Gamma-rays are theoretical “electromagnetic particles” called photons. Due to the supposed “duality” of matter, they exist as both waves and particles, and they are “massless,” as astrophysicists define mass. However, since they travel at enormous velocity (up to 3 x 10^10 centimeters per second), so-called “relativistic effects” come into play.
Well not quite that fast
light by definition doesn't go faster than 2.998 x 10^10 cm / s. I love the Alfvén quote, he is right on here. As applied to gamma rays for example, they -are- consistently measured, created, and understood in the laboratory. We do have some of the tools required to understand at least some of gamma ray astronomy.
Well... we might have some of the tools but I'm not sure how to use them
