Gallium

This may be a little outside of the physics range, but I just thought it was cool.

Gallium is the 31st element on the periodic table. It was predicted to exist by Dmitri Mendeleev, and was discovered soon after by Lecoq de Boisbaudran in 1875. At the time, Gallium provided few if any practical applications. Things have changed though; but first, a little bit about how cool gallium is.

Gallium is a solid at room temperature – this is most times defined as twenty-two degrees Celsius, or something fairly close. Warm it up a few degrees, to 29.7°C (85.5°F), and it melts. This means that a block of gallium will turn liquid on a hot day, or even just in your hand.

gallium 1 (this is not photo-shopped)

Or how about you try a spoon made out of gallium? I wouldn’t suggest using it to stir your coffee:

gallium spoonWarning: Don’t actually use a gallium spoon for anything except to make fun little gifs; although it is considered non-toxic, you don’t want that stuff in your food.

And if you want to see something very cool, get a coke can (empty or full, each will provide a slightly different result considering the full can is under pressure).

Aluminum is actually an extremely reactive element, which is strange because we encounter it in our everyday lives. The reason that we don’t encounter reactive aluminum is that solid aluminum actually forms layer of non-reactive aluminum oxide that protects the aluminum from reacting with other materials.

When gallium is placed on aluminum (and the oxide is scratched off for a better, faster reaction), gallium atoms invade the aluminum, resulting in an extremely fragile and brittle material.

gallium pop can

There are a few practical uses of gallium too (not nearly exciting). It is used in thermometers in replace of mercury because gallium is much less toxic. It is also used in semi conductors, LED’s, and lasers. Hope you enjoyed this; go buy some gallium if you wanna have some fun.

Radiant Energy

Radiant is more commonly, and mistakenly, called static electricity. Recently, scientists have been investigating using this energy as a renewable energy; it could be a source of “free energy.” It is not that absurd of an idea. Multiple inventors and scientists have created devices that take advantage of radiant energy. Nikola Tesla created a magnifying transmitter, T. Henry Moray developed a radiant energy device, as well as Edwin Grata and Paul Baumann. Radiant energy has been used to operate a motive device and store static electricity.

Static-Electricity-tw

Static electricity is different from the current that powers everything we know. Static is created by the collection of excess charge on a surface. The discharge of this charge is what transmits energy, but it is not like current electricity. Static electricity is described as “sound waves of electrified air” (Clear Tech). This means that the energy is traveling as a longitudinal wave rather than a transverse wave (electromagnetic radiation and electricity as well as magnetic fields are all transverse waves). Longitudinal waves vibrate in the direction of the traveling wave. This means that the pressure of the way changes, whether it is air pressure from a sound wave of electric pressure from static discharge.

The potential of radiant energy as a source of power is unfathomable. It can perform similar tasks as electricity for less than 1% of the cost. Some technology, like Edward Gray’s Electro-Magnetic Association Motor (Pulsed Capacitance Discharge Engine) have been created and successfully used. In search of renewable energy sources for the future, radiant energy might be an extremely viable solution. Plus, static electricity is fun.static

 

Rogue Planet

Exoplanets are planets that orbit stars outside of our solar system. While they were theorized for many years, there was no confirmed detection until 1992. Being such a young field, astronomy with a focus on studying planets outside of our solar system is extremely dynamic. Recently, astronomers have discovered CFBDSIR2149, what seems to be a rogue planet.

rogue planet

CFBDSIR2149 is located in a cluster of stars called AB Doradus, 75 light years from Earth. While it is not the first rogue planet found, it is by far the closest. There is still debate, though, about whether this is truly a rogue planet. It seems to be traveling with the stars o the AB Doradus cluster, but is not orbiting any of these stars. There is a small chance that it is actually behind the AB Doradus cluster and is just seen as a member of the cluster. Scientists have used Doppler spectroscopy to find out more about this planet. Results show that it is about the same age as the surrounding stars of the cluster, leading scientists to be pretty confident (they say about 85%) that this rogue planet is part of the cluster.

Through their studies, astronomers have found some interesting qualities of CFBDSIR2149. First of all, it is massive; they believe it is anywhere between four and seven times as massive as Jupiter; so massive, in fact, that they believe it could be a failed star rather than a planet.These are called brown dwarf – a larger than planet object that is not quite hot or massive enough to produce internal nuclear fusion.

