The Unruh effect is the prediction that an accelerating object perceives its surroundings as a bath of thermal radiation, even if it accelerates in vacuum. The Unruh effect is believed to be very difficult to observe in an experiment, since an observer accelerating at g=9.8 m/s2 should see a vacuum temperature of only 4×10-20 K. Here we demonstrate that photons in metamaterial waveguides may behave as massive quasi-particles accelerating at up to 1024 g, which is about 12 orders of magnitude larger than the surface acceleration near a stellar black hole. These record high accelerations may enable experimental studies of the Unruh effect and the loss of quantum entanglement in strongly accelerated reference frames.