Sunday, January 31, 2016

31 January 2016- White Dwarf | PWN Physics 365

On this day in physics: 31 January 1982 A white dwarf companion to Sirius is discovered by Alvan Graham Clark using an 18.5-inch telescope. [Source] Sirius is the brightest star in the night sky. It is now known as Sirius A, because of this discovery, which saw that a second White Dwarf star, Sirius B, existed and orbits Sirius A.

Word of the Day: White Dwarf- a type of star-leftover which is considered to be the final stage of stars which are not massive enough to become Neutron Stars. These dwarfs were once small to medium mass stars, then entered the red giant phase, which have very large radiuses with relatively low temperature (5000 K or less). Red giants are essentially giant fusion reactors, which fuse helium into carbon, releasing massive amounts of energy. When they run out of energy, what you're left with is a white dwarf. It's the core of the reactor which doesn't have enough energy to react anymore. Imagine the nuclear waste in a nuclear reactor once it's been used up. They are extremely dense, imagine something the size of the sun compressed down to the size of the Earth.

White dwarfs, in this stage, radiate out tons of energy, in the form of white light, and as they have no source of energy, they simply lose energy, dim and fade away. The white will get slightly redder as it ages. They should reach a point of cooling where they will no longer radiate light, and will become the theorized "black dwarf". There are no known black dwarfs to exist. The amount of time that it takes a white dwarf to cool to the black dwarf stage is longer than the current age of the universe. We may see some in the future, but the coolest and oldest White Dwarfs known to exist are still a few thousand Kelvins.

Killer Resource: Drums and Cymbals in Slow Motion. World Record holding drummer, and current Dream Theater drummer Mike Mangini was filmed with high speed cameras to see how drums behave in slow motion.



Keywords: White Dwarf, Star, Black Dwarf, Steller, Universe, Fusion, Reactor

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Saturday, January 30, 2016

30 January 2016- Momentum | PWN Physics 2016

On this day in physics: 30 January 1991, we said Goodbye to John Bardeen, an American Physicist and Electrical Engineer. John so far is the only person to have won the Nobel Prize TWICE! The first time he won in 1956 with two others for the invention of the transistor. As if once wasn't enough, the next time he won again with colleagues in 1972 for the development BCS theory, which is a theory which describes superconductivity and breaks it down into a property which exists at the microscopic scale. [Source]. PWN Physics 365 salutes you!

Word of the Day: Momentum- It would be hard to do a word of the day about mass and inertia and not follow it up with momentum. As if mass and inertia weren't hard enough to describe, I think momentum is even harder. This is what momentum is. It is the product of the velocity and the mass of an object. If you are stationary your momentum is zero. The faster you're going, the more momentum you gain. There is also something called conservation of momentum, which means that the total momentum of a system must be conserved. This is very important for collisions! If two bodies collide, the total momentum of the system will be conserved, which means that one body could leave the collision with a much higher velocity than it entered! This is especially the case when a small object moving slowly collides with a massive object moving quickly!

Killer Resource: Conservation of Momentum- Newton's Cradle Explained.

Keywords: Momentum, Newton, Cradle, Transistor, Superconductor.

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Friday, January 29, 2016

29 January 2016- Mass | PWN Physics 365

On this day in physics: 29 January 1926, we say Happy Birthday to Abdus Salem, one of three physicists to share the Nobel Prize in 1979 for unifying the electromagnetic and weak force to the electroweak force. [Source].

Word of the Day: Mass- First, let's take a look at a couple of definitions. From wikipedia: "It is generally the amount of matter of an object. It is determined by the strength of its mutual gravitational attraction to other bodies, its resistance to being accelerated by a force, and in the theory of relativity gives the mass–energy content of a system. The SI unit of mass is the kilogram (kg)." [Source] From Hyperphysics: "The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else." [Source] Isn't that the truth. Unofficially, Mass is "how much stuff there is". It can be quantified in a couple of ways. First, as mentioned in both of the definitions, it is a way to quantify inertia. If you have two objects of the same volume, but one is more massive, it will be harder to move, a lot harder to slow down, do more damage if it collides (i.e. more momentum), etc. Next, it is a cause for gravitational attraction. Mass attracts more mass. Next, we have Newton's Second Law: F = ma. If you have an object, which will have constant mass, the more force you give, the more acceleration you will get. So mass defines how much force you need to generate acceleration. Lastly, mass is a quantifiable measure of energy, think about Einstein's E = mc^2. c^2 is the speed of light squared it will always be the same, so mass, by this equation is the same as energy, or energy waiting to be released.

One thing that most people confuse is that mass is the same thing as weight. This makes sense since we're on earth, and the earth is a monster constant mass next to us, so gravity is constant. So, the more massive something is, the more weight it has on Earth. However, the same mass on the moon will have 1/6 of the weight. Weight is equal to mass times gravity, so on Earth, they are totally linearly related. However, mass and weight are separate quantities, so be careful, you cannot use those words interchangably!

Killer Resource: The way that various atoms are created: This periodic table is color coded to show how different elements are created, either via the Big Bang, Supernova, Man-Made, Large Star, Small Star, and/or Cosmic Rays.



Keywords: Mass, Inertia, Momentum, Einstein, Elements, Stars, Astronomy, Supernova, Small Star, Large Star, Cosmic Rays, Big Bang.

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PWN E089: Anatomy Of A Line

So, last episode I had mentioned a really great article which mentioned how it's currently possible to see 5 planets in the morning sky. Well, this weekend, I had a chance to check it out and managed to see Venus, Saturn, Mars, and Jupiter in the sky! Check out the pics below.

On to the line. In this episode we dig deep into the three major "anatomy points" of a line: the slope, y-intercept and x-intercept.

The slope: The "angle" of the line. From 0-45, the slope of the line is less than 1. From 45-90 we go from 1 to infinite slope. From 90-135 degrees, we go from the infinite back to -1, all negative. From 135 to 180, we go from -1 down to 0 again.

Next we introduce three critical linear equations. First the classic: y = mx + b, where m is the slope and b is the y-intercept. Example, y = 3x + 2, the slope is 3, and the line will intersect the y-axis at +2. Just think about what happens if you plug in x = 0, y = 3*0+2 = 2. Second we have the equation for slope: m = (y2-y1)/(x2-x1) using any two points on the line (x1,y1) and (x2,y2). We can then morph this into the "point-slope" form: y-y1 = m(x-x1) using any one point on the line.

