science

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National Poetry Month: Rhymed Tercet

Posted by Aibird on April 4, 2017
Posted in: Art, Author, Poetry, Science, Writing. Tagged: , , , , , . Leave a comment

My second poem for National Poetry Month is a Rhymed Tercet. The title of the Fractal is the Echoes of Spacetime.

Creation
by A. A. Zingler

Blazing hot inferno explodes into life
in its superheated soup of particles
the spark of inflation rapidly spikes.

Dust coalesced by gravity’s attraction
form the weave of all galaxies’ bones
and jumpstart protostars’ inner ignition.

The seeds for life erupts into existence
cooked in the crucible of massive stars–
their supernovas spew out ingredients.

New stars birthed in the galaxy’s nurseries
Gather supernova dust into planets
These abodes cultivates life’s biology.

Fractal created by A. A. Zingler

Traveling the Internets Again

Posted by Aibird on September 8, 2014
Posted in: Author, Blogging, Feminism, History, Writing. Tagged: , , , , , , , , , . Leave a comment

I may make this a regular post. I read a lot, and sharing what I read may be helpful to some. So without further ado, here is what I’ve read this past week:

Writing

How to Structure a Premise for Stronger Stories <— Great article to help you strengthen your stories.

The Different Levels of Editing <— An awesome article from an editor on the forum I help moderate. It explains in detail the different levels of editing, and this can be very useful for writers to understand. Each level has its place and its purpose, and knowing when and where to use each can be helpful in how we utilize editors and how we edit our own work.

“We have always fought.” Challenging the Women Cattle and Slaves Narrative <— By far one of the best articles I've read this week, especially in pertains to writing and other forms of media. Must read.

PSA: Your Default Narrative Settings are not Apolitical <— Also a must read.

Culture/Society and Us

Things I’ve Learned from being Transgender that aren’t about being Transgender <— Can relate to this article a lot.

What President Obama has done for Transgender People <— As the article name says, he has been heralded as the first transgender president. To be honest, I would say he is the only president that cared enough to act. For him to stick his neck out like this for people like me is pretty huge, especially in a culture that still vilifies us as monsters or curiosities that are publicly stripped apart.

The Militarized Mind: How a Narrative Becomes a Weapon <— A must read for everyone.

Violence Against Indigenous Women: Fun, Sexy, and No Big Deal on the Big Screen

What if we all carried that weight? <— If we all carried the weight of injustice, then we would not be able to bear it, and maybe, just maybe we would stop tolerating what we have forced others to carry alone. It is a good wake up call for us all.

How Men and Women are Critiqued in Performance Reviews <— I see the gender bias every day, and since I sit on the border of both genders, being trans, I notice it even more heavily. Here is yet more proof that gender bias exists and it hurts people.

I am not Afraid to Die: Why America Will Never be the Same Post Ferguson

The Police Violence We aren’t Talking About

The Brutalizing of Women in Video Games, and its Apologists

Science and Technology

Laniakea: Our Local Supercluster <— A fun article that explores our place in the universe.

Betelgeuse: Astronomers give it 100,000 years before it explodes <— A deep look into the science of astronomy.

Impact: Earth! <— Not really an article, but an interesting look into what would happen if an asteroid hit Earth. You can alter the parameters in various ways to see the differences based on size, density, approach vector, and so forth.

Books I read and am reading

The Four Agreements: A Toltec Wisdom Book by Don Miguel Ruiz (Finished.)

How to Know God: The Soul’s Journey into the Mystery of Mysteries by Deepak Chopra (1/3 of the way through the book.)

Beautiful Outlaw by John Eldredge (1/3 of the way through the book.)

Now Write! Science Fiction, Fantasy, and Horror Edited by Laurie Lamson (Just started. Will write a review of this in the future.)

Update on Blog

I am working on a few articles that are specific to worldbuilding and one specific to genres. This has been a painful and busy few weeks for me, so my posts are taking longer to write than I would have liked. Thank you for your patience, and let me know your thoughts on the above articles! If you have any interesting articles to share, leave them in a comment, and I will be sure to read them.

