Nature abhors a vacuum. At least on the surface of Planet Earth which supports a gaseous atmosphere at a pressure of 760 mm Hg. How did we know this number? One of Galileo’s students, Torricelli, turned a tube of mercury upside down into a bowl of mercury. As long as the tube is more than 760mm long, there will be a gap of nothing at the top. It’s not an air gap. It’s a gap of Nothing.
Toricelli was actually looking for the mystical aether, the sacred material breathed by the gods, the fifth element, the quintessence. Supposedly it “allowed light from the stars to propagate” and was “also holding planets in their orbits”. I’m learning about this history reading through Mark Miodownik’s It’s a Gas. Toricelli had finally isolated the aether, a quest of the alchemists, some of whom thought it associated with the philosopher’s stone that would balance the four humours and cure all illnesses. Perhaps it could even prevent death. No wonder that Voldemort coveted it.
The trick to creating vacuum is to pump out all the air molecules from a closed container. That container must be truly air-tight. No leaks! Miodownik writes: “We take the accuracy and intricacy of screws, gaskets and valves for granted today. In the seventeenth century such precision engineering was just beginning.” What shot vacuum to fame was the famous demonstration at Magdeburg by Otto von Guericke. He didn’t use the chemical techniques of the alchemists. He just used mechanics to make an airtight pump. Once the air was pumped out of two hemispheres cupped into a sphere not held together by any other means, two teams of eight horses each could not pull the hemispheres apart.
What are the properties of Nothing? Now that scientists could reliably make it. They could start running tests. No living thing survived. (Oxygen was yet to be discovered.) Sound does not travel through vacuum, although light does, and magnetism is unaffected. Turns out that metal wires will glow hot in an enclosed vacuum tube when a voltage is applied, and Voila! Electric lighting is invented! Even if the wire breaks, you can sometimes get electricity to flow. (Electrons leap across but they didn’t know that yet!) This led to vacuum tubes. And now you have TV. Once you’ve mastered manufacturing silicon chips in vacuum conditions, you now have computers and all manner of smart devices. Who would have anticipated that Nothing would be so important!
Miodownik also relates the now-familiar story of the discovery of the noble or inert gases. They upended Mendeleev’s Periodic Table. It took painstaking evidence to show that they existed. They weren’t just Nothing even though they seemed to have no chemical reactivity. How were the noble gases discovered? Rayleigh was unhappy with the imperfections of the masses of the chemical elements. They almost followed a beautiful mathematical pattern, but not quite, and so he decided to measure their masses again with high precision. This is much harder than it sounds. You needed to create a vacuum in a flask and weigh it, then pipe the gas in and weigh it again. But the pressure, temperature, and humidity of the room can affect this measurement. You needed to more than triple-check everything. Most scientists didn’t believe Rayleigh, even after Ramsay provided an independent confirmation. Eventually argon was joined by helium, neon, krypton and radon. Chemistry’s 1904 Nobel Prize went to Ramsay for his discoveries. And eventually scientists and engineers found uses for all these gases that at first glance did Nothing!
