Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  
Author: Subject: One more drop
Endimion17
International Hazard
*****




Posts: 1468
Registered: 17-7-2011
Location: shores of a solar sea
Member Is Offline

Mood: speeding through time at the rate of 1 second per second

[*] posted on 20-7-2013 at 09:14
One more drop


This is not the most famous pitch drop experiment in the world, the one in Brisbane.
This is a similar experiment in Dublin, and for the first time ever, it has been recorded on video.

Behold.

<iframe sandbox width="420" height="315" src="//www.youtube.com/embed/k7jXjn7mIao" frameborder="0" allowfullscreen></iframe>



But seriously, this is very cool.
I wanted to witness the drop over streaming video so I was a bit disappointed, but later learned that this is not the original pitch drop experiment, which is expected to give one drop during 2013, so I hope there'll be some media notifications before it actually happens.

I think it's kind of stupid they've used a timelapse video. I want to see the drop falling down in actual speed.
And they use damn webcams instead of HD cameras.

Here's the official page for the oldest experiment, by University of Queensland.

[Edited on 20-7-2013 by Endimion17]




View user's profile Visit user's homepage View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 09:24


<strong>Endimion17</strong>, you are my hero! I was trying to remember what this experiment was called, but it just kept eluding me. For some reason, I brought it up while talking at someone about long term experiments, a couple months ago. I was telling the person that I'd love to set up one of those funnels in a bell jar filled with tar, but couldn't remember the name "pitch". Thank you so much for sharing this! I'm <em>definitely</em> going to set one up now.



View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 10:21


How would one obtain pitch with just the right consistency for this experiment?
View user's profile View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 11:06


I have a chunk of refined <a href="http://en.wikipedia.org/wiki/Asphalt" target="_blank">asphalt</a> <img src="../scipics/_wiki.png" /> that I picked up while the road outside my apartment had been torn apart to replace a water main. The viscosity is surely different than that of the pitch in the above experiments, but of what concern is that? It's not exactly a quantitative experiment, more of a demonstration piece. You can easily purchase <a href="http://en.wikipedia.org/wiki/Pitch_(resin)" target="_blank">pitch</a> <img src="../scipics/_wiki.png" />, bitumen, or asphaltum from lab suppliers, eBay, or local construction suppliers.

<strong><a href="http://www.physics.uq.edu.au/physics_museum/pitchdrop.shtml" target="_blank">The Pitch Drop Experiment</a></strong> <img src="../scipics/_ext.png" /> - R. Edgeworth, B.J. Dalton and T. Parnell
Quote:
The pitch was warmed and poured into a glass funnel, with the bottom of the steam sealed. Three years were allowed for the pitch to consolidate, and in 1930 the sealed stem was cut.
My plan has been to use a powder addition funnel and to simply stopper the stem (PTFE wrapped cork) while waiting for the fluid to harden. I think I actually set aside a bell jar I found several years ago, for this exact experiment, if I could only remember where I put it.

<strong><a href="http://www.dailymail.co.uk/sciencetech/article-2142928/Is-boring-experiment-Scientists-watch-drops-pitch-form--75-years.html" target="_blank">Is this the most boring experiment ever?</a></strong> <img src="../scipics/_ext.png" />

[Edited on 7/20/13 by bfesser]




View user's profile View All Posts By User
Pok
potassium Prometheus
***




Posts: 168
Registered: 5-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 14:55


Very cool! This pitch has a viscosity of about 2.3 * 10^11 mPa*s (water = 1 mPa*s). A really long experiment could be done with glass. The viscosity of glass is 1 billion times larger. So each drop would take 8 billion years (?). A long time to wait, but I think it's worth the time. But in comparison to the pitch experiment, it might be a little bit more frustrating if you miss the falling event. :D
View user's profile Visit user's homepage View All Posts By User
testimento
National Hazard
****




Posts: 351
Registered: 10-6-2013
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 15:26


I think you could do similar experiment with lead. It creeps too at room temp. :P
View user's profile View All Posts By User
Endimion17
International Hazard
*****




Posts: 1468
Registered: 17-7-2011
Location: shores of a solar sea
Member Is Offline

