Vacuum
For everyday use, vacuum refers to the volume of space that is basically empty of mass, so that its gas pressure is lower than atmospheric pressure. The word in English comes from the Latin term for "empty". Despite putting aside the complexity of the vacuum, the classic view of perfect vacuum with gas pressure equals zero is the concept of philosophy and never shown in practice. Physics members often discuss ideal experimental results that will result in a perfect vacuum, where they say "vacuum" or "free space", and use the term partial vacuum to refer to real vacuum. The term Latin in vacuo is also used to describe the object as being in the opposite setting in the vacuum. The quality of slaughter refers to how much it matches the perfect vacuum. Gas residual pressure is the main indicator of quality, and is usually measured in units known as torr, even for metrics. Low pressure shows high quality, although other transformers also need to be taken into consideration. See ultra high vacuum.