Hypothetical Arms in the Milky Way

   Most images of the Milky Way that have not been photographed through a telescope have been computer engineered. The previous photo, from NASA, was evidently created on a computer, since the farthest probe, Voyager 1, has only just reached Pluto. We have no real  way of telling what the Milky Way looks like, unless there was something that could  travel 100,000 light years in a very short time to escape the Milky Way, to reach a more deep and empty space, where the probe could photograph our galaxy, then turn around and come back to Earth with the data. By doing so, we could know whether or not these hypothetical arms really exist, or if they are simply imaginative. 
    Below is a diagram of the Milky Way, with the hypothetical arms as dotted lines.