Lastly, there are three combinations of two required pieces of information to define a line. Ideally, we would be given two points on a line, from this we could easily calculate m and then plug in for b. We could also be given a point and the y-intercept, and be able to make similar calculations. Lastly, we can be given one point and the slope, and do calculations to get everything we need.

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Wednesday, January 27, 2016

28 January 2016- Inertia | PWN Physics 365

On this day in physics: 28 January 1613, the planet of Neptune may have been discovered, unbeknownst to its observer, Galileo Galilei. According to his observation records of that night, he noticed what he believed to be a star, very close to the planet Jupiter. This star does not match any current records. For three nights it was observed, and then had moved to an unobservable part of the sky. Neptune remained under the radar for another 233 years, until it was formally discovered as a planet by Urban Le Vernier, who predicted its existence using only mathematics, and by Johann Galle, an observational astronomer who actually first found it in 1846. Neptune's year is 164.8 earth years long, meaning that since we've first discovered it has only gone around the sun once (2011!) plus a very little bit.

Word of the Day: Inertia can be embodied by the following phrase: "A body at rests remains at rest." Inertia is an objects opposition to motion, or its desire to remain inert. It is also responsible for "A body in motion tends to remain in motion unless acted on by an outside force" (courtesy Isaac Newton). So, if we have an object "at rest" or not moving, we will not see this object move unless something happens to it which would induce motion, such as a wind, push, or other action. And, if this motion were to occur in a deep space vacuum (we're going to ignore air resistance here), it would continue to move along with a constant velocity, until something were to stop it. These properties are referred to as inertia. When you get in your car, and finally turn on the highway, getting on the on ramp, starting at a presumable 0 mph, your car's engine must burn a considerable amount of gas to get us up to the 65mph speed limit, and what the engine is doing is overcoming the inertia of the car, or its desire to remain at its 0mph velocity. Once on the highway, we still need to have our foot on the gas, but we're burning considerably less gas. In a frictionless and air resistance less world, we wouldn't need to have our foot on the gas at all, we'd just cruise along forever, although braking would be something of an issue. On the highway, the only energy expenditure of gas is to overcome the resistive friction of your tires on the road, because once in motion, the car's inertia wants to keep it going at whatever speed you've set.

Killer Resource: What if the moon was replaced by various planets visualized.



Keywords: Inertia, Mass, Velocity, Car, Friction, Highway, Neptune

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27 January 2016- Meson | PWN Physics 365

On this day in physics: 27 January 1936, Happy Birthday to Samuel C. C. Ting, a Nobel Prize winning physicist for discovering the J/ψ (J/Psi) meson or psion. He turns 80 today. Happy Birthday! He is currently the lead researcher on the 1.5 billion dollar alpha magnetic spectrometer research experiment aboard the ISS (Word of the day!) It is working to detect specific cosmic rays in search of Dark Matter [Source].

Word of the Day: Meson- a particle composed of one quark and one antiquark. These can be comprised of their own "species", i.e. a Charm and Anticharm, aka "Charmonium", or different "species" such as in a Pion, which consists of an up and anti-down quark. Mesons which consist of the same type of quark and antiquark, such as Charmonium, are referred to as Quarkonium. Now, one thing that I thought about when I was researching about this, most particle/antiparticle pairs annihilate, releasing energy. How is it that these particles exist? Well, the short answer is that the lifetimes of something even like a pion, which is made of an up/antidown pair, lives for something on the order of 1e-8 seconds, or 10 nanoseconds. Protons and Neutrons are not mesons, since they are not made of 2 quarks, but rather 3 quarks, none of which are quark/antiquark pairs.

Killer Resource: Jupiter is sometimes referred to as a failed star.



Keywords: Quark, Meson, Antiquark, Pair, Up, Antidown, Quarkonium, Charm, Charmonium, Jupiter.

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Monday, January 25, 2016

26 January 2016- Magnetic Moment | PWN Physics 365

On this day in physics: 26 January 1911 Happy Birthday to Polykarp Kusch, Nobel Prize winning physicist who shared the prize in 1955 with Willis Lamb. The Nobel Prize in Physics 1955 was divided equally between Willis Eugene Lamb "for his discoveries concerning the fine structure of the hydrogen spectrum" and Polykarp Kusch "for his precision determination of the magnetic moment of the electron" [Source].

Word of the Day: Magnetic Moment is related to the amount of torque generated by an object in the presence of a magnetic field. If you're a totally electrically neutral object, you're moment is 0. Neutrons, for example, will travel through a magnetic field as if it wasn't there. Now, if you're something like an electron, or a planet, or a charged atom, or a current carrying wire, the situation is slightly different. It can be thought of as a vector, or an arrow of a specified length and direction, for any given item that you are considering. For the extremely small, like electrons studied by our birthday boy Polykarp, the magnetic moment is dependent on the particle's spin and some constants, notably planck's constant, and the Bohr Magneton (maybe future words of the day? tweets please). For something like a current carrying wire, it's related to the diameter of the wire, as well as the current travelling through the wire. This magnetic moment is important because the overall magnetic properties of a material are highly dependant on the magnetic moments of their component atoms. Anything that you see in everyday life that deals with magnets, i.e. the ones that stick to your fridge, the ones in your speakers, etc. are behaving this way because of the component magnetic moments of the atoms which make up the materials (mostly ferromagnetism.)

Killer Resource: Motion of a Charged Particle in a Magnetic Field.



Keywords: Magnetic, Moment, Charged, Particle, Electron

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Sunday, January 24, 2016

25 January 2016- Wave Function | PWN Physics 365

On this day in physics: 25 January 1839, Michael Faraday announces the first photographs have been taken during his Friday Night Discourse meeting. They were referred to as "Photogenic Drawings" and a paper revealing more about this process was published in the following weeks.

Word of the day- A Wave Function is a quantum mechanical property of everything that exists. A wave function of an object is the probability finding that object at any particular place at any particular time. If you calculate the wave function over all of space, the value will be 1, since there is a 100% chance of finding everything that exits somewhere in space at any given time. The wave function is critical in Schrodinger's Equation, which are most student's first introduction to the concept of a wave function. It is most usually described with the Greek letter phi. Let's go back to the word of the day a few days ago: electron. An electron which is in an atom's orbit has its wave function distributed around the atom, known as the electron shell. However, an electron's wave function is stretched across all space, and there is a very small chance of finding it somewhere else for a brief moment. Electrons "take advantage" of this wave function in a phenomenon known as tunneling. Consider it in this way. There is an electron on one side of a wall. There is a very small part of the electron's wave function on the other side of the wall, meaning there is a small small small chance that the electron's position will be on the other side of this wall. If the electron is to crash into the wall over and over, billions, and billions of times, sooner or later this probability becomes more of a certainty, and the electron is able to "tunnel" to the other side of the wall.

