If a small object, such as a grain of sand, were to travel at extremely high speeds close to the speed of light, it would indeed have significant kinetic energy. However, the effects of such an object colliding with other matter would not simply result in "punching holes" as you described. Instead, several other factors come into play:
Relativistic effects: As an object approaches the speed of light, relativistic effects come into play. These effects, such as time dilation and length contraction, would impact how the object interacts with its surroundings. For example, from the perspective of the high-speed grain of sand, time would appear to pass more slowly for the objects it encounters, potentially affecting the nature of the collision.
Energy release: When a high-speed object collides with another object, the kinetic energy it possesses is transferred to the target. The energy release would depend on the relative masses and velocities of the objects involved. In the case of a grain of sand traveling close to the speed of light, its tremendous kinetic energy could result in a release of energy upon impact, potentially causing various effects, such as heating, structural damage, or even an explosion.
Interaction with matter: When the high-speed grain of sand encounters matter, such as air molecules or solid objects, it would experience interactions that go beyond simply punching holes. The extreme speed and kinetic energy would likely cause intense friction, heating, and ionization of the surrounding material. This can lead to the creation of a plasma state or other energetic phenomena, affecting both the grain of sand and the impacted material.
Disintegration or annihilation: At speeds approaching the speed of light, other fundamental physical phenomena, such as relativistic time dilation and high energy densities, can come into play. Depending on the circumstances, the high-speed grain of sand could undergo severe disintegration due to the enormous forces experienced, or it could even potentially undergo particle annihilation, converting its mass into energy.
It's worth noting that achieving speeds close to the speed of light with macroscopