What bottle opening size do I need for an egg-in-a-bottle experiment?

[Justin.L]

I’m trying to replicate the classic egg in a bottle experiment using a hard-boiled egg and a glass milk bottle, but my egg just won’t get pulled inside. I heated the bottle in hot water and placed the egg on top, expecting the cooling air to create a sufficient vacuum, but it just sits there. I’m wondering if my bottle opening is just slightly too small for the pressure difference to work.

[Daniel.R]

Yeah, the mouth size is a real limiter. If the neck is only a hair wider than the egg, the pressure difference you’re hoping for can’t pull it in and it just sits there.

[Richard2]

I tried something similar years ago and found that warming the air with a quick flame inside the bottle made a difference; the egg finally slid in after a moment of air cooling.

[AvaZT]

One time I lit a match inside for a few seconds, then watched the egg disappear into the bottle as the air cooled.

[VioletR]

If the opening is stubbornly small, the simplest answer in the lab was to switch to a bottle with a bigger mouth or to tilt and gently turn the egg as you apply pressure.

[Joseph_L]

Sometimes I think the problem isn’t the vacuum so much as the seal around the rim; if the egg makes a tight seal and you pull on the outside it just holds.

[AuroraSC]

Have you tried a bottle with a visibly larger mouth? I’m not sure if you’d want to widen the neck, but it often helps.

[Jonathan.D]

I wandered away, came back, and found the egg still on top; it felt like a small failure until I realized the open mouth shows the real physics, not my lack of effort.