In an Equestria where the Sonic Rainboom never happened, Sunset Shimmer is the prized pupil of the Princess of the Sun. As Sunset struggles to make up for her past misdeeds and come to terms with the pony she wants to be, Celestia sends her to find the classic work The Application of Unified Harmony Magic from the Royal Canterlot Archives.
  Right after lunch, some meddling by her friends and meeting somepony with firsthoof experience of the Sunset she used to be.

Cast: Sunset Shimmer, Moon Dancer, Minuette, Twilight Sparkle & Princess Celestia

Featured on Equestria Daily on August 18, 2016!
Appeared in the FimFiction Featured Box!

Stories set in the Wavelengths Timeline in chronological order:

Origins Arc
The Alchemy of Chemistry
Bards of the Badlands
Grading on a Bell Curve
Habits of the Equestrian Phoenix
How Not To Use Your Royal Prerogative

Applications Arc
The Application of Unified Harmony Magics
Princess Celestia: A Brief History
The Cloudsdale Report

Dreamers Arc
Tactics of Snowbound Unicorns
A Study in Chaos Theory
Teahouses of Saddle Arabia
As the Raven Flies

Cover Credits
Cover Design by Amber Spark
Sunset Shimmer Vector by TigerBeetle
Pony SciTwi Vector by Osipush
Canterlot Bookshelves Vector by FavoriteArtMan
Sunset Shimmer Cutie Mark by MillennialDan

Beta Reader Credits
Ebon Quill - Worldbuilding Writer on The Manehattan Project
Quantum State - Technical Director of The Manehattan Project
The Albinocorn - Master of Sunset Shimmer Stories

Strongly Recommended Stories:
The Brightest and the Best by Pineta - The events in this story are considered to be completely canon to this timeline and explain Twilight's entrance exam to Celestia's School for Gifted Unicorns. I cannot recommend this story enough.
MLP Annual 2013 - "The Fall of Sunset Shimmer" - As above, the 8-page short comic in the beginning of the Annual is also considered to be canon, though with some major variations.

Version 3.0 Edit: Extensive grammatical and mechanics changes. Adjustment to timeline of Sunset's second mirror experience.