Thank you, a fascinating half hour listen. I enjoy being in the room with big minds.
Even if I’m just catching on to the coat-tails
My speciality is much narrower, but my research supervisor is now one of the Profs here. (taster)
I must thank him for taking apart everything I thought I knew, and then being made to re-examine it.
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Winter cometh in. How cold can you get?
is this science? nevertheless I find it fascinating…
The script-in-an-unexpected-place thing is two-way of course. The enormous Hagia Sophia building in Istanbul has been a museum for nearly a century and was a mosque for the five centuries before that and was a Christian basilica for the nine centuries before that. Among the graffiti inside it are Viking runes !
VB
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Wow!!
I did my doctoral research in that building in the 80’s and I walked past that bell every day. I was pleased she said “it’s been running almost continuously”. Because when I was there once between Christmas and New Year, when the heating was off and it had been bloody cold for a few days, I saw the thing not running. With my own eyes. It started again when the place warmed back up.
VB
Now that’s interesting. Why would extreme cold stop it working?
It’s not unusual with batteries. The cold makes their internal resistance rise (maybe due to reduced ion mobility in the electrolyte, but that would be electrochemistry and I don’t know much chemistry) which limits the current they can supply. Charge is current times time and if the pile couldn’t deliver enough charge during the brief contact time to repel the clanger all the way across to the opposite bell then the clanger would just sit in the gap, gradually losing what charge it did have into the surrounding air (like the gold leaf electroscope discharging because of background radioactivity/cosmic ray ionisation). The gap is so very tiny that random vibrations of the building (trucks passing, people bumping into the display case, etc) would be enough to set it going again.
VB
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OK, showing my ignorance here but I though cold dropped resistance. That is what superconductors are yes?
Superconductivity is a very different thing and very weird (Cooper pairs, BCS thoery, Nobel Prize stuff). It has a very sudden onset.
Cold can often drop resistance in metals but the conduction mechanism is different there from that in electrolytes - conduction band electrons are essentially ‘delocalised’ i.e. not bound to the metal’s crystal lattice and the only thing which resists their motion is scattering off things like crystal defects and phonons. Phonons are lattice vibrations which act as quasi-particles (no I can’t really remember either, but it’s all in Ashcroft and Mermin). At lower temperatures there are fewer phonons so electrons in metals meet less resistance.
VB
A battery is a chemical reaction, reducing the temp reduces that reaction.
I guess with a battery like that producing such a low current the reduction is not enough to ring the bell anymore.
I wonder if I can use that to explain the"wife cold arse" phenomenon, particularly when combined with early onset of central heating theory.
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The counter “put a jumper on” theorem has been debunked by scientific review.
I always liked this as a demonstration:
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