Pitch Drop Experiment | Hacker News Reader

Pitch Drop Experiment

en.wikipedia.org

82 pointsluu32 comments

I used to have a version of this experiment myself -- there was a desk toy that was a transparent tube with dark caps at either end and a somewhat viscous liquid inside. Because of refraction, bubbles in the tube looked much larger than they were, and so perhaps 30 of them would flow up, in about a minute, each time the tube was flipped. I bought one in 1996 or so, and picked the one that was the slowest -- it took maybe two minutes at the time.

This turned out to be because the liquid was -- very slowly -- evaporating out of the tube, and getting thicker.

Within a year, it took about 5 to 10 minutes.

Within five years, it took over an hour.

After ten years it took weeks.

After fifteen years, it took most of a year.

I last flipped it over in something like 2015, and after several years it appeared to be pretty much unmoving, although I assume it was still making progress. I used to joke that I wanted it to be flipped one last time and placed beside me in my coffin, but I lost it in a move several years ago.

Do you remember what it was called? Brand?

But that says it takes 30 minutes, which is definitely slower than even my slowpoke version was at the start.

I was happy to discover an inadvertent pitch drop experiment in my 100 year old house attic. The blob of glassy pitch was used to seal a spot in the original roof sheeting and has made 2 drops underneath so far and is working on a 3rd.

Photos would be awesome! For science.

One thing the article doesn't mention, but which the text visible in the image does, is that Kelvin's pitch glacier was created to demonstrate ideas about how the luminiferous ether worked! https://en.wikipedia.org/wiki/Luminiferous_aether

Is John Allen the only scientist to miss out on both a Nobel and an Ig Nobel? https://en.wikipedia.org/wiki/John_F._Allen_(physicist)

Another fun fact, Lorentz transformation was created to explain why we can’t detect ether even though we move relatively to it.

https://en.wikipedia.org/wiki/Lorentz_ether_theory

I am not sure what I expected, but when I visited it ~10 years ago, it was surprisingly unspectacular. Just an open-door university building with a small hallway. On the wall a glass cabinet with the experiment&camera, and a few texts. But if I hadn't known the building, I would never have found out about it, no signs, nothing.

I love the picture with the Duracell 9v. Geologists traditionally use pennies to show scale. A penny was sent to mars on the Curiosity rover. Nope. Physicists are different than, to quote Sheldon, the "dirt people". They will use a Duracell.

https://science.nasa.gov/resource/lucky-penny-on-mars/

To be fair I have no idea how large an American penny is - it's not a very precise indication of size for anyone who's not American.

> To be fair I have no idea how large an American penny is - it's not a very precise indication of size for anyone who's not American.

It is reasonably precise, at least "good enough for government work"—the size is federally specified https://www.usmint.gov/learn/coin-and-medal-programs/coin-sp... —just not familiar.

Provided your audience realizes that a US "penny" is a thing. I live in a land that actually has a unit of currency called a penny, the US does not. W Germany used to have a pfennig and I can't remember what 100th of a Dutch gilder was called

Thankfully we have tamed our penny somewhat, from the wild beast it used to be. It used to be abbreviated to "d" and there were 12 of them to the shilling (s) and 20 shillings to the pound (l ie: £, which is what happens when you get the ink pen out).

In 1971 we decided to stop taking the piss and fall in line with the rest of the civilized world and decimalise: One squid = 100 pennies!

So the US call their cents "pennies". How cute 8) Those odd abbreviations I mentioned earlier - LSD for pounds/shillings and pence. They are sort of derived from libra/sestertii/denarius ie Roman currency units. I've glossed over florins, sovereigns, groats and all the other weird and wonderful coinage of the realm. We were not alone, most countries have some pretty odd past coinage and currency ... or didn't bother and stuck with barter for simplicity.

The parent comment you are replying to is making a statement about precision vs other metrics such as user familiarity, accuracy, etc. The size of an American Penny and a 9v battery are both very precise, the former even more so. The lack of universitality is a different argument, the tangent your comment discusses.

"Precise" has a precise meaning, and it was a pedantic (though in a way I appreciate) comment on that. Your lack of familiarity with "American" pennies does not change that they are a very well defined size.

