For our biannual Physics & Astronomy Open House our group presents a brief show on lasers, their properties and uses. The show includes demonstrations and an interactive presentation introducing ideas such as wavelength and power.
This video was used as part of an outreach presentation I did for our Physics Open House entitled "Sharks with lasers on their heads". The laser was a SpectraPhysics Millenia 10 and we used an air filter to safely remove the smoke from the lab so as to not damage any optics.
The Ohio Valley Museaum of Discovery (OVMoD) has provided our group opportunities to engage with the community. We have brought a scaled down version of the "Sharks" presentation and discussed properties of waves. The OVMoD is a great conduit to the community through their mission of "Inspiring visitors of all ages to explore and discover the world we live in through interactive exhibits and creative experiences."
Simple harmonic oscillations (SHO) and the underlying concepts of frequency and wavelength are abundantly present in our everyday life. Colors and sounds bombard our senses daily and we, necessarily, think very little of their basic properties. However, as a physicist, the power and central importance of frequency, wavelength, and SHO is undeniable. Making a connection between such seemingly disparate things as light and sound can help foster an appreciation for the fundamental nature of SHO and the power of understanding their role in everyday life. For example, teaching undergraduate courses on optics, light, electricity and magnetism, etc., whenever we arrived at the topic of atomic spectra I would discuss how each element has its own optical fingerprint, allowing us to identify their presence in objects from neon signs to stars. I would mention how each element basically played a chord of optical frequencies, which stuck with me and kept me wondering “what would helium sound like?” The more I thought about it the more intriguing it became, including the possibilities of playing a molecular compound such as caffeine or creating an entire musical piece based on the elements.
In writing the program, the biggest question was how exactly to map the optical frequencies of elemental spectra to audible frequencies. A simple linear mapping wouldn’t work due to the relative separation of lines in the optical spectrum. For example, the frequency difference between a line at 600 nm and one at 601 nm is approximately 832 GHz, vastly larger than the range of audible frequencies. As an alternative, using values collected from the NIST Handbook of Basic Atomic Spectroscopic Data (http://www.nist.gov/pml/data/handbook/index.cfm), it is found that the optical frequencies for the elements in the periodic table span the range from 24 GHz, for Hydrogen, to 17485 GHz, for Lithium. So by simply dropping the ‘giga’ prefix we find that the significands, 24 to 17485, fit nicely into the range of audible frequencies. Though this represents the most straightforward, and potentially intuitive, mapping, other mathematical mappings will be investigated and potentially incorporated into the final product, providing an even richer set of variables for the end user to play with.
Below is the conversion of the neon spectrum to a audio wave form. The top panel is the visible spectrum of neon in Angstroms. The middle panel is the converted spectrum to frequencies consistent with audible sound. The bottom panel is the resulting waveform.