Cochlear Implants: applying physics to improve hearing

by Kate Williams AP Physics 1 Student

Most Americans who have the ability to hear cannot fathom the lifestyle changes that come with deafness or profound hearing loss. In the United States, twelve thousand babies are born partially or completely deaf every year. Conservative ways to support deafness are Sign Language, mouth reading, or just living life in complete silence. However, throughout the past few years, physics has allowed cochlear implants to become the first medical device used to replace a human sense.

Although cochlear implants have not been around for a very long time, physicists have been trying to invent a hearing device since the early 1800s. Physicist Alessandro Volta conducted an experiment in which he connected a battery to electrodes in his ear. Through this experiment, Volta heard “unpleasant noises” and started the phenomenon of artificial hearing. The first surgically implanted cochlea was designed by Williams House and passed by the Food and Drug Administration in 1984.

To fully understand the brain’s reaction to sound, scientists use physics and the study of sound waves. There are two different types of waves: longitudinal and transverse. Transverse waves move perpendicularly to the direction of motion (as shown in the bottom part of the diagram). Longitudinal waves are the opposite; their waves move parallel with the direction of motion (as shown in the top portion of the diagram). Before creating the cochlear implant, physicists had to fully understand that sound is a longitudinal wave. Mechanical longitudinal waves must have a medium in which to travel. This characteristic of longitudinal waves is an important principle of the implant that allows sound to always go through the skin and into the device.

A cochlear implant is very different from a hearing aid. Hearing aids simply use vibrations to reach the remaining hair follicles in the cochlea. However, profoundly deaf people may not have much, if any, hairs left in the cochlea which is why the cochlear implant is surgically placed and is constructed of an inner and outer part. The inner part of the implant has a small soft wire that is placed within the ear and wrapped around the inside of the cochlea. The outer part of the implant is constructed of a microphone and a speech processor. The processor must be with the user at all times for the device to work; although, it may be taken off to shower or sleep. This processor is important because it picks up the nearby noises and converts them using a transmitter that is attached to a magnet that connects the internal and external parts of the device. The transmitter sends the signals to the internal part of the implant and then on to the brain.

Even though this discovery has helped thousands of deaf people, it does not come without risks. One major risk of the surgery is that it just may not work. The human ear is a very sensitive area and sometimes the surgery is not successful for certain people. A common misconception about cochlear implants is that the effect on hearing is immediate; however, six weeks are required for the surgical site to heal and be ready for the external portion of the implant. When the audiologist first attaches the outer piece, the recipient may not hear anything at first. It is the doctor’s job to then adjust the frequency of the implant until sound is heard. Once sound is heard, deaf people do not automatically understand what they are hearing. Most of the recipients have spent the majority of their lives using Sign Language and staying completely mute to outside sounds. So, although they hear sounds, the recipient must then go through long months of speech therapy to learn how to speak and understand spoken words. Many deaf adults who get the implant end up never wearing it because their brain has gotten so used to hearing no sounds that tiny noises such as the sound of a dishwasher or the starting of a car cause them a great disturbance. There is also the concern in the deaf community that cochlear implants are taking away the use of Sign Language and a culture that has been around for a very long time. In the deaf community, the appropriateness of cochlear implants is still a controversial issue, but in the physics community, it is a discovery worth sharing.

Works Cited

Cochlear Implant. Digital image. Kids Health. Nemours, n.d. Web. 20 Apr. 2016.

“Cochlear Implants.” Cochlear Implants. NIH Publications, 18 Aug. 2014. Web. 19 Apr. 2016.

“How It Works.” Hearing with a Cochlear Implant. N.p., n.d. Web. 22 Apr. 2016.

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The Physics of Skydiving

by Ashley Hazel AP Physics 1 Student

Every one has heard of the extreme sport of skydiving, yet does everyone know the physics involved with it? Physics plays a monumental role in every aspect of our lives, and for this intense hobby, physics dishes up a major dose. So let’s break things down.

The first jump.

