(Part 2) Best products from r/askscience

My main hobby is reading textbooks, so I decided to go beyond the scope of the question posed. I took a look at what I have on my shelves in order to recommend particularly good or standard books that I think could characterize large portions of an undergraduate degree and perhaps the beginnings of a graduate degree in the main fields that interest me, plus some personal favorites.

Neuroscience: Theoretical Neuroscience is a good book for the field of that name, though it does require background knowledge in neuroscience (for which, as others mentioned, Kandel's text is excellent, not to mention that it alone can cover the majority of an undergraduate degree in neuroscience if corequisite classes such as biology and chemistry are momentarily ignored) and in differential equations. Neurobiology of Learning and Memory and Cognitive Neuroscience and Neuropsychology were used in my classes on cognition and learning/memory and I enjoyed both; though they tend to choose breadth over depth, all references are research papers and thus one can easily choose to go more in depth in any relevant topics by consulting these books' bibliographies.

General chemistry, organic chemistry/synthesis: I liked Linus Pauling's General Chemistry more than whatever my school gave us for general chemistry. I liked this undergraduate organic chemistry book, though I should say that I have little exposure to other organic chemistry books, and I found Protective Groups in Organic Synthesis to be very informative and useful. Unfortunately, I didn't have time to take instrumental/analytical/inorganic/physical chemistry and so have no idea what to recommend there.

Biochemistry: Lehninger is the standard text, though it's rather expensive. I have limited exposure here.

Mathematics: When I was younger (i.e. before having learned calculus), I found the four-volume The World of Mathematics great for introducing me to a lot of new concepts and branches of mathematics and for inspiring interest; I would strongly recommend this collection to anyone interested in mathematics and especially to people considering choosing to major in math as an undergrad. I found the trio of Spivak's Calculus (which Amazon says is now unfortunately out of print), Stewart's Calculus (standard text), and Kline's Calculus: An Intuitive and Physical Approach to be a good combination of rigor, practical application, and physical intuition, respectively, for calculus. My school used Marsden and Hoffman's Elementary Classical Analysis for introductory analysis (which is the field that develops and proves the calculus taught in high school), but I liked Rudin's Principles of Mathematical Analysis (nicknamed "Baby Rudin") better. I haven't worked my way though Munkres' Topology yet, but it's great so far and is often recommended as a standard beginning toplogy text. I haven't found books on differential equations or on linear algebra that I've really liked. I randomly came across Quine's Set Theory and its Logic, which I thought was an excellent introduction to set theory. Russell and Whitehead's Principia Mathematica is a very famous text, but I haven't gotten hold of a copy yet. Lang's Algebra is an excellent abstract algebra textbook, though it's rather sophisticated and I've gotten through only a small portion of it as I don't plan on getting a PhD in that subject.

Computer Science: For artificial intelligence and related areas, Russell and Norvig's Artificial Intelligence: A Modern Approach's text is a standard and good text, and I also liked Introduction to Information Retrieval (which is available online by chapter and entirely). For processor design, I found Computer Organization and Design to be a good introduction. I don't have any recommendations for specific programming languages as I find self-teaching to be most important there, nor do I know of any data structures books that I found to be memorable (not that I've really looked, given the wealth of information online). Knuth's The Art of Computer Programming is considered to be a gold standard text for algorithms, but I haven't secured a copy yet.

Physics: For basic undergraduate physics (mechanics, e&m, and a smattering of other subjects), I liked Fundamentals of Physics. I liked Rindler's Essential Relativity and Messiah's Quantum Mechanics much better than whatever books my school used. I appreciated the exposition and style of Rindler's text. I understand that some of the later chapters of Messiah's text are now obsolete, but the rest of the book is good enough for you to not need to reference many other books. I have little exposure to books on other areas of physics and am sure that there are many others in this subreddit that can give excellent recommendations.

Other: I liked Early Theories of the Universe to be good light historical reading. I also think that everyone should read Kuhn's The Structure of Scientific Revolutions.

I'm assuming you're looking for things geared toward a layman audience, and not textbooks. Here's a few of my personal favorites:

Sagan

Cosmos: You probably know what this is. If not, it is at once a history of science, an overview of the major paradigms of scientific investigation (with some considerable detail), and a discussion of the role of science in the development of human society and the role of humanity in the larger cosmos.

Pale Blue Dot: Similar themes, but with a more specifically astronomical focus.


Dawkins

The Greatest Show on Earth: Dawkins steers (mostly) clear of religious talk here, and sticks to what he really does best: lays out the ideas behind evolution in a manner that is easily digestible, but also highly detailed with a plethora of real-world evidence, and convincing to anyone with even a modicum of willingness to listen.


Hofstadter

Godel, Escher, Bach: An Eternal Golden Braid: It seems like I find myself recommending this book at least once a month, but it really does deserve it. It not only lays out an excruciatingly complex argument (Godel's Incompleteness Theorem) in as accessible a way as can be imagined, and explores its consequences in mathematics, computer science, and neuroscience, but is also probably the most entertainingly and clearly written work of non-fiction I've ever encountered.


Feynman

The Feynman Lectures on Physics: It's everything. Probably the most detailed discussion of physics concepts that you'll find on this list.

Burke

Connections: Not exactly what you were asking for, but I love it, so you might too. James Burke traces the history of a dozen or so modern inventions, from ancient times all the way up to the present. Focuses on the unpredictability of technological advancement, and how new developments in one area often unlock advancements in a seemingly separate discipline. There is also a documentary series that goes along with it, which I'd probably recommend over the book. James Burke is a tremendously charismatic narrator and it's one of the best few documentary series I've ever watched. It's available semi-officially on Youtube.

Answering your edit, time dilation does occur at the speed of light. So much so that at exactly the speed of light, no travel in time occurs. To a photon, this means it "feels like" it was born and dies at the same instant, if we're going to anthropomorphize here, even though to us we can see it existing in time.

EDIT: as u/Aliudnomen points out, "a frame traveling at c is not a valid inertial frame", which means it's not precise to say that time dilation is happening at the speed of light. Got a bit carried away with the explanation here :) You see infinity time dilation at the speed of light, but that's because the denominator trends to 0, which is a place that inertial objects can't get to. It doesn't really mean that time dilation is infinite, but rather nonexistent. This is why it's often said information is the only thing that can appear, to us, to travel at the speed of light: anything with an inertial reference frame can never get to the speed of light.

With you being in 10th grade, I'll use an analogy/projection that I find helpful. Imagine a Cartesian set of axes (the normal kind), where the y axis is time-velocity and the x axis is space-velocity. Draw a big circle of radius the speed of light, we'll call that "1 unit". Now, you need to replace the idea of "speed of light" (which implies movement of light in the space velocity coordinate frame) with c, the celerity constant: celerity means "rapidity of motion", but it was chosen specifically because it can mean speed in the 4 dimension coordinate system of spacetime. In other words, you can travel in space or you can travel in time, and both of these will be measured, not with mph, but with some fraction of c. With me so far?