Review: The Book of Barely Imagined Beings

Posted by Aibird on March 26, 2014
Posted in: Biology, Science. Tagged: , , , , . 1 Comment

The Book of Barely Imagined Beings by Caspar Henderson

I picked it up out of curiosity. It just sat on the new book shelf at the library; the front cover a mix of bizarre creatures, many in the form of letters. This book takes the idea of a medieval bestiary — all those lovely imagined beasts and the commentary on society they induced — and slathers it with the bizarre nature of our actual reality: the true fascinating stories of weird looking beasts within our own world. Through the examination of their appearance, lives, and other intricate details, he looks deep upon humanity itself, especially our interactions with these animals and what they represent within human society and identity. It’s a lovely book that explores life, society, and our impact on the world and each other in beautiful detail.

As stated in his introduction, this isn’t meant to be a full examination of the natural world.

This book is envisaged as an ‘aletheiagoria’ — a new coinage so far as I know, which alludes to phantasmagoria (a light-projected ghost show from mthe era before cinema) but uses the world ‘aletheia,’ the Greek for ‘truth’ or ‘revealing.’ It suggests (to me, at least) flickering ‘real’ images of a greater reality. I have tried to look at a few ways of being from different angles and, through ‘a wealth of unexpected juxtaositions’, explore both how they are like and unlike humans (or how we imagine ourselves to be) and also how their differences from and similarities to us cast light on human capabilities and human concerns.*

The book itself explores much more than just the animals themselves; it often wanders into fascinating analogies and digressions, where the author makes a deliberate attempt to use the animals to think with and ponder more than just the animals themselves. One of the major themes within the book is how evolutionary biology (and the scientific method contained within it) provides a “richer and more rewarding sense of the nature of existence than a view informed by myth and tradition alone**.” Through this lens, the author is able to examine the creatures in detail, but in any easy to approach manner. Written for the lay person, the majority of the discussions won’t be overly focused upon the biology of the creatures but upon their impact upon us. The digressions into philosophy, the consequences of humanity’s actions, and our impact upon the creatures will be just as relevant as the creature’s own stories. We are all intertwined, growing up on this same planet together, and the author writes of these connections beautifully.

Another interesting theme within the book is the ocean; two-thirds of the animals contained within are from the sea, and for a very good reason: the oceans inhabit seven-tenths of the surface and contain the vast majority of Earth’s biodiversity. It’s also full of great mysteries as one of the least well known areas on the planet. Some of the creatures examined will be far more alien than anything we’ve imagined, and others are familiar and almost comforting, yet their stories will weave a sense of connection and grief, for much of the great biodiversity and creatures within the sea suffer from the consequences of our overfishing, whaling industries, heavy amounts of pollution, and the acidification of the oceans due to climate change. Those connections between us and the world in which we live are laid bare within the tales of these creatures, and through them, we see aspects of ourselves, the soul of humanity, and what is revealed will be a challenge as much as it is liberating.

The creatures you find within these pages, some you may have heard of before such as dolphins are types of whales, but others may seem like alien lifeforms, bizarre if not perhaps frightening, but no less real. There may be no dragons or unicorns or mythical beasts of old in this bestiary, but what lies inside is a wealth of wonder and beauty, far beyond what we can even begin to imagine. So take your time, sit back, and walk with the author on this fascinating journey through some of the most fascinating and/or bizarre creatures that inhabit or have inhabited our planet.

 

 

* and ** taken from the Introduction.

The Uncertain Universe: How Science Discovers its Truths

Posted by Aibird on February 21, 2014
Posted in: Physics, Science, Writing. Tagged: , , , , . 3 Comments

Science explores the universe, and one of it’s main tenants isn’t to explain everything exactly. No, it’s to try to validate explanations (and ideas) through experiments, or to put in other words: any idea someone has devised to explain an event in our universe, that idea must be validated through experiment in order for it to be considered a scientific fact. This is perhaps the most basic definition of science, but as we shall soon see, science is a bit more complicated than this definition would lead us to believe. First let’s take a look at what our universe is actually like.

