Physicists 3D-printed a Christmas tree of ice

Researchers from the University of Amsterdam have unveiled a remarkable creation: a miniature Christmas tree crafted from ice, standing at just 8 centimeters tall. What sets this festive ornament apart is that it was produced without any refrigeration technology, utilizing a novel approach that leverages evaporative cooling. The process, detailed in a recent preprint on the physics archive arXiv, draws upon the well-documented principles of evaporative cooling, a phenomenon familiar to many. For instance, mammals rely on it to maintain their body temperature, and it can be observed when steam rises from a hot cup of coffee. This cooling technique also plays a significant role in various scientific processes, including the formation of Bose-Einstein condensates. Interestingly, the researchers noted that evaporative cooling can lead to challenges in cooking, particularly for BBQ enthusiasts, where the moisture released from meat can cool it down due to evaporation. Traditionally, methods for ice printing use cryogenics or cooled surfaces. However, this groundbreaking work marks the first instance where evaporative cooling principles have been effectively integrated into 3D printing. The team discovered a unique technique by using a jet nozzle within a vacuum chamber, which allowed them to eliminate air drag while spraying water. This innovative setup enabled precise, layer-by-layer construction of the ice tree, showcasing a new frontier in 3D printing technology.