OK, what relativity is saying here is that we are always traveling on a circle with radius c. If we don't travel along the space-velocity x axis (we're at rest), we travel along the time-velocity(y axis), and whenever we travel along the x axis, we rotate our point from (0, 1) around this circle clockwise toward (1, 0).

To see this, we can rearrange the time dilation equation:

t' = t / sqrt(1 - (v/c)^2) Original equation
t' / t = 1 / (sqrt(1 - v/c)^2) Move the t in the numerator over
t' / t = 1 / sqrt((c^2) - (v^2)) Multiply the guys under the sqrt by c^2
(t' / t)^2 = 1 / (c^2 - v^2) Square both sides
1 / (t' / t)^2 = c^2 - v^2 Invert both sides
1 / (t' / t)^2 + v^2 = c^2 Add v^2 to both sides
t^2/t'^2 + v^2 = c^2 Square under the first term denominator and invert.

This is an equation of a circle with radius c: the axes can be chosen so that the y axis is "ratio of time", which is what I'm calling "time velocity" and the x axis is "space velocity".

We are always traveling at c, and so we're always somewhere on this circle. This is why it's a constant: nothing in the universe travels faster or slower than this celerity, we can only change which coordinates add up to get us there. If we're perfectly at rest in the space-velocity dimension (x = 0), all of our travel is along the time dimension (y = 1): we're at (1, 0) on this point of the circle. With me so far?

This is what "spacetime" means: right here we're dropping the fact that space is 3 dimensional and considering all velocity to be along the one axis, but if you add in higher dimensions, this is spacetime: x, y, z, t all involved in the same equations. Events - which are used to describe "something that happens somewhere in spacetime" - always travel within a 4 dimensional hypersphere that relativistic folk call the light cone.

Back to our 2d example. As you start to increase your x dimension - that is, start moving - your celerity starts to rotate around the circle. When you travel half the speed of light, where x = 0.5, you can imagine the line drawn from the origin to the point on the circle that corresponds to this x coordinate slanting up and to the right, which happens to be solved by (x^2 ) + (y^2 ) = c^2. Solving for y, we get 0.866 - that is, we're traveling at 0.866 the normal rate of time flow.

Keep increasing space velocity, and you'll plot points like (0.6, 0.8), (0.7, 0.714), (0.8, 0.6), (0.9, 0.435), (0.95, 0.31), (0.99, 0.14), (0.999, 0.045), (0.9999, 0.014)

You see, we're putting more and more of our celerity into the space-velocity coordinate and taking it from the time-velocity coordinate. This is time dilation.

Finally, anything with mass requires energy to convert its travel in time to travel in space. As you keep attempting to get closer to (1, 0), it requires more energy to shift the angle around the circle, until the last little bit is infinite. This is why only massless particles (like photons) can travel at the speed of light.

You can also, then, intuitively grasp the other parts of this circle: what does it take to make time slow down? Well, we would have to move from the 1st quadrant (the top right quadrant) to the 3rd and 4th quadrants (the bottom quadrant). We don't really know for sure how to do this, but we do know that it seems possible that more exotic particles could behave just like matter, except progressing backwards. In other words, at rest, their velocity is (0, -1). What does it take to get from matter going forward in time to backwards? Well, you can't do it by increasing your space-velocity alone: no matter how much you increase your velocity, you can only ever get to almost (1, 0) with something that has mass. This is the "tachyon" idea: a massive particle that travels so fast that it loops around the coordinate frame into quadrant 4 (bottom right), that is, think about moving so fast that you move faster than the speed of light (perhaps you became massless for a second, then gained mass as you somehow started traveling in the negative time direction. This can't happen, AFAIK, because you'd have to travel through infinite energy to loop around, but you can imagine the symmetry here). Real particles can't do this, but it's theoretically possible that particles do exist that travel "faster than the speed of light", but only in a way that breaks what it means to have velocity: they're traveling backwards in time, so their motion is some fraction of c to them; they're not moving faster than the speed of light. To us observing them, they're moving faster than we can achieve with our motion on the x coordinate: their motion backwards in time makes them seem to us as if they're moving faster than c. They're not, remember: all of us are always moving at c.

If something has anti-mass, however (that is, antimatter), it seems possible to have it traveling at (0, -1) all on its own! It's hard to jump on something that has anti-mass, though, so this is still theoretical in many ways. That is, the equations say it should be moving backwards in time, but what that actually means is far more complicated: it maths out that way, but it's not like causality is broken (that is, when we create antimatter in particle accelerators, they don't appear "before" the collision, but they do get "younger" before they annihilate. What does "younger" mean to a particle? How do you define "younger" when it's getting "older in negative time"? What is the sound of one hand clapping?

Also interesting is the idea of time dilation with negative velocities: the 2nd (top-left) quadrant. What does it mean to move "backwards" in space? Does that even have a meaning? I mean if I walk down the street, I'm moving forward in a direction, but if I walk the opposite way, I'm moving forward in the opposite direction. I'm not aware of anything discussing "negative velocity", but that's just my ignorance: perhaps someone else can chime in if they know more.

Finally, Carl Sagan here to describe what life looks like as you approach the speed of light. You can start to see from his example what it would be like to travel so fast that no time passes for you at all.

Finally, one of the most accessible books I've ever read is Stephen Hawking's a brief history of time. If you're at all remotely curious about either relativity or quantum mechanics, this guy, along with being just about the most brilliant mind in these fields, has a fantastic way of explaining the concepts while still staying true to the equations involved.

Not much, the nice thing for upper math courses is they do a good job of building up from bare bones. If you have some linear algebra and a multivariable calc course you should be good. The big requirement is however mathematical maturity. You should be able to read, understand, and write proof.

A very basic intro to proofs course is usually taught to first year math students, this covers set notations, logic, and some basic proof techniques. A common reference is "How to prove it: a structured approach", I learned from Intro to mathematical thinking. The latter isn't as liked, it does seem to cover some material that I think should be taught early. A lot of classical number theory and algebra, for example fundamental theorem of arithmetic, and Fermat's little (not last) theorem are proven. Try to find a reference for that stuff if you can.

It's really important to do a proof based linear algebra class. It helps build the maturity I mentioned and will make life easier with topology. But even more importantly teaching linear algebra in a more abstract way is important for a physics undergrad as it can serve as a foundation for functional analysis, the theory upon which quantum mechanics is built. And in general it is good to stop thinking of vectors as arrows in R^n as soon as possible. A great reference is Axler's LADR.

