The letter æ was used in Old English to represent the vowel that's pronounced in Modern English ash, fan, happy, and last: /æ/. Mostly we now spell that vowel with the letter a, because of the Great Vowel Shift.
When æ appears in writing Modern English, it's meant to be a typographic variant of ae, and is pronounced the same as that sequence of vowel letters would be. So Encyclopaedia or Encyclopædia, no difference.
https://english.stackexchange.com/questions/70927/how-is-%C3...Highly recommend the protracted arguments in the comments, that's a wonderfully pedantic StackExchange. Big shoutout to someone in 2012 defining "NLP" as an unusual word -- how the world has changed! It's only a matter of time before they open an AP/IB course in NLP...
The Great Vowel Shift indeed makes written English much more confusing than it perhaps should be. English is already a messy hodge-podge of a language, then our writing system started to get standardised (or standardized, if you're American!) right as pronunciation started to change, leading to the written version of words suddenly no longer being anything like the pronunciation.
But I pronounce the first vowel in aesthetic differently. For me, it's somewhat in between the vowels in "bed" and "bad" but closer to the former.
As a fellow Californian, I’d say we have authority anyway - I was taught in school that Ohio has the least specialized dialect, but that’s based on newscasters and such. The 21st century is the Californian century!
…that is, assuming Brussels’ English is out of the running, I suppose ;)