Mood: speeding through time at the rate of 1 second per second

[*] posted on 20-7-2013 at 15:49


Quote: Originally posted by Pok  
Very cool! This pitch has a viscosity of about 2.3 * 10^11 mPa*s (water = 1 mPa*s). A really long experiment could be done with glass. The viscosity of glass is 1 billion times larger. So each drop would take 8 billion years (?). A long time to wait, but I think it's worth the time. But in comparison to the pitch experiment, it might be a little bit more frustrating if you miss the falling event. :D


No, you can't do it with glass because glass doesn't flow. It's an old myth. Glass is an amorphous solid with tiny crystal domains and that has been discussed ad nauseam. Let's keep this pitchy, not glassy. ;)

Quote: Originally posted by testimento  
I think you could do similar experiment with lead. It creeps too at room temp. :P

No, lead is not a fluid. It does not flow. It bends, but it does not flow.
Wood bends under stress over time, too, but it will not flow.




View user's profile Visit user's homepage View All Posts By User
dontasker
Harmless
*




Posts: 40
Registered: 19-12-2012
Member Is Offline

Mood: Plopping

[*] posted on 20-7-2013 at 16:11


Very cool.

The glass myth was explained to me as coming from observations of old windows where the bottom was thicker than the top. Some thought this was proof of it being an extremely viscous fluid, but was really a result of glass manufacturing being imperfect and being installed so that the thickest section was at the bottom to help it bear the load of its own weight. I'm not sure if this is true or just a myth about a myth, but it makes sense to me.
View user's profile View All Posts By User
watson.fawkes
International Hazard
*****




Posts: 2793
Registered: 16-8-2008
Member Is Offline

Mood: No Mood

[*] posted on 20-7-2013 at 16:13


Quote: Originally posted by garage chemist  
How would one obtain pitch with just the right consistency for this experiment?
I would imagine fractional distillation, though for this material that would ordinarily mean having access to an oil refinery.

The only reason I know anything at all about this is that I was researching an old brand name "Apiezon Wax W" from Procedures in Experimental Physics, published in 1938, which is a vacuum sealing compound. Turns out it is still in manufacture 75 years later (datasheet). From what I can tell, its the very highest boiling (highest molecular weight) fraction from distilling asphalt. They sell two other compounds with lower softening points that I presume come out of the same still.

So if you want to improve on the demonstration, make multiple units with different fractions so that they drop at different rates.
View user's profile View All Posts By User
unionised
International Hazard
*****




Posts: 4918
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 02:33


Quote: Originally posted by Endimion17  


I hope there'll be some media notifications before it actually happens.


There has been, that's why you know about it.
However nobody can know exactly when it will fall so there's no way to get a media friendly prediction like "it will happen today" never mind "it will happen at 13:45 today"
View user's profile View All Posts By User
Pok
potassium Prometheus
***




Posts: 168
Registered: 5-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 03:37


Quote: Originally posted by Endimion17  
No, you can't do it with glass because glass doesn't flow. It's an old myth. Glass is an amorphous solid with tiny crystal domains and that has been discussed ad nauseam. Let's keep this pitchy, not glassy. ;)

You can. I know that the window glass is a myth (thicker at the buttom at extremely old windows), but glass has a viscosity of about 10 ^ 20 mPa*s at room temperature. So it could be observed in some million years (but not in hundred as claimed by the original myth) that the window becomes thicker at the buttom and in some billion years that glass forms drops like in this pitch experiment, I think.

Lead has a viscosity of 100 times that of pitch (10 ^ 13 mPa*s), so this should work as well (1 drop in 800 years).

But if the dropping time doesn't linearly increase with viscosity, these estimations (800 and 8 billion years) would be wrong.