In the past few years, astronomers have discovered a large amount of rogue planets. They believe that these may actually be the norm, rather than planets revolving around stars. Some scientists contest this though, because exoplanets can be hard to find; the light of the nearby star masks us from seeing the planets. This is why a close rogue star, which could possibly be CFBDSIR2149, would be so important; astronomers are free to study this new planet unobstructed by the light of a local star. Further studying will lead to concrete information about the nature of this planet, whether it is a planet, and where it came from – scientists believe these planets were ejected from their original solar system. Studying a rogue planet up close (relative on an astronomical scale) can lead to further insights into the beginnings of our planet, our solar system, and our universe.

http://www.slate.com/blogs/bad_astronomy/2012/11/14/astronomers_find_the_closest_rogue_planet_yet_in_a_cluster_of_stars_near.html

http://www.huffingtonpost.com/2012/11/14/orphan-alien-planet-starless_n_2128848.html#slide=809200

http://www.space.com/17738-exoplanets.html

 

Aerogel

Think about holding a solid block of material in your hand. Whether it is wood, brick, rubber, or metal, you can feel the edges as well as the weight of the object. Now, instead of these common materials, let’s say you’re holding a block of aerogel.

aerogel 1

You will not feel much of anything. The corners of this material seem to fade into the air. It is nearly transparent in some parts, and is literally lighter than air. “Aerogels are the world’s lightest solid materials, composed of up to 99.98% air by volume” (aerogel.org). This ultra low-density class of material has some very astounding characteristics. It’s low density structure allows it to support thousands of times its own weight.

aerogel 3

While it is extremely strong under compression, it is very brittle. It can easily be snapped like a twig. But its amazing properties don’t stop here. Aerogel is one the best insulators in the world to block out intensely high and low temperatures.

aerogel 5 aerogel 4

Furthermore, aerogel is one of the world’s best acoustic barriers and electric insulators. And this is just the general properties of aerogel. Scientists have created aerogel substances out of silica, metal oxides, carbon, and other materials. They have been discovering more and more amazing uses of this type of solid. Because of its superior insulating properties, silica aerogels are used on space equipment, including on the Mars exploration rovers. Metal oxide aerogels, on the other hand, can act as catalysts for chemical transformations and carbon nanotubing and can be made magnetic. And some forms of aerogel have completely different properties than the rest. Cross-linked aerogels are not brittle like most aerogels, but rather have immene strength and flexibility.

Aerogel was first created back in 1931, but the practical uses are just being discovered. Because it is expensive to produce, aerogels have not been integrated into current technology. Once the production process is developed further, this material may provide a cheap and effective solution to many problems. It could become the primary means of insulating houses and buildings. With its incredible absorbing capabilities, it could be used to clean oil spills.

 

 

 

Electricity

In the early 19th century, the history of the world was changed. Michael Faraday discovered electromagnetic induction. From here, electricity evolved to completely dominate many sectors of life in the developed nations of the world.

The laws of electromagnetic induction state voltage is created in a loop of conductive wire when the magnetic field inside of the loop changes. I won’t go into gory detail because the majority of us have learned in physics, will learn this in physics, can use Google, or just don’t care.

But I bring up electromagnetic induction because it is the property that led to the creation of electricity. Magnets are rotated around loops of thick wire to create the current of moving electrons that is electricity. For years, and through today, the main form of electricity production is using a turbine and generator.

Fuel, whether it is coal, natural gas, geothermal, nuclear, etc., is used to create heat. This heat is used create steam from water. The steam, which is pressurized, turns a turbine, which turns the magnets in the generator that cause the magnetic field to change within the loop of wire, creating electricity.

Even some of the newer energy sources rely on the same concept. Wind turbines and hydroelectric plants use the power of the wind and water, respectively, to turn the turbines directly to create electricity.

As I was pondering the future of energy (especially after our sustainability discussion), I wondered why there is such a reliance on this turbine-generator system. Looking into it, I found some very interesting things.

You may have noticed that I left out solar energy in my list of sources earlier. This is because it does not use a turbine. Solar panels contain photo-voltaics. These convert energy directly from sunlight (photons) to electrons – the photons transfer energy to electrons which, with the added energy, can be freed from their material to flow through wires, creating electricity.

Furthermore, I stumbled upon thermocouples, which are called thermoelectric generators (TEG) when discussing electricity. They transfer heat directly into electricity without using turbines. To my surprise, they are not just prototypes or theoretical; TEG are used in satellites that are sent to Jupiter and Saturn – they are too far from the sun to rely on solar power.

