As the weather grows cold this winter, you may be one of the many Americans pulling their winter jackets out of the closet. Not only can this extra layer keep you warm on a chilly day, but modern winter jackets are also a testament to centuries-old physics and cutting-edge materials science.

Winter jackets keep you warm by managing heat through the three classical modes of heat transfer – conduction, convection and radiation – all while remaining breathable so sweat can escape.

The physics has been around for centuries, yet modern material innovations represent a leap forward that let those principles shine.

Physicists like us who study heat transfer sometimes see thermal science as “settled.” Isaac Newton first described convective cooling, the heat loss driven by fluid motion that sweeps thermal energy away from a surface, in the early 18th century. Joseph Fourier’s 1822 analytical theory of heat then put conduction – the transfer of thermal energy through direct physical contact – on mathematical footing.

Late-19th-century work by Josef Stefan and Ludwig Boltzmann, followed by the work of Max Planck at the dawn of the 20th century, made thermal radiation – the transfer of heat through electromagnetic waves – a pillar of modern physics.

All these principles inform modern materials design. Yet what feels new today are not the equations but the textiles. Over the last two decades, engineers have developed extremely thin synthetic fibers that trap heat more........

© The Conversation