Sweet Nothing:

     The denial, discovery and modern advantages of the vacuum

BY ANITA MARTIN

Perhaps in the beginning there was nothing.  But today we see a world packed with stuff: people, places, things.  Even what we call “thin air” is really a vast ocean of mostly nitrogen and oxygen.  It’s no wonder that the observations of classic logician Aristotle led him to proclaim: “Nature abhors a vacuum.”  Based on this belief, Newtonian physicists decided that the universe—including outer space—is brimming with a material medium called ether. 

Now we know better. 

The universe is not some cosmic ether cocktail, but an amalgam of matter, energy and mostly just empty space (99.999…% to be exact).  Outer space comes the closest to being a perfect vacuum at an average of less than 1 particle per cubic centimeter (cc).  For vacuums on Earth, we’re lucky to get that number down to 100,000.  If that still sounds like a lot, keep in mind that at sea level, the average cubic centimeter of air contains 30 billion billion molecules of gas.

The air is thicker than we thought.  In fact, just moving through it provides a constant workout.  At sea level, each time you lift an arm or take a step, you meet an air pressure resistance of 14.7 pounds per square inch (psi).  It follows that any uncontained area of low air pressure (i.e. vacuum) near the Earth’s surface is promptly plugged up.  Remember that this results from surrounding air pressure pushing air in. 

That is to say, vacuums don’t suck.

In fact, they can make for a pretty good show.  One of the best acts of vacuum air pressure dynamics was performed by German Otto Van Guericke.  In 1650, Guericke invented the air pump.  Then he discovered that if he placed two copper hemispheres together to form a hollow sphere and pumped out all of the air between them, the surrounding air pressure would cause them to “stick” together.  A few years later (1657), Guericke presented his vacuum pump to Holy Roman Emperor Ferdinand III in Regensburg, where sixteen horses (two teams of eight) could not pull the vacuous copper sphere apart. 

So, beyond sphere and horse tricks, what are the scientific applications of vacuums?  An investigation of vacuums in science leads to one inevitable conclusion: scientists are control freaks.  But no matter how you regard the other control freaks in your life, for scientists, there’s a very good reason for it—especially for nanoscientists, who work at atomic and sub-atomic levels.

The nanoscale (one billionth of a meter) is what you might call the “nitty gritty.”  Down there, experiments have to be very precise and that means eliminating what scientists call “uncontrollable variables.”

Ohio University’s nanoscience researcher Nancy Sandler explains what would happen if a particle with a certain velocity were inserted in a vacuum.  “If there were another particle floating around,” she says, “they might collide, thus changing the velocity of the first.  If the particles were magnetic, the collision would change the magnetic properties.  This brings in something random.”

As we know, a perfect vacuum is not possible.  Nevertheless, scientists seek to create vacuums that are, according to Sandler, “as perfect as possible—that is, as controllable as possible.”  Among the purposes of vacuums, they remove atmospheric components that might cause unwanted chemical reactions during an experiment, allow particles to move collision-free between source and target, and reduce the contamination of prepared atomic surfaces. 

Now that scientists have accepted and embraced the vacuum, they use it for processes like molecular beam epitaxy, gas sampling, filtration, degassing of oils, and distillation, to name a few.  In more familiar terms, vacuums are to thank for freeze-dried ice cream, suction cups, torpedoes and of course, the vacuum cleaner.  (Not to mention that a vacuum can make a marshmallow Peep nearly triple in size.) 

And they say something can’t come from nothing.