I am just trying to figure out my Physics lecture today

Isn't less than zero gauge pressure defined as vacuum? Then yes.

Guys, there are different pressures:
PSIA - PSI Absolute
PSIG - PSI gage

You need to know which one your dealing with. PSIA is ~14.7 lb more than PSIG
PSIG + atmospheric pressure which is about 14.7 PSI is PSIA

I hope I got that right.

Captain:

Sort of. Less than atmospheric pressure is a vacuum and does show as negative pressure on refrigeration gages which is PSIG.

But, 0 pressure absolute doesn't seem to exist on earth, but it's a very small positive number.

That would be a Micron Gauge, zero = full vacuum, on Earth you can only get down to a little less than 50 microns with good equipment.

In a perfect vacuum of 0 microns, then a reading of 50 would be more pressure, would it not, or just less of a vacuum?? 50 microns has a weight and weight exerts a pressure, there are still molecules available to measure.

Varian, Inc. VacIon Plus 20 Specifications

Specs would be about 1E-13 PSI.

1e-11 millibar = 7.500615613e-9 micron of mercury [0 °C]

Absolute Pressure is:

The total pressure exerted on a system, equal to the gauge pressure plus atmospheric pressure.

-or-

Absolute Pressure is the sum of the available atmospheric pressure and the gage pressure in the pumping system

Absolute Pressure(PSIA) = Gauge Pressure + Atmospheric Pressure

Attachment 5297

Absolute Pressure = 150 PSIG(Gauge Pressure) + 14.7 PSI(Atmospheric Pressure) = 164.7 PSIA (PSI Absolute)

So, again, less than zero gauge pressure is system vacuum. Yes, it is possible.

One example: when installing, or after repairing air conditioning systems, the newly sealed system is placed into a vacuum to evaporate any condensation or moisture, before charging the system with refrigerant.