In the context of the early universe and recombination, it is correct that light was able to reach us from that time period. Recombination refers to the time when the universe cooled down enough for electrons and protons to combine and form neutral hydrogen atoms. This process occurred approximately 380,000 years after the Big Bang. Prior to recombination, the universe was filled with a hot, dense plasma that was opaque to light, preventing it from traveling freely.
Once recombination took place, the universe became transparent to photons, and light could travel relatively unimpeded through space. As a result, the cosmic microwave background (CMB) radiation we observe today is essentially the afterglow of the light emitted at the time of recombination.
However, it's important to note that the transparency of the universe to light does not necessarily mean that all relativistic particles, such as high-energy cosmic rays or neutrinos, from the recombination era would reach us. These particles interact with matter and radiation differently than photons.
Spaceships, on the other hand, would indeed face challenges in traveling vast distances through space. The concept of a spaceship having a larger cross-section generally refers to the potential for collisions with interstellar particles, which could pose a risk to the spacecraft and its occupants. The specific challenges and requirements of interstellar travel are complex and depend on various factors, such as propulsion systems, shielding, and navigation.
In summary, while light from the recombination era has reached us and can be observed as the CMB, it does not guarantee that all relativistic particles from that time would also reach us. The ability of spaceships to traverse the vastness of space depends on several factors, including their design, propulsion, and protection mechanisms.