Once you leave that plane, your heart is racing, your palms are sweating, and probably the only thing on your mind is “Ahh!.” But, have you ever stopped to think about what’s going on around you as you joyfully plummet towards the ground? As you are capturing those Instagram-worthy Go-Pro selfies, there are two forces acting on you: gravitational pull and friction with the air. As you leave the plane, Earth’s gravitational pull will carry you straight towards the ground, and you’ll gain speed with each second. While you begin to travel, the resistance from the air around you begins to increase and pushes up in the opposite direction of your fall (luckily it’s not as strong as gravity). Thanks to the relationship between gravity and air resistance, you won’t keep falling at a rapidly increasing speed, but as your speed increases, so does air resistance. The air resistance will keep increasing until it reaches the magnitude of the force of gravity. Once this happens, the forces become balanced, and you’ll no longer accelerate.

Body Position

Ever heard of the term aerodynamics? Well, it plays a major role in skydiving, as well. The position and shape of your body dictate your speed as you fall. For example, say you and your friend decided to race down. You go with the method of tucking your arms and legs in as tight as you can into your body. Your friend, on the other hand, decides to go full flying squirrel. You’ll notice that as you fall, like the graceful armadillo you embodied, your friend will lag behind you because of the difference in body positions. Your stretched-out friend has more surface area than you do. Air resistance has a greater surface to work on, thus slowing the body down. However, while you might be the speedy one of the group, stretching out while falling is actually a better skydiving technique because this position creates dynamic stability – keeping you more stable as you descend.

The Parachute

Now comes the moment of truth: the parachute. This simple little device holds the most important job of all-SLOWING YOU DOWN. But how? The answer is simple, air resistance. Just as your body position controlled your speed, the parachute’s broad surface area works to keep you from regretting your spontaneous skydiving adventure. The parachute’s huge size proves vital and is the sole reason you can significantly slow down to a speed that promises safety. This significant change in speed is why you always see the huge snap up once the parachute has been released. The huge amount of air being trapped by the parachute causes a dramatic slowdown.

Skydiving is no joke and neither is the physics involved with it. These forces that so many of us remain unaware of are responsible for so many great things in the world. Physics allows us to jump out of planes safely. I mean what else can do that, right?!? So maybe if you ever work up the nerve to go skydiving you can stop and think about what’s really going on around you. Maybe even share it with your diving instructor. Your extensive and intriguing knowledge might even make up for that full face of hair you gave him during the jump.


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Exploring the Possibility of Time Travel

by Paige Harriss AP Physics 1 student

“A civilized man…can go up against gravitation in a balloon, and why should he not hope that ultimately he may be able to stop or accelerate his drift along the Time-Dimension, or even turn about and travel the other way?” H.G. Wells encapsulated popular interest in time travel through this quote and others in his novel The Time Machine written in 1895. Believed to be the first novel written about time travel, The Time Machine has been in print continuously since its initial publication and reveals our national intrigue in this extraordinary concept. More recently, time travel has been studied by physicists as a plausible theory – one that may or may not be within the bounds of modern physics. Albert Einstein, Nathan Rosen, and later Kip Thorne contributed to the idea of a black hole providing a portal to the past. Other recent theories also support the idea of time travel; however, an opposing viewpoint based on the grandfather paradox refutes the notion entirely.

The theory of a black hole providing a mode of time travel has long been suggested. Black holes have the ability to bend the space and time surrounding them to the point of breaking, creating a small rip. In 1935 Nathan Rosen and Albert Einstein theorized that this small rip could connect to a rip in another black hole, creating a bridge; the Einstein-Rosen bridge, that would provide a passage through which a time traveler could be transported into another dimension. However, there are disparages with the bridge. Too small for even an atom to fit through, these “wormholes” are unusable for a time traveler, and close so quickly even light would not have the ability to pass through to the other side. In the 1980s, Kip Thorne elaborated on the Einstein-Rosen bridge and theorized a way to use anti-gravity to hold the portal open long enough for a person to pass through. Anti-gravity, pushing apart the space around the wormhole, would be channeled in large amounts to hold the portal open. To supply these large reserves of anti-gravity energy, Thorne hypothesized the Casimir effect; that two metal plates in close proximity could eventually generate enough negative energy to hold open the portal. Lastly, to create a true time portal, Thorne theorized a way to desynchronize the two black holes so that time would run differently in each. By containing one of the holes in negative energy and somehow transporting it around the universe at the speed of light, the two holes would desynchronize, with one black hole existing in a different era than the other, but in the same location. True time travel would thus be achieved. Although one of the first extensive approaches toward time travel put forth, this elaborate theory has been doubted by some physicists.

