Does Nature Really Abhor a Vacuum?
Aristotle once postulated “horror vacui” (Nature Abhors a Vacuum). It turns out nature really can’t stand a perfect vacuum.
How do vacuums “suck?” In physics “vacuum” means “true empty space,” an environment with nothing in it and thus low air pressure. The inside of a vacuum cleaner has low air pressure causing the higher pressure air around it to get “sucked” in, but this doesn’t mean empty space has an intrinsic “sucking” quality. Instead, it is a matter of escape velocity. The gas, in this case “air,” in the higher density area is “escaping” to the low-density vacuum. The result is non-empty space. In words, empty space does not want to be empty, nature abhors a vacuum.
Why doesn’t the atmosphere get sucked into space? The reason outer-space doesn’t suck up our atmosphere, despite its relatively lower air pressure, is because of gravity (i.e. general relativity). Planets with lower gravity can lack an atmosphere (as the partial vacuum of space “sucks” the atmosphere off into space).
Aristotle, Pascal, Newton and the Search for the Perfect Vacuum
Aristotle’s idea was that there was no true empty space (that empty space was unnatural and went against the laws of physics). Instead, Aristotle thought, there was a medium (what we might call aether) that explained why things once set in motion stop.
Most of Aristotle’s theory would later be explained better by the theories of general relativity (curved spacetime as gravity) and Newton’s laws of motion. Great minds contested or debated this concept including Galileo Galilei, Blaise Pascal, Thomas Hobbes, Robert Boyle, Sir Isaac Newton, and Gottfried Leibniz, mostly in the context of 17th-century fluid mechanics. It turned out that Aristotle’s insight was right about nature abhorring empty space and he wasn’t too far off on his laws of motion either, but that is another story.
Theoretically, if we were to remove the fundamental particles of the standard model from the universe, we would have only a perfect vacuum and flat spacetime left (as opposed to lots of curvature and quantum field fluctuations). TIP: We know this today, Aristotle didn’t.
So, with all particles removed, the universe is only a giant flat vacuum. This might make one think that Aristotle was dreadfully wrong, but the thing is, we have yet to prove that a perfect stable vacuum (“nothing”) can actually exist in nature and in fact we know that the entire universe is filled with “somethings”.
In search of the perfect vacuum — Jeremy Webb — Nothing event. The search for a perfect vacuum and the near-perfect vacuums achieved.
FACT: Vacuum pressure is measured in the pascal unit PA, named after Pascal.
Can we Create a Perfect QED Vacuum?
Like absolute zero in temperature, a perfect vacuum is attainable only in principle. It is a philosophical idealization; it can be approached, but never actually realized.
In a lab, we can create a near-perfect vacuum for a fraction of an instant, and then it immediately collapses into quantum fluctuations resulting in anything but “true empty space.” What Pascal thought he found when he studied the “Torricellian void” (found by Evangelista Torricelli) isn’t “a true vacuum,” it is just vacuum-like.
Thus, although a few of the only physical constants in the universe are related to vacuums. “Z0 vacuum impedance (impedance of free space)” and “ε0 vacuum permittivity (permittivity of free space)” are two. Both are deduced from other constants rather than observed. Nature truly does abhor a perfect vacuum in practice especially at the quantum level.
Quantum electrodynamics (QED): theory. The basics of the standard model and the mother of all theories QED. QED predicts that no volume of space can be perfectly empty (a perfect vacuum with a gaseous pressure of absolute zero).
“The quantum theory asserts that a vacuum, even the most perfect vacuum devoid of any matter, is not really empty. Rather the quantum vacuum can be depicted as a sea of continuously appearing and disappearing [pairs of] particles that manifest themselves in the apparent jostling of particles that is quite distinct from their thermal motions. These particles are ‘virtual’, as opposed to real, particles. …At any given instant, the vacuum is full of such virtual pairs, which leave their signature behind, by affecting the energy levels of atoms.” – Joseph Silk On the shores of the unknown (Amazon), p. 62 (explaining that neither QED vacuums or classical vacuums are truly empty).
What Happens if Your Body is Exposed to the Vacuum of Space?. In space you don’t explode, you boil (strange right?), also in space no one can hear you scream (because sound is a mechanical wave). Space is awesome, but even “the vacuum of space” isn’t a perfect vacuum.
FACT: Our Universe is a combination of Dark Energy+Dark Matter+Matter. According to NASA: ~68% Dark Energy, ~27% Dark Matter, ~5% Normal Matter.
FACT: Even using infinite energy, a Three-dimensional container can not be used to create a perfect vacuum.
FACT: Light only travels at the light speed constant (the physical constant c) in a perfect vacuum, we have never witnessed this as we have never created a perfect vacuum. This, like other constants related to empty space, are deduced from imperfect vacuums that come close enough to run experiments and mathematic calculations.
Neil deGrasse Tyson Explores The Vacuum of Space. Even the vacuum in space is not a perfect vacuum, it too is filled with quanta.
“One reason [a vacuum is not empty] is that the walls of a vacuum chamber emit light in the form of black-body radiation…If this soup of photons is in thermodynamic equilibrium with the walls, it can be said to have a particular temperature, as well as a pressure. Another reason that perfect vacuum is impossible is the Heisenberg uncertainty principle which states that no particles can ever have an exact position …Each atom exists as a probability function of space, which has a certain nonzero value everywhere in a given volume. …More fundamentally, quantum mechanics predicts …a correction to the energy called the zero-point energy [that] consists of energies of virtual particles that have a brief existence. This is called vacuum fluctuation.” – Luciano Boi, Creating the physical world ex nihilo? p. 55
Nature abhors a vacuum can mean when there is a vacuum in us, our mind, or emotions, it one day gets filled up, I think. This is good news. Even bad information is better than the void.
Interesting concept. ?