Again not strictly required, but it helps build maturity and it serves as a good motivation for many of the concepts introduced in a topology class. You will see the practical side of compact sets (namely they are closed and bounded sets in R^(n)), and prove that using the abstract definition (which is the preferred one in topology). You will also prove some facts about continuous functions which will motivate the definition of continuity used in topology, and generally seeing proofs about open sets will show you why open sets are important and why you may wish to look at spaces described only by their open sets (as you will in topology). The reference for real analysis is typically Rudin, but that can be a little tough (I'm sorry, I can't remember the easier book at the moment)

Edit: I will remove this as it doesn't meet the requirements for an /r/askscience question, we usually answer questions about the science rather than learning references. If you feel my answer wasn't comprehensive enough feel free to ask on /r/math or /r/learnmath

>but as a photon travels through a substance, it is absorbed and re-emitted by the atoms of that substance

no! no! no! a thousand times no! This is a common misconception and shame on you for propagating it!

The index of refraction of a material is not due to simple atomic absorption and re-emission. Absorption features are typically very spectrally narrow. The index of refraction is very broad and nearly constant over long regions of the spectrum. The index of refraction does not depend only on the type of material but its bulk properties. Take the case of carbon: Diamond (n=2.4) and soot (n=1.1) are both made of carbon, but have very different indices of refraction. Index of refraction depends heavily on the organization (crystal or noncrystal) of the material and other bulk material properties.

If you do insist on using the photon model, this is the best explanation I have found - its a bit of a mess:

>A solid has a network of ions and electrons fixed in a "lattice". Think of this as a network of balls connected to each other by springs. Because of this, they have what is known as "collective vibrational modes", often called phonons. These are quanta of lattice vibrations, similar to photons being the quanta of EM radiation. It is these vibrational modes that can absorb a photon. So when a photon encounters a solid, and it can interact with an available phonon mode (i.e. something similar to a resonance condition), this photon can be absorbed by the solid and then converted to heat (it is the energy of these vibrations or phonons that we commonly refer to as heat). The solid is then opaque to this particular photon (i.e. at that frequency). Now, unlike the atomic orbitals, the phonon spectrum can be broad and continuous over a large frequency range. That is why all materials have a "bandwidth" of transmission or absorption. The width here depends on how wide the phonon spectrum is. Fowels

A more brief explanation comes from wikipedia

>The slowing can instead be described as a blending of the photon with quantum excitations of the matter (quasi-particles such as phonons and excitons) to form a polariton; this polariton has a nonzero effective mass, which means that it cannot travel at c.

To use the wave model:

To use the wave model, let's go back to the derivation of the wave equation from Maxwell's equations. When you derive the most general form of the speed of an EM wave, the speed is v=1/sqrt(mu epsilon). In the special case where the light travels in vacuum the permittivity and permeability take on their vacuum values (mu0 and epsilon0) and the speed of the wave is c. In materials with the permittivity and permeability not equal to the vacuum values, the wave travels slower. Most often we use the relative permittivity (muR, close to 1 in optical frequencies) and relative permeability (epsilon_R) so we can write the speed of the wave as c/n, where n=1/sqrt(epsilonR muR).

Ah, I feel so smart knowing (what I hope is) the answer to a question. As for the first question, sexual reproduction constantly mixes and matches genes and allows for a much greater diversity within a population. A population that is genetically diverse is much less likely to be wiped out by any single cause, such as a virus or bacteria targeting a specific gene or feature. As hosts we are in an evolutionary arms race, trying to evolve faster than the parasites targeting us. Sex is an efficient mechanism to accomplish this.

As for gender, the answer is similar, but a little more complicated for me to explain (probably because I know so little of the subject). As it turns out, not only do we as hosts compete against parasites that wish to infect us, but it turns out that our genes are also competing against each other to determine which we be passed down. Now genes must work together to some extent, or the organism they exist within may possibly fail to reproduce and pass them on. But it is also possible for genes to be a parasitic freeloaders, or to pass itself along without actually improving the fitness of the organism (transposons). Sex is advantageous to genes because they are allowed to move freely within the population of hosts, and not be stuck with genes that are of poor quality or worse yet, parasitically catching a free ride at their expense (think of a superstar player on a sports team, leaving their losing team to be traded onto a winning one).

As it turns out, the mechanisms through which we have sex are very effective at dealing with these parasitic genes, reducing the chance they may be passed on, as well as filtering out any viruses or bacteria that may also try to accompany the males sperm to the egg (remember, the sperm is stripped of EVERYTHING as it enters the egg, leaving only the genetic material). Gender was the outcome of the process by which two parent cells could form a new cell; the larger immobile gametes (female) could contain the information necessary for the cytoplasmic genes, leaving the male gametes smaller and more mobile (also, since this male gamete only had to pass on its nucleus, this cut down on the risk of infection by any parasitic organisms). This rise of two roles is what created male and female genders. I don’t really have any information on when this process evolved, sorry.

This is the Red Queen Hypothesis, probably poorly explained, and GROSSLY oversimplified. Even better than the wiki page is Matt Ridley's book, The Red Queen, from which I crudely summarized most of this answer (specifically, Chapter 4; Genetic Mutiny and Gender). It is easily one of my favorite books, and if you were curious enough to ask this question I think you would find this fascinating as well.

Ordinary sexual selection explains it without requiring some sort of gene proximity hypothesis. Animals with characteristics that are found attractive tend to pass on their genes more successfully. Attractive characteristics are those that are associated with animals that pass on their genes most successfully. That's the feedback loop, and it can result in all sorts of characteristics being selected for attractiveness.

The common factor between characteristics that are found attractive is that they're generally associated in some way with health - either directly, as with healthy musculature or healthy skin/fur, or indirectly, as in decorative displays that indicate an excess of energy. The peacock's tail is the classic example of a purely decorative feature. Large human female breasts are a combination of decorative and functional.

The book "The Red Queen: Sex and the Evolution of Human Nature" provides a very accessible exploration of this topic at a popular level (i.e. it's not a scientific textbook.)

[Edit: relevant post on /r/MapPorn today: Boobs vs. Butt Searches on PornHub].

There are several reasons that many of us in the strength and conditioning field outright avoid all grains.

The primary concern with grains is the presence of lectins, which are proteins that are only present in grains and have unusual qualities. Normally, when you ingest proteins from a meat source, the enzymes in your stomach cleave apart the peptide bonds that hold the proteins together, and you then easily absorb chains of 3 to 10 aminos, which are used throughout the body. Lectins, however, are of a design such that they aren't readily digested and are absorbed in their full state. Now, here's where the science gets somewhat cutting edge, but from what I've read, here's what happens: Once floating around in the blood, the body has a hard time recognizing them for whatever reason. They then readily bind to all sorts of tissue, inhibiting cellular turnover, most especially in the intestines (keep in mind that the intestinal lining replaces itself very rapidly). Plus, while only about 1% of the US population has Coeliac's disease (a genetic disorder which produces a marked autoimmune response in the gut leading to pain and GI issues due to a sensitivity to wheat and other grains), there's evidence to suggest that a majority of people in the US have minor autoimmune reactions to wheat and other grains. Constant autoimmune reactions to what is supposedly the basis of our diet is certainly not conductive to good health, and after all, lectins are classified as an anti-nutrient.

