system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come there’s just 1 line of continuous bubbles coming from the bottom of the glass if you’re drinking something like champagne?
gpt
When you see a line of bubbles coming from a single point, that point is called a 'nucleation site'.

What is happening is that there is probably a small imperfection in the glass there where a tiny bubble of air can be trapped.  

It is much easier for an existing bubble to get bigger than it is for a new bubble to form out of nothing.  So, what happens its that this tiny trapped bubble grows until it gets too large for the imperfection and it then breaks off and rises to the top of the glass.  When the bubble breaks off it leaves behind another tiny bubble trapped in that imperfection in the glass.  The cycle then repeats.

You can reproduce the experiment by putting a large grain of sand in the bottom of the glass.  This grain of sand is likely a lot rougher than the glass and will contain small trapped bubbles.  After filling the glass with a carbonated drink, the rough grain of sand will likely be one of the locations from which lines of bubbles rise.