This often comes up in science discussions because to many lay people "Precise", "Accurate" and other terms are used interchangeably, when they have distinct meanings

> Provided your audience realizes that a US "penny" is a thing. I live in a land that actually has a unit of currency called a penny, the US does not. W Germany used to have a pfennig and I can't remember what 100th of a Dutch gilder was called

If it's being used for scale in an image, why does it matter if they know the name of it rather than knowing how big it is? Do people need to know who the bearded man is on the front of it as well?

> Do people need to know who the bearded man is on the front of it as well?

Robert V. Barron, right? ;P

> I've glossed over florins, sovereigns, groats and all the other weird and wonderful coinage of the realm.

You omit the guinea. I read once that high-end auctions are conducted in guineas so that bidders from all currency areas are equally handicapped.

Not sure about auction payments.

A guinea is a pound and a shilling - a sort of fat or posh pound I suppose. Horse race prizes here are still priced in guineas eg here's a random link, noting guineas:

https://www.racingpost.com/news/festivals/guineas-festival/c...

I can imagine that in the past, a popinjay or boastfool (made that one up) caused the guinea to be created because they wanted to outflance someone else. I don't think £1 1s is a useful lump of money, ever. I think it is simply there for bragging rights and further nonsense.

There is also the sovereign - "sov" - also a nickname for a pound but it isn't one. Gold sovs are worth a shit load these days.

I also missed out tanners and a lot more 8)

I always remember that a U.S. nickel (5 cents) weighs 5 grams.

That's cool.

British cartwheel pennies weighed exactly one ounce and British bronze halfpennies were an inch across - made sense for these things to be useful 100+ years ago.

A while ago I noticed that the full name of the UK currency was "pound sterling" and that "sterling silver" describes relatively high-purity silver. Because of this, I wondered if the coin was supposed to be of equal value to 1 lb of silver, and it turns out, yes: https://web.archive.org/web/20131203201915/http://www.britan...

The weights of the dime, quarter and half-dollar are in a 10:25:50 ratio, and weigh 0.8 oz/dollar. A roll of quarters, $10, weighs a half pound.

So we can weigh mixtures of those coins and get an exact value out the other side? Neat.

'Dirt people'... I love the way that physicists sneer at other sciences. To quote Rutherford: 'All Science Is Either Physics or Stamp Collecting'.

Relevant XKCD: https://xkcd.com/435/

When I was young and dumb and student-teaching high school Physics class, I called the study of Biology the "Naming of Parts" in an ill-advised effort to dissuade one of my students from pursuing Biology.

While kind of funny, it was a cruel thing to try to dissuade anyone from their passion. Also, unbeknownst to me, the Biology teacher had just walked in behind me at that precise moment.

Also, I think engineers generally get the brunt of it — as in the joke:

Mathematician: Three is prime, five is prime, seven is prime, so by induction all odd numbers are prime.

Physicist: Three is prime, five is prime, seven is prime, nine is .... experimental error, 11 is prime, 13 is prime, etc.

Engineer: Three is prime, five is prime, seven is prime, nine is prime, eleven is prime, etc.

He who dies with the most different chemicals wins.

A pitch drop was first captured on camera on 11 July 2013 at Trinity College Dublin:

https://www.youtube.com/watch?v=k7jXjn7mIao

I always wondered who is watching this stuff happen. The 2013 drop was "televised" according to the article (they pointed a webcam at it) - in all other cases, did they just shut the lights on the experiment only to find the drop gone the next day?

I don't see why this seems strange. Heck, every time a corpse flower blooms (in the US, at least) it's publicized and frequently streamed on the web.

https://wtop.com/local/2022/06/rare-exotic-and-very-stinky-f...

> In October 2005, John Mainstone and the late Thomas Parnell were awarded the Ig Nobel Prize in physics, a parody of the Nobel Prize, for the pitch drop experiment.

Embarrassing that the Ig Nobel prize has so little understanding of what valid science is. The awarders seem to be motivated by chasing the approval of very ignorant and biased people in the general public and the media.

The Ig Nobel prize isn't always intended to target 'invalid' science or otherwise mock the awardees. It's mostly meant to highlight odd or obscure work. The wording they use is scientific work that "makes people laugh and then makes them think". Though it does look like it's more like a mix of both: earlier years especially do have awards that are more satirical in nature.

In other words they have attempted to rebrand themselves after justified criticism that they were promoting the mindset that sees climate change as fictional and academic enquiry as a waste of time.

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