Killer Resource: Astronomy Picture Of The Day App.



Keywords: Wave, Function, Quantum, Mechanics

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24 January 2016- ISS | PWN Physics 365

On this day in physics: 24 January 1947, Happy Birthday to Dr. Michio Kaku, theoretical and popular physicist. I first heard of Michio reading his book Hyperspace: A Scientific Odyssey through Parallel Universes, Time Warps, and the Tenth Dimension. Michio has been making his way into more into the media spotlight, currently making him maybe the most popular scientists outside of Stephen Hawking and Neil Degrasse Tyson.

Word of the day- ISS is an acronym (Like FBI, KFC, NATO, or VIP) for the International Space Station. Its first component was placed in orbit in 1998 and is referred to as a "habitable artificial satellite". It is the largest artificial body in orbit and can be often seen with the naked eye from the surface of the planet (more on this in a minute). It has been continuously inhabited since November 2000. It provides a place for long term experiments to take place, which can be monitored by human researchers. Crew stay on board the space station for continues 6 month increments, and then rotate out with other researchers from U.S., Russia, Japan, Canada and Europe. The gravity in th ISS is actually not much less than that of earth, but because it is orbiting, and in a perpetual state of freewill, there is a perceived weightlessness. It stays somewhere between 205 and 270 miles above the earth and maintains this height with something known as "reboot maneuvers", or else it would eventually come crashing back to Earth. It makes roughly 15 orbits a day.

Killer Resource: ISS Finder App- Find every single change to see the ISS across your view of the sky.



Keywords: ISS, International, Space, Station, Research, Orbit, Gravity

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Saturday, January 23, 2016

23 January 2016- Wave-Particle Duality | PWN Physics 365

On this day in physics: 23 January 1907, Happy Birthday to Hideki Yukawa, 1949's Nobel Prize winner who predicted the existence of the pion. He won the nobel prize for "for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces".[Source.][Source.]

Word of the day- Wave-Particle Duality is an embedded property of everything that exists. Every atom, quark, photon, car, person, planet, galaxy, can partially be described as a particle, and partially described as a wave. Louis de Broglie was able to describe the wave-like property of matter as follows: lambda = h/p, where lambda is the wavelength, h is Planck's Constant (6.626 × 10−34 J seconds), and p is the particle's momentum. So how come if everything has a wave-like part, we're not oscillating all over the place? The answer lies with this de Broglie wavelength. When you consider something as large as a fly, or even as large as a person, the wave-like part is so small it is simply unnoticeable. However, when you're considering something the size of an electron, this becomes much more noticeable. The wavelength of a 0.511 MeV electron is roughly 1.23 nm. Still very small, but these wavelengths are now on the same scale as the particle to which it is associated. By comparison, "A 50-kg (~110-lb) person walking at a speed of about 2 m/s would have a deBroglie wavelength of 6.63x10-36 m." [Source].

Killer Resource: An article where the particle and wave properties of light are imaged for the first time. (WIRED MAGAZINE)



Keywords: Photon, Electron, Wavelength, Wave, Particle, Duality, Nobel, Prize, de Broglie

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Thursday, January 21, 2016

Episode 087: Lines, Linear Equations, Parabolas, & Quadratic Equations - An Introduction.

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Moon Phase: Waxing Gibbous, Full Moon in 2 days.

There's a great New York Times article about how every morning for the next month, Mercury, Venus, Mars, Saturn, and Jupiter will be visible in the morning sky.

FAQs that are answered on this podcast:

What is a line?

Why are lines important?

What is a linear relationship?

What is a parabola?

Why are parabolas important??

What is a quadratic equation? Why is it called quadratic and not parabolic??

What are roots?

22 January 2016- Electron | PWN Physics 365

On this day in physics: 22 January 1997, Lottie Williams becomes the first person to cross paths with a piece of falling space-vehicle debris. On a walk at 3 a.m. in Tulsa, OK (What??) she sees overhead what she believes to be a meteor, a bright glowing object in the sky. Some time later she gets struck in the shoulder by a six-inch piece of metal. It is believed to be the debris of a Delta II rocket which had burned up in Earth's atmosphere earlier that night.[Source.]

Word of the day- Electron- A fundamental particle, meaning that it does not break down into any other particles. It is one of three types of particles which makes up all atoms of matter: Protons, Neutrons, and Electrons. As stated before, whereas protons and neutrons are made up of up and down quarks, electrons do not break down. They can be modeled as "orbiting" the protons and neutrons, which make up the nucleus of the atom. The "distance" of the electron's orbit can be thought of as follows: If an electron was to "orbit" circularly around the very highest seats of a football stadium, the nucleus would be a quarter on the 50 yard line.

We know very well in 2016 that electron's don't actually orbit the nucleus of an atom, the way the earth orbits the sun. Instead, electrons don't really have a definite position of any sort. Rather, they have "probability densities", places where they are most likely to be, were you to measure their position. Hydrogen has a single electron orbiting a single proton. This makes the overall charge of the atom neutral, because the electron's charge exactly opposes the charge of a proton.

As we look at atoms with more and more protons, generally we find atoms with more and more electrons. These electrons all orbit the nucleus, but the shape of the probability densities changes based on how many electrons there are. They actually group together in clusters with different "radiuses" and shapes of their probability densities. These are called shells.

Killer Resource: Hydrogen Atom Orbitals Very excellent poster of the the different electron orbitals, or "shells".



Keywords: Electron, Proton, Atom, Orbital, Shell, Particle, Quark

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Wednesday, January 20, 2016

21 January 2016- Entropy | PWN Physics 365

On this day in physics: 21 January 1962- Happy Birthday to Dutch Theoretical Physicist Erik Verlinde, who turns 54 today. Erik's specialty is in string theory, and introduced a controversial theory for gravity known as "entropic gravity." This explains gravity not as a fundamental force, but rather as a byproduct of the fact that systems tend to increase in entropy. One draw to this theory is that it correctly predicts the strength of Dark Energy, a previous word of the day![Source.]