Another aspect is that, to me at least, it's a junk carbohydrate. It provides almost nothing other than carbohydrates. The fiber in wheat isn't nearly as high-quality as the fiber in actual vegetables, and I believe the FDA is even moving to classify grain fibers differently than vegetable fibers for that very reason. Other carbs like sweet potatoes and white rice are much more superior, in my opinion. For those that just can't get away from bread though, there is an option called Ezekial bread, which is sprouted grain bread. Sprouting doesn't get rid of all the anti-nutrients, but it does eliminate many of them.

Last of all, the evolution argument is one I find interesting but one that is difficult to consider anything more than psuedo-science without more hard data. In short, agriculture has only existed for roughly 10,000 years. Humans have existed for around 200,000 years, and during that time, they thrived on a diet of meats and vegetables. Even before that, pre-human ancestors maintained a similar diet as well. While anthropologists do note that life expectancy increased with agriculture, general wellness decreased pretty drastically using a measure of pelvic depth and height of the human. Between humans that were hunter-gatherers and humans that were farmers that lived at the same time, the hunter-gatherers were on average taller, had greater pelvic depth, and lower body fat. Agrarian cultures saw a drastic reduction in quality of life based on those biological markers.

If I may suggest, there is an incredible book that talks at length on this subject called The Vegetarian Myth. I don't think I could do the author's work justice by trying to repeat it, but she's certainly done her legwork on the topic.

It's the blog of the author, and that's the first chapter of his whole book where you can find references to further reading. The main issue is about the fundamental differences between animal fats and proteins versus vegetal fats and proteins and how they're metabolized in completely different ways by the body. This among hundreds of other bits of information, especially the critics upon ethical and social aspects of vegetarianism and ecological concerns like sustainability itself. Like I said in another comment, veganism is better than the average post-industrial world diet but is no better than a healthy omnivorous diet. Furthermore, vegan diet is extremely easy to mess up and end up hurting yourself and is mostly impossible to attain a perfect vegetarian diet without chemical supplements of nutrients.

EDIT: Further read: New York Times article can be backed up with this article.

Additional data

There's also the issue of what does a true vegetarian diet consist of. Eggs or milk count? yogurt? fish? bugs? Morally would you renounce to reading books, using plastics, wearing leather, and consuming certain medicines and other product produced out of farm animals? how does this would play out on an ideal Vegan world?

Looking on their website it seems as if they do not let outside people borrow from their library, sorry :(.

I know many libraries have "partnerships" for the lack of a better word, where if you try to borrow a book from the library, and they don't have it, they will request it from somewhere else they are partnered with and get it for you.

Some ideas of books:

For my undergraduate astrophysics class I used - Foundations of Astrophysics by Ryden and Peterson, ISBN13: 978-0-321-59558-4

I have also used (more advanced, graduate level) - An Introduction to Modern Astrophysics by Carroll and Ostlie, ISBN13: 978-0-805-30402-2

There are plenty of other undergraduate text books for astrophysics, but those are the only two I have experience with.

Some other books that may be just fun reads and aren't text books:

A Brief History of Time - Hawking

QED: The Strange Theory of Light and Matter - Feynman

Random popular science books:

Parallel Worlds - Kaku (or anything else by him Michio Kaku)

Cosmos - Sagan

Dark Cosmos - Hooper

or anything by Green, Krauss, Tyson, etc.

Videos to watch:

I would also suggest, if you have an hour to burn, watching this video by Lawrence Krauss. I watched it early on in my physics career and loved it, check it out:

Lawrence Krauss - A Universe From Nothing

Also this video is some what related:

Sean Carroll - Origin of the Universe and the Arrow of Time

Hope you enjoy!

Edit: Formatting.

Talking about one universal electric field is counterintuitive. While RRC is technically correct, (EM fields do obey superposition, and are defined throughout all space), this is semantics and detrimental to learning if you are not an expert. Unfortunately, this is reddit, where semantics are the most important aspect of a post. There ARE individual electromagnetic fields. If you want, you can say that these all add together to form one giant universal field, but why would you (considering most drop off to ~zero in a relatively short distance)? When it comes to the universal aspect, think of the electromagnetic force as being universal.

To get to the questions.

1. Not really. Electromagnetic fields are somewhat mathematical constructions. In fact, you can't actually measure an electric or magnetic field; you can only measure it's influence (the force it produces). I have always been taught that sources create electromagnetic fields. That is, distributions of charged particles create electric field, and current distributions create magnetic fields (these are static fields). In electrodynamics, electric and magnetic fields exist simultaneously. So much so, that they depend on one another. This all comes from Maxwell's equations. Maybe modern interpretation says that the electric field is more fundamental than charges, but I have never heard this before, and it is definitely not what they teach in university. This may be some more advanced and therefore subdued theoretical stuff.
   
   I can't actually DEFINE a GENERAL electromagnetic field in a common definition. I can only tell you that there are a set of partial differential equations that define how EM fields behave (Maxwell's equations, Lorentz force law), and solutions to these equations are electromagnetic fields.
   
   
2. Do not think of electric fields in this matter. It isn't incorrect to say that there is a universal electromagnetic field, but it is not very insightful. It's better to think that charged objects create these fields, which affect other charged objects.
   
   
3. Generally speaking, if there was no charge in the universe, there would be no electromagnetic fields. Again, you are confused with electromagnetic theory terminology. I recommend picking up a copy of Griffiths book on electrodynamics if you are interested in the subject matter.
   
   
4. Yes. Classically, mass creates gravitational fields, while charges create electromagnetic fields. If two charges are placed near each other, they will experience an electromagnetic force, with it's strength and direction determined by the particle's position (as a function of time) and charge. Masses are similar, except the force is the force of gravity.
   
   Also, light does not propagate THROUGH electromagnetic fields. Light IS propagating electromagnetic fields. Light is known more generally as electromagnetic radiation, and it is simply energy that propagates in a wavelike fashion out to infinity, generated from the motion of charged particles.

The Turing machine answer is a fantastic theoretical one, but if you want to see a practical answer for "how do you build a computer (like most people would think of a computer) from scratch", which seems to be what you were looking for when you wrote this:

> What is going on at the lowest level? How are top-level instructions translated into zeroes and ones, and how does that make the computer perform an action?

...then this book is a fantastical down-to-earth, extremely approachable first read for such things (and designed such that you don't need *any* prior knowledge to start reading it).

