Where is our space in space? Will we ever travel through space and through time?
It is very sad, but I have to admit I doubt it. The amount of energy that is
required to transport even a small mass to an orbit close to earth is simply
gigantic (the ISS is located between 280 km and 460 km above the earth’s surface). The situation is even worse, since this energy is usually stored via chemicals, which have are transported until they are consumed.
The main energy source is currently oil or a mixture of its derivatives. The slump in research on nuclear fuels makes it very unlikely that nuclear power of any kind will contribute to space exploration in any reasonable amount.
For very much the same reason, we will also never really be able to move through time. Neither I nor most likely anybody else has any clue how we would move through time in the sense that we would drop out of the current presence and re- or pre-appear at some other time in a location close-by. In any case, it seems quite likely that the amount of energy required for time travel would be enormous. Otherwise, i.e. if the energy levels were very low, we should permanently see things (not only people) disappear and appear all the time.
A very nice and at the same time very depressing book (for those of us who dreamt about space exploration when they were young and innocent) is “The Physics of Star Trek” by Lawrence Krauss.