Word of the day- Entropy- According to Wikipedia: "In thermodynamics, entropy (usual symbol S) is a measure of the number of specific realizations or microstates that may realize a thermodynamic system in a defined state specified by macroscopic variables. Entropy is commonly understood as a measure of molecular disorder within a macroscopic system." Okay great but what does that mean exactly?? It means that entropy is a concept heavily involved with the thermodynamics of a system. The second law of thermodynamics is as follows: In a reaction, or any sort of interaction between bodies, the entropy always increases. OK, so we know that it's always increasing, but so are a lot of things, it doesn't really explain what entropy is. From hyper physics: "Entropy is a measure of the amount of energy which is unavailable to do work." An lastly, and probably most simply, it is the measure of disorder in a system. So, the the second law of thermodynamics really says that the disorderedness of a system is always increasing. This is probably the easiest way to think about it. Entropy is also known as "time's arrow". Entropy is always increasing, so if you were to see a series of images of a system's evolution, and you know the amount of disorderedness of each image, ordering them from least to greatest would put them in chronological order. Think of it this way. If you were to see a series of pictures of a glass of water falling off of a table and shattering on the floor, it would be possible to place them in chronological order, yes? Why is that? If you were to place a few drops of red dye into a glass of water, and not interact with that system in any way, eventually the dye would evenly disperse through all of the water, making it with the lightest reddish hue possible. This is the most disordered state possible. When a system cannot possibly become any more disordered, it is considered to be in equilibrium.

Killer Resource: Neil DeGrasse Tyson talks about Entropy and how life exists on Star Talk. We are somewhat ordered organisms, and we like to "order" items. How is this possible if entropy is always increasing???



Keywords: Thermodynamics, Entropy, Star Talk, Equilibrium, Disorder, Chaos, Order

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Tuesday, January 19, 2016

20 January 2015- Superfluid | PWN Physics 365

On this day in physics: 20 January 1931- Happy Birthday to physicist David Lee, a nobel laureate who was awarded the nobel prize in 1996 (along with two others) for the discovery of the superfluidity of the Helium-3 isotope. [Source.] David is 85 today!

Word of the day: Superfluid- A superfluid is a state of matter which generally occurs at very low temperatures (~1 K, or 1 degree above absolute zero) where the atoms become a liquid, which has absolutely no viscosity whatsoever. They are attracted by temperature gradients (i.e. they will move from lower to higher temperatures) and seem to do so defying gravity and surface tension (i.e. electromagnetism). It also "crawls around". Imagine you have a bucket of water on the beach, and you place a small cup in the bucket. Because the cup is filled with air it will float and the water will remain on the outside of the cup, unable to fill it. If that bucket were instead filled with a superfluid helium, the superfluid would "crawl" up the sides of the cup, and fill it, creating its own equilibrium. It's a very interesting and extremely new field of physics.

Killer Resource: The Story Behind the Discovery of Superfluidity in Helium Three. The Birthday Boy's Nobel Prize-winning mate Douglas D. Osheroff gives a lecture about the story behind and the work done which earned them Science's greatest of awards.



Keywords: Nobel Prize, Superfluid, Helium

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Monday, January 18, 2016

19 January 2016- Entanglement | PWN Physics 365

On this day in physics: 19 January 2014- "The first secure quantum computer has been made by combining entanglement, a bizarre property of tiny particles, with the power of apparent randomness.

The technique is similar to quantum cryptography, which guarantees the secrecy of a message sent from one place to another, but in this instance guarantees the privacy of data-processing. It could enable code-breakers, governments or private individuals to harness the power of a quantum server remotely without having to worry that the owner can snoop on their data or calculations." [Source.]

Word of the day: Entanglement- Quantum Entanglement is a phenomenon which occurs when two or more particles are related in such a way that they CANNOT BE DESCRIBED on their own, but rather as an entire system. Example: There is a highly famous paradox regarding entanglement. It's known as the EPR paradox, named after its creators, Einstein, Podolsky and Rosen. They had this idea that if you had a particle which had a spin of zero, which decayed into two separate particles, one would need to have a spin of opposite amount, say 1/2 and -1/2. Both would need to add up to the original particle's spin of zero. Now these particles during the decay would be traveling in opposite directions, existing in a superposition of states, being both 1/2 and -1/2 at the same time, and these particles will not have a definite spin until they are measured. Now imagine that these particles travelled in opposite directions to the end of the known universe. One of the particles, is traveling and waiting for you to measure it, at the end of the universe. When you measure it's spin, the superposition of states collapses, and you find out its state is +1/2. On the other end of the universe, the other particle's state immediately collapses -1/2 spin, and will never change its state. Now, as these particles are entangled, they are related in such a way that when one state collapses, the other does so IMMEDIATELY. This is alarming because there is a speed limit at which information can be transmitted, which is the speed of light, or 3E8 m/s. However, quantum mechanics can experimentally verify this as being the truth of nature. Entangled particles exist, and we are learning to make use of them on small scales to do extraordinarily fast computing.

Killer Resource: 8 Hot Tips to PWN Next Semester! This older blog entry from the website comes equipped with a printable pdf of 8 hot tips to PWN next semester. Something to hang above your bed and think about as you drift off into slumber with dreams of physics dancing in your head.



Keywords: Entanglement, Quantum, Spin, Photons

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Sunday, January 17, 2016

18 January 2016- X-Ray | PWN Physics 365

On this day in Physics: I couldn't say it better myself so here it is: "In 1896, an x-ray machine was not exhibited at Casino Chambers, New York City, though some sources state it was. The news of Wilhelm Röntgen's discovery of the astonishingly penetrating X-rays had only been revealed to the world earlier in the month. So, riding on the wave of that publicity, the Cabaret du Neant opened, charging 25 cents admission to see the “Parisian sensation.” What the audiences actually saw was only a theatrical illusion of an x-ray image using only magic lantern techniques and the Peppers Ghost effect. No actual x-ray equipment was used." Source

Contained within this story is a powerful lesson about science. The truth is out there, but don't take anyone at their word. You need to believe what even your scientific colleagues tell you based only on what you know to be true and what you can deduce. Take nothing on faith.