I still wonder which of these sources is the most efficient. I assume it is the turbine system because it is most widely used, but I don’t know. In the quest for sustainability, the focus is many times the fuel source. The discussion usually revolves around technology as well. I think it would be interesting, and maybe more beneficial, to change the focus of research. With all of these new methods of creating electricity, could there be way to create electricity without using the usual fuels, which pollute our Earth and deplete our natural resources.

A final random thought: why electricity? It took years and many developments in many different times to discover electricity, to then create electricity (later improved to make efficient), and finally to learn that it can be used to power things, and to take advantage of this power. What if there is something other than electricity that can do the same?

The Doppler Effect

The siren of an ambulance is blaring, you pull over and wait for it to pass, and as you do so you notice something. As the ambulance approaches, the sound of the siren becomes intensified, as expected, but the really interesting phenomena occurs when the ambulance passes you. While intensity changes because of the change in distance between you and the siren, this is not the interesting phenomenon that I am talking about. As the ambulance approaches, a high frequency sound is heard. Just as the ambulance passes, the suddenly frequency drops, and you hear a lower pitch. This is the Doppler Effect.

The Doppler Effect applies to all waves: sound, visible light, radio waves, etc. It is defined as a change in an observed frequency due to relative motion between the source of the wave and the observer. The basic explanation for this is represented using waves generated from the source at even time intervals.doppler

The circles int his picture represent sound waves being emitted at even time intervals. As the police car approaches the man on the right, the wave fronts are closer together because while each wave front is depicted during the with the same time interval between two waves, the car moves during this time interval. This causes the wave fronts on the right to be closer together, which is heard as a higher pitch or frequency. On the left, the wave fronts are spread out and therefore the observed frequency is lower. This is displayed really well by the last animation on this site. Because the wave fronts are pushed together or spread out due to the motion of the car, this phenomenon depends on the relative speed between the source and the observer.

doppler equ

This equation shows how the observed frequency, f ‘, is a function of the original frequency that is emitted, f, the speed of the wave in the given medium, v, the speed of the observer, vo, and the speed of the source, vs. The signs depend on the situation. If the source is moving towards the observer, only v is left on top of the equation, and the sign of the +/- on the bottom of the equation is chosen to be minus. Because the source is moving towards the observer, the observed frequency is higher; subtracting on the bottom gives a lower number which increases the factor by which f is multiplied. The sign is switched if the source moves away. The situation is switched if the observer is moving. The sign on top is a plus if the observer is moving towards the source and negative if moving away; this will correspond to the correct type of frequency shift.

I found it interesting that the Doppler Shift depends on not only the relative speed between the source and the observer, but also depended on which of the two were moving. I found the explanation was actually much more simple than I had expected.

Doppler Effect Derivation

This link is a mathematical representation of two wave fronts, both emitted from source S, with a time interval in between the two occurrences. An equation can be written to relate the two distances traveled, and worked out as follows:

vsnd t = vsT + vsnd(t-T) +λ’

vsnd t = vsT + vsndt – vsndT +λ’

0 = vsT – vsndT +λ’

λ’ = (vsnd – vs)T

where T is the period and T=1/fS

therefore λ’ = (vsnd – vs)/fS

and λ’ = vsnd / fD

so fD = fS vsnd / (vsnd – vs)

This equation represents the source moving towards the detector, D, in the image. To analyze the situation where the detector approaches the source, we imagine time going backwards. The detector can now be seen as the source; the wave fronts are leaving from this moving object (the detector now acting like the source) and converge onto the stationary source which is acting like the detector. In the Doppler Effect equation that was derived above (the last line of the work above), this is represented by switching  fwith fS  and changing vwith vD; this will lead to the other form of the overall Doppler Effect equation that is seen above, where v(the same as vD), is on the top of the equation affecting frequency as opposed to vwhich is on the bottom of the equation when the source is moving.

Solid or liquid

You may have heard of oobleck, but if not, you are missing out greatly. Ooobleck consists of 1 part water mixed with about 2 parts cornstarch. It is a non-Newtonian fluid. Don’t be intimidated by the name, it’s lots of fun.

Non-Newtonian fluids differ from Newtonian fluids in one simple way, they do not hold a constant viscosity. With most fluids, the ability to flow (viscosity) is a variable that is constant for any given temperature and pressure. The viscosity of non-Newtonian fluids, on the other hand, is also affected by stress.

