Reaching the boundary of the universe, as currently understood by science, is an immensely daunting and likely impossible task for humans due to a combination of factors:
Cosmological Expansion: The universe is expanding, and the space between galaxies is increasing over time. This expansion is happening faster than the speed of light in some regions, due to the influence of dark energy.
Speed Limit: According to the theory of relativity, nothing can accelerate to or surpass the speed of light within the framework of our current understanding of physics. This limit greatly restricts how far we can travel.
Energy and Resources: The vast distances involved would require immense amounts of energy and resources that are beyond current technological capabilities and perhaps even unattainable with any conceivable future technology.
Time Scale: Even if we could travel at a significant fraction of the speed of light, the time dilation effects predicted by relativity would mean that the journey to the edge of the observable universe would take many billions of years as experienced by an observer on Earth.
Observation Limitations: Our knowledge of the universe comes from observing light (and other forms of electromagnetic radiation) from distant objects. The observable universe has a "cosmological horizon" that delineates the boundary of what we can see, and this horizon is constantly moving outward as the universe expands.
Unknowns: There are still many unknowns in cosmology, including the nature of dark matter and dark energy, which could potentially alter our understanding of the universe and its boundaries.
Physical Barriers: There might be physical barriers such as radiation belts or intergalactic dust clouds that could pose insurmountable challenges to any theoretical space travel.
In conclusion, while the idea of reaching the boundary of the universe is fascinating, it is currently beyond the scope of human capability. The universe is vast, expanding, and governed by the laws of physics which limit our ability to traverse such distances. Future discoveries and advancements in science and technology might change our understanding, but at present, reaching the boundary of the universe remains a theoretical concept rather than a practical goal.