Originally Posted by: Svanholm
Can I mix between, lets say, E minor pentatonic, E minor(aeolian) and E blues scale while jaming to a backing track in the key of E?

There are 12 notes on the fretboard for you to choose from at any given time. If it sounds good, have at it!

You may find yourself "accidentally" using a note or notes outside of a given scale that you thought you were using (very common with pentatonic scales). You have the option of just going "hey, that note sounds really cool" and try to remember it in the future, or you can figure out what the note is, the other notes it sounds good with, and then determine the scale that you're actually using.

People combine the three scales you mentioned all the time. Another scale you may want to familiarize yourself with is Mixolydian. It tends to work very well over rock progressions. It has kind of an upbeat flavor, so it will take a bit of getting used to at first, but when you find a tune it fits with, you'll probably really like it.