[surya]

I think that other universe are not dimensionally connect.(i am considering parallel unverse as the part of our universe) i,e it is impossible to reach there because we are made up of dimensions and energy in which we are living.
other universe will be like different thoughts i,e what i am thinking and what you are thinking while sitting in front of your computer,there will be no relation between our thoughts.the Laws of nature will be totally different in those universe,laws may be impossible to belive,there may be different laws in different univere.
some times we think this is obvious and this will take place every were but that thing may not remain obvious there.
Let us suppose that our universe does't exist i,e it we dont't have dimensions to define our universe(universe without vacuum) it does't mean that dimensions will not be there to define some other universe