Word of the day: X-Rays are electromagnetic radiation. They are waves, just like visible light, although we are not able to detect them with our eyes. The wavelength of x-rays exists in the .01-10 nm range. Because they have such small wavelength, and high frequency, they pass right through our tissue, and bones, which allow us to produce images of our bones, sometimes called X-ray photographs. This is very useful in medical diagnosis. Extended exposure however is very dangerous, as such high frequency radiation will cause deformities in our DNA, and cause defects, tumors, and cancers.

Killer Resource: Electromagnetic Spectrum Shown in this image is the full electromagnetic spectrum, including the word of the day X-rays, as well as the very narrow band which we call the visible light. It gives a great perspective on how little we can detect about our universe.



Keywords: X-Ray, Electromagnetic, Spectrum, Light

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17 January 2016- Electrical Ground | PWN Physics 365

On this day in physics: Happy birthday to Benjamin Franklin born 17 January 1706. Benjamin Franklin almost needs no introduction, but as far as physics goes, was one of the first supporters of the concept of the electrical ground, the lightning rod, and of course made his famous kite flight with a key attached.

Word of the day: Electrical Ground is a reference point and method of protection in electrical systems. Voltage is a quantity which only makes sense when specified with respect to a reference potential. On this planet, the earth itself makes a very reliable reference potential, since it's so much larger than anything humans can make thus far. Ground is also referred to as "potential earth" because it is usually connected to the earth.

For safety, it acts as a method of discharging static electricity built up. It also protects against any wire on which insulation has failed. This makes electrical systems very reliable and safe.

Our birthday boy, Ben Franklin, was the first to popularize the idea of using a lightning rod, which is a long metal rod attached to buildings and houses, which allows lightning to go directly to ground, preventing fires and other calamities associated with homes beings struck by lightning.

Killer Resource: Exploring Electronics: Electrical Symbols App. The symbol of this app fits nicely with our word of the day, Electrical Ground.



Keywords: Electron, Benjamin Franklin, Ground, Grounding, Electronics, Lightning Rod

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Friday, January 15, 2016

16 January 2015- Friction | PWN Physics 365

On this day in physics: 16 January 2003 - Space Shuttle Columbia takes off on its would-be final 28th mission, during which the space shuttle broke apart during re-entry. To all who perished in the mission, PWN Physics 365 remembers and solutes you.

Friction- A resistive force in nature which opposes motion. There are several causes for this. Examples of this are dry friction, fluid friction, kinetic friction, static friction, lubricated friction, internal friction, etc. From wikipedia: When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy (that is, it converts work to heat). This property can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. [Source]

In the case of the Columbia incident, the space shuttle re-enters the atmosphere with such speed, that as particles begin to crash into the space shuttle, they collide with such force that vast amounts of thermal energy are created. The wing was damaged, and the heat was able to make its way into the wings and damage them, causing the space shuttle to disintegrate in the atmosphere.

Friction is a very powerful force which has a great variety of uses. Without friction you wouldn't be able to drive your car. The tires allow the car to move because of friction with the road. If you've ever been on an ice skid, you can appreciate why friction can be useful. The friction between your brake pads and your rotors or brake drums are what causes your car to stop. Friction between your feet, or shoes, or sandals, is also what allows you to walk around. In fact almost all animals rely on friction in one way or another to move around.

In Physics, we categorize how resistive objects are with what is known as a "coefficient of friction". Sandpaper has a much higher coefficient of friction than say, ice. Sandpaper will oppose motion much more and generate a great deal of heat, whereas ice will NOT facilitate motion, but rather oppose motion much less, and generate much less thermal energy in the process.

Killer Resource: A World without Friction. This is an awesome video from MIT which describes what your world might be like without friction, and gives you an appreciation for how much of a role friction plays in your everyday life.



Keywords: Friction, Space, Shuttle, Columbia, Static, Force, Resistive, Motion, Coefficient.

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Thursday, January 14, 2016

15 January 2015- Mho | PWN Physics 365

On this day in physics: 15 January 2005 the SMART-1 Moon Orbiter confirms that there is indeed calcium present on the moon.

Word of the Day: Mho. Electrons travel at very fast speeds (close to the speed of light!) in all the wires that power everything from your phone, computer, television, refrigerator, stove, car, et cetera. Very specific metals are chosen because they allow the electrons to flow freely, and without any interference, sort of like friction. This friction generates a lot of heat, and slows down the electrons, also reducing the current. Sometimes this effect is desired, so engineers will add what is known as a resistor, to give a desired current, or to actually generate heat. The unit Ohm describes the measure of difficulty with which electrons pass a current through a conductor. The inverse, or opposite of resistance is called conductance. It is the measure of ease with which electrons pass through a conductor. Thus items with high conductances are called good "conductors".

And now the light side and bad jokes that physicists have come out. Since the measure of resistance is known as the Ohm, the opposite is Ohm spelled backwards, or the Mho. It is also known as the Siemens, which is equal to exactly the reciprocal of one Ohm.

For more on the Mho, check out this article on the "real" unit of conductivity, the Siemens

Killer Resource: Units of Measure App. Check out this FREE app made by yours truly. In honor of the units of measure, dig deeper and make sure you can identify all the units of measure for length, time, mass, energy, force, and more!



Keywords: Mho, Ohm, Resistance, Inverse, Conductivity, Mars, Orbiter

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Episode 086- How to Get Unstuck in Physics & The Anatomy of a Vector!

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How To Overcome Getting Stuck In Physics

Recently I've been working on an app. Which one doesn't really matter. It's about a topic that I really enjoy and I'm excited about it. In working on it, it has easily been the hardest app I've ever developed, although absolutely nothing about it is different. In general, my apps follow a formula, because they are modular; they deal with different sections of physics and offer a very similar solution. First, understand the topic. Next, break that topic into easy, doable, step by step solutions. Next, go through sample problems to see the steps in action. Lastly, review what you've learned in a flash-card style review. It's a great system. For me, the app just wasn't taking off in my head. I could not visualize what to do or where to go. This reminded me a great deal about when I was in college and I'd be working on a problem and halfway through I'd get totally stuck. I just couldn't see it. No matter what the deadline, I always do the same thing. Drop it. Usually I don't work on something else. I take a walk. I take a shower. I let it go, and let my brain continue to work on it, but not in the forefront. Sometimes you're so concerned about due dates, or scheduling, or how many other problems you need to do that it all gets lost in the shuffle and you get totally, totally stuck. For me the exit is to drop everything and come back fresh 30 minutes later. For my app, it was more like 30 days. But now revisiting it, I'm enthused, and it's going very smoothly. I don't want to hate my work, and coming back fresh makes me not hate it. It doesn't seem like work any more.