We live in a universe ruled by uncertainty on the tiniest scales. There’s a good reason for this, and part of that explanation is summed up in how the atom is structured. One of the most notable features of an atom is how much space it has. The center of it contains a small, densely packed nucleus, where protons and neutrons cluster tightly together. There’s a cloud of electrons in orbit around the nucleus. For all those who have taken or read about physics, one may already know about how plus (positive) charges attract minus (negative) charges. This is easily proven with magnets, where the north pole and south pole are opposite charges and thus attract one another. Now, protons and electrons are also opposite charges, and thus they do attract one another, but what is stopping them from being piled atop the nucleus?

Part of that is due to the uncertainty inherent within our universe. According to Quantum Mechanics, we cannot know both the position and the momentum of a particle. Richard Feynman has an excellent lecture about this very topic, and I’ll quote his explanation here:

Quantum mechanics has many aspects. In the first place, the idea that a particle has a definite location and a definite speed is no longer allowed; that is wrong. To give an example of how wrong classical physics is, there is a rule in quantum mechanics that says that one cannot know both where something is and how fast it is moving. The uncertainty of the momentum and the uncertainty of the position are complementary, and the product of the two is bounded by a small constant. We can write the law like this: ΔxΔp≥ℏ/2, but we shall explain it in more detail later. This rule is the explanation of a very mysterious paradox: if the atoms are made out of plus and minus charges, why don’t the minus charges simply sit on top of the plus charges (they attract each other) and get so close as to completely cancel them out? Why are atoms so big? Why is the nucleus at the center with the electrons around it? It was first thought that this was because the nucleus was so big; but no, the nucleus is very small. An atom has a diameter of about 10−8 cm. The nucleus has a diameter of about 10−13 cm. If we had an atom and wished to see the nucleus, we would have to magnify it until the whole atom was the size of a large room, and then the nucleus would be a bare speck which you could just about make out with the eye, but very nearly all the weight of the atom is in that infinitesimal nucleus. What keeps the electrons from simply falling in? This principle: If they were in the nucleus, we would know their position precisely, and the uncertainty principle would then require that they have a very large (but uncertain) momentum, i.e., a very large kinetic energy. With this energy they would break away from the nucleus. They make a compromise: they leave themselves a little room for this uncertainty and then jiggle with a certain amount of minimum motion in accordance with this rule. (Remember that when a crystal is cooled to absolute zero, we said that the atoms do not stop moving, they still jiggle. Why? If they stopped moving, we would know where they were and that they had zero motion, and that is against the uncertainty principle. We cannot know where they are and how fast they are moving, so they must be continually wiggling in there!)

The interesting part about this discussion is that experiments have validated the above numerous times. We literally cannot precisely know both position and momentum of any given particle at any given moment. This is why scientists often quip that no one truly understands Quantum Mechanics, because of this uncertainty principle and because of another interesting aspect of the theory: wave-particle duality, where light (and matter when examined on a tiny, tiny scale) are both particles and a wave simultaneously. Although we cannot ever precisely measure both position and momentum, what we can do is calculate the probability of the most likely event within the system we are examining, and then in experiments, validate if that calculation is correct the majority of the time or not.

What does this mean on a philosophical level?

For one thing, quantum mechanics shows how we cannot ever be absolutely precise. All experiments result in statistical findings, where the finding is an average of what happens. The important point here is that there is no knowing exactly what is going on, but we can determine to a high statistical probability what is going on. This is how scientists over time have been able to determine general laws about the universe. All of these laws have been validated through experiments that show that the majority of the time these laws are correct. Has there been experiments that disprove a general law of physics? Not necessarily. For example, the law of conservation of energy states that the total energy in a closed state cannot change, as in it’s conserved, and thus cannot just randomly disappear. If one calculates out the probability of a violation of the conservation of energy, the possibilities of that violation do exist, but they are statistically fairly tiny percentages. So it can be safe to assume that in our lifetimes, we probably won’t see a violation of the conservation of energy. Experiments thus far seem to validate that idea. (This is of course a simplification of the example, but a more detailed explanation is beyond the scope of this post.)