Numerous alternative approaches have permeated modern time travelling physics research. In 1991 Princeton astrophysicist J. Richard Gott proposed the idea of a shoestring. These cosmic strings, formed since close to the beginning of the universe, would pass each other in anti-parallel directions, running at the speed of light. A time traveler would thus be able to wait nearby and enter in between these strings which have twisted space-time due to their infinitely long and incredibly dense structure. Edward Witten is at present developing his super-string theory, while Stephen Hawking has even proposed lining up infinite parallel universes to achieve time travel. It seems that even if such theories prove viable, the mathematics behind each is nearly impossible to solve. Physicist Michio Kaku, commenting on the superstring theory, stated, “At present, superstring theory is the leading candidate for such a theory (in fact, it is the only candidate; it really has no rivals at all). But superstring theory…is still too difficult to solve completely. The theory is well-defined, but no one on earth is smart enough to solve it.” Theories abound, and deeply committed physicists are convinced that eventually the mystery will be solved, though perhaps, not in their lifetime. There are also those who reject all propositions of time travel, doubting the possibility that even a future generation might find the key to a parallel universe.

The Grandfather Paradox presents an argument silencing any notion of time travel. Described as early as 1931 in various science fiction novels including Ancestral Voices by Nathaniel Schachner, published in 1933, and Future Times Three by René Barjavel in 1943, this paradox seems irreconcilable with the notion of travelling through time. The Grandfather Paradox presents the idea that if a person were able to travel to the past and then kill his/her parents, then that person would never have been born and thus it would be impossible to travel back in time in the first place. There have been responses to this paradox, such as the idea that the individual “would fail for some commonplace reason…her gun might jam, a noise might distract her, she might slip on a banana peel…” or that travelling in the past “merely creates a parallel universe.” So we are changing someone else’s past by saving, perhaps, Abraham Lincoln from being assassinated at the Ford Theater, but our Lincoln is still dead. A concrete answer to this fundamental complexity still has not been established. Clearly, modern mathematics must be more advanced before we are able to answer such paradoxes, or the disparagement between quantum mechanics and gravitational relativity; the fact that they “dominate in disparate domains, and…seem to converge only in enormously dense, quantum-size black holes,” must be resolved.

Even with the abundance of theories including the Einstein-Rosen bridge and superstring theory, numerous paradoxes still remain unanswered. The Grandfather Paradox will continue to discourage many from the seemingly irrational research of time travel, and, even in the event that time travel becomes possible, many will question the morality of attempting to change events of the past. However, current research on the topic has become more plausible, and it is clear that “our heirs, whatever or whoever they may be, will explore space and time to degrees we cannot currently fathom…creating new melodies in the music of time.”

Works Cited

Kaku, Michio. “The Physics of Time Travel.” Explorations in Science Official Website of Dr Michio Kaku RSS. N.p., n.d. Web. 17 Apr. 2016.

Koks, Don. “What Is the Casimir Effect?” The Casimir Effect. N.p., 2002. Web. 17 Apr. 2016.

Moyer, Michael. “The Physics of Time Travel.” Popular Science. Bonnier Corporation, 19 Feb. 2002. Web. 17 Apr. 2016.

Person, and Annalee Newitz. “Are We about to Reconcile Gravity with Quantum Mechanics?” Io9. I09, 07 Nov. 2013. Web. 17 Apr. 2016.

Pickover, Clifford. “Traveling Through Time.” PBS. PBS, 12 Oct. 1999. Web. 17 Apr. 2016.

Smith, Nicholas J.J. “Time Travel.” Stanford University. Stanford University, 14 Nov. 2013. Web. 17 Apr. 2016.

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