When you're stuck on a physics problem, many times you don't have the luxury of stepping back that far, it's due in the morning, or you're in the middle of a test. For homeworks, start early. Then when you get stuck you can drop everything for a day and you're not really in trouble. In tests, I would spend 2-3 minutes just staring at the ceiling, letting my mind wander, thinking about music, looking out the window. Sometimes you just have to clean out the pipes to let the creative juices flow again. It's not easy, and most of the times the problem to overcome is getting out of your own way. As a human, you are a pattern seeking creature. You are good at solving problems. If you've studied for the test, you're equipped to solve the problem. Get out of your own way and let your brain do what it does best, solve problems! For me, the best way to do this was to distract myself with something else, and let my brain continue to process.

Don't misunderstand me. Please, don't play video games all night and tell me that you were just getting out of your own way. You have to use it with responsibility. But if you know yourself, and you can be disciplined about it, many times clearing out your head is the best way to get unstuck. Proceed with caution.

1: The Vector- The arrow in magenta is the vector in question. Everything else in the image serves to describe this vector. It's represented as an arrow and can be slid anywhere in the coordinate system and still retain its properties: the magnitude and direction.

2: Y-Axis- The black vertical arrow represents the y-axis in our coordinate system. This gives a reference point for all of the vectors in our system.

3: Origin- Most physical systems only make sense when there is a point of reference. The intersection of the two axes, is referred to as the origin.

4: Vector Magnitude- In pink arrow is the vector in question. The length of this arrow is referred to as the magnitude.

5: Angle- The angle is a critical part of what makes a vector a vector. Usually denoted by the Greek letter Theta, this provides the direction. Theta is usually given with respect to the positive horizontal axis, but any reference point will provide sufficient direction, making this a vector with both magnitude and direction.

6: Coordinate Representation- Typically, vectors are represented with brackets, e.g. [x,y], so that they are not confused with the same coordinate point represented with parenthesees, (x,y). This point describes the location of the head of the vector, with the tail assumed to be at the origin, (0,0).

7: x-component- The red dashed horizontal arrow is referred to as the x-component of the vector v. This describes 'how much' of the vector is pointed in the x-direction. This makes one leg of a right triangle which describes the vector v, the vector itself being the hypotenuse.

8: X-Axis- The black horizontal arrow represents the x-axis in our coordinate system. This gives a reference point for all of the vectors in our system.

9: y-component- The red dashed vertical arrow is referred to as the y-component of the vector v. This describes 'how much' of the vector is pointed in the y-direction. This makes one leg of a right triangle which describes the vector v, the vector itself being the hypotenuse.

Wednesday, January 13, 2016

14 January 2015- Black Body Radiation | PWN Physics 365

On this day in physics: 14 January 2005 Huygens space probe lands on Saturn's moon, Titan. The Huygen's spacecraft was named for Christian Huygens, who discovered the moon Titan. We also nod to Kurt Godel, who died on this day in 1978. His incompletness theorem proved that there are certain things that cannot be proven or disproven within a set of axioms in a system.

Word of the Day: So before we dig into what Black Body Radiation is, let's first talk about what a Black Body is. Most objects have color. This is because they reflect a specific wavelength of white light. The rest is absorbed. If a body reflects absolutely no light whatsoever, it will appear black. Now, we see black objects all the time. This isn't a true blackbody though. Most black objects do reflect at least some light. Shine a laser pointer on any black object you see. If it was a true black body, as soon as the laser pointer "touched" the object, you wouldn't see the pointer anymore. All the light would be absorbed. Black bodies are for the most part theoretical, although many objects are very very close to being true black bodies. Now, a true black body does emit electromagnetic radiation, unrelated to what it is absorbing. This is known as Blackbody Radiation. The wavelength of the electromagnetic waves are proportional to the temperature of the blackbody, and this wavelength is highly calculatable. This is what Wein, our birthday boy from yesterday's day in physics, brought to our attention.

Stars can be modelled as being very close to black bodies, i.e. nonreflective. All the energy going into the star does not come out. It is then possible to calculate the "effective" temperature of a star by using measuring the wavelength of the light that we see as starlight. This is a powerful tool for astronomers.

For a deeper dive on blackbody radiation check out this hyperphysics article or the wikipedia article.

Killer Resource: iBlackbody app Since today is a black body day, if you really want to dig deeper on blackbody radiation, and see how temperature changes the wavelength at which blackbody radation is emitted, there is a really cool app available, made by not me, called iBlackbody. It was created by a team at Georgia Tech. University, and you can read a little more about it here. At the time of this recording it's only $0.99 in the app store. I love how for a dollar you can dig so deep into something that you can keep in your pocket at any time. It's truly a great time to be alive.



Keywords: Wein, Displacement, Law, Black Body, Radiation, Huygens, Titan, Saturn

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Tuesday, January 12, 2016

13 January 2015- Dark Energy | PWN Physics 365

On this day in physics: On 13 January 1864, we celebrate the birthday of Wilhelm Wien, known for his work on blackbody radiation and the Wein Displacement Law which was his namesake. (More on this tomorrow. I was going to do black body radiation today but we're on a roll with the matter, dark matter, dark energy.)

Word of the Day: So now that we've covered Matter, and Dark Matter, we might as well finish up the puzzle with Dark Energy. The universe: 5% Dark Matter, 25% Dark Matter, 70% Dark Energy. So what the heck is it?? Again, we don't really know. But Dark Energy is what scientists currently attribute to be the cause of our expanding universe. Not only is the universe expanding, but it's expanding faster every day, which means the expansion is accelerating. Currently, the cause of this acceleration, Dark Energy. And we can't see it. And it makes up 70% of our universe. Go figure.

Killer Resource: Hyperphysics Article about Dark Energy If you want to dig a little deeper on dark energy, this is the place to start. Hyperphysics is so great.



Keywords: Dark Energy, Universe, Expansion, Black Body, Radiation.

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12 January 2015- Dark Matter | PWN Physics 365

On this day in physics: On 12 January 1968 scientists conducted what they called a "controlled excursion", burning up a nuclear rocket in Nevada. It produced a radioactive cloud over Los Angeles. Not everything that's history worthy is great. This should definitely be a reminder that as scientists we should act as responsibly as possible and always consider every possible consequence to our experiments and actions.