Seriously, if you want to dive a little bit deeper, I highly recommend it.


edit: seems someone already recommended Code. Still, can't give it enough praise. Or The Elements of Computing Systems (TECS) which a (only *slightly*) more technical read designed around building everything that a computer "is", piece by piece...

Edit2: And as for "what's going on with the Minecraft ALU", TECS is a good read there as well, since the machine described in that book is what I based the ALU on. Also, the fact that Minecraft can simulate logic gates is what links the "real world" and the "minecraft world" together, because logic gates are all you need to build any computer (that's how Minecraft can let you build Turing Complete devices)

For Cosmology, check out Carl Sagan's Cosmos. It is a fantastic book and a favorite of many astronomy, cosmology enthusiast. It was also produced into a TV series which you can watch online for free. It's a bit dated, as it came out in the 80's, but still a fantastic read and very good for a layman understanding of a lot of science.

Let's first clarify something: we don't exactly know what it is that allows us to be so intelligent. Sure, we know that the brain does something, but exactly what that is we can't describe to a level of detail sufficient to duplicate. So this is a problem in knowing what to select for.

That being said, we could select for things we think led to the evolution of our brains, like bigger skulls (simply having more space for the brain to grow into might do...this is discussed in the book "The Red Queen" [1]), or perhaps some other physical neurobiological feature that would make their brains at least look like ours. Whether that would generate a human-level intelligence though...it's not possible to tell at this point with any degree of confidence past speculation.

[1]: http://www.amazon.com/Red-Queen-Evolution-Human-Nature/dp/0060556579 )

Sure!

The Physics of Solar Cells by Jenny Nelson is a nice book. Very dense, a little mathy, and assumes some prior knowledege.

This book by Martin Green is the gold standard, though it is probably less accessible than Nelson's and harder to find.

It's probably necessary to have a good grasp of freshman physics, and it would certainly be helpful to understand classical electrodynamics and some solid state physics, which itself requires a little bit of quantum mechanics.

Necessary math for all of this is some calculus, some differential equations, and some linear algebra.

There may be a much friendlier resource out there; I understand if this is a formidable stack.

Absolutely!

Math is everywhere and it's just about seeing the patterns emerge from simplicity. My knowledge on this topic has mainly been from my own work in Artificial Life and encoding AI genetic knowledge combined with my general interest in biological patterns (which are everywhere in nature) but the first thing that got many things to click for me was playing around with Turtle Logo in high school that is all about using simple constructs to create amazingly complex structures (i.e. one, two - look familiar?).

Sadly I don't work on my AI research anymore due to ethical concerns so I'm a bit out of date but I'd highly recommend the following that weren't mentioned in the original post though:

• "Godel, Escher, Bach: An Eternal Golden Braid" Book
  
• "The Fractal Geometry Of Nature" Book
  
• Procedural Generation
  
• Gene Expression Programming

Shavera made a nice answer, but I'll try too.

Einsteinian relativity doesn't break the notions of "past" and "future", it formalizes the notion of the "present" and breaks the idea of a universal simultaneous present. Under special relativity, your world is divided into events that can causally affect you (the locus that is inside your past light-cone), called your "past"; events that you can causally affect (the locus that is inside your future light-cone), called your "future"; and events that can have no causal relationship to you (the locus that is between the two light-cones), which could be called your "present".

The example you gave about the human and the alien is a nice demonstration of how events in the present aren't simultaneous in the sense that we're used to (different observers see them as happening in different temporal orders, depending on how the observers are moving relative to the events). But lack of simultaneity is OK, since it only happens in the non-causal part of the Universe. In your example, there's no way that the alien could affect anything that happened at Earth in either 2011, 1811, or 2211, since he's so far away that it would require a faster-than-light signal, which is impossible. So all the shenangans with the date on Earth versus his home world is all just bookkeeping games -- it doesn't change anything real.

If you'd like to explore these ideas on an intuitive level, a very nice book is Mr. Tompkins in Paperback, which explores modern physics by a series of short stories in which a stodgy British banker falls into alternate worlds where the various constants have a more human scale than our own. In the first chapter, he finds himself in a place where the speed of light is about 30 mph.

Just read this:
https://www.amazon.com/Flatland-Romance-Dimensions-Thrift-Editions/dp/048627263X/ref=sr_1_1?ie=UTF8&qid=1474906134&sr=8-1&keywords=flatland

and extrapolate to 3 dimensions. You'll have a great understanding, I promise, and it's fun to read. I'm assuming here you're wanting an expression of a 4th SPACIAL dimension, and not an exposition on "time as a 4th dimension of spacetime."

Think of a safe in 2 dimensions...a 3 dimensional person can hover OVER the safe and see everything that's in it. That same person could pluck an item out of the safe with ease. The 2 dimensional person would crap themselves when they opened the safe only to find that object mysteriously missing.

I doubt there are 4 dimensional people who can look into our safes and steal stuff, because, well, they haven't so far. Unless you count my socks that are constantly being stolen out of my dryer.

I also have that book. I think it's great if you already understand orbits. If you don't, it might be a little too technical. However, to anyone that already has a base in orbits, that is a great book.

Another good one!

We DON"T know that, its just every time we check on them (do experiments) the results come out that in such a way that makes us think that the laws that we have deduced from previous experiments still hold true. The interesting thing about scientific paradigms is that we do something, then see a result and then try to come up with an explination of why that result happened, the better our explanation explains the result and explains other results and survives repeated testing the better our explanation is to determining how the world really works, from which we can do things that build on our explanation.

This in the end does allow false assumptions to exist in science (think phlogistion chemistry) but as the field of science requires more complicated and complicated excuses for why different events happened, they are replaced with a new paradigm that explains the physical world differently.

In the end we may find at some point down the road something that scientists believe an unquestionable rule of physics is actually incorrect because it cannot explain X,Y, or Z but a new explanation comes forth and explains the stuff the first law explained and X,Y, or Z, in a better, cleaner way.

To read more I suggest : The Structure of Scientific Revolutions by Thomas Kuhn
http://www.amazon.com/Structure-Scientific-Revolutions-Thomas-Kuhn/dp/0226458083

As other comments here have made clear, the math that describes speeds of objects is different than what you would intuitively think it would be from your everyday life. Here is a nice illustration from Wikipedia as to how space transforms when you speed up.

Also, Mr. Tompkins in Wonderland is a great book about what the world would be like if the speed of light was much slower (5 km/hr) and how we would perceive it.

Cooked food is absolutely easier to digest. As for the intestinal tract, my understanding is that it has shrunk since the invention of cooking, but you'd get a better answer from an evolutionary biologist. Richard Wrangham has an excellent book on the topic.

First of all, OP is definitely talking about terraforming - for what other reason would humanity attempt to create an artificial atmosphere?


> As far as the technology, it is just a matter of scale and materials engineering to build large enough generators.

