Sonoluminescence — By the Physics Club@TISB
Do you want to stroll down a phenomenon which has not been termed in the dictionary yet? Do you want to defy the laws of physics? Do you want to make the dream of creating energy on earth a reality? If that is the case, then you have spotted the right article for provoking your imagination and developing your interest in physics. The complexity of this word very well defines how captivating this topic is: Sonoluminescence occurs when a small gas bubble is acoustically suspended and periodically driven in a liquid solution at ultrasonic frequencies, resulting in bubble collapse, cavitation, and light emission. Now many of you might be wondering what exactly that means?
Well, to put it simply, when sound is passed through water, a bubble forms which converts sound energy into light and thermal energy. Research has found that the temperature of this bubble exceeds temperatures of 6000K which is hotter than the sun. Thus, it is believed that, in this phenomenon, energy is not only converted but also created through nuclear fusion. Therefore, this experiment is more popularly recognized as ‘star in a jar’ experiment because the bubble resembles the properties of a star which also creates energy through nuclear fusion. An even more fascinating fact is that the experiment is simple enough to be carried out in a school laboratory through a setup similar to the one shown below.
Amusingly enough, the discovery of this phenomenon was an accident. In 1934, two German scientists discovered the phenomenon as a result of videoing their experiment. Since then, many researchers have delved deeper into the topic, but we are yet to have an accepted theory.
There have been many interesting theories including one who claimed the emitted light to be a form of Hawking radiation which compares the process of Sonoluminescence to a process that occurs in black holes! Other theories include Triboluminiscence, and Shock wave SL. It may be beyond the scope of this article to cover the ideologies behind this theory. (Note: you could choose to read the references for more information.)
One of the most intriguing and most debating fact is that the insertion of a noble gas increase the heat and light produced by the bubble dramatically. There is no clear cut reason for why this happens. We all know that noble gases do not react, hence, making this phenomenon a peculiar one. A possible explanation is that as the number of electrons increase in the stable homo nuclear atoms, the intensity of the emissions increases due to the atom’s non-conductivity.
While exploring this nerve racking phenomenon, researchers have also found that plasma physics is used during the process (which provides evidence for nuclear fusion; the process that creates energy in stars). It was noted that the bubble has an inner core of plasma through videography analysis and experimental, research based evidence.
Through its relation, or rather resemblance, to astrophysical concepts, we know that sonoluminescencehas wide ranging aspects. These aspects are not only limited to astrophysics, but are interestingly enough also related tomarine life. An engrossing phenomenon called bioluminescence occurs in living organisms. It is defined as the production and emission of light by a living organism: when a living organism, for instance, a pistol shrimp, knocks its pray down by slamming its claws shut at such an extreme velocity that the light and heat released is said to resemble a sonoluminescent bubble (and thus, also black hole radiations!!).
This occurs through a chemical reaction which occurs inside the body of the organism. For a reaction to occur, a species must contain luciferin, a molecule that produces light when it reacts with oxygen. There are different types of luciferin, which vary depending on the animal hosting the reaction. Many organisms also produce the catalyst luciferase, which help to speed up the reaction. The most surprising fact is that they can also control the intensity of light they emit.These organisms can bundle the luciferin with oxygen in what is called a “photoprotein” — like a pre-packaged bioluminescence bomb — that is ready to light up the moment a certain ion (typically calcium) becomes present. They can even choose the intensity and color of the lights. The figure below illustrates shrimp bioluminescence which is essentially just bioluminescence in a shrimp. The blue figure depicts the photothreptin in the presence of an ion.
-Written by Vishal Agarwal, Keshav Dalmia, Hem Aashish Juvvaladinne, Aryan Jayanty
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http://prola.aps.org/abstract/PRE/v60/i2/p1759_1 (real 9…push others up)
http://www.nature.com/cgi- taf/DynaPage. taf?f ile=/n ature /journa l/v413/n6855 /abs/413477a0_fs.ht ml