Let's venture together for a minute here, on a speed of light journey, with the benefit of virtual reality and data. lots of data!.
Our galaxy is The Milky-way, pictured below is around 100,000 light years across. Milkyway info page
From the point of view of a photon beyond a black hole event horizon time at the speed of light is zero. It hits a wall at that speed because they can't escape the overwhelming gravity.
Think of it this way the energy is the field and it can not escape this psychical reality, it can only change form. It cannot be destroyed, it disappears from view.
Any rocket-man observers traveling across a spiral arm at the speed of light, would still take more than 2 thousands years from our perspective, to cross it.