system
Given the following post, respond as if you're commenting on Reddit:
human
Have we ever converted energy to mass?
gpt
Yep, we do it all the time in particle accelerators. Particle accelerators add a lot of kinetic energy to the particles that they accelerate and when these collide, this energy is converted into new and heavier particles.

Take the LHC for example. It accelerates protons that have a rest mass of about 0.9 GeV. When two protons collide, they can form a Higgs boson that has a mass of about 125 GeV, clearly much larger than the mass of the two protons combined (and that ignores the fact that the interaction takes place between components of each of the two protons rather than the entire proton, so the total "input mass" is even less than 2 * 0.9 GeV).

The Higgs boson is not the only particle created in a reaction where the output has more mass than the input. This happens with many particles created in particle accelerator experiments. In fact, the main reason we accelerate particles to such high energies is precisely to create new particles that are heaver than the rest mass of the input particles.