As we, being objects with mass, approach relativistic speeds, our masses continue to increase, and the energy required to propel us continues to increase; once we are near enough to the speed of light, a major mathematical and physical conflict occurs: not only are we now composed of infinite mass, but we also require infinite energy to propel ourselves. Considering the fact that there is not an infinite amount of energy, or mass, for that matter, in the universe, it is reasonable to believe that the speed of light is unattainable for us massive beings. Our travels are limited to short, interstellar neighborhood voyages. Even so, our failure in breaking physics, at least now, raises the question: what does actually travel at the speed of light, or for that matter, what even is the speed of light? In this chapter, we are to discuss the speed of light and the objects it is restricted to.

References:

Speed of Light - Wikipedia

https://en.wikipedia.org/wiki/Speed_of_light

Parallax Angle (Seconds of Arc) - NASA JPL

https://www2.jpl.nasa.gov/teachers/attachments/parallax.html

Luminiferous Aether - Wikipedia

https://en.wikipedia.org/wiki/Luminiferous_aether

Lorentz Transformation - Wikipedia

https://en.wikipedia.org/wiki/Lorentz_transformation

Caesium Standard - Wikipedia

https://en.wikipedia.org/wiki/Caesium_standard

History of Light - Photon terrace

https://photonterrace.net/en/photon/history/

A Very Brief History of Light - M. Suhail Zubairy

https://link.springer.com/chapter/10.1007/978-3-319-31903-2_1

Refractive Index - Wikipedia

https://en.wikipedia.org/wiki/Refractive_index

Lorentz Factor - Wikipedia

https://en.wikipedia.org/wiki/Lorentz_factor

Massless Particle - Wikipedia

https://en.wikipedia.org/wiki/Massless_particle