Credits: Alejandra Abad-holding the bubble, Jared Moya- camera, Dimario Cancanon- lights and soap, Nebiyu Tadesse- camera and general support

This was shot on the 2001 Phantom Miro C110 at 900fps at a resolution of 1280×1024

https://freemusicarchive.org/music/MIT_Concert_Choir/Carmina_Burana_Carl_Orff/01_1355

Hold my Life in your Hands- Team Second

Jamie Frankel

(Assistance from: Alejandra Abad, Jared Moya, Dimario Cancanon, and Nebiyu Tadesse)

Flow Visualization

11/11/19

This artistic endeavor was meant to allow our group to view the beautiful colors apparent in soap bubbles (Figure 1) changing over time. However, as we quickly discovered, food coloring was not a bright enough dye to truly color our soap bubbles. As a result of our misunderstanding, we instead attempted to observe interesting physics surrounding bubbles.

Figure 1: Beautiful Soap Bubble Colors Visible in Still Image.

The procedure we used to capture the bubble shown in Figure 1 is as follows: Two parts water were mixed with one part Dawn dish soap and five drops of food coloring. About one foot of string was tied in a loop and then doubled about itself. The high speed 2001 Phantom Micro C110 was set up across from where Alejandra Abad and I were standing (in front of a white projector screen). Two 250W type T bulbs illuminated the screen behind us (Figure 2).  Alejandra extended her hands which were covered in soapy water and I blew the soap film captured within the string loop into her hands until she held a bubble of my breath gently in her hands and it popped.

Figure 2: Experimental Setup.

We would have been unable to capture the phenomenon in the video without the use of a surfactant (Dawn dish soap). When the soap is mixed with water, a chemical interaction decreases the surface tension allowing the solution to hold its shape. The soap molecules have both hydrophobic and hydrophilic sides. When water and soap mix, the different attitudes toward water cause the soap molecules to form two layers pushing their hydrophobic tails out of the water while sandwiching a thin layer of water between themselves (Figure 3) (Hipschman, 1995).

Figure 3: Soap Water Bubble Interface (0.1-10 μm)

The bubble is shaped like a sphere because it is the geometric configuration that uses the least amount of energy to enclose a particular volume of air (Why Does Soap Make Bubbles?, n.d.). These tails sticking out from the surface of the bubble help to protect the bubble from evaporation which increases the lifespan of the bubble.  It was imperative that Alejandra had soap on her hands for the bubble to retain its shape and not dry out. The bubble in the video eventually popped because enough of the water molecules evaporated as the bubble thinned out over time. This difference in surface tension across the bubble due to differing thicknesses actually creates movement of the surface itself and can be seen by watching the colors change as the local thickness affects the thin-film light interference (Cheng & Feitosa).

The bubble popped when the layer of water between the detergent evaporated. The bubble was shot at 900fps with an exposure set to 1100. The resolution was 1280 x 1024 pixels. The field of view was roughly seven inches by five inches.  The camera was about two feet from the bubble. The post processing procedure consisted of only cropping the length of the video to focus on the time when it popped and featuring the video in three different speeds. The introduction is at 200% speed while the pop is at 20%. After the pop, the rest of the video was at normal speed.

I really like that this video is slow enough to be able to see where the pop begins and how it almost seems like a grape being peeled. I intended to make the music that accompanied the video as ironically intense as possible. For this reason, I used a version of O Fortuna by the MIT Choir. While I did attempt to play with the contrast before determining the effort was futile, I wish that I had shot this video on a black background and with different lighting which was less hot and more of a white hue for better visualization.

Bibliography

Cheng, S., & Feitosa, K. (n.d.). Properties of Bubbles. Retrieved from http://www1.phys.vt.edu/bubble/properties-of-bubbles.html</p>

Hipschman, R. (1995). Soap. Retrieved from Bubbles: https://www.exploratorium.edu/ronh/bubbles/soap.html

Vang, R. (n.d.). How soap and water interact to form a bubble:. Retrieved from Bubbles!!!!: http://ffden-2.phys.uaf.edu/webproj/211_fall_2016/Roger_Vang/Roger_Vang/Project%20template/Slide2.htm</p>

Why Does Soap Make Bubbles? (n.d.). Retrieved from Wonderopolis: https://www.wonderopolis.org/wonder/why-does-soap-make-bubbles</p>