What this means is that if you take a bowl of oobleck and flip it sideways, the fluid will slowly ooze out of the bowl like any other highly viscous material (syrup or honey for example). The difference comes when you decide to squeeze it in your hand. Syrup and honey will obviously ooze out of your hands and make a mess, but the non-Newtonian fluid does not follow suit. The stress applied by your grip increases the viscosity of the material so greatly that it is essentially in a solid state as you grip it in your hand. Once the stress is released though, it will return back to its oozing self.

Time for some fun. All you need is cornstarch, water, tape, cellophane, and a sub-woofer. The force caused by the low base of a sub-woofer turned up nice and loud causes the oobleck to jump around as it is fluctuating between the solid and liquid state due to the changing force on the material. IMG_0397 (The cellophane and tape are just so that your sub-woofer doesn’t end up a mess). How well this works also depends on the quality of the oobleck, so don’t be afraid to mess with the ratio to find the best combination (1 part water and a range of 1.5-2 parts cornstarch). If you’ve ever watched the Big Bang Theory, you may have seen the episode with oobleck in it. Mythbusters also had some fun running on a pool of this stuff.

Jerry

A long time ago, in a galaxy far, far away – more specifically, 950 light-years from Earth, about 5.58×1015 miles away – a star was born. Two actually. Twins.

Last week, on February 7, 2013, NASA released a time-lapse movie of a pulsing light in the sky taken by the Hubble Space Telescope. The star-system’s name is LRLL 54361. We’ll call it Jerry.

pulse star

Jerry is actually a binary system, with two stars at its center, gravitational bound in rotation with one another. He is still just an infant, though, both of his stars being protostars (the protostellar phase is early in the process of star formation). The flashing, pulsing light seen by scientists is called pulsed accretion. This system is one of only three “strobe-light” systems ever found; Jerry is actually “the most powerful stellar strobe found to date,” letting out a pulse every 25.34 days (Clara Moskowitz). “The strength and regularity of this accretion signal is surprising; it may be related to the very young age of the system, which is a factor of ten younger than the other pulsed accretors previously studied.” Jerry’s youth, though, provides both opportunities and difficulties to scientists.

Since this system is in its early stages of life, its stars are surrounded by a dense disc of gas and dust. This causes makes it hard for scientists to study Jerry’s twin stars, but it also is in large part the reason the system was found. Scientists believe that the bright pulsing is a result of the dust and gas. The two stars drag some of the gas and dust along around them, and when they come near to one another in their orbits, the materials are  collected by the other star, causing a blast of radiation – the pulsing, strobe nature of Jerry.

Furthermore, the surrounding disc of gas and dust create a “light echo.” The flashes of light (blasts of radiation just mentioned) propagate through the dust and gas and reflect toward earth, causing the light released to be enhanced, creating the increased brightness seen by scientists.

hubble                             spitzer

With the discovery of LRLL 54361 scientists hope to gain knowledge into the formation of stellar systems. Further studying of the system using the Hubble and Spitzer telescopes will lead to insights of the nature of pulsing stars. With luck and these huge telescopes, scientists can discover why the pulsing occurs and what determines the period of alternating luminosity. They will learn more about the binary systems, especially those in the early stages of life. These insights will help further our understanding of solar systems and even the origins of our entire universe.

Colder than Cold?

A team of physicists at the University of Munich, headed by Ulrich Schneider, have generated negative temperatures. We’re not talking Fahrenheit here folks, and I don’t mean Celsius. I am talking about Kelvin. The scale that starts at a true zero temperature, absolute zero that is. The point at which atoms are said to have zero kinetic energy, zero entropy; they are at a standstill. So how do you get below this?

It has to do with the way temperature and our universe work. At any temperature, the kinetic energy is just an average value. The majority of atoms exist at very low energy levels while a couple more energetic atoms are at higher levels. The distribution of these is represented by the Boltzmann distribution:

boltzmann

 

It shows that there is a range of velocities, with certain velocities having greater probabilities than others. The lower the temperature, the greater probability of finding atoms of a particular velocity (the red graph is not as wide, and has a lower average velocity, with a higher peak at that temperature). This distribution of atoms can be thought of using potential wells and hills.

temp well

At a low temperature, the majority of atoms, with low kinetic energies, will settle into the potential well as shown on the left figure. As temperature is increased, the Boltzmann distribution widens greatly, as seen in the first figure. This means that there is a very large range of kinetic energies for the atoms, represented by the middle of the second figure; atoms exist in a chaotic pattern, with many velocities, therefore particles exist at all energy levels, in the well, on the plain, and on the hill.

