Exotic 'Second Sound' Phenomenon Observed in Pencil 'Lead'

So let me get this straight, if I put one end of a pencil lead on a hot surface, the other end will get hot instantly? Is that right? ....or it has to be at a certain temperature...

"Heat" is a relative term.

I don't see any practical, "around the house" use of this phenomenon.

"At temperatures of 120 kelvin, or -240 degrees Fahrenheit, they saw clear signs that heat can travel through graphite in a wavelike motion."

Squeaky pencils in a one room schoolhouse northern style (every student brings a junk of wood for the stove)... not cold enough?!

That image is great, reminds me of BBQ. If you see spring, send north... getting desperate....

Been there.

120 Kelvin for graphite, possibly higher than room temperature (300K) for "magic graphite", graphene. Graphene just keeps giving and giving...

With so many amazing forms of carbon, you'd think we would find a method to process excess CO2 and even waste plastic into a useful form.

"random plastic to graphene".... impossible? It can't be impossible.

"Relatively balmy" is a wee overstatement.

SE. At -240 your pencils erasure should catch fire if the lead is heated with a laser pointing through it..

I'm guessing. .. it's either that or it will burst into flames.

And there was I thinking this thread was the usual advertising sexual spam.

...and then you clicked on it.

Sorry to disappoint you!

I looked at who the author was before clicking to open the thread.

I think we’ve all known Rixter long enough to trust his postings.

So super dense carbon can transfer heat well....I know they test diamonds by their ability to conduct electricity...at least one way of testing...Diamonds are also great conductors of heat, about 6 times better than silver which is about twice that of aluminum, but diamonds are only about half that of graphene...

https://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html

Pure diamond (undoped) is a good electrical insulator, (except for blue diamonds, which are naturally doped). The diamond's high thermal conductivity is due to the very strong covalent bonds between each carbon atom and its 4 tetrahedrally spaced neighbors.

https://www.thoughtco.com/diamond-a-conductor-607583

Fourier's law of heat conduction states that heat flow in a substance is proportional to the thermal gradient, the ratio being the thermal conductivity. There is evidence that graphene violates Fourier's law and so has a variable thermal conductivity depending on sample size.

https://www.iflscience.com/chemistry/graphene-defies-thermal-conductivity-law/

..."All lab grown diamonds will be correctly identified as diamonds by thermal testers. The second type of tool checks for electrical conductivity. Moissanite is electrically conductive, while mined white diamonds are not, so this tool is usually used to distinguish between the two."..

https://www.jewelrynotes.com/how-diamond-testers-work/

Grandma's Iron Skillet

So, if I season my cheap iron skillet just right, producing a graphene monolayer, I can put to shame all of those infomercial diamond coated skillets just like my grandmother used to do.

____________

thewildotter

The ceramic coated pans in my experience are only non-stick for about 6 mos, then you throw them out and get a new one, but iron skillets last forever....

Was the heat flow directional?

Apparently, it's not ready for prime time! It's easy to get too exuberant in dreaming up applications for what is now just a laboratory curiosity. Perhaps in isotopically pure graphite or graphene results will be better.

A different method has to be used to test graphene. The original experiment with graphite created an interference pattern on the graphite using two laser beams. The lighted area was warmer and expanded and this expansion could be detected by a third beam. Graphene, being one atom thick, doesn't expand in thickness when heated.