Tar Pitch Drop Captured On Camera 142
New submitter Ron024 sends this news from Nature:
"After 69 years, one of the longest-running laboratory investigations in the world has finally captured the fall of a drop of tar pitch on camera for the first time. A similar, better-known and older experiment in Australia missed filming its latest drop in 2000 because the camera was offline at the time. The Dublin pitch-drop experiment was set up in 1944 at Trinity College Dublin to demonstrate the high viscosity or low fluidity of pitch — also known as bitumen or asphalt — a material that appears to be solid at room temperature, but is in fact flowing, albeit extremely slowly. ... The Trinity College team has estimated the viscosity of the pitch by monitoring the evolution of this one drop, and puts it in the region of 2 million times more viscous than honey, or 20 billion times the viscosity of water. The speed of formation of the drop can depend on the exact composition of the pitch, and environmental conditions such as temperature and vibration."
Re:Ok.... (Score:4, Informative)
Didn't you notice that the titration device was made of glass and showed zero sign of change? That's because glass isn't an amorphous solid.
Re:Ok.... (Score:3, Informative)
Glass *is* an amorphous solid. The point is that it isn't some sort of superviscous liquid.
Re:Ok.... (Score:5, Informative)
Nobody seems to be able to decide what the heck glass is.
Actually the Nature article [nature.com] on the pitch drop states:
"Scientists used to believe glass to be a slow-moving liquid as well — in part because old church window panes are thicker at the bottom — but it is now considered a solid."
and points to this as a reference. Zhao, J., Simon, S. L. & McKenna, G. B. Nature Communications [doi.org]
Nature is a fairly reputable journal so I think I'll go with glass as a solid for the time being.
The issue regarding the windows panes appears to be that the differing thicknesses from one side of the window to the other is because of the manufacturing method. Also they put the thicker side at the bottom in order to prevent breakage because they weren't idiots.
Re:Ok.... (Score:5, Informative)
The cathedral glass reports have nothing to do with glass flowing and everything to do with how glass was made hundreds of yeas ago.