Immersion is the moment when I forget peripheral thoughts and focus all my attention towards anything. I have be immersed in a burger and become light headed because I had forgotten to breath. Everyone experiences this type of stuff such as when your running and you get stuck in the rhythm and movement of your running that its easy (but still hard) to keep on moving.
I way too often become entranced with music while studying and the feelings of the song will come through into my head. Even if its the most mundane task like putting bulk stamps on letters it can turn teh vibes into something very different.