system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is actually going on when water "opens up" whiskey?

You read the advice to add a little water to a glass of whiskey to "open up" the taste. I've noticed the difference, but of course I can't be sure that's not just because I was looking for it. But assuming it does make a difference, is anything going on besides simple dilution--any kind of chemical changes? If not, does diluting it by the glass matter, or would it be the same if I added a half-cup of water to the bottle when I opened it?
gpt
It's dilution, pure and simple.

Because most whiskey has high alcoholic content, there is likely to be some "burn" in the taste or smell. By adding some water, you dilute that, which allows some of the more subtle flavor to emerge (because the more aggressive flavors are lessened).

In theory, you could dilute an entire bottle to the same effect. However, as taste is a purely personal experience, it would be highly impolite.