>
>I suppose you are talking about Flash memory. Are you sure that there is no
>current? I mean, not "no current for practical purposes in most cases" but
>/no/ current? Why do Flash devices have limited (and for long-term or
>high-temperature applications actually relevant) data retention times?
>Somehow the charges seem to be slowly moving out of their location (or
>charges moving in, depending on the POV). Maybe as slowly as a few
>electrons per second, but isn't that more than nothing?

The stored charge leaks off by quantum effects, and the wearout mechanism is where the electrons get stuck in the insulator.  There is no current flow.


>>>Again, how can you measure a resistance without moving any current (charge
>>>carriers) through the resistance?
>>
>> It doesn't stop being a resistance when there's no current flowing.
>
>How do you know? So far, I thought that resistance was being defined by the
>ratio between a voltage and a current. What would be the value of 0/0 (if
>there really was a 0)?

No, resistance is intrinsic to the material. Don't confuse the thing, with how it's measured.  A gallon is not a container.


>Don't you have to measure the resistance in order to know it?

Yes, but it's still  whatever value it was, when you aren't measuring it.

> I agree that
>every material has a resistance. But the value of it under certain
>conditions is not known until it has been measured.

Ok, but it still is resistive.. This makes as much sense as putting resistors in a box, and saying that they aren't resistors anymore.


>> Yes, you can. Messiner effect in superconductors demonstrates this quite nicely.
>
>I'm not familiar enough with superconductors to be able to discuss this
>with any depth. But in my (engineering and other) experience there is not
>really much if anything in nature (which includes technology, in this
>context) that's literally 0 or infinity.

Superconductors are like quantum mechanics, they don't follow the rules that you are used to for other things.


>Actually, if you take it by face value, no scientist would ever say that
>there's 0 (or infinity) of anything. In order to be able to say so, you
>have to measure. You can't measure neither.

You can measure the magnetic field produced by a current flowing.
Since the field remains constant, you know the magnitude of the current flow, and that it is not changing.


>Back to superconductors: The fact that there is no potential difference in
>the first place that makes the charge carriers move when applying a
>magnetic field to a superconductor doesn't necessarily mean there is no
>potential difference once they started moving.

Apply ohm's law. When R is zero, E must be zero, even when I is non-zero.

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