Just now I watched a video on YouTube about space travel.
It made the point that distances are huge and even if we reach speeds approaching that of light, it would take so long that a human space traveller, even with time dilation for the traveller, would arrive back on Earth millions of years in the future.
Even unmanned probes do not solve this problem. Inter-stellar travel really poses all sorts of problems. Essentially any such space travellers have a one way ticket.
