How will we reach other galaxies in the future?
A great question with no good answers.
The closest star to earth is Alpha Centauri and it is 4.3 light years away. That means at a minimum it would take 4.3 years to get there but there's a catch. The amount of energy needed to propel a space craft at the speed of light is infinite.
Now, consider, using some of our more recent technology it still took over 9 years for the New Horizons satellite to get from the earth to Pluto, and even that is not the end of our solar system. New Horizons traveled at a speed of 36,373 MPH. Light travels at the rate of 669,600,000 MPH.
The Andromeda Galaxy, the nearest to us, is a mere 2.537 million light years away. Every bit of light we observe through our telescopes coming from Andromeda left there 2.5 million years ago.
Curiously, Star Trek offered a method which scientists actually consider as a viable way of breaching the great distances. The idea of "warp speed" implies that you somehow warp, change the shape of, space in front of you. Black holes warp space but how would we come up with a usable black hole? No one knows.
We have to perfect the Art of controlled dreaming using our minds.
We all have experienced the dream state when we are sleep. Our dreams can be as real in terms of sensory perception as we would normally encounter when awake in our physical body. If we have complete control over our dream state it is possible to travel at the speed of the mind to any destination of our choice. Of course the confines of the physical body is no longer present which is a huge limitation for high speed space travel. There are also barriers to such means of travel as the mental body cannot stay too long during space travel in separation from our earthly body.
As we cannot carry any cameras and scientific tools, it means science needs to find a technology that allows human visual stimuli to be decoded, recorded and displayed on a computer. Such technologies which sound like Science fiction, would have other major benefits in the area of human education enabling high speed learning of subjects and telepathy.