2. The Baghdad Batteries.
This one is particularly fascinating because they genuinely look like batteries and can, using electrolytes that would have been easily available at the time, generate a voltage.
Not much of a voltage. About what you'd get from a standard dry cell these days, around 1-3 volts. So, the idea that they were used to power 2000-year-old arc lights is, let's say 'unlikely' to be generous. Especially as no arc lights, nor indeed any kind of electric light, has been found.
There is a theory that they were used to electroplate metals, but no contemporary electroplated metal has turned up. Another theory was that they were used as some kind of joke-buzzer by priests to persuade their flock that there really was power in the statues of their gods. Again, no wired-up statue, nor indeed any wires at all, have shown up.
What do I think? Well, suppose, two thousand years from now, someone uncovered my laboratory. There are all kinds of gadgets in there, some of which have proved to be no use at all. However, maybe in two thousand years, one of those devices actually does do something and is then in common use. Those archaeologists might wonder 'How did that Crowe chap come up with this? Was he two thousand years ahead of his time? Why, this machine looks like a crude defibcombulator, a common household appliance these days.'
The truth would be that I have no idea what a defibcombulator might be nor what it does. I have no idea why anything would need defibcombulating nor what anyone might want to defibcombulate. I just made this interesting thing, found no use for it and put it to one side as 'something that might be useful one day'.
Now go back two thousand years to a scientist in Baghdad. He has access to copper, iron, clay pots and acidic electrolytes such as grape juice, wine and vinegar. He has access, therefore, to everything he needs to build a battery. While playing around, as scientists used to do before politics took over, he gives himself a little electric shock from some wine-covered metals.
'Oh,' he thinks. 'That was interesting.' So he sets about building a device to replicate that mild shock. Now he has a battery - but he has no radio, no phone, no TV, not even a light bulb. He has no actual use for the device he has built. It's just an interesting thing that he'd put to one side as 'something that might be useful one day'.
At that time, it might not have occurred to the scientist that the electricity he generated could be transported from his battery to somewhere else along a strip of metal. Why would it? He had nothing to power with this new device, and nobody had thought to build anything. Besides, it would soon run out of charge and need replenishing so to the minds of the time, it would have been just an interesting thing with no practical application.
So we have batteries but no wires, and no evidence they were ever used for anything. I think they really were batteries. I think they were the product of an enquiring mind but abandoned as being of no practical use.
What they found in Baghdad was that cupboard all scientists have, where we store things that don't actually do anything useful but which look interesting.