Charged 2026

Tag: physics

  • Badass Biology: The Pistol Shrimp

    Badass Biology: The Pistol Shrimp

    “Wtf, shrimp!!? I make it all the way to this website from who knows what part of the internet, and I see ‘Badass Biology’. Man, Kevin, you flip my brain out with possibilities of flying sharks, rabbits of doom, or a half-honeybee half-unicorn rainbow pollinators. And what do you deliver? A stupid shrimp??! I hate you, and I quit this website. (╯°□°）╯︵ ┻━┻)” To which I reply, “Charles Barkley, I think you’re over-reacting. Please repair my table at once”.

    It was hard to find a chart that even went up to 150dB, let alone the 220 these guys produce.

    Yes, it’s a shrimp. A measly two-inch-long shrimp. But you don’t understand. This one single stupid shrimp is just about the coolest thing I’ve ever heard. Trust me, and when you hear one too, you’ll probably go deaf, because this one little shrimp IS ONE OF THE LOUDEST ORGANISMS ON THE PLANET. I’m talking 220+ decibels, much louder than a gunshot and louder than standing next to a jet engine at take-off. O_o.

    First, I want to talk about some other wicked cool stuff this little guy does apart from being a tiny walking firework of sonic pain. These shrimp garner lots of attention from ecologists because of their symbiotic, or mutually-beneficial, relationship with gobies, a type of small marine fish. The coral reef populations of this shrimp build burrows and recruit the help of a goby to stand guard out front while being no more than an antennae’s distance from the shrimp, using the goby’s well-developed vision to watch for danger. Once danger comes, the goby flicks its tail to signal a threat, and both the goby and the shrimp retreat into the same burrow. Then they start slapping five. It’s flippin sweet.

    The mutualisms don't just end at gargoyle-ing.

    From an ecologist’s point of view, this is totally mutualistic, and some scientific literature lists this interaction as “totally f-ing amazing” [citation needed] (Good luck with finding THAT reference -ed.). Yeah, both the goby and the shrimp live to see another day should a shark, barracuda, squid, rogue buoy, really fast snail, very-misplaced land predator, sinking boat part, cloud of wasps, or sentient shrimp-hating spear come around to threaten them. The goby gets a burrow, and the pistol shrimp gets a gargoyle. Selection at work.

    I like to think of the goby as the pistol shrimp’s pet, kinda like me buying a falcon and parading it around the neighborhood on a leash. And once danger comes, the falcon goes “Hey yo, Kevo, you might need to reconsider this route”, we split, we don’t find danger, and I buy the falcon ribs for a job well done (and because I really want ribs right now). So in a sense, pistol shrimp are danger shepherds equipped with sun-blasting cannons of glory that we’ll get to in a moment.

    I need to take a break to collect myself. Holy balls, these shrimp own everything own-able. Next time I see one, I’m buying it ribs. The whole rack.

    Let’s get to that “pistol” thing, why don’t we? Pistol shrimp have one very distinct set of front appendages, like two arms extending outwards from its body. Only, one of these arms is disproportionately larger than the other, and it’s quite a contrast. Like no foolin’ man, this one arm alone can be as long as half the entire length of the shrimp’s body. Imagine walking around with one of your arms the size of the Hulk’s and you get the idea. This may look pretty stupid, but this powerful musculature operates one of the most badass weapons nature can offer.

    Yeah, kinda like this

    When in serious danger or when hunting, the pistol shrimp cocks its massive claw backwards into a 90o position. Once the claw snaps shut, it produces a jet of water propelled forward at 60mph. Yeah, woo, a fast water jet. Big deal. But here’s the amazing part. Are you ready to have your mind blown? If you have ever listened to me before, now is a pretty good time, too: This jet of water creates a bubble that cavitates, or implodes, generating a pressure wave that creates a sound loud enough to break glass in an instant. Not only that, but once the bubble cavitates, the heat generated by the force of the implosion causes the temperatures inside the bubble to reach about 18,000 degrees Fahrenheit. Yes. Eighteen. Thousand. Oh, and to top it off, the whole process takes three tenths of a second. 