Looking at these two figures, we can picture what zero kelvin as well as infinite kelvin would look like. At zero kelvin, all of the particles would exist in the potential well. The probability graph would not be a curve. Every particle would have a velocity of exactly zero. At an infinite temperature, the probability graph would be spread out to the point that every velocity would have the same, extremely low, probability. It would look like a flat line close to zero on the y-axis extended forever in the x-direction. The particles therefore exist at all possible locations on the “well and hill” picture, similar to the middle of the second figure. So if that’s what infinite temperature looks like, how is the right most configuration of that picture formed?

It is negative kelvin.

The scientists at the University of Munich discovered a process that makes this possible.

“Schneider and his colleagues began by cooling atoms to a fraction above absolute zero and placing them in a vacuum. They then used lasers to place the atoms along the curve of an energy valley with the majority of the atoms in lower energy states. The atoms were also made to repel each other to ensure they remained fixed in place.

Schneider’s team then turned this positive temperature system negative by doing two things. They made the atoms attract and adjusted the lasers to change the atoms’ energy levels, making the majority of them high-energy, and so flipping the valley into an energy hill. The result was an inverse energy distribution, which is characteristic of negative temperatures.”

– Jacob Aron

temp flip

As I said earlier, the majority of atoms in any system exist with low kinetic energies, with a few particles at higher energy levels. The scientists at the University of Munich switched this, creating the existence of a system where the majority of the particles have high energies and only a few are at lower energy levels. This creates the configuration at the right of figure two.

“The resulting thermometer is mind-bending, with a scale that starts at zero, ramps up to plus infinity, then jumps to minus infinity before increasing through the negative numbers until it reaches negative absolute zero, which corresponds to all particles sitting at the top of the energy hill.”

Clay Dillow

This negative zero value is important because it is actually the highest possible temperature. All of the particles exist on the top of the hill, but they don’t like most hill representations do. Rather than being an unstable equilibrium, it is actually stable. Energy must be added in order to get the particles away from the stable equilibrium. Because the system was created in a vacuum, there is no energy for the particles to gain energy, therefore they stay in the equilibrium. Another way to look at it is in terms of kinetic energy. If the particles were to “roll” down the hill, they would have to gain kinetic energy. The problem is still the same though, there is no energy for them to gain in the vacuum.

And if you know anything about science, you probably know the next question that is asked (you are probably thinking it yourself). Why does it matter?

Studying this negative temperature scale is believed to give us insights into dark matter, which scientists believe have negative temperatures as well as negative pressures. Some hypothesize that this fact is why our universe is expanding at an accelerating rate. On the more practical side, scientists believe that the discovery of negative temperatures can lead to super efficient engines that can absorb energy from both hot and cold substances.

The Space Program

A little bit away from the usual, but I was reading the news and found some interesting stuff. I think a lot of the articles I found bring up some good reasons as to why we must keep our space program alive.

I’m sure many of you have heard about North Korea in the news lately; they have been testing nuclear devises which have been reported to aim at the United States – don’t panic your life is not in that much danger, we live in State College so I doubt we’d be the ones bombed. Our Japanese sources, who have been monitoring the nuclear program in N. Korea informed the U.S. that “Pyongyang will likely experiment with a fusion-boosted fission bomb in a ‘high-level’ nuclear test” – Yoshihiro Makino. By using a small fusion reaction to help fuel the fission explosion, the Koreans would be able to make a smaller bomb, “about one-fourth the size of an ordinary nuclear bomb” says Makino. This lighter bomb could then be launched using long-range ballistic missiles that don’t have the capability of carrying average sized nuclear bombs. These long-range missiles would give N. Korea the ability to target the U.S. mainland.

The space program is where the majority of research occurs in the United States, including programs for missile weapons and ballistics. Since other countries are continuing their research, especially in area like nuclear warfare, we must keep NASA alive and thriving in order to protect the sense of security that has been established in the U.S.

North Korea is not that the only country pursuing advances in ballistics, though. Iran announced this weekend “that the country’s scientists had succeeded in send a monkey into space” (with a safe return) – NY Times. This is a prelude to attempts of sending a human into space. Iran claims the goals of its space program is to “orbit its own satellite in space to monitor natural disasters, improve telecommunications, and expand military surveillance,” (USA Today) but many countries fear that these ballistic missiles could be used as nuclear weapons.