pwn physics 365: physics history, vocabulary, and resources every day of the year

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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???

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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. 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.

Dig deeper at pwnphysics.blogspot.comOn 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."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.

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."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: 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.

Dig deeper at pwnphysics.blogspot.comOn 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.

Dig deeper at pwnphysics.blogspot.comOn 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. 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.

Dig deeper at pwnphysics.blogspot.comOn 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.

Dig deeper at pwnphysics.blogspot.comOn 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.

Dig deeper in pwnphysics.blogspot.comOn 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: If you want to dig a little deeper on dark energy, this is the place to start. Hyperphysics is so great.

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 on the blog pwnphysics.blogspot.comKiller 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 at pwnphysics.blogspot.com