Yes, the universe itself is. And, lots of matter within it is moving away from each other at “speeds” faster than light. However, travelling for us is limited by the universal speed limit. It’s not the speed of light, it’s really about the speed of causation, a fundamental limit built into spacetime. So, any discussion of speed needs to define movement and domain. It’s all relative.
Let’s explore and make sense of this.
Let’s start with our part of the universe. No, I’m not talking about Earth or our solar system. Heck, I’m not even talking about the Milky Way Galaxy. I’m starting with the Local Group. Our gravitationally bound corner of the universe. The material we are travelling with through space, nearly forever. You may have heard of the three great galaxies: Andromeda, Triangulum, and our very own Milky Way. The three much larger galaxies among 100 plus galaxies.
What about the trillions of galaxies? Everything else in the universe is flying away from us at an average middle rate of about 2.5 times faster than the speed of light, faster than causation itself. Billions of years ago, that rate was lower. In billions of years, that rate will be higher. And, there will be a time in the future where intelligent life will claim there are only 100 or so galaxies, and nothing else. From our spacetime point now, we know that’s wrong.
So, within our Local Group, travelling is limited by the universal speed limit. What most people call the speed of light. But the so-called “speed of light” isn’t really about light at all. It’s the speed of causation, a fundamental limit built into spacetime itself as seen “within” our Local Group and throughout the universe.