This bothers some people because they want everything to be cut and dried, either/or, black and white. Either we know it exactly or we don’t, but nature just isn’t like that. Nature is complex, convoluted, and full of wonderful surprises. There’s a lot of probable events that can happen, and are fairly likely to always happen, but there is also the remote possibility that other events could happen instead. All we can do is examine the data and extrapolate and refine theories with what we have available within that data. Scientists examine what they can observe and test, and that data provides a framework for which theories are developed.

It’s also nice to note that on a macro level — as in if we’re examining things on a large scale — the odd effects of quantum mechanics are fairly minuscule, and so we can predict events with very high probabilities. Science is never about trying to find the exact answer to everything. As Richard Feynman puts it so well, “The sole test of the validity of any idea is experiment.” So any idea that people have about the natural world needs to be validated by experiments and observations. Does someone’s idea align with what we actually see and experience within nature? If it doesn’t, well that idea is rather useless for explaining what is actually happening, and so the idea is thrown out and a new idea is examined in its stead. Through this long process of examining various ideas and validating them through experiments and observations, the general laws of physics has been developed. These laws, although they hold some degree of uncertainty, are still very good with predicting what is the most probable idea of what is happening within nature. These laws tend to be called laws because they have withstood many experiments and have been validated by the results of those experiments and observations. That validation shows that these explanations are the most probable and most accurate explanations we have for describing our universe. So although our universe is based upon uncertainty on its most minuscule level, that doesn’t mean we still can’t come to understand how things happen.

Science, as a tool, is a very useful tool and can help explain a lot of what we experience within our universe, but it also is a slow process. It takes time to go through the process of experiments in order to validate the ideas people put forth to explain nature. As much as our universe can be harbor uncertainty, we still can come to understand it through science. All the technological advances you see today — and if you’re reading this on your computer, that’s a good example of technological advance! — stems from research in science, where people have undergone the long process of validating ideas and determining explanations for how various parts of the universe work. This is also why breakthroughs in science often are surprises, where experiments sometimes finds something unexpected, and thus new ideas are born and then tested for their validity. As slow as this process can be, because of it, it’s lead to the technology and medical advances we have today.

It’s also why I truly think that science literacy is very much needed within our culture. Because of our reliance on technology, we need to understand the basics of science, how science works, how science progresses, how technology is developed, and so on and so forth. Why? Because if we want to be active citizens within our country, we need to be science literate so we can make sound decisions on policies about technology, science, and our futures. To be science literate doesn’t mean you need to run out and get a degree in physics or anything. What it does mean is an openness to learning about science and the various research being conducted, and learning a bit about the history of science and its impact on our society. There’s a lot of great books out there written specifically to help people understand science, technology, and how it all works without requiring you to get a degree or perform any complex mathematical calculations.

For those interested, I’ve provided a list of where to start if you want to learn more about all of this: Continue Reading

Review: Time Travel And Warp Drives

Posted by Aibird on January 10, 2014
Posted in: Physics, Science. Tagged: , , , , , , . 1 Comment

As a science fiction writer, I find examining science’s current stance on futuristic ideas, such as time travel, warp drives, and other possible technological advances to be fascinating and insightful. This book by Allen Everett and Thomas Roman takes the reader on an incredibly thorough examination of the science of time travel, the paradoxes of time travel, wormholes, and warp drives.

The book starts with the basics: special and general relativity, and it spends quite four chapters examining these topics because it’s important for understanding the following chapters, which will dig into the questions of time travel, wormholes, warp drives, and paradoxes in depth. They do use some math — most of it placed in appendices for readers who enjoy examining mathematical proofs — but it’s there to illustrate and enhance their points, and they do an excellent job of explaining each of the terms in the mathematical formulas. Perhaps the most important point to take away from these preliminary discussions is the idea of the light cone, which is used extensively in the following arguments concerning time travel and warp drives. It’s a method of graphing reference frames and the worldline of the object you’re studying (such as the a spacecraft). It will prove exceptionally helpful in understanding the discussions about time travel and wormholes.

The diagrams provided in each of the chapters are clear and generally easy to understand with a close reading of the text. The most difficult chapters will probably be the last three before the Epilogue, which explore the quantum mechanics side of the discussion. It’s important to note that the book shows, quite well in fact, that for general relativity, there isn’t much restricting the possibility of time travel and warp drives. However, once you add quantum mechanics to the mix, the restrictions prove numerous. Another important point is that negative energy is necessary for the creation of a warp drive and/or time machine, but how to actually find a feasible way to harness negative energy? The book seeks to answer that question in the latter chapters and does its best to examine all the possible routes that current scientific research has examined, and possible ways it could be built and if it can be achievable at all.