Seriously? This simply isn't true.

>so there is no point in doing the math at this time.

Actually, the math dealing with volume of gases involved and amount of energy in the total system are hugely relevant in terms of human scale vs. planetary scale.

The thing is - your argument is arbitrary as hell no matter how much you write. There's nothing wrong with thought experiments. But there's a difference between those born in good theory and daydreams. The fact is that this technology may never be developed and may be impossible. It is certainly WELL beyond the range of human endeavors and will remain so for a very long time, more on the 10,000-100,0000 year scale, if ever. You speak of it as an inevitability, which it isn't.

Have a look at Dr. Kaku's book, Physics of the Impossible, for a good speculative overview of technological advancement in regards to energy manipulation and generation. I think you'll have a better appreciation of the scales involved after reading it (though he doesn't mention terraforming specifically, if I recall.)

Dan Levitin, a psych prof in my department, has a pretty good book on music and the brain, and he discusses this issue a little bit.

I'd recommend you check it out if you are generally interested in music - why it is important to us, how it is processed in the brain, etc.

If you want to learn serious mathematics, start with a theoretical approach to calculus, then go into some analysis. Introductory Real Analysis by Kolmogorov is pretty good.

As far as how to think about these things, group theory is a strong start. "The real numbers are the unique linearly-ordered field with least upper bound property." Once you understand that sentence and can explain it in the context of group theory and the order topology, then you are in a good place to think about infinity, limits, etc.

Edit: For calc, Spivak is one of the textbooks I have heard is more common, but I have never used it so I can't comment on it. I've heard good things, though.

A harder analysis book for self-study would be Principles of Mathematical Analysis by Rudin. He is very terse in his proofs, so they can be hard to get through.

This may help with some of your questions. I've been interested myself, but haven't bought the book yet. I was told that he explains a lot of the science behind creating the scenes and that he goes on to explain some of the things they had to fudge for a better viewer experience. https://www.amazon.com/Science-Interstellar-Kip-Thorne-dp-0393351378/dp/0393351378/ref=mt_paperback?_encoding=UTF8&me=&qid=

Good answer, I just wanted to let you know I provided some sources and the same information in a thread above, just as an FYI

> This is a bit different. When a situation like this happens, all of our muscle fibers act as a single unit disregarding long term stimulation in favor for one great forceful hoorah!

1. Zatsiorsky, V., Kraemer, W. Science and Practice of Strength Training. Champagne: Human Kinetics, 2006.
   Defines the terms absolute strength (max force our muscles, bones and tenodns can withstand), maximum strength (maximum force our muscles can produce), and the somewhere in between (~92% absolute strength - where all muscle fibers act as a unit)
   
2. Walker, A. "The Strength of Great Apes and the Speed of Humans." Current Anthropology. 1 Apr. 2009, Volume 50, Number 2: 229-234.
   > "There is also the upstream control of motor neurons to consider. There are well‐known cases of “hysterical strength,” where people suffering seizures exhibit considerably more muscle power than normal. There are also many anecdotes about people in very stressful situations being able to do things that would normally be considered impossible—lifting cars off trapped people, for instance. Add to this the effect of severe electric shock, where people are often thrown violently by their own extreme muscle contraction, and it is clear that we do not contract all our muscle fibers at once. So there might be a degree of cerebral inhibition in people that prevents them from damaging their muscular system that is not present, or not present to the same degree, in great apes. I do not know of any experimental evidence to support or refute this idea, although cortical inhibition of motor impulses has been experimentally demonstrated in animal models and with magnetic inhibition in people."
   
   
3. Hysterical Strength
   > "Hysterical strength can result in torn muscles and damaged joints. This is why, in addition to high lactic acid production, the body limits the number of muscle fibers the human body uses"
   
   
   
   
   My response above

Earth rotates (nearly) freely in space around a principal axis of rotation which, as you say, we know as the north-south axis. If you were to apply some torque to the Earth to change that, the rotation would change to some other axis. In other words, you wouldn't really see any more complicated behaviour than today, just a different axis, and there would be new "north" and "south" poles.

That's the boring answer. Now for something slightly more interesting.

Now as it happens the Earth does actually not rotate freely. It is subject primarily to tidal forces from the Moon and the Sun, but also a few others. This causes the axis of rotation to change over a period of roughly 26,000 years, an effect known as axial precession or precession of the equinoxes. The apparent north pole, currently in the vicinity of the star Polaris, will trace a circle over 26,000 years. The center point of that circle is the "orbital" north pole, i.e. the axis around which the Earth orbits (not rotates). This looks similar to how a spinning top sometimes slowly spins around its own axis of rotation, if you set it spinning with a slight tilt on a surface.

There are other changes to Earth's rotation too, they are called nutation, the principal effect of which varies over about an 18 year period.

So yes, it is possible to have such complicated rotation and in fact it already happens. However I do not wish to speculate on how exactly precession and nutation would look like if you modified the Earth's primary axis of rotation and/or angular momentum.

Source: Explanatory Supplement to the Astronomical Almanac.

The book that kindled my interest in Artificial Intelligence and started my journey toward getting a PhD in Computer Science was Gödel, Escher, Bach: An Eternal Golden Braid. It's not current with respect to the state of the art, but it is a compelling, high-level tour through some of the biq questions in Artificial Intelligence, Cognitive Science, and Computer Science in general.

Both of your aanswers are legit. 1. Maths is not strictly about the techniques you learn but about learning aa different way to think or even a different way to learn. 2. Although this answer may be true asking people to learn math for the sake of learning more math might not go down to well.

For me, the currency of maths that get's people excited is stories. For every subject that you're trying to teach I would start with a story where that particular peice of math has impacted on people's lives in a very dramatic way. Perhaps they didn't know a bit of math that could have saved them money or even saved their lives. Perhaps knowing all the math in the word wouldn't have saved them, but the math is inherent in a corrupt system which we all need to fight to change.

Not to push it too mucch, but this was the idea I hit upon in my book, so if you're looking for these sorts of stories you could do worse than start there: https://www.amazon.com/Math-Life-Death-Mathematical-Principles/dp/1982111879/ref=sr_1_fkmr0_1?crid=VWXFWH6IJA6W&keywords=the+maths+of+life+and+death+kit+yates&qid=1564181090&s=gateway&sprefix=the+math+of+life+and+death+%2Caps%2C120&sr=8-1-fkmr0

If you want to learn more about this, I would recommend a book called This Is Your Brain On Music. It's an amazing breakdown of the brain's ability to process music by a neuro scientist who had been previously been employed as a sound engineer for many prominent bands during the 70's.

http://www.amazon.com/This-Your-Brain-Music-Obsession/dp/0525949690

The Top post has got most things covered for a LEO satellite (cube and buying space for a launch)

If you want to quit this boring earth orbiting shit and go into deep space (or to Mars), communication and tracking is going to be a major problem. Staying in LEO has major advantages as theres a package deal to use internet through other satellites (for coms) and also using GPS for tracking. Going outside that range means hiring telescopes all around the world and/or very large ones for short periods of time, and I would consider it undoable to do it alone, un-affiliated.

