There would be a way to travel inside a black hole. All you need is a ship that is basically an electromagnet with thrusters. The intense magnetic field would balance the field of the black hole resulting in a kind of force field. A modified version of the containment field used inside a fusion reactor would be sufficient for this purpose. Albert Einstien was hired by the US gov. for a similar project using electromagnets to bend light around a ship for a crude cloaking device.
Since the structure of the atom and that of the universe is almost identical one can conclude that our universe is just an atom in another universe. Therefore parallel universes to our own would be neihboring atoms.
Keep in mind that parallel universes and alternate dimensions are two different things. For one, parallel universes exist in our reality; our plane of existence. They elude us because we haven`t the balls to explore that far. We have the technology though. Alternate dimensions exist like time, in layers. For instance; all time exists in the same time. This is what makes time travel possible on the astral plane. On the astral plane your mind is anchored to your body by what resembles a string and without this anchor, time travel would not be possible. The fact that all time exists in the same time is also how people can have premonitions; either waking or sleep induced. The subconscious contains all this information and more. The chinese developed a way of bringing the subconscious to the consciousness and they call it meditation through Tao, Nirvana etc. In the monastary of the white clouds is a stone tablet which describes the steps needed to raise the subconscious.
Alternate dimensions, existing in the same way as time are actually contained in our reality; ie: our realities are melded together only seperated by a thin layer. Though these alternate dimensions are contained in our reality they exist on a different plane. For instance, the astral plane is an alternate dimension. The nether world exists as well in a kind of antimatter. When people see ghosts what happens is ectoplasm particles in our plane are magnetised to the "ghosts" and when a sufficient concentration of them is on the "ghost" the ghost becomes visible. This concentration of ectoplasm actually burns a hole in our plane.
As for time dilation, it is proved that when you achieve the speed of light time slows and eventually stops when the speed of light is obtained. Any speed capable of surpassing that of light (the speed of thought) results in a retardation of time as it begins to move backwards. This has been tested by astral projectionsists who through prolonged travel have recieved negative effects to internal organs resulting in a retardation of the tissue. We still have much to learn about the physical effects from such types of travel as well as the travel itself. I hope this clarified things for some of you for I only speak from my personal experiences.