My high school chemistry teacher said that there is no such thing as a “vacuum,” it’s just a difference in air pressure. But you always hear about the “vacuum” of space, or when something is “vacuum-sealed.” I am not scientifically inclined, so I don’t even know where to begin. Im also not sure if “physics” is the correct flair lol. I was wondering if it could be explained from either side of the argument.
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Referring to things we generally care about here on Earth, “vacuum” means an absence of air (or, realistically, very low air pressure). Things that are “vacuum-sealed” have the air pumped out as part of the process. A “vacuum cleaner” forces air out of an internal space, pulling in dust and debris when the outside air rushes to fill it.
There is a second definition of vacuum that you may see that comes from physics. This is referring to the background energy of space itself. A truly empty region of space still has a positive, non-zero energy associated with it – we don’t entirely know why, we just know that it does. This energy is sometimes called “vacuum energy,” “the vacuum,” or “zero-point energy,” and it has important implications in physics and cosmology. If you’re interested in further reading, there is actually a major unsolved problem in physics related to this called the “vacuum catastrophe.”
To make things even more confusing, “vacuum of space” has been used in reference to both definitions.
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