I personally heat up the pan first, then put the oil in and after it's heated up add the ingredients. I go with the line of reasoning that doing it this way gives the oil less time to burn, thinking that if you do it the other way, by the time the pan and oil has heated up, the oil could already be starting to burn.
I've never experimented, but I think this is more of an issue with electric stoves since you can modulate the heat more quickly with gas, ie turn it off if the oil's starting to smoke.
The researchers found that about 90 photons had to enter the eye for a 60% success rate in responding. Since only about 10% of photons arriving at the eye actually reach the retina, this means that about 9 photons were actually required at the receptors. Since the photons would have been spread over about 350 rods, the experimenters were able to conclude statistically that the rods must be responding to single photons, even if the subjects were not able to see such photons when they arrived too infrequently.
Piecing these and your findings together, it hints to an interesting sub-question, what do we really mean when we ask the original question?
Can the human eye physically detect it? Seems like…yes?
Which suggests the subsequent physiological thresholds involved, various human signal processing chains etc. What a fascinating topic.
The choice of a 60% success rate is an interesting one, too.
It is my understanding that metals are a crystal lattice of ions, held together by delocalized electrons, which move freely through the lattice (and conduct electricity, heat, etc.).
If two pieces of the same metal are touched together, why don't they bond?
It seems to me the delocalized electrons would move from one metal to the other, and extend the bond, holding the two pieces together. If the electrons don't move freely from one piece to the other, why would this not happen when a current is applied (through the two pieces)?