Suppose a current is flowing in an infinitely small diameter wire. For a fixed current, the magnetic field strength is inversely proportional to the distance to the wire. But if this really holds, then the field strength goes to infinity. And this does not make sense

How is it possible that phylogenies based on sequences from nuclear genomes and organellar genomes (i.e., chloroplasts and mitochondria) from the same group of species yield phylogenetic trees with different branching orders?   answer :   the genome of the endosymbiont is more closely related to members of the group in which it originally evolved, while the nuclear genome of the engulfing organism has its own evolutionary trajectory.