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Baffling Beer Glasses: Newsletter Challenge (April 2017)

Posted March 31, 2017 5:01 PM
Pathfinder Tags: beer challenge question optics

This month's Challenge Question: Specs & Techs from GlobalSpec:

Typical beer mugs have thick walls and a thick bottom. This design serves two purposes. First, it makes the mug heavier, so the drinker assumes the beer is “good.” The second reason is to give the impression that the mug holds more beer than it actually does. Why is this so? Why would the volume appear greater than it is?

And the answer is:

This is an illusion caused by refracted light coming from the beer and passing through the glass and then moving into the air. See, for example, the following figure in which a ray leaves the left edge of the beer. When the ray reaches the edge of the mug it bends when it reaches the air near a viewer’s eyes.

When the viewer’s eyes interact with the ray they mentally extend it back into the glass (mug) and conclude that the original start of the ray is to the left of the actual starting point, as shown in the figure. The mug appears to have a bigger diameter, so the drinker assumes they will enjoy more beer than they actually paid for. Of course, the bartender is happy!

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#1

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

03/31/2017 5:41 PM

The glass acts like a lens and magnifies the beer inside.

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#2

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

03/31/2017 8:04 PM

The thick bottom lowers the center of mass, allowing a full mug to be slid down the bar surface to a customer without tipping over (back when that was commonly done). The slightly convex bottom helps create the cushion of air it moves on.

The thick glass walls serve two purposes. Glass is an insulator so a thick wall helps the beer maintain temperature.

And of course the refractive properties of the glass make it appear that the volume of beer in the mug is larger than it really is.

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#6
In reply to #2

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/01/2017 11:26 PM

You've got it half right. The refractive & REFLECTIVE properties of the multi sided (NOT round) mug that doesn't allow you to see the round edge, of the inside of the mug.

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#3

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

03/31/2017 8:15 PM

The mugs are properly stored in the freezer, and when served the beer should be just above freezing, the thick glass prolongs the temperature sweet spot...A seasoned beer drinker is never fooled by the mug, until after several beers when judgement in general fades....

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#4
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/01/2017 12:15 AM

Question: Brits drink warm beer, not iced. Do they also drink out of these same kind of mugs? What would be rationale for that if they did? Any Brits care to field this question?

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#8
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 9:40 AM

As long as the beer is good I don't mind what i drink it from.

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#17
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/03/2017 7:39 AM

UK cask ales should be served at 10 - 14ºC to get the correct flavour. If too warm, some nasty tastes start to come through, and if too cold, much of the flavour will be lost.

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#18
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/03/2017 8:03 AM

Re. the glasses, all sorts of old-shaped, and pretty impractical, types are turning up (mostly with the fancy foreign lagers). For, ale, it's largely personal preference (or availability). These days, the "sleeve" (AKA "jam-jar") type glass is most common:

My preference (once ubiquitous, now becoming hard to find, except in dedicated "Real Ale" establishments), is variously called a "jug", "dimple jug (or mug)", or sometimes "pineapple":

It's very stable and unlikely to be knocked over, and the handle gives me something to hang on to towards the end of a heavy session!

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#5
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/01/2017 10:10 AM

Ah, beer goggles, i think they were responsible for marriages 1.2 and 3.

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#7
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/01/2017 11:29 PM

2 at 10, 10 at 2.

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#12
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 6:59 PM

Beer, helping ugly people reproduce since 1384...

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#14
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 10:37 PM

It started long before that, by several thousand years!

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#13
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 7:57 PM

The difference between beer glasses and beer goggles is the former make things larger and the latter make things more attractive.

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#9

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 10:18 AM

First of all, irrelevant to the question posed, one good reason for the thick mugs in a decent place, is that they chill the mugs and this preserves the 'coldness' of the drink for a greater time, but, as to your question..

The thick mug, with its fluting, creates the visual impression that the beer fills the entire EXTERNAL dimensions of the mug, not just the internal dimensions.

Michael Ryan

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#10
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 2:45 PM

You're right on your first comment, at least in the US. I'm not a major consumer of beer, but the only beverage I will happily drink at cool room temperature is red wine; I find warm beer absolutely repulsive. All other beverages (including water) I want either ice cold or pretty hot (yet not to burn my lips, like some wife seem to want).

As to fluting, look at post #8. None of those mugs was fluted.

Also, The OP did not specify that the mugs were transparent. When I think of beer mugs, I usually have a mental image of something made of metal or ceramic.

(Edit) Upon re-reading, The title of the OP did say "glasses", while the text said "mugs". I was remembering the text, not the title...

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#11
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/02/2017 4:31 PM

US beers, being of the lager type, are indeed better drunk cold. That does not exclude other beer types, more common in Britain, from being much better drunk warm. The parallel is with white wine and red wine. The darker the beer (stouts like Guinness) the better it is drunk at room temperature.

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#20
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/04/2017 10:13 AM

Yes, but why?

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#15

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/03/2017 12:27 AM

As they tip up the glass to drink, their view of the mugs contents is distorted, so the amount drank and the amount remaining is ALL IN THE MIND?

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#16

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/03/2017 3:13 AM

The beer glasses took that form to be durable when glass replaced tankards

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#19

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/03/2017 12:44 PM

The thick walls make the mug more durable. Less likely to break when coming to a stop on someones head. The thick bottom makes it bottom heavy so it's less likely to tip over and waste all that good beer. And have to waste time mopping it up.

Don't think the old tavern keeper cared about any thing else. A pint is a pint no matter was type glass it's put in.

Could also be heavy because if you had so much and can't lift to your lips then you know it's time to quit.

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#21

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/05/2017 11:58 AM

the reason for this is the different refraction of beer and glass, but also an empty (filled with air) bottle made of glass looks in an other way than it is.

A massive glass-stick acts like a (cylindircal) lens.

First Neandertaler couldn't produce bottles with regular walls.

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#22
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/05/2017 2:25 PM

Can you explain?

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#24
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/07/2017 12:09 PM

what is to explain?

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#23

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/05/2017 10:39 PM

Geez,, you must be one heck of a boob if you think a heavy mug makes a beer taste better, then again quite a number of people that drink more than one beer at a sitting may say that any type of beer in any type of mug may taste better.

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#25

Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/11/2017 6:41 PM

Is it a manufacturing cost (raw material+process)/durability trade off?

Presumably publicans choose on the basis of lifetime cost of the glasses - initial cost +lifetime.

Bill

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#26
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Re: Baffling Beer Glasses: Newsletter Challenge (April 2017)

04/11/2017 7:02 PM

"publicans "

If they own two or more pubs, then I suppose they are re-publicans.

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