Approx. 1st time life could appear in universe?

[Tero]

Looks interesting. What is the core made of? How is it different? They article discusses lack of tectonics.

[mistermack]

Looks interesting. What is the core made of? How is it different? They article discusses lack of tectonics.

I don't think it's known for sure, but the density of Venus is pretty much the same as that of Earth, so it probably has a similar makeup.

It seems that the lack of a magnetic field is down to a hotter core, which is down to lack of plate tectonics, which is down to the lack of lubrication by water :

The principal difference between the two planets is the lack of plate tectonics on Venus, likely due to the dry surface and mantle. This results in reduced heat loss from the planet, preventing it from cooling and providing a likely explanation for its lack of an internally generated magnetic field.[21]

I would have thought that it was probably the loss of the water that caused the massive increase in CO2 in the atmosphere, which multiplied the greenhouse effect.
So having an extremely hot atmosphere held in the internal heat, preventing cooling of the core, preventing a magnetic field from developing.

I don't see where plate tectonics would have cooled the core so much more. It's bound to have some effect, but I don't know how that would compare in magnitude to the extra heat from the runaway greenhouse effect.