Unless.... you build your own large telescope and operate the spacecraft with it for a brief period once every day.

•For the inside of the craft, getting a nice on board computer(GNU license), memory storage, power maintaining unit and energy (solar) is pretty cheap and easy. The only cost driving factors is that radiation kills the computer, and that space computer technology is about 5-10 years behind modern society.


• Also, remember to coat the spacecraft correctly so you don't overheat/freeze the computer. If you wanna go further away from the Sun than mars, heating might be something you want to look into.


•Omni-directional antennae are decently cheap but have a shitty bandwidth, but it's still a better idea than using a directed antenna.


•Use a honeycomb structure of aluminium as casing, it's durable and light weight.


•The hard part might be getting your hand on a propulsion system that works in space, many are super toxic and/or high-tech and not easily bought (ion thrusters, etc). You might want to look into solid rocket fuel, but it's basically like lighting a bomb, and gives you no maneuverability.


The cost driving factors though are really your work hours, your targeted failure rate level and the length of your mission, but I think it's feasible to send something nice and with decent survivability chance to Mars Orbit for 100'000€


Source: SMAD
( http://www.amazon.com/Mission-Analysis-Design-Technology-Library/dp/1881883108 ), ESA, MSc in Space physics

Things are a bit different for hearing, but the "such and unexplored area" feeling will be the same. For reference, this is what science is.

http://matt.might.net/articles/phd-school-in-pictures/

OH, also read Thomas Khun's, The Structure of Scientific Revolutions only 200 pages, and you'll probably get the point around page 50. Best book on human knowledge ever.

N-dimensional space. I literally just now started reading Edwin A. Abbott's Flatland: A Romance of Many Dimensions. I highly recommend this book if this type of dimensional thinking intrigues you.

If the characters wake up with an astronautical book or data base, then the positions of the moon and planets would be the best bet for telling the date and location. The stars would give them only the latitude, not the longitude. Although the astro almanac is recalculated for each year, it should be accurate enough to project the equations a few hundred years into the future. If you need a few thousand years, then you need a long-term epidermis, like JPL DE431 (covers years 13201 BC to AD 17191). Of course, you need a computer to run it on.

https://www.amazon.com/Explanatory-Supplement-Astronomical-Almanac-Urban/dp/1891389858

https://www.amazon.com/Astronomical-Almanac-Year-Nautical-Office/dp/0707741920/ref=pd_lpo_sbs_14_img_1?_encoding=UTF8&psc=1&refRID=XRMFS7E3NGSC2CT46FQC

https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Development_Ephemeris

I read a book that had some science of music in it. "This is Your Brain on Music". I don't remember the specifics of it so I won't try to repeat it here because I'll probably say something inaccurate. That book isn't the only one of it's kind (good book by the way). If you are really interested in the subject I'm sure you can find some interesting information.

http://www.amazon.com/This-Your-Brain-Music-Obsession/dp/0525949690

http://www.amazon.com/gp/product/1400033535/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0525949690&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=02HTPTSMBADCZZE5BDMV

just in case some readers aren't aware... there is a really cool (and short) book called Flatland about 2D creatures that can only conceive of the world in 2D. One of them starts understanding 3 dimensions and things get interesting. Here is a link (normal) for the book I mean:
http://www.amazon.com/Flatland-Romance-Dimensions-Thrift-Editions/dp/048627263X

most of those books looked like they were $2-$4. Go get a copy if you haven't read it yet.

What level do you want it pitched at? The Wikipedia article is pretty good, and there's always Griffiths Electrodynamics.

Here is a good summary of the issue: The Vegetarian Myth: Food, Justice, and Sustainability

How do you get a 3D display? As others have mentioned, computer screens are 2D. Perhaps a separate screen for each eye? There are also auditory cues to suggest 3D.

It is an interesting question. Some suggest we have a hard time imagining 4 spatial dimensions since we have no experience outside of our 3 spatial dimensions. See Edwin Abbott's Flatland as well as Dewdney's Planiverse.

A computer game world could be set in 4 spatial dimensions. Presently a lot of 4 dimensional polychora exist in digital form. Perhaps a player of this game might become accustomed to 4 spatial dimensions and have a better understanding.

All brightness in that image is the accretion disk - light emitted by the part of the disk on the opposite side of the black hole is bent around it by gravitational lensing, causing the image above and below the black hole. It is a minimally aesthetically tweaked depiction based on an accurate computer model, yes.

e: got the book in front of me, here's some pages showing the lensing.

http://www.amazon.com/The-Elements-Computing-Systems-Principles/dp/0262640686

This text book goes through building a computer starting at logic gates and going all the way to building a CPU and writing a compiler. It might take a while to get through, but after you do you will have a really good understanding of how computers work.

This book also explains this phenomenon in great detail.

This is an incredibly broad and complex set of questions.

Here is a good video describing why there are so many programming languages.

Wikipedia has multiple pages comparing programming languages. Here is the beginning.

Students will spend years in school learning about the different layers of abstraction in programming and how code gets turned into something the computer will understand. This website along with the companion book is an excellent overview of the subject.

If you have more specific questions after perusing through the resources, I can answer them. The links the other poster and I have posted will give you a high-level overview of what you asked, but if you want all the details, you'd be halfway to a computer science bachelors degree.

Well, let's go back to your analogy with throwing a ball to your sister. Here, you and your sister would represent both positive (or both negative) charges. Now imagine that you're both standing on ice. When you throw the ball, you'll recoil a bit, and when the ball hit's your sister, she'll go backwards as well. The analogy breaks down for attractive charges. If you really want to understand how these forces work, I highly suggest getting a copy of Griffith's Intro to Electrodynamics. I'm not sure where you live, but I know in many countries this book comes in an "international edition" which has the same content, but is phenomenally cheaper.

you expend a lot of energy to break down food in your digestive system, ex: chewing, your gut rumbling around. Additionally, the food is only in the digestive tract for a finite amount of time, and the rate of nutritional uptake would be faster for a pre-blended steak than an unblended one. The same mass of peanut butter vs raw peanuts would give you different net energy gains.

I learned a lot of this from the book, Catching Fire: http://www.amazon.com/Catching-Fire-Cooking-Made-Human/dp/0465013627

You might find Stephen Hawking's "A Brief History of Time" to be an interesting read.

http://alleeshadowtradition.com/pdf/stephen_hawking_a_brief_history_of_time.pdf

http://www.amazon.com/Brief-History-Time-Stephen-Hawking/dp/0553380168

In Hawking's A Brief History of Time, he explains the reason why we can only live in a universe of three spatial dimensions.

