If you keep moving, you can stay liquid even when packed tighter than a solid brick.
April 17, 2026
Original Paper
Absence of solid phase in dense amorphous active granular matter
arXiv · 2604.14610
The Takeaway
Usually, if you pack grains or atoms tight enough, they 'jam' together and become a solid. These researchers found that if the particles are 'active'—meaning they move themselves, like bacteria or tiny motors—they refuse to freeze. They stayed in a fluid state even at densities that should physically lock them in place. It is like a mosh pit that never turns into a crowd crush because everyone keeps dancing. This discovery could help us design new self-healing materials that flow through tight spaces without ever clogging.
From the abstract
Solid phase of dense granular matter is inevitable because of jamming transition when the packing fraction or the pressure suffered is high enough. The experiment suggests that active Brownian granular matter will keep fluid phase even under the highest packing fraction (higher than the packing fraction of crystallization) if crystallization is prevented by mixing granular particles of different sizes. The findings encourage us to reconsider the role of activity in affecting the global dynamical