Contactless inductive sensor for position measurement in the centimetre range

Perhaps a Longtitude prize to solve railway line problems. "extreme heat causing further disruption through rail buckling and power line...

The problem with a Tokamak shape for the fusion plasma, is that the magnetic field from the central solenoid reduces from the centre outwards, leading...

how do the maths actually stack up - as if you need 300MW to to produce the 50MW of thermal energy which then produces 500MW of thermal energy -...