Although the final conclusions in the book are not promising as to whether warp drives, wormholes, and time traveling machines can ever be constructed, it’s important to note — as the authors do — that these conclusions are based upon the current scientific evidence and theories. It is quite possible that other theories will arise that may showcase a way to circumvent the current restrictions the theory of quantum mechanics puts on these possibilities.  For example, there is not yet a solid theory for quantum gravity, and it is possible that such a theory could shed more light on this topic and possibly offer a way to circumvent the current restrictions imposed by our current understanding of the universe.  It’s also important to note that any new theory has to take into account experimental evidence, necessary to prove its validity, and that the current theories of quantum mechanics, general relativity, and special relativity as well as Newtonian classical physics all still are valid in their respective regions (each govern a different subset of the universe). As an example of what I mean: general relativity describes gravity and how objects react in gravity fields more accurately than Newtonian physics, and special relativity describes how objects act and how time acts at speeds close to the speed of light, but at speeds much, much less than light, Newtonian physics works just as well and for that region (of speeds much, much slower than light), special relativity equations can simplify into Newtonian equations. Each govern a slightly different region of the scales of spacetime, and so would still be valid in those regions even if we develop a more complete theory for all of physics.

That is probably the hardest part about speculation involving future technologies. We have current theories that work extremely well at predicting real life phenomenon in their current realms, but it’s not a complete picture. We still have not found a way to explain gravity on the quantum scale, and there is still some fascinating finds in our universe that have no theoretical explanation as of yet. For example, we have experimental evidence that there is something causing the accelerated expansion of the universe which has been experimentally verified numerous times, but we have no idea what it is, and hence gave it the name “dark energy” for the lack of any better descriptor. It’s possible that once we learn what exactly dark energy is, we may be able to find a way to utilize it to find a way to create a warp drive, wormhole, or other superliminial travel. There is still a lot more for us to discover and understand before we can reach a definitive conclusion as to whether these exotic and science fiction styles of travel are even possible. The book, in turn, does a great job of exploring some of these more speculating ideas as well as ideas grounded in the already known theories of physics.

Overall, the book does a wonderful job of explaining and showing the physics of these science fiction concepts, and how plausible they are with our current knowledge of the universe. It’s well worth the read for any science fiction fan and writer, and I highly, highly recommend it to those interested in such topics. The science is sound and thorough and well explained for a lay person. You don’t need a physics degree to understand it, nor need to have taken physics before in any high school or college class. Some may find the book a bit difficult to understand if your math skills are poor, but the conceptual discussion of the topics is well-rounded and thorough, so it’s really just the difficulty in wrapping one’s mind around some of the bizarre aspects of nature.

The Most Astounding Fact

Posted by Aibird on October 10, 2012
Posted in: Author, Writing. Tagged: , , , , . 1 Comment

When I am in need of inspiration, I love to go through images of space.  Seeing the beauty that is our universe.  It amazes me so much how we came from those stars. How the elements that make us were boiled and cooked within those stars and then spewed out into the universe to seed space around them. It’s just so incredible.

Neil deGrasse Tyson, a physicist, put it beautifully in the following video:

 

 

 

(Transcription will be edited in at a later date.)

World-building Part 4 – Atmospheres and Natural Cycles

Posted by Aibird on July 3, 2012
Posted in: Physics, World Building, Writing. Tagged: , , , , , , . 5 Comments

Note this is a series: Part One, Part Two, and Part Three.

In order to have a planet house life, an atmosphere is absolutely essential, unless the sentient species is capable of enclosed domes, which even then they’d still have an atmosphere within that enclosed dome. This brings us to the fourth part of building a planet: Atmospheres and natural cycles.

