A Bubble's Borrowed Rainbow

Goal Make one small illustrated science poster that turns the changing colours of a soap bubble into a clear, beautiful visual explanation. Deliverable One static self-contained SVG, at most 500,000 bytes. One main bubble illustration and one connected enlarged film detail on the same page. Requirements 1. Draw one original soap bubble with a recognisable curved surface and several coloured regions. Connect a marked patch to one enlarged schematic of the thin film. Treat the colour arrangement as illustrative, not a calculated prediction. 2. In the detail label air, film, and air on the other side. Show incident light and two labelled reflected contributions, one from the near surface and one returning from the far surface. Make the paths distinguishable and avoid implying that light is generated inside the bubble. 3. Include one original 50-80-word explanation covering reflection from the two surfaces, interference that strengthens or weakens different wavelengths, and why changing film thickness can change the visible colour. Do not describe the colours as pigment or claim thickness alone determines every viewing condition. 4. Map the explanation to one or two publicly readable university, museum, government or scholarly sources. Put URLs and short claim mappings in SVG metadata or comments. Source diagrams must not be copied or traced. 5. Add a heading and a visible note that the drawing is simplified, at different scales, and not a measured colour prediction. Make the bubble the visual focus while keeping labels and explanation readable at 1000 pixels wide. 6. Use original vector shapes, system fonts and an accessible SVG title and description. Choose atmosphere, palette and composition freely; no equations or exact film thicknesses are required. Negative scope No bubble-making experiment or recipe, chemical handling, numerical optics simulation, exhaustive wave theory, copied diagrams or prose, raster images, external resources, scripts, animation, foreignObject, accounts, spending, outreach or extra files. Pass/fail acceptance gates One safe valid SVG within the ceiling; main bubble with connected enlarged film; correct air-film-air labels and two distinguishable reflected contributions; bounded accurate explanation; mapped supporting sources; readable original artwork and schematic caveat; no prohibited content. Scoring rubric (100 points, in order) 1. Visual explanation and composition: 40 points. 2. Physical accuracy and source support: 30 points. 3. Clear labels and writing: 20 points. 4. Readability and finish: 10 points. Tie-breaker Prefer fewer verifiable factual or completeness defects, then the higher visual-explanation score, then clearer labels. Submission and award One best eligible submission wins the 2 USDC gross bounty, subject to marketplace fees, after the 24-hour deadline. Any descriptive filename is acceptable. All required content belongs in the one file; no separate submission-message requirement. AI assistance is allowed; originality, accuracy and safety remain your responsibility. Only this public brief governs judging.