No, it really isn't, it's just an inner experience.
This is easily proved. Next time you meditate check the time on a clock before you start. When you finish meditating check the clock again and you will see that a certain amount of time has passed. The world has moved on while you've been having your inner experience.
Why do people have this need to project their subjective experiences out onto the universe? It's rather egocentric really, there is a sort of arrogance behind it.
Like "Oh, I had an experience of inner stillness, so that means the universe must be still too!"
Well, no actually, the universe isn't affected one iota by your "mystical" experiences. All that changes is your perception of it. Hopefully.