[Edited on 21-7-2013 by Pok]
View user's profile Visit user's homepage View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 04:46


<strong>Pok</strong>, where are you getting these numbers?<a href="http://www.cmog.org/article/does-glass-flow" target="_blank">
Quote:
<strong><a href="http://www.cmog.org/article/does-glass-flow" target="_blank">Does Glass Flow?</a> <img src="../scipics/_ext.png" /></strong>

Speaking of time, just how long should it take—theoretically—for windows to thicken to any observable extent? Many years ago, Dr. Chuck Kurkjian told me that an acquaintance of his had estimated how fast—actually, how slowly—glasses would flow. The calculation showed that if a plate of glass a meter tall and a centimeter thick was placed in an upright position at room temperature, the time required for the glass to flow down so as to thicken 10 angstrom units at the bottom (a change the size of only a few atoms) would theoretically be about the same as the age of the universe: close to ten billion years. Similar calculations, made more recently, lead to similar conclusions. But such computations are perhaps only fanciful. It is questionable that the equations used to calculate rates of flow are really applicable to the situation at hand.
. . .
It is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about 10 to the 11th power, (1011) poises, that is, perhaps a billion times less viscous—or a billion times more fluid, if you prefer—than glass. Presumably, then, the lead ca[n]ing that holds stained glass pieces in place should have flowed a billion times more readily than the glass. While lead ca[n]ing often bends and buckles under the enormous architectural stresses imposed on it, one never hears that the lead has flowed like a liquid.
. . .
When all is said and done, the story about stained glass windows flowing—just because glasses have certain liquid-like characteristics—is an appealing notion, but in reality it just isn't so.
</a>See Also:
<strong><a href="http://www.phys.ncku.edu.tw/mirrors/physicsfaq/General/Glass/glass.html" target="_blank">Is glass liquid or solid?</a> <img src="../scipics/_ext.png" />
<a href="http://www.sciencedaily.com/releases/2007/08/070809130014.htm" target="_blank">Is Glass A Solid Or An Extremely Slow Moving Liquid?</a> <img src="../scipics/_ext.png" />
<a href="http://prl.aps.org/abstract/PRL/v99/i2/e025702" target="_blank">Colloidal Glass Transition Observed in Confinement</a> <img src="../scipics/_ext.png" /></strong>

[Edited on 7/21/13 by bfesser]




View user's profile View All Posts By User
Endimion17
International Hazard
*****




Posts: 1468
Registered: 17-7-2011
Location: shores of a solar sea
Member Is Offline

Mood: speeding through time at the rate of 1 second per second

[*] posted on 21-7-2013 at 06:29


Quote: Originally posted by unionised  
There has been, that's why you know about it.
However nobody can know exactly when it will fall so there's no way to get a media friendly prediction like "it will happen today" never mind "it will happen at 13:45 today"


Actually, I know about this just because I've thought of it and checked it out. I don't really know why have I started thinking about it. You know, random Wikipedia spree... huge number of tabs...

They should be able to predict it at least few days ahead.

Quote: Originally posted by Pok  
You can. I know that the window glass is a myth (thicker at the buttom at extremely old windows), but glass has a viscosity of about 10 ^ 20 mPa*s at room temperature. So it could be observed in some million years (but not in hundred as claimed by the original myth) that the window becomes thicker at the buttom and in some billion years that glass forms drops like in this pitch experiment, I think.

Lead has a viscosity of 100 times that of pitch (10 ^ 13 mPa*s), so this should work as well (1 drop in 800 years).

But if the dropping time doesn't linearly increase with viscosity, these estimations (800 and 8 billion years) would be wrong.

[Edited on 21-7-2013 by Pok]


Glass was thought to be a liquid and those numbers could be early calculations based on pretty wild assumptions. However, in more recent times, glass was found to be an amourpous solid, with perfectly static systems of molecules. It does not flow. Glass beaker will not turn into a puddle over the next billion years.

Pitch is a liquid with horribly low fluidity. It has a totally different situation at a molecular level. Heavy hydrocarbon chains slide one next to another at very slow speeds.
Glass is made of tiny crystal domains that are locked together. There is no flow at all. Glass rod might bend if weighted in the middle, after few hundred millenia, but it will not flow. Flowing and bending under stress are not the same thing. Flowing requires layers of molecules sliding one next to another, and bending is a collective distortion at a macroscopic level.




View user's profile Visit user's homepage View All Posts By User
unionised
International Hazard
*****




Posts: 4918
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 06:32


Quote: Originally posted by Endimion17  
Quote: Originally posted by unionised  
There has been, that's why you know about it.
However nobody can know exactly when it will fall so there's no way to get a media friendly prediction like "it will happen today" never mind "it will happen at 13:45 today"


Actually, I know about this just because I've thought of it and checked it out. I don't really know why have I started thinking about it. You know, random Wikipedia spree... huge number of tabs...


