>We can compress gas to tens of thousands of PSI, why not draw as much?<
Think about it this way: increasing gas pressure comes from increasing the density of gas molecules in a confined space (e.g., cramming more molecules into the same space). You can increase the density that way by a great deal, until molecules become so close together that the gas behaves like a liquid. But going in the opposite direction, once you've removed all the gas molecules from the space, you cannot go any further. There's a limit in that direction; there's nothing less than nothing (except for non-real integers, LOL).
Of course, pressure can also be increased indefinitely by compressing the same number of molecules into less space. Same effect: more molecules per unit of volume. Similarly, for the same number of molecules, pressure can be decreased by expanding the volume. Fewer molecules per unit of volume. But you can't expand the volume enough to make the density as low as zero molecules would be. So a perfect vacuum won't be reachable by that method.
>Have one unit of space, pull 300 times that, see what happens<
No matter how far we draw a piston from a cylinder, the same number of molecules are still in there. There's just fewer per unit of volume. So we'd never be able to reach perfect vacuum inside. And a perfect vacuum inside only causes ~15 psi squeezing inward (on earth).
Wayne
WB4OGM
On Wednesday, September 23, 2026 at 09:00:04 PM MDT, Facility 406 <facility_406@bruteforcedevelopment.com> wrote:
> I'm not sure minus 10000 psi has a meaning. Can you make a vacuum that's
> a harder vacuum than a perfect vacuum?
Draw harder. Drawing -15 just means hitting neutral to what we are
familiar with.
Have one unit of space, pull 300 times that, see what happens, not
pulling against the ambient pressure we happen to be within, to relative
nothing, but what the equipment can actually do, independent of the
atmosphere. We can compress gas to tens of thousands of PSI, why not
draw as much?
Yes, PSI, is that a thing when it hits zero? What is PSI when it's less
than zero. I'd go with negative, as it's relative, and whether pushing
a pound, or pulling a pound, it' still a pound, so PSI seems to apply,
whether it's plus, or minus a pound.
I really don't know, honestly, but I've had problems, so minus a lot,
may be a thing.
Kurt
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