Atmospheres are an envelope of various gases that are held in place by gravity; pressure is used to describe the weight of the atmosphere that’s held down by the gravity of a planet. (There’s various terms to measure pressure, but for our purposes the reasoning behind these terms isn’t necessary for the discussion: I can provide resources for those interested in how measuring pressure works, but for now, we’ll use the unit of atmospheres (atm) when appropriate for the discussion.) Since atmospheres are composed of several types of gases, often the idea of partial pressures is used to describe the total pressure times the percentage of a specific constituent within an atmosphere. For example: on earth, oxygen makes up 21 percent of the atomsphere (or in decimal units: .21). The total atmospheric pressure of Earth is 14.7 psi (pounds per square inch). So the partial pressure of oxygen is: (.21) x (14.7) = ~3.1 psi. An interesting side note on this discussion: if you had an all oxygen atmosphere within a spacecraft, the spacecraft can be lighter and simpler than if a more varied atmosphere is used due to the ship needing to hold in a much smaller pressure from the oxygen. This tidbit of information may be useful in discussions of spacecraft, but we can discuss that in a later post if anyone is interested. (Also note, from here on out, I will focus on terrestrial planets. If people are interesting, I can have a separate post concerning gas giants.)

An important point to note about volatiles is that the molecules within a gas move freely, often colliding with other molecules. These collisions cause the molecules to careen off each other, and if the molecule is moving fast enough in the right direction, it might exceed the escape velocity and escape into space. All atmospheres will experience some ‘leakage’ of gas particles to space, but the percentage and composition of those that escape depend upon the weight of the molecule, the surface temperature of the planet, and the escape velocity of the planet.

Escape velocity is determined by the mass of your planet and it’s radius. It can be computed by the following equation: Escape velocity = square root(2GM/r), where G is the gravitational constant, M is the mass of your planet, and r is the radius. If your planet is too small in radius and mass, the escape velocity would be too low, allowing a lot of the crucial ingredients of an atmosphere to escape into space, thus leaving your planet with little to no atmosphere whatsoever (Mercury and the Moon are good examples of this in our solar system). This concept can be further visualized in the following graph:

Escape Velocity and Temperature of Gas Molecules
This graph shows how escape velocity and temperature affects what particles a planet can keep in its atmosphere, and if a planet can keep an atmosphere at all. It also shows how the large mass and extremely high escape velocities of gas giants allows for them to keep more of the lighter volatiles than terrestrial planets. Temperature plays a role simply in the sense that the higher the temperature of air molecules, the faster they tend to go, for as you can see in the above graph, the velocities of the escaping gas increases with surface temperature. Also, lighter gases tend to escape more easily, as seen in the above graph, due to their lesser mass, which allows them to achieve higher velocities than a heavier gas. This is why for terrestrial planets, hydrogen – one of the lightest gases in the universe – is rarely if ever retained in the planet’s atmosphere.

Terrestrial planets will often produce atmospheres (or else thicken already formed ones) depending on the volcanic and tectonic activity of its surface. During planetary formation, volatiles, often in their icy/solid form, will become trapped within the mantle of a forming planet. If the planet is warm enough, it will undergo significant tectonic activity, and the volcanic eruptions – sometimes termed ‘outgassing’ can release these volatiles into the atmosphere. Whether these volatiles are retained in the atmosphere once again depends on the escape velocity of the planet and it’s surface temperature. The surface temperature also plays a role in the tectonic activity of the planet, thus forming a cycle. If the escape velocity is enough to retain much of the volatiles spewed forth from tectonic activity, then what’s called a ‘secondary atmosphere’ will form. This way of creating an atmosphere is the generally accepted theory of how the Earth’s atmosphere came to be. This is also how atmospheres can differ from planet to planet – this process produces a different composition of volatiles depending on the composition of your planet.

However, it isn’t quite enough for a planet to be able to hold an atmosphere. As we’ve established, any atmosphere can leak gases over time due to the collisions of molecules, especially in the upper most parts of an atmosphere. Since gases can ‘leak’ out into space due to such a process, then how does a planet ‘buffer’ its atmosphere in order to replenish what was lost in such leakage? This is done through various cycles on the planet itself, in which the atmosphere interacts with crust of the planet; the most common cycle is the carbonate/silicate cycle. However, in order for this cycle to exist, the planet must be large enough to keep the activity in its crust moving, which, as noted before, is powered by its internal heat. If the planet is too small, then the internal heat will be lost far too quickly and tectonic activity soon stalls, and then the atmospheres is not replenished and is thus diminishes over time to leakage.