Actually, you checked it out via the medium of the internet.
It's still the case that you found out about it via the media.

Just a thought, but if someone is planning to set up this experiment with a camera and web link etc, might I suggest having a few different funnels with different lengths/ diameters of stem?
That way you will get more data.

[Edited on 21-7-13 by unionised]
View user's profile View All Posts By User
Pok
potassium Prometheus
***




Posts: 168
Registered: 5-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 08:06


Quote: Originally posted by bfesser  
<strong>Pok</strong>, where are you getting these numbers?

I got these viscosity numbers from several books (e.g. here - 1 poise = 100 mPa*s). My estimations of dropping time of glass and lead are based on the assumption of a linear dependence between dropping time and viscosity. As I said, this doesn't need to be the case. If the calculations of 10 angstrom units in 10 billion years is correct, my assumption is either not correct or these guys have other data for the viscosity of glass (e.g. 10 ^ 30 mPa*s) - if they used this value then there indeed is a rough linear dependence between dropping time and viscosity.

Quote: Originally posted by Endimion17  
Glass was thought to be a liquid and those numbers could be early calculations based on pretty wild assumptions.

It's very easy to calculate the viscosity of glass at RT. You can just measure the viscosity at different high temperatures (1000 °C or so) and from these data calculate the v. at RT. That's how I would do it.
And it doesn't matter whether glass is a liquid or a solid. Solids can also behave like a liquid. Otherwise they would have an infinite viscosity. And they don't have it.
View user's profile Visit user's homepage View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 08:37


<strong>Pok</strong>, I'd like to point out that your first reference cites "Brill 1962" for the data; presumably the same <a href="http://www.cmog.org/bio/robert-brill" target="_blank">Dr. Robert Brill</a> <img src="../scipics/_ext.png" /> who wrote the Corning article I posted, which states "When all is said and done, the story about stained glass windows flowing—just because glasses have certain liquid-like characteristics—is an appealing notion, but in reality it just isn't so." If <a href="http://en.wikipedia.org/wiki/Robert_H._Brill" target="_blank">Brill</a> <img src="../scipics/_wiki.png" />, a well respected scientist and an authority on glass, says we shouldn't think of glass as a liquid, I think we should heed his advice.

I deduce that this is the paper the Archaeological book cites, as it's his only listed publication that year:
<del><strong>Brill, R. H.</strong> (1967) <a href="http://www.cmog.org/library/great-glass-slab-ancient-galilee" target="_blank">A Great Glass Slab from Ancient Galilee</a> <img src="../scipics/_ext.png" /> <em>Archaeology</em> 20 (2) pp. 89–96</del> [correct paper 2 posts down]

<strong><a href="http://en.wikipedia.org/wiki/Viscosity#Viscosity_in_solids" target="_blank">Viscosity in solids</a></strong> <img src="../scipics/_wiki.png" />

[Edited on 7/21/13 by bfesser]




View user's profile View All Posts By User
Pok
potassium Prometheus
***




Posts: 168
Registered: 5-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 13:21


The paper is: Brill, Robert H. (1962) A Note on the Scientist’s Definition of Glass. The Journal of Glass Studies, 4, 127-138.

The question is: is there a threshold pressure for materials with very high "viscosity" below which they don't deform at all? If yes, this is not viscosity but plasticity or so. My assumptions were based on these viscosity values. And if they are wrong, I also was wrong.
View user's profile Visit user's homepage View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 13:37


I mistakenly read 1962 as 1967. You are correct.

<strong>Brill, Robert H.</strong> (1962) <a href="http://d3seu6qyu1a8jw.cloudfront.net/sites/default/files/collections/6A/6ACA10D0-4EEE-43F4-AF6A-7A89F9589607.pdf" target="_blank">A Note on the Scientist’s Definition of Glass.</a> <img src="../scipics/_pdf.png" /> <em>The Journal of Glass Studies,</em> 4, 127-138.




