Vacuum FAQs:

Q: Is a vacuum space void of matter?

A: Yes.

Q: Is a vacuum a state with no matter particles?

A: Yes, and also no photons.

Q: Is a vacuum used in the study of atomically clean substrates, as only a very good vacuum preserves atomic-scale clean surfaces for a reasonably long time?

A: Yes, High to ultra-high vacuum removes the obstruction of air, allowing particle beams to deposit or remove materials without contamination.

Q: Was a vacuum incoherent?

A: Yes.

Q: Is a vacuum called outgassing?

A: Yes.

Q: Was a vacuum present?

A: Yes, if only for an instant, between two flat plates when they were rapidly separated.

Q: Is a vacuum primarily measured by its absolute pressure?

A: Yes, but a complete characterization requires further parameters, such as temperature and chemical composition.

Q: Is a vacuum measured in units of pressure?

A: Yes, and typically as a subtraction relative to ambient atmospheric pressure on Earth.

Q: Is a vacuum needed?

A: Yes.

Q: Is a vacuum terms that are defined with a dividing line defined differently by different sources?

A: Yes, such as 1 Torr, or 0.1 Torr, the common denominator being that a hard vacuum is a higher vacuum than a soft one.

Q: Is a vacuum vacuum that can be achieved with a single pump?

A: Yes, but the pressure is too low to measure with a liquid or mechanical manometer.

Q: Is a vacuum useful in a variety of processes and devices?

A: Yes.

Q: Was a vacuum thought to be filled with a medium called aether?

A: Yes.

Q: Is a vacuum defined as the state with the lowest possible energy?

A: Yes, In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum.

Q: Is a vacuum an ideal state of no particles at all?

A: Yes.

Q: Was a vacuum used for traction on Isambard Kingdom Brunel's experimental atmospheric railway?

A: Yes.

Q: Is a vacuum indicated by the amount of matter remaining in the system?

A: Yes, so that a high quality vacuum is one with very little matter left in it.

Q: Is a vacuum a region with a gaseous pressure much less than atmospheric pressure?

A: Yes.

Q: Is a vacuum truly perfect?

A: Yes, and not even in interstellar space, where there are still a few hydrogen atoms per cubic meter.

Q: Is a vacuum created by filling a tall glass container closed at one end with mercury?

A: Yes, and then inverting the container into a bowl to contain the mercury.

Q: Is a vacuum lethal to small animals?

A: Yes.

Q: Is a vacuum often also measured on the barometric scale or as a percentage of atmospheric pressure in bars or atmospheres?

A: Yes.

Q: Was a vacuum called horror vacui?

A: Yes.

Q: Is a vacuum vacuum where the MFP of residual gases is longer than the size of the chamber or of the object under test?

A: Yes.

Q: Is a vacuum often measured in torrs, named for Torricelli, an early Italian physicist?

A: Yes, A torr is equal to the displacement of a millimeter of mercury in a manometer with 1 torr equaling 133.

Q: Is a vacuum often measured in millimeters of mercury or pascals below standard atmospheric pressure?

A: Yes.

Q: Is a vacuum also useful for electron beam welding?

A: Yes, and cold welding, vacuum packing and vacuum frying.

Q: Is a vacuum to expand the volume of a container?

A: Yes.

Q: Is a vacuum a region of space and time where all the components of the stress–energy tensor are zero?

A: Yes.