Another point to consider is the composition and pressure of a planet’s atmosphere isn’t static over time. Over time, it can be modified by various things such as chemical reactions with the surface of the planet, life on the planet, photodissociation at the outer edge of the atmosphere, as well as changes over geologic time due to altering composition of crust from the lost of lighter elements and/or the sun’s changes which can influence the temperature of a planet over time. Life itself can also alter the composition within a crust and the atmosphere. I’ll discuss each of these in turn:

Photodissociation is a process where solar ultraviolet light can break up molecules at the outer edges of the atmosphere; for example, water molecules that drift into the outer edges of the atmosphere can be broken up into oxygen and hydrogen by this light from the sun; however, hydrogen is much lighter than oxygen, and so can achieve the escape velocity far easier, causing it to be lost to space. This effect is often how hydrogen bearing molecules can be lost over time. In order to avoid this effect, a planet needs to have a ‘cold trap’ where molecules like water can be frozen out before it gets high enough to be destroyed by solar UV, but without this effect, even an ocean’s worth of water can be lost in a fraction of geologic time; for Venus in particular, this had devastating consequences. Another consequence of this effect is that ammonia and methane are more easily broken up than other hydrogen-bearing molecules, and thus are easily broken up by solar UV. In the case of our earth, this was a good consequence, because it allowed our type of life to evolve more readily.

Another important factor is greenhouse gases such as ammonia, methane, carbon dioxide, and chlorofluorinated hydrocarbons (CFCs). Certain gases are transparent to visible light, but are nearly opaque to infrared light, which is what is radiated by the ground once it’s warmed by the visible light rays from the sun. These gases that are opaque to infrared light absorbs it, which traps the energy and warms the atmosphere. Although ammonia, methane, carbon dioxide, and CFCs are the most potent gases when it comes to trapping energy, water vapor can play a rather large role as well.

Water vapor is not a free parameter due to the cycle water vapor goes through on a planet with liquid water on its surface. At a given temperature for liquid water to exist, there must be a certain partial pressure of vapor over it, and this partial pressure increases with temperature. To demonstrate: when the temperature is higher, more water evaporates thus increasing the water vapor within the air, which equalizes the partial pressure in the water cycle. When the atmosphere cools, the water vapor content drops as liquid water condenses out in the form of clouds (which can release their condensation through various types of precipitation). This water cycle is one of the many cycles that influence the weather of the planet. Now examine a scenario where an ocean planet experiences a raise in temperature – various situations can cause this, some being the presence of other greenhouse gases that trap heat and thus causing a temperature increase or the sun evolving from one phase of its life into another thus causing its radius to be larger and closer to the planet in question: with the higher temperature, the more water evaporates from the oceans; however, water vapor helps trap energy from sunlight, which in turn increases the temperature of the atmosphere. This, in turn, causes more water to evaporate, which in turn increases the temperature, and so on and so on. This positive feedback amplifies the effect of the other greenhouse gases within the atmosphere, thus increasing the temperature more.

How is this effect mitigated to avoid too high of a positive feedback? By the condensation of clouds which reflect sunlight incredibly well, which in turn can help lower the temperature of the atmosphere and allow more clouds to form, thus cooling everything down and reversing the positive feedback. The problem here is when the temperature gets too high, then this amplification of other greenhouse gases can throw this cycle out of whack and cause the positive feedback to grow out of control – this scenario is often called a “runaway greenhouse effect.”