Newton originally discovered this purely mathematically. The force of gravity must be inversely proportional to the square of the distance in order for stable orbits to be possible. The force would be inversely proportional to the square of the distance only if the force-carrier (gravitons, photons, however you want to imagine the force propagating) was emitted in three spatial dimensions.

If you had two spatial dimensions or four, planets (electrons) wouldn't form stable orbits and nothing that we can imagine being matter would form.

A prominent hypothesis has to do with 3 factors: Lice, Fire, and Smell.

Hair around the armpits, neck, and crotch are very prone to use sweat to amplify hormones and other smell signals. Armpits are noticeably close to the nose, allowing people to sniff out familiar armpits in a crowd.

Lice, and other hair parasites might have been affected by fire and senses of beauty. Obviously, when you have less hair, notable lice are more out in the open. But when you add in the abundance of provided warmth (such as the discovery of fire), the hair is no longer needed in the mid-regions, and sickness-purity-detection would be more revealed.

Regarding your question, I think you can determine the difference between top-of-your-head-hair, which grows in a spiral pattern (visable in the crown of the head approaching a circular point), or a twisted set of pubes, versus non-axial which grows on your arms, legs, back.


Please let me know which of these ideas have been discredited.

Sources:

1-Catching Fire

2, this one helps to disprove usage of clothing as hair-reduction

If you're interested in this kind of question, This book gives a fascinating overview of this whole topic.

It gives the answers, as much as they are known, to questions of why there are sexes at all, why some animals are polygamous or monogamous, why they cheat on their spouses. When science doesn't know the answer, the book details competing ideas and gives the reasons their proponents support them.

Your question was also answered, IIRC, in a particular chapter of Richard Dawkin's "The Selfish Gene".

On your particular question, it boils down to the fact that a female, purely because of biology, invests heavily in their offspring. If they can persuade the male to also invest, that's a win for the female. The male, however - or rather, the male's DNA - has an "incentive" to quickly find as many partners as possible; although, there's also some benefit to staying around hand helping the kids grow.

Imagine the female DNA implements one of two strategies:

• H: hard-to-get: insisting the male go through a long courtship before allowing insemination
  
• F: fast-and-loose: the opposite
  
  On the other hand, suppose the male DNA implements one of these strategies:
  
  
• S: Solid, faithful: willing to stick it out with the partner they chose
  
• C: Cheater: moves on quickly.
  
  If the female population is predominantly F, then the male population will be shifted towards C. Cheaters spread more of their DNA than Solids.
  
  If the male population is predominantly C, then this may be stable, but if (for biological reasons) it's really costly to raise a child as a single mother, the female population may suffer pressure to move from F to H. The hard-to-get females often end up with no partner at all, but when they do find someone, it's a solid man who'll stick around.
  
  So the population of females may shift towards H. When the H predominate, the cheating males have no more luck. The male population undergoes selective pressure to move from C to S.
  
  Finally, if the males are mostly S, the few F females have an advantage - they avoid a costly, time-consuming mating ritual, and still have a good chance of landing a faithful husband. The female population might swing back to F, and the cycle begins again.
  
  You don't always get cycles, it depends on exactly how much each sex's strategy gains or loses in light of the strategies the other sex is using. And creatures with complex brains can switch strategies based on what they observe. And, of course, there are more strategies possible than this: cheating while pretending to be faithful, maintaining a harem, neither sex caring for the young, eating your husband, dispensing with sex altogether, changing sex, being both sexes at once and more are all actually implemented in the animal, plant and other kingdoms. each having their own advantages and disadvantages in different circumstances.
  
  One last thing: a complex, expensive mating ritual makes abandonment less likely. The male in a partnership is more likely to choose to stick around and give his DNA (in his kids) a better chance of propagating, if he expects that finding a new partner will be costly and difficult.
  
  
  
  

GEB

Child development researchers have found a lot of interesting "milestones" that seem to differentiate our cognition from that of other primates. An interesting one is called Theory of Mind -- basically the ability to reason that other people are conscious beings as well.

At around 2-5 years old, children tend to understand that other people have a mind too, and the children learn to empathize with others (empathize in this context just means being able to imagine what a situation appears like from another person's point of view). The "Theory of Mind" clip on [this episode] (http://science.discovery.com/videos/through-the-wormhole-did-we-invent-god/) of the excellent series Through the Wormhole has a really great explanation.

At around 6-7 years old, children add another level of indirection -- a child not only realizes that other people have minds, but they realize that other peoples' minds are aware of their own minds. First you realize that you have a mind, then around 2-5 years old your mind can imagine other minds, then at around 6-7 you realize that those other minds can imagine your mind as well. That's the point when kids learn what deception is and become sneaky little bastards.

There's a lot of other really interesting child development milestones. For example, most animals lack the ability to realize that what they see in the mirror is actually themselves instead of another animal. Part of what it means to be human appears to be this ability to think about and layer self-referential concepts -- you've got a mind, this other person has a mind, but in the same way that your mind can think about the other mind, the other mind can think about you, and you can use that understanding of awareness to then change how you interact with the other mind (i.e. "I didn't steal the cookie from the cookie jar!", "These white lines on a blueprint show you how you build a skyscraper"). If you're up for a challenge, the 1979 classic [Godel, Escher, Bach: An Eternal Golden Braid] (http://www.amazon.com/G%C3%B6del-Escher-Bach-Eternal-Golden/dp/0465026567) touches on a lot of these self-referential concepts. Be warned: it's not an easy nor a short book.

-----------
: The worst thing "Through the Wormhole" has going for it is its incredibly cheesy name that mares an otherwise fantastic documentary series about the "rockstars" of current science. Other shows that have fallen into the terribly-cheesy-name-but-otherwise-excellent-show trap include "Battlestar Gallactica".

I've been writing for over an our... and then everything was lost because I pressed a wrong button. FML

Sorry but I won't write it all again. I will just say the main points and some links I had. Here is one regarding the whole point of the conversation.

> pμ = mvμ (this is the ratio of four-momentum to four-velocity) and is also the ratio of four-acceleration to four-force when the rest mass is constant, or, Fμ = mAμ.

There are some misconceptions here which I had all worked out... I will just say this so that you know. Basically any book about special relativity can explain this quite well. I think that Griffiths has a pretty good explanation of all that (although it's a electromagnetism book). You can look up the chapter 12.

There are some misconceptions like "So an object with zero mass means that it has no resistance to being accelerated by a force,". I won't explain all that again...

I'm really sorry and really pissed that I lost my comment, but this will have to do.

If life can grow out of the formal chemical substrate of the cell, if consciousness can emerge out of a formal system of firing neurons, then so too will computers attain human intelligence.