    THIS TINY SHRIMP MAKES A BUBBLE SO AWESOME THAT IT’S LOUDER THAN A JET AND MORE THAN TWICE AS HOT AS THE SURFACE OF THE SUN.

     

    You can imagine the horribly bubbly doom the pistol shrimp’s enemies must face. Stunned (or killed) by the force of that kind of pressure change, the pistol shrimp’s prey has basically just become lunch in an instant. The shrimp pulls its quarry into its burrow, and goes to town, just how I could go to town on some ribs right about now. I dug up a video about this whole process in case what I said wasn’t convincing enough:

    http://www.youtube.com/watch?v=eKPrGxB1Kzc

    If you want me to write about any other badass biological bosses, leave a comment. I may talk about them, or I may just tell you that your suggestions are awful. Probably not the latter though. I like people.

    Well, I like most people except you, Charles Barkley. I really miss that table. Now I’ve got nothing to rest my wine on when Glee’s on.

    Photo credits:

    http://www.airpowered.co.uk/images/dbachart.jpg

    http://loyalkng.com/wp-content/uploads/2009/11/arm_wrestling_champion_03.jpg

     

     

  • Water: Prankster of the Natural World Part 2

    Water: Prankster of the Natural World Part 2

    If you haven’t read part 1 (why would you do that?), here is a review of the scenario we are considering in part 2:

     

    Two identical containers of water (same volume, same container size and material) are placed into a freezer. One container contains water at just below its’ boiling point (< 100 °C) and the other at roughly room temperature (21 °C). Which will freeze first?

     

    Well I have two jars right here!

    In part 1 I discussed the Leidenfrost effect, named after a guy named Leidenfrost. In part 2 I will discuss the Mpemba effect named after, you guessed it, a guy named Mpemba. Interestingly, Erasto Mpemba was a young student when he made the initial observation that hot water can freeze faster than cold water. While he was not the first to make this discovery, his observation led to the first scientific study of the topic so it bares his name.

     

    At first glance, the second scenario is decidedly less exciting. No boiling, no sizzling, and unfortunately no shoddy videography, but unlike the Leidenfrost effect the mechanism behind the Mpemba effect is still hotly debated. During the boiling experiment the lower thermal conductivity of a trapped steam layer prevented efficient heat transfer to the remaining liquid droplet. Several competing explanations are offered for the Mpemba effect, but I will only consider the influence of variation in heat transfer upon freezing. In general “heat transfer” can be considered to explain both the Mpemba and the Leidenfrost effect, and there are three modes of heat transfer. Last time I described conduction which is the transfer of heat within a solid material or between two physically connected bodies. Conduction assumes that the atoms involved in the transfer of heat are fixed in space, like they would be in the solid pan from the Leidenfrost scenario or the walls of the container for the Mpemba effect. Thermal conductivity as described in part 1 is a measure of heat conduction. In a fluid convection is the major mode of heat transfer and implies that atoms or molecules are free to move around. Convection is the reason a bath of cold water with hot water poured into it will eventually reach a single homogenous temperature or opening the front door on a cold day will “let the cold in”. When dealing with both solids and “fluid” phases (a fluid means a non-solid phase) both conduction and convection can be considered. A more detailed explanation of conduction and convection can be found here.

    The third mode of heat transfer is radiation, which is the transfer and absorption of electromagnetic radiation. This was indirectly discussed in a previous article but is not important for these scenarios. A nice animation of each of the three modes mentioned here can be found on the web.

