How is it possible, even in vaguest theory, for an experiment inside this universe to test the holographic universe theory? Even if this experiment had found the hypothesized effect they would have been no closer to verifying the holographic theory because there could be any arbitrary number of other hypothetical explanations for the effect that had nothing to do with the holographic theory, no? Never mind the particulars of the experiment, how was it even possible in theory that this experiment would offer any insight at all as to the veracity of the holographic universe theory? To test the holographic universe theory would require not being confined to this universe, to be able to interact with or detect existence outside of the universe being tested, no?
A learned hamster scientist looking for tenure wants to test the ball universe theory. He shoots a laser at a right angle to the bottom of his universe and again at a 45 degree angle to the bottom of his universe. He repeats the 45 degree experiment 360 times, increment the bearing each time. The light comes right back to his laser in the right angle experiment. In the 45 degree experiment it comes back to him from 45 degrees elevation and 180 degrees opposite bearing with 3 times the energy loss as seen in the right angle experiment. All the 45 degree experiments get the same result. He has just proven the ball universe theory, right? NO. He's just proven the inside of his universe is a ball. He still knows nothing about the outside of his universe or the nature any part of his universe beyond its inner boundary.
How is the experiment in the article any different from the hamster scientist's experiment? The only thing they can possibly test is the nature of existence inside the universe and not the nature of the universe itself.