Word of the Day: It was too tempting not to cover Dark Matter after covering matter yesterday. It's kind of an interesting word of the day since noone knows exactly what it is. Remember yesterday how I told you how almost everything is made up of matter? Well, it wasn't really true. Roughly 5% of our universe is made of matter. Another 25% is made up of what we refer to as Dark Matter. As we understand the motion of planets and galaxies, based on the mass that we can calculate from what we see, their motion behaves as if they are much more massive, or as if more mass exists somewhere close, but does not emit light in any way that we can detect. That's how it got its name dark matter.

A couple of weeks ago, China launched a probe whose entire purpose is to go on a search for dark matter. Read more about it here.

Killer Resource: Space Shuttle Launch From an Airplane- If this doesn't get you pumped up I don't know what will. Also, if that's not enough, check out these pictures of a shuttle launch from a high-altitude research aircraft here.



Keywords: Dark Matter, Radioactive Cloud, Dark Energy, Matter, China, Space Shuttle

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Sunday, January 10, 2016

11 January 2015- Matter | PWN Physics 365

On this day in physics: On 11 January 1787 William Herschel, discovered the first two moons of Uranus, Titania and Oberon, roughly six years after he discovered the planet itself. The names were given 65 years later by Herschel's son.

Word of the Day: Matter is the stuff around you. It is anything that has takes up space and has mass. This definition is designed to exclude energy such as light, or the motion of particles, such as sound. The majority of matter is made up of atoms, which are made of protons, neutrons, and electrons. Protons and neutrons are then of course made up of up and down quarks.

There are four states of matter. The state with the lowest energy is a solid. Next is liquid. Next is gas. Finally, the least commonly known state of matter is a plasma. Matter behaves distinctly different in each state.

Killer Resource: Wolfram Online Integrator.

If you need to do a quick integral (you know, like you do...) look no further. It does algebraic integrals for you in the snap of a finger. The wonder of Mathematica for your online pleasure.



Keywords: Matter, Wolfram, Online, Integrator, Mathematica, Uranus, William, Herschel

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Saturday, January 9, 2016

10 January 2016- Speed | PWN Physics 365

On this day in physics: 10 January 1936 Birth of Robert Woodrow Wilson, one of the discoverers of the cosmic microwave background radiation along with Arno Penzias (Source).

Speed is...wait what? Didn't we just do this on Tuesday? The answer is no. On Tuesday we covered velocity, which is drastically different from speed. Let's explore.

Speed describes the rate at which an object is changing position, or moving through space, or any other medium, just like velocity. However, speed solely indicates the rate of change of motion. Nowhere in the speed can you find the direction of this motion. Consider the speedometer in your car. It tells you that you're going 65 mph regardless of which direction you are travelling. If it were to be coupled with a compass, and tell you, for example 65 mph, Northwest, you would then have a velocity.

Speed is what is known as a scalar, since it doesn't contain any of the direction information. Velocity is what is known as a vector quantity, since it contains the direction component as well.

Killer Resource: Star Talk Podcast hosted by Neil Degrasse Tyson



Keywords: Position, Kinematics, Acceleration, Physics, Podcast, Derivative, Jerk

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Friday, January 8, 2016

09 January 2016- Jerk | PWN Physics 365

On this day in physics: 09 January 1942 Happy Birthday to Vladimir Steklov, "Steklov's primary scientific contribution is in the area of orthogonal functional sets. He introduced a class of closed orthogonal sets, developed asymptotic Liouville–Steklov method for orthogonal polynomials, proved theorems on generalized Fourier series, and developed an approximation technique later named Steklov function. He also worked on hydrodynamics and the theory of elasticity." (Source).

Jerk is the rate of change of acceleration, or how fast the change of speed is changing. Consider how you might feel sitting in the passenger seat of a car when someone steps on the gas versus lightly pressing the pedal. This is the difference between high and low jerk. It can be described mathematically as j(t), or a'(t), or v''(t), or x'''(t). Each of these mean the exactly same thing, which is that jerk is the third derivative of position, second derivative of velocity, and first derivative of acceleration.

Very interesting inference from wikipedia: "Because of involving third derivatives, in mathematics differential equations of the form


are called jerk equations. It has been shown that a jerk equation, which is equivalent to a system of three first order, ordinary, non-linear differential equations, is in a certain sense the minimal setting for solutions showing chaotic behaviour. This motivates mathematical interest in jerk systems. Systems involving a fourth or higher derivative are accordingly called hyperjerk systems."

As jerk is the third derivative with respect to time, its units are length per second per second per second, or length per second cubed.

Killer Resource: Astronomy Pic of the Day. NASA's picture of the day.



Keywords: Position, Kinematics, Acceleration, Physics, Podcast, Derivative, Jerk

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Episode 085b: Cross Product Example Pt. 2

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This second part of Episode 085 is going through a subtraction and cross product example, to just get the gears moving again after the New Year. Check it out!

Subtraction Example:

Cross Product Example:

Thursday, January 7, 2016

08 January 2016- Acceleration | PWN Physics 365

On this day in physics: 08 January 1942 Happy Birthday to Stephen Hawking, the theoretical physicist and cosmologist best known for his work on black holes and for authoring the popular-science book A Brief History of Time. He also holds the once Newton-seated Luciasian Professorship at Cambridge University. (Source).

Word of the day: Acceleration is the rate at which an object in motion is changing its velocity, or how fast it is changing its change in position. It is typically described mathematically as a(t), or x''(t), pronounced x "double prime". The double prime notation is to indicate that it is the second derivative of position, or the change, or the derivative of velocity. Acceleration has units of length per second per second, or length per second squared. Humans are very sensitive to changes in acceleration. Massive objects create accelerations towards them because of their gravity. Because earthbound items are being accelerated towards the center of the earth at 9.81 m/s^2 when airborne, the acceleration due to gravity on earth is given the abbreviation g.

Killer Resource: A Brief History of Time. The most popular book written by our birthday boy above.



Keywords: Position, Kinematics, Acceleration, Physics, Podcast, Derivative

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Wednesday, January 6, 2016

07 January 2016- Velocity | PWN Physics 365

On this day in physics: 07 January 1610 Galileo makes the first observation of four of Jupiter’s moons, which would be named the Galilean Moons after him (Source).

