Converting Energy to Mass

Hi, I had this question coming from my litle bro that if people say that we CAN convert energy into mass then HOW?How will energy be converted into mass, what exactly should happen. Like if we say, in accalerators the mass of the particle increases as it nears the speed of light...are any particles getting added to it or something like that?
- Frank Wills (age 30)
mumbai, India

We say that the mass of a particle increases as it approaches the speed of light because its inertia increases as it gets harder and harder to accelerate it further.  Also its contribution to gravitational fields goes up.More particles are not being added to it.  In the rest frame of the particle, its mass does not change.

We generate new particles (typically particle/antiparticle pairs) by colliding highly energetic particles; some of their kinetic energy is thereby converted to rest mass energies of the new particles.  This is done routinely in particle accelerators like the one at CERN.   But the process is very inefficient.

Richard

for more background, we suggest: https://van.physics.illinois.edu/qa/listing.php?id=16351

(published on 03/20/2016)