    To observe the Mpemba effect I took two identical salsa jars and ate their contents. This did not result in the Mpemba effect so I cleaned the jars and set about a second experiment. In one jar I put ¼ cup of tap water and allowed the water to reach room temperature by setting it on the counter for a few minutes. The temperature of my room was about 24 °C (75 °F). In the second jar I put ¼ cup of boiling water. By the time I poured the water it had cooled slightly from the boiling point (100 °C or 212 °F) to about 88 °C (190 °F). I checked these temperatures with a meat thermometer intended for porkchops and roasted chickens so the accuracy is not perfect but for this experiment it doesn’t matter – we only want to confirm that one container has water at a significantly higher temperature than the other. I placed both containers into my freezer which according to the same thermometer is somewhere around -15 °C (5 °F). After two hours I took the containers out and had a look-see. The room temperature water was mostly frozen except for a cavity between the ice at the top of the jar and the bottom of the jar itself. The boiled water was frozen solid. If I moved both jars around motion of the remaining liquid water in the tap water jar was obvious. From left to right below is both jars from the top after freezing, the room temperature jar from the bottom, and the boiling water jar from the bottom. The opening image for this article shows both jars unfrozen.

     

    Both jars after freezing – tap water on left
    Boiled water frozen
    Frozen tap water

     

    The heat transfer explanation that fits my results goes something like this: due to a difference in density between hot and cold water, hot water in the boiled container rises to the top and delays freezing. When the hotter water cools slightly it sinks to the bottom of the jar and stirs the rest of the container, keeping the temperature in the container homogenous. These movement within the water due to relative density differences are called convective currents. The convective currents are strong enough to keep the average temperature in boiled hot water jar above freezing until the entire container freezes simultaneously. Convective currents due to temperature differences are responsible for many naturally occurring events like the movement of an atmosphere around a planet. Meanwhile, the initially cooler tap water freezes at the top of the container preventing convective heat transfer between the water and the cold air in the freezer. Convective currents are also present in the tap water jar, but the remaining heat distributed by them is not enough to prevent a top layer of ice from forming.

     

    I feel obligated to admit that I had some difficulty getting this experiment to work. At first I tried using a whole cup of water in the same jars, checking the temperature in each container every five minutes. In this test I found that the boiled water dropped in temperature very rapidly at first whereas the tap water changed temperature very slowly. Both jars reached around 34 °F, just above the freezing point, at about the same time. The tap water jar froze on the top first making subsequent measurements of the underlying liquid difficult. Eventually both containers were mostly frozen but I couldn’t tell when the interior of either jar had frozen. Repeatedly opening the freezer door to inspect the jars also manipulates the experimental conditions, so when trying this at home I recommend you only check the freezer once an hour or so to see if anything is frozen. Transparent containers like my glass salsa jars make a quick inspection easier, but using containers of different materials could lead to some interesting results. It is this apparent sensitivity to experimental conditions that makes the mechanism responsible for the Mpemba effect subject to question. You can read more about some of these on the Wikipedia article for the Mpemba effect, but I encourage you to try some of your own tests and see what you find!

  • Water: prankster of the natural world part 1

    Water: prankster of the natural world part 1

    If you’ve ever taken a life sciences course your teacher probably mentioned one of several properties that make water particularly interesting. Water is cohesive meaning it sticks to itself, adhesive meaning it sticks to other things (superhydrophobic surfaces notwithstanding), and is considered the “universal solvent” because it readily dissolves many other substances. These properties are some of the most critical that allow water to function as the key to most terrestrial forms of life. Another interesting fact about water is that it is one of the few substances that exists in all three states of matter (solid, liquid and gas) in fairly non-extreme locals on earth. Furthermore, these phases exist within a relatively narrow range of temperatures – the entire transformation from solid to gas spans only 100 degrees Celsius (from melting of ice at 0 °C to boiling of liquid water at 100 °C). Compare that to ethyl alcohol (the alcohol in “alcoholic” beverages) which solidifies at -114 °C  and boils at 78 °C (a range of only about 200 °C, but with freezing occurring at a temperature below the coldest temperature ever recorded on earth) or a pure metal like iron with a melting temperature of 1538 °C and boiling temperature of 2862 °C  – that’s a phase range of over 1000 °C!