Word of the day: Velocity describes the rate at which an object is changing position, or moving through space, or any other medium. It can be described mathematically as v(t) or x'(t). x'(t) is said x-prime of t, which denotes that it is the derivative of the position vector. This is because the a derivative calculates the rate of change, and velocity is the rate of change of position. Velocity is also a vector quantity, meaning the direction of motion is also included in the information. The units for velocity are distance per time, in whatever unit you like. Common velocity units are miles per hour, meters per second, inches per second, kilometers per hour, the list goes on.

Killer Resource: Exploring Physics: Greek Letters. Free app that reviews all the greek letters in display, and flash card still. It's free, what do you have to lose??



Keywords: Position, Kinematics, Velocity, Physics, Podcast

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Tuesday, January 5, 2016

06 January 2016- Position | PWN Physics 365

On this day in physics: 06 January 1745, 1745 Birth of Jacques-Étienne Montgolfier, co-inventor of the hot air balloon along with his brother Joseph-Michel (Source).

Word of the day: Position- Position is where something is with respect to a given reference point, or coordinate axis. For example, on earth, we are able to describe accurately any position on the face of the planet with specific latitude and longitude coordinates. In physics, usually the position of objects is described with respect to a coordinate axis. In 2 dimensions, which represent the flat ground, like a parking lot, we can say a car which is about to drive is currently at rest, at position (5,0). This means that if you know where our reference point is, (0,0), without even seeing the car you can predict where it is. Position, and the change of position, is analyzed in a study of motion referred to as kinematics.

In mathematics, the position is generally denoted x(t), or y(t), depending on which direction the object is moving. The (t) is to denote that the position will change as time moves on, as most objects do.

Killer Resource: PWN Physics're already here!



Keywords: Position, Kinematics, Velocity, Physics, Podcast

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Episode 085a: Wardenclyffe Tower Pt. 3 & Isaac Newton's Birthday!

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I went back to Wardenclyffe Tower! Not much has changed since last I went (check out episodes 029 and 30 for the original Wardenclyffe pilrimage), except all of the conifers were decorated for the season. I also noticed a plaque with many Tesla pictures under plastic, including the classic photo of him with the light bulb, as well as several pictures of the original tower. I can't wait until this place opens for real. I hope I'll be able to go decorate one of the Christmas trees there next year.

So, during the "On this day in physics" section of PWN Physics 365, I wish a happy birthday to Issac Newton, born 04 January 1643. I post the episode, and then during my internet travels, came across a tweet from Neil Degrasse Tyson from Christmas which very cleverly alludes to the birthday of a very special man who will change the future of humanity, only at the end of the tweet to reveal that it's not the expected Jesus H. Christ, but rather Issac Newton. Very funny!

Wait...what?? I thought his birthday was January Fourth. Did I get it wrong?? So, I continue to research online and came across this very interesting article. It turns out that that both of those dates are right. When Issac Newton was born, he was indeed born on 25 December 1942, on what was known as the "Old Style" calendar. This was what was called the "Julian" calendar. When the current "Gregorian" calendar was adopted, the new calendar shifted everything by 10 days.

05 January 2016- Event Horizon | PWN Physics 365

On this day in physics: 05 January 1940, FM radio is demonstrated for the first time. (Source).

Word of the day: Event Horizon- The point of no return at the edge of a black hole. Because black holes are so massive, and so dense, there exists a point where space time is so warped, that even light cannot escape, but rather gets bent back into the black hole. The escape velocity is greater than the speed of light. This means that nothing can escape from inside the event horizon, not even light. This is why black holes are black. Because of this, it means that to an outside observer, there is no way to retrieve information from beyond the event horizon. We cannot know what is actually happening inside a black hole.

Killer Resource: Exploring Physics: Force App. This app gives the user steps to solve any Newton's 2nd Law problem.



Keywords: Event Horizon, Black Hole, Radio, Force, FM.

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Sunday, January 3, 2016

04 January 2016- Absolute Zero | PWN Physics 365

On this day in physics: 04 January 1643, Happy birthday to Issac Newton, the father of classical physics, inventor of calculus, author of principia, discoverer of universal gravitation, three laws of force, etc.

"It is impossible for any process, no matter how idealized, to reduce the entropy of a system to its absolute-zero value in a finite number of operations." -Nernst

Absolute Zero- The absolute floor in terms of temperature. Temperature is in some sense a measure of energy of a system. Because particles are always moving, and vibrating, they always have some energy. At Absolute Zero, the particles or objects would be completely devoid of energy. According to the Third Law of Thermodynamics, it is not possible to achieve absolute zero. In America, we predominantly measure temperatures using Farenheight, and the rest of the world using Celsius. Absolute Zero is accepted to be -459-67 Farenheight and -273.15 Celsius. There are two analog scales, Rydberg for Farenheight and Kelvin for Celsius, which keep the same gradation of degrees, such as 1 degree Farenheight is the same as 1 degree Rydberg, and 1 degree Kelvin is the same as 1 Degree Celsius. However, Rydberg and Kelvin both set their 0s to align with Absolute Zero, whereas 0 Celsius is aligned with the freezing point of water, and 0 Farenheight is aligned with absolutely nothing. (It's actually based on some really convoluted mixtures of ice water, brine, and other chemicals. I'm not sure what they were thinking)

Recently it has been proposed that some scientists have managed to create a temperature colder than absolute zero. The idea is that if you heat something up to an infinite temperature, it "swings around" and becomes a negative temperature. In doing so they have managed to come to a temperature lower than absolute zero. However, absolute zero at the time of this writing has as of yet been unachieved.

Killer Resource: Hyperphysics



Keywords: Absolute Zero, Thermodynamics, Kelvin, Newton, Hyperphysics

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Saturday, January 2, 2016

03 January 2016- Light Year | PWN Physics 365

On this day in physics: 03 January 1999- Mars Polar Lander is launched. (Source)

Light Year- A light year is the measure of distance which describes the amount of distance travelled by light in a vacuum during 1 Earth Year. It's a little misleading because the name can be easily misunderstood to mean an amount of time.

A light year is a vast amount of distance. Light travels 300,000,000 m/s, or 3 million km in on second. It takes roughly 8 minutes for light to travel from the sun to the Earth. New Horizons just travelled all the way to Pluto, roughly 7 billion miles. This immense distance represents roughly .0007 light years. The nearest star, except our Sun is something like 4 Light Years. A light year is a very long distance, but it can be very useful when measuring large distances and exploring our Cosmos.

Killer Resource: Symphony of Science



Keywords: Light Year, Distance, Astronomical, Pluto.

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