Barack Obama on Instagram: "When the Obama Presidential Center opens next year, it will be a hub for change — a place for our @ObamaFoundation leaders and people from all over the world to come together, get inspired, and take what they learn back to their own communities. You can learn more about the Obama Presidential Center at the link in our bios."

Phil Cook on Instagram: "I built a simple setup to demonstrate how Li-Fi: light-based wireless communication, can be used to transmit sound using visible light. An audio signal from my iPad is amplified and sent to a light-emitting diode (LED), converting the sound into rapid fluctuations in light intensity. When the flickering light shines on a solar panel, the panel converts the light back into an electrical signal that can drive a speaker, reproducing the original sound. Because light waves c