Discussing the potential for multiple dimensions using terms that are limited by the physical boundaries of human senses and our limited technology. I don't think you can actually get there from here.
All this stuff boggles my mind........ I was not aware that dark matter particles moved through human bodies without harm.
Though I'm not sure what dark matter actually is? I know it can be bad like black holes etc.
Mind blown
IC 1101. located in the Abell 2029 Galaxy cluster. distance 1.04 Billions light years from earth. Virgo Constellation. 100 Trillions Stars and 6 Millions light years across.
Nothing is the absence of matter and energy we can sense and detect. So no, it doesn't need to be expanding into something else. It can be the matter and energy we can sense and detect expanding into the place there is no matter and energy we can sense and detect. It doesn't need a defined edge like a balloon.