Can Plasma Be Less Dense Than Vacuum?

[maria clara]

Water and glass are considered denser than vacuum for their dielectric coefficient is greater than the dielectric constant of vacuum. The plasma's dielectric constant is
\epsilon₀(1-(\omega_p/\omega)²)
Does this mean that plasma can be considered less dense than vacuum?...

thanks in advance.

 

[platipo]

imho density is associated with mass per unit volume, so...by definition nothing can be less dense then vacuum. Maybe I'm not understanding what you mean...