    It is important at this point in my introduction to define a phase: a phase is one of several atomic or molecular configurations for a given composition. When considering melting and boiling points, we are observing only the transition between the three states of matter mentioned above, however it is equally correct to consider multiple crystal structures for one composition of solid as different phases. Some of these solid phases are not easily distinguishable without sophisticated analytical techniques, while others have characteristic changes in physical properties.  No one would confuse graphite and diamond though they are in fact different phases of the same element. Plasma, also known as a superheated gas, is considered a fourth phase of matter but not one normally observed in nature with a notable exception being bolts of lightning. However, when heated to the point of being a plasma the atoms defining a given composition become ionized and for this reason plasma is normally considered separate from the more conventional states of matter. Fun fact for gamers: this is the plasma in all your favorite late game super-weapons.

    This is where things get weird for our old friend agua.

    Consider the following scenarios:

    1) Two identical pans are pre-heated to temperatures above the boiling point of water. The first pan is heated to 150 °C and the second pan to 300 °C. If drops of water at room temperature are placed into each pan, which drop will undergo the phase change from liquid to gas (boil) first?

     

    2) Two identical containers of water (same volume, same container size and material) are placed into a freezer. One container contains water at just below its’ boiling point (< 100 °C) and the other at roughly room temperature (21 °C). Which will freeze first?

     

    If considering only the energetics of each scenario, the logical conclusion is that a higher temperature pan means faster boiling, and a lower starting temperature means faster solidification. But if you were to perform these exact experiments at home (which I hope you do!) the opposite would occur.

     

    So whats going on? Is water playing by the rules (of thermodynamics)? Fortunately for us, Gibbs will remain stationary in his grave. As it turns out, both of these scenarios are good examples of how the properties of matter can change dramatically after a phase change. In both of these cases, variations in heat transfer between phases is likely to blame.

     

    For the water in the pan scenario, there exists a temperature above which water is so quickly vaporized upon hitting the pan a thin layer of steam is trapped below the liquid droplet, causing it to literally levitate above the surface of the pan on cushion of water vapor. Think air hockey table, but droplets of boiling water replacing the plastic puck. This temperature is called the “Leidenfrost point”, which according to unreferenced figure from Wikipedia is about 200 °C. Steam has a thermal conductivity roughly 10-100 times lower than that of liquid water depending on the temperature. In an idealized example, thermal conductivity is a measure of how easily a quantity of heat in a high temperature region can travel from one side of a 100% dense (no porosity) slab of material to the other. Thermal conductivity has units of energy per length per degree per second (Joules/(meter*°C*seconds)), meaning for a fixed length and temperature a material with lower thermal conductivity will take more time than a material with higher thermal conductivity to transfer the same amount of energy.

    At temperatures above the Leidenfrost point the Leidenfrost effect is observed and drops of water on a pan will take longer to boil because the steam trapped below the liquid water takes more time to transfer heat to the droplet from the pan. The videos below demonstrate drops of water into a pan below (top) and above (bottom) the Leidenfrost point. Above the Leidenfrost point, the droplets can barely be heard to sizzle as they zoom around on cushions of steam. For the pan heated above the Leidenfrost point, occasional contact with the edges of the pan, which are actually at a lower temperature or placing drops repeatedly in the same area which leads to local cooling will lead to momentary sizzling as the entire droplet boils. For the videos below, I used a nonstick pan and an eyedropper to put a few drops of tapwater onto the pan at a time. For the lower temperature I set my range to setting of 2 out of 10 and for the higher temperature I set it to about 6 out of 10 and waited a few minutes at each temperature for the pan to heat up.

     

     

    You may have heard of ole’ Leidenfrost’s namesake before associated with dipping things (namely one’s hand) into boiling lead after placing it in water. The Myth Busters did it after significant deliberation and preliminary testing, but somehow the alpha geeks at PopSci seemed to think it would make a good “DIY” project. I have to say, I can understand why dipping digits is the sexier version of the Leidenfrost effect demonstration, but the pan + water trick seems a little less invasive. In their defense, PopSci also covered this demo and the equivalent effect with boiling Nitrogen instead of steam as well.

    However you plan to enjoy the Leidenfrost effect, do so under proper supervision and be careful.

    Check out part 2 for a discussion on the second scenario!