View user's profile View All Posts By User
phlogiston
International Hazard
*****




Posts: 1350
Registered: 26-4-2008
Location: Neon Thorium Erbium Lanthanum Neodymium Sulphur
Member Is Offline

Mood: pyrophoric

[*] posted on 21-7-2013 at 14:04


If you had a large pool of pitch, would it be possible to make a very slow wave on its surface? Or would the viscosity also dampen the wave 'immediately'?



-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer
View user's profile View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 21-7-2013 at 14:23


My intuition is that all of the energy would quickly dissipate thermally&mdash;no wave. But speaking of viscous waves; <a href="http://en.wikipedia.org/wiki/Boston_Molasses_Disaster" target="_blank">Boston Molasses Disaster</a> <img src="../scipics/_wiki.png" />.

[edit] I assume you meant rippling surface waves like when you throw a stone in a pond, not sound waves, etc.

<a href="http://www.acs.psu.edu/drussell/demos/waves/wavemotion.html" target="_blank">Acoustics and Vibration Animations</a> <img src="../scipics/_ext.png" />
<a href="http://scholar.lib.vt.edu/theses/available/etd-12062002-152858/unrestricted/Chapter2.pdf" target="_blank">Wave Propagation in Viscous Fluid</a> <img src="../scipics/_pdf.png" />

[Edited on 7/21/13 by bfesser]




View user's profile View All Posts By User
Endimion17
International Hazard
*****




Posts: 1468
Registered: 17-7-2011
Location: shores of a solar sea
Member Is Offline

Mood: speeding through time at the rate of 1 second per second

[*] posted on 21-7-2013 at 17:03


There could be absolutely no waves on pitch. The more viscous the fluid, the stronger the energy dissipation is. Compare water, honey and lava. It's very hard to make waves on lava.

That thing in Boston was not a wave. It was merely a flood from a burst tank. It must've been pure horror for the victims. Ever since I've seen this scene I've been terrified of molasses.




View user's profile Visit user's homepage View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 27-7-2013 at 10:15


As luck would have it, the alley outside my apartment window is being resurfaced today. In preparation, they poured some hot liquid pitch onto the existing pavement (to help the new layer to adhere?). As soon as I smelled that delicious aroma blowing in through my open windows, I ran outside with glee, small soup can in hand. I scraped up as much clean liquid asphalt as I could before it hardened (had to wait until the public works men left, because they were giving me angry looks). I plan to try filling a funnel with it later today, and hope to take some nice photos of the shiny black liquid--if I can keep my <em>foedis feles</em> from trying to eat it!

On a side note, does anyone know what compounds constitute that wonderful aroma? I believe they're sulfur containing, but I haven't been able to find much, beyond that.

It's a shame I don't live in California:
<a href="http://en.wikipedia.org/wiki/McKittrick_Tar_Pits" target="_blank"><img src="http://upload.wikimedia.org/wikipedia/commons/3/33/McKittrick_Tar_Seep_North_of_Highway_58.jpg" width="400" /></a> <img src="../scipics/_wiki.png" valign="top" />

<em>Feles mala! Cur cista non uteris? Stramentum novum in ea posui.</em>




View user's profile View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 9-8-2013 at 08:54


It hasn't happened yet, right?

<img src="http://i.imgur.com/5JZLQ.gif" width="150" />




View user's profile View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 1-2-2014 at 20:53


[yawns] Still waiting and <a href="http://www.theninthwatch.com/feed/" target="_blank">watching</a> <img src="../scipics/_ext.png" />.



View user's profile View All Posts By User
Sedit
International Hazard
*****




Posts: 1939
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

[*] posted on 1-2-2014 at 23:57


Quote: Originally posted by Endimion17  


No, you can't do it with glass because glass doesn't flow. It's an old myth. Glass is an amorphous solid with tiny crystal domains and that has been discussed ad nauseam. Let's keep this pitchy, not glassy. ;)


Sorry to side track but are ya'll sure about this?
The windows to the attic in my old house where well over 150 years old and there was an obvious bulge at the base of them. They where not thicker but there was a very obvious bend in them that looked exactly how one would expect it to look if it was a slow moving liquid. I really don't think they where made like this as it really looked like the glass had slumped over time.





Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
View user's profile View All Posts By User
 Pages:  1  

  Go To Top