To return to an earlier point, the thickness and composition of an atmosphere over time is controlled by reaction with the crust and oceans on a planet; I’ve already discussed the ocean’s effect, so let’s take a look at the crust. The carbonate-silicate cycle is what regulates the carbon dioxide content of the atmosphere through atmospheric interaction with a planet’s crust. I’ll use Earth as an example for clarity: on earth nearly all of its carbon dioxide is locked in the crust within limestone. Limestone mostly consists of calcium carbonate, which precipitates easily in a water solution if dissolved calcium is present along with dissolved carbon dioxide, thus producing limestone. Calcium is one of the most abundant element in Earth’s crust, and so it tends to be present to some degree somewhere on the planet. The more carbon dioxide in the air, the more it can be dissolved into any exposed water – this carbon dioxide solution is fairly acidic allowing for more efficient weathering of a planet’s crust. If carbon dioxide becomes too plentiful in the atmosphere – causing the temperature to warm – efficient weathering can release a lot of calcium, which then over time brings the carbon dioxide levels down. Tectonic processes in turn raise new rock for weathering over time, and crustal rocks newly formed are cycled through various tectonic processes into the earth, so that through volcanic activity the carbon dioxide can be spewed out into the atmosphere again, which resets the cycle. Over time, this cycle tends to keep the atmosphere of Earth at a fairly constant temperature.

This cycle can also happen due to the effects of life. Limestone can also be created from biological debris such as coral reefs, shells, and other lifeforms that are cemented with carbonates formed inorganically. So limestone isn’t just made inorganically as I just described in the above paragraph, but is also formed through the effects of life. This helps contribute to the cycle, spurring it forward, and it also helps guard against excess water acidity since limestone has drawn the carbon dioxide from the water to form itself.

Another biological process that effects carbon dioxide in the atmosphere is plants on the Earth’s surface: photosynthesis. Plants captures carbon dioxide within the leaves of the plant and through the process of photosynthesis, release oxygen. Animals on the surface of Earth in turn take in oxygen and breathe out carbon dioxide, and thus an organic cycle of carbon dioxide and oxygen is formed.

All three process are at work on Earth, and can also be at work for your planet if you utilize oxygen breathing organisms. (If you decide not to, the composition of the atmosphere and the cycles that will appear over time will be slightly different from Earth’s cycles, but I’ll save this for a different post.)

One of the last topics I’ll discuss in regards to atmospheres is how it thins the further one travels from the surface of the planet. This thinning of atmosphere can effect how high the denizens of your world can climb and how high they can fly without technological help. It’s also something inherent within all atmospheres; the larger and thicker an atmosphere is, the more slowly it thins as one travels away from the surface. How slowly or how quickly an atmosphere thins is called the scale height, which depends, as I said, with how large the atmosphere is as well as the composition of the atmosphere. Atmospheres with heavier molecules tend to have smaller scale heights than those with lighter molecules. The thinning of an atmosphere happens at a near exponential rate: p = p(0) exp( -gh/H), where p is pressure at an altitude h, p(0) is pressure at sea level, g is gravitational pull in terms of Earth (so for Earth this is 1), and H is scale height. This equation can be used to calculate how thin the atmosphere is at certain heights on the planet, for example – at the tops of mountains, which in turn can help you determine if any denizen on your planet would have enough air and pressure to survive. Another example is if you have a spot located far below sea level that contains no water, the pressure of the atmosphere can be calculated to determine what the environment would be like at that depth. If the basin contains water, the calculation would differ greatly due to the pressure of water being far greater than the pressure of air, so the actual pressure at the bottom of the ocean includes both.

The last point I’ll make is that an ozone layer is absolutely necessary in a planet if it wishes to harbor life. Ozone is a fairly active and toxic form of oxygen where it has three molecules bonded together instead of two. Ozone is what absorbs the ultraviolet rays from the sun, thus preventing these rays from reaching the surface of the planet. Why is this so necessary? Because UV is energetic enough to break apart molecules, especially those necessary for life. In order for life to survive, there must be a mechanism that blocks these rays from hitting the surface, and ozone is one of the main molecules for the job. Thus some variation of an ozone layer has to exist for life to survive; ozone isn’t the only molecule for the job, but it is the most studied one due to is presence on Earth. Also note, if ozone is used, then oxygen has to be present in the atmosphere since it’s the reactions of oxygen molecules that form the regular form we can breathe (two oxygen atoms bonded together) and the ozone variety.

If you have any questions or would like clarification on any of this, feel free to comment below! For my next world-building post, I can discuss weather, oceans, and land. Maybe then I’ll be ready for the flora and fauna.