In his book Our Mathematical Universe: My Quest for the Ultimate Nature of Reality, Max Tegmark writes that “time is not an illusion”
We’ve seen a lot of examples of how things feel very different from the way they look in the equations. I would argue that almost all of the big breakthroughs in physics have this as their most difficult element. If you rewind to when Einstein came up with special relativity, you would find people like Lorentz and Minkowski had already written down a lot of the math. But Einstein was the guy who managed to figure out what it was going to feel like. He said if these are the equations, the way it’s going to feel is if you go near the speed of light, you’re going to feel time slowing down. And people said, Whoa, that’s really weird! Then they did the experiment and it’s correct. I had a fun conversation with physicist David Wineland. He told me that he’d built two atomic clocks that are super precise, and put one of them one foot below the other, and was able to measure that it runs slower!