It is possible to reduce some of the climate risks of accumulated CO2 by deliberately altering the Earth's albedo using Sunlight Reflection Methods (SRM) also called solar geoengineering. It is possible to remove carbon from the atmosphere at large scale using various methods for Carbon Dioxide Removal (CDR). Estimates of the cost, risks, and efficacy these tools will remain uncertain but it is now possible to make some policy-relevant quantitative comparisons between risks and benefits, and to speculate about the appropriate use of energy-system decarbonization, CDR, and SRM.

Whereas the governing equations of fluids and solids as single phases were derived over a century ago, the physics at the interface between these continua can be surprisingly rich and complex – instabilities emerge, interfacial forces become dominant, and mechanical fields vary across scales, from the molecular- to the sample-scale. Our lab probes these phenomena with impacting droplets and cracks in hydrogels, where we directly image the kinematics of obscured interfaces using 3D microscopy. In this talk, I will discuss two vignettes: first, the emergence of an interfacial instability beneath an impacting droplet of alcohol on an atomically smooth mica substrate, and second, the geometry and stability of complex cracks. These seemingly disparate systems are connected on a variety of levels, from their sensitivity to defects, to the duality of contact formation and bond rupture, which implicate mechanical fields across scales. A discussion of some open questions and future perspectives will conclude the talk.

Lipid membranes are nanometer-thin soap-like films composed of molecules with hydrophilic and hydrophobic segments. To eliminate their edge energy lipid membranes form closed spherical shells or vesicles, structures that are ubiquitous and versatile, with applications in encapsulation, molecular transport, and drug delivery. Controlling vesicle topology is essential in these processes. The rapid dynamics and small scales make it challenging to study topological transitions of lipid vesicles. We develop and study fluid colloidosomes, which are micron-sized analogs of lipid vesicles assembled from rod-like particles. Their unique features enable real-time visualization of colloidosome assembly and disassembly pathways. Increasing the lateral size of a fluid two-dimensional disk-like sheet induces mechanical instability generating monodisperse permeable capsules. Closed vesicles disintegrate into open disks via an intermediate state that is topologically distinct from both the initial and final state.