The world lost a great physicist by the name of Heike Kamerlingh Onnes. While this is not a name most people know, he was the first person to liquify helium and to discover superconductivity — both of which are critical to the modern technological age. Liquid helium, which has a temperature of 4K (4 degrees above absolute zero on the Kelvin scale, and 73 degrees below the boiling point of liquid nitrogen which can freeze a banana in as little as 3 minutes) is a key ingredient in superconducting magnets and the primary cryogenic refrigerant.
But more importantly, superconducting is used to make ultra-fast digital circuits, microwave filters for your movie phones, and, most importantly, superconducting magnets (which are the most powerful electromagnets that are required by MRI machines, mass spectrometers, and particle accelerators).