Is it really possible to create some mass only from equivalent energy?

Question

From Special theory of relativity we know that $E=m_0 c^2$, which says about mass energy equivalency. But my question : **Is there any real experiment where some mass is created purely from energy? **

Answer 1

Every particle collider does that. You shoot two very fast particles at each other, and the (sum of the) mass of the many resulting particles after collision is greater than the rest mass of the initial two particles.

Answer 2

Sufficiently high energy photon can spontaneously convert into a pair of leptons as long as there is a heavy charged spectator (i.e. an atomic nucleus) nearby to absorb some momentum. This is the largest energy-loss mechanism for very energetic photons in high $A$ materials.

You can also get two-photon interaction to ends with massive particles in the final state, but that is suppressed by a coupling constant relative the single-photon plus spectator case.

Answer 3

Photons, which have zero rest mass, can be "collided" to form particles with nonzero rest mass if the original photons had sufficiently high energy (in the gamma range), see two-photon physics. See this article for discussion of some experimental confirmation.