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

  • Sequins + Dress + Spotlights = Laserdress

    Sequins + Dress + Spotlights = Laserdress

    I had a chance to catch some of the Golden Globes the other night. By had a chance I mean, I elected to watch the Golden Globes. For a little bit. You know how it is, when you have a choice between watching celebrities clap or watching reruns of M*A*S*H you have to ask yourself, “When is the next time I can watch M*A*S*H?”

    When I did stick around, it wasn’t just because I think Emma Stone is a stone cold fox (I do), or because I thought Ricky Gervais is particularly funny (I didn’t), and it’s not because I really care what the celebrities are wearing (I don’t). It was all the dang sequins.

    Maybe this is just from a fashion uninitiated, but there were a lot of sequins going on at the Golden Globes. But then I thought about it – why not? Sequins do a pretty good job of catching the eye, and that’s kind of the red carpet Modus operandi, right? Sequins’ secret lies in their ability as a reflector of incident light. Much like a signal mirror used to reflect the sun towards a rescue plane, sequins sewn onto a dress (or a pair of hideous shoes at DSW) reflect any light that hits their surface at an angle equal in magnitude to the incident angle reflected through a plane perpendicular to the reflecting surface. This is analogous to bouncing a ball off of a smooth surface. If the ball is dropped straight down the angle of incidence is 0° and so the ball bounces straight back up. Meanwhile, if the ball is bounced at an angle like a basketball being bounce-passed between two players, after striking the ground the ball will travel towards the second player at an angle identical to that thrown by the first player. This is called specular reflection (with light not basketballs). When considering this concept from the viewers perspective of a be-sequined dress, the dress appears to shimmer and flash. If the light-source comes from a single direction (like a spotlight) then the incident angle is fixed and the relative angles of the sequins change with the motion of the wearer. The result is flashes of light as individual sequins pass through an orientation which places the reflection angle directly towards your eyeballs!

    Maybe that’s not that surprising to you, given that you have observed this phenomenon first hand dozens of times in mirrors. However consider this – not all light is made equal. Light can be described as wave traveling through space from the source. These waves have the shape of the trigonometric sine function when visualized in two dimensions, and have an associated wavelength that is related to the energy of different forms of light. To humans and many other species, our eyes detect this difference in wavelength as color, but only in a relatively narrow range of wavelengths. This is referred to as the “visible spectrum” , and the acronym ROYGBIV known by many a grade-schooler as the colors of the rainbow actually orders the visible spectrum correctly from longest to smallest wavelength!

     

    Thus, while sequins are reflecting the crap of out the visible spectrum, light waves with appreciably longer or shorter wavelengths will have different interactions. For this reason, reflectors designed to reflect these different wavelengths can require drastically different shapes and materials. Some examples include a satellite dish whose curved edges reflect microwaves (these are of similar wavelength to the ones used in microwave ovens!) towards central antenna (the prong in the middle) increasing the signal, and metal coated Mylar (a type of flexible plastic) used in space blankets and on satellites (the ones in space, not the dish on your roof) to reflect infra-red radiation. In the case of space blankets, these reflect infra-red radiation (light waves with wavelengths just above the color red in the visible spectrum responsible radiative heat transfer – this is why heat lamps in restaurants are red!) emitted by the wearer back to their body. On satellites this wavelength is emitted by the sun and reflected away from heat sensitive electronics. In the case of metalized Mylar, the reflection is diffuse rather than specular, meaning the reflection takes place at many angles.

     

    So we’ve learned that sequins are sparkly because they reflect light at discrete angles. If they operated with diffuse reflection, the entire dress would appear to glow rather than sparkle. Fingers crossed that the fashion community will one-up themselves at next years GGs. A simple experiment you can try at home can be done with a mirror, a yard stick, and a flashlight (or ideally a laser pointer). Measure one yard from a wall and place the mirror on the ground, then place yourself one yard away from the mirror facing the wall. Hold the flashlight at the top of the yardstick pointing towards the mirror. The reflected light should strike the wall at the exact height you are holding the flashlight! This is specular reflection in action!

     

     

    Image: m_bartosch / FreeDigitalPhotos.net