressure of a working fluid. This fluid is typically a gas, but in some cases it may undergo phase changes from gas to liquid and back to a gas during a cycle.

When gas is heated, it expands; however, when that gas is confined, it increases in pressure. If the bottom wall of the confinement chamber is the top of a movable piston, this pressure exerts a force on the surface of the piston causing it to move downward. This movement can then be harnessed to do work equal to the total force applied to the top of the piston times the distance that the piston moves.

There are numerous variations on the basic heat engine. For instance, steam engines rely on external combustion to heat a boiler tank containing the working fluid, typically water. The water is converted to steam, and the pressure is then used to drive a piston that converts heat energy to mechanical energy. Automobile engines, however, use internal combustion, where liquid fuel is vaporized, mixed with air and ignited inside a cylinder above a movable piston driving it downward.

Refrigerators, air conditioners and heat pumps

Refrigerators and heat pumps are heat engines that convert mechanical energy to heat. Most of these fall into the category of closed systems. When a gas is compressed, its temperature increases. This hot gas can then transfer heat to its surrounding environment. Then, when the compressed gas is allowed to expand, its temperature becomes colder than it was before it was compressed because some of its heat energy was removed during the hot cycle. This cold gas can then absorb heat energy from its environment. This is the working principal behind an air conditioner. Air conditioners don’t actually produce cold; they remove heat. The working fluid is transferred outdoors by a mechanical pump where it is heated by compression. Next, it transfers that heat to the outdoor environment, usually through an air-cooled heat exchanger. Then, it is brought back indoors, where it is allowed to expand and cool so it can absorb heat from the indoor air through another heat exchanger.

A heat pump is simply an air conditioner run in reverse. The heat from the compressed working fluid is used to warm the building. It is then transferred outside where it expands and becomes cold, thereby allowing it to absorb heat from the outside air, which even in winter is usually warmer than the cold working fluid.

Geothermal or ground-source air conditioning and heat pump systems use long U-shaped tubes in deep wells or an array of horizontal tubes buried in a large area through which the working fluid is circulated, and heat is transferred to or from the earth. Other systems use rivers or ocean water to heat or cool the working fluid.

Additional resources

Here are three other explanations of the First Law of Thermodynamics: