What Caused the Dancing Pint Glass at the Pub?

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Discussion Overview

The discussion revolves around the phenomenon of a pint glass appearing to "dance" on a bar top, with participants exploring potential explanations for the observed movement. The scope includes both anecdotal experiences and speculative reasoning regarding the physical principles that might be at play.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant describes witnessing a glass making deliberate movements on a bar top, suggesting it was not supernatural but rather a physical phenomenon.
  • Another participant proposes that a thin film of water or liquid under the glass could cause it to move, allowing it to float along the surface.
  • A further explanation suggests that small amounts of liquid escaping from under the glass could change the shape of the supporting film, leading to random movements.
  • Some participants express interest in replicating the effect, discussing methods such as dampening the bottom of the glass or the table surface to achieve similar movement.
  • One participant notes that it might be easier to wet the table top before placing the glass down, rather than wetting the glass itself.

Areas of Agreement / Disagreement

Participants generally agree that the movement of the glass can be attributed to physical factors, such as liquid dynamics, but there is no consensus on the exact mechanism or the best method to replicate the effect.

Contextual Notes

Some assumptions about the conditions under which the glass moves, such as the surface texture of the bar and the presence of liquid, remain unexamined. The discussion does not resolve the specifics of the physical interactions involved.

Who May Find This Useful

Individuals interested in physics, fluid dynamics, or those looking for entertaining bar tricks may find this discussion relevant.

MisterDavy
"Dancing" Pint Glass

Not sure if this really should go here, as I don't personally think it was anything supernatural, though I do lack an explanation for it.

I'd called into a local pub for a quick drink after work a few weeks back. It was pretty empty, just myself, the barmaid, and an older guy, and we were all standing at the bar.

After a while, I noticed that an empty glass on the bar top near me was "dancing."

It was making short, almost deliberate looking movements, drifting forward a little way before sharply turning direction, then doing the same, seemingly moving of its own violition. I pointed it out to the barmaid, who got kind of excited and said it was the ghost of the old landlord, who "slammed doors".

There were no obvious breezes, and when I got the barmaid to give me another empty glass and set it down beside the first, it sadly refused to join in the dance with its friend. When I eventually put a finger on the top of the dancing glass to stop it moving, it refused to start up again. I felt kind of bad that I'd spoiled its fun.

I'm assuming it was being moved by either vibrations or tiny air currents I couldn't feel, but the glass I tried to make dance with it was unaffected, and I tried several times to "reanimate" the first without success.

I'd basically like to know any suggestions to what caused it so that I can replicate the effect - it was a curiously relaxing sight.
 
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MisterDavy said:
Not sure if this really should go here, as I don't personally think it was anything supernatural, though I do lack an explanation for it.

I'd called into a local pub for a quick drink after work a few weeks back. It was pretty empty, just myself, the barmaid, and an older guy, and we were all standing at the bar.

After a while, I noticed that an empty glass on the bar top near me was "dancing."

It was making short, almost deliberate looking movements, drifting forward a little way before sharply turning direction, then doing the same, seemingly moving of its own violition. I pointed it out to the barmaid, who got kind of excited and said it was the ghost of the old landlord, who "slammed doors".

There were no obvious breezes, and when I got the barmaid to give me another empty glass and set it down beside the first, it sadly refused to join in the dance with its friend. When I eventually put a finger on the top of the dancing glass to stop it moving, it refused to start up again. I felt kind of bad that I'd spoiled its fun.

I'm assuming it was being moved by either vibrations or tiny air currents I couldn't feel, but the glass I tried to make dance with it was unaffected, and I tried several times to "reanimate" the first without success.

I'd basically like to know any suggestions to what caused it so that I can replicate the effect - it was a curiously relaxing sight.
Quite common, a film of water on the bar will cause the movement, seen it a number of times.

http://www.madsci.org/posts/archives/2000-03/952562476.Ph.r.html
 
Last edited:


A thin film of water (Or beer, etc) under the glass would act to float the glass along, mostly based on the shape and texture of the bar, nibbling along the path of least resistance. Small amounts of liquid would escape, further changing the shape of the supporting film and paths to follow.

This would explain little seemingly random movements, twists, etc.
 


Wow, thanks for the rapid replies!

So all I should have to do to replicate this is to dampen the bottom of a glass, and "launch" it gently onto the table top, so the water cushions it from the table surface?

I am going to practice this. Being able to make glasses dance to my whims sounds like a good trick to have in the repertoire.
 


MisterDavy said:
Wow, thanks for the rapid replies!

So all I should have to do to replicate this is to dampen the bottom of a glass, and "launch" it gently onto the table top, so the water cushions it from the table surface?

I am going to practice this. Being able to make glasses dance to my whims sounds like a good trick to have in the repertoire.
It'll take practice to do it at will. Mostly I'll place a wet glass on a counter and then have to stop it before it goes off the edge. I've never tried to do it on purpose.
 


I just tried it...its easier to wet the table top, and put the glass down onto it, rather than wetting the glass.
 

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