Vacuums and The Quest for Nothing

Vacuums and The Quest for Nothing

 

Vacuums are spaces devoid of any matter, and in certain cases anything. True vacuums are unattainable; even outer space has a hydrogen atom or two. Our most powerful man made vacuums can go down to 100 particles/cm3 and the humble vacuum cleaner only reduces air pressure by 20%. These are called partial vacuums for obvious reasons, as was any vacuum created before the ultra-high vacuums of today.

Although vacuums were the subject of many thought experiments in Ancient Greece, the first recorded man made partial vacuum was created by Evangelista Torricelli in 1643. It was made by flipping a tube filled with mercury over into a bowl, so that the empty space left at the top would be an approximation of a vacuum. Shortly after, German scientist Otto van Guericke created the vacuum pump. By the 20th century, partial vacuums were industrialized for incandescent light bulbs and vacuum tubes, and now ultra-high vacuum chambers used for particle accelerators can bring the air pressure down to 100 nanopascals. To put that in perspective, atmospheric pressure is 101325 pascals.

Sadly, as stated before, the quest for a completely empty space is never-ending, as there is always going to be one or two interrupting molecules at any given place. However, that hasn’t stopped physicists from dreaming. Many theoretical vacuums have been created, although even those aren’t perfect.

Take the QED vacuum for example. It is completely devoid of matter, but is still swarming with vacuum energy and virtual particles. As explained in previous blog, Science Fiction vs Science Fact: The Flash!, vacuum energy is the underlying form of energy that exists almost everywhere in the universe. Virtual particles behave similarly to normal particles, but they pop in and out of existence. Their brief existence is responsible for the magnetic field between two magnetic dipoles and the strong nuclear force that holds quarks together.

So even “perfect” vacuums aren’t actually perfect. Even with theoretical vacuums, a true vacuum is unattainable. On the bright side, no matter how empty a vacuum you are in, there is always a uncountable number of particles around you.

Sources:

http://en.wikipedia.org/wiki/Vacuum

Comments

  1. Christina Cheung says:

    Cool post! Before I used to wonder through what means did the previous scientists use to discover that electromagnetic radiations travel through vacuum; now I realize that true vacuums don’t exist, why are electromagnetic radiations then said to travel without any need of medium? Furthermore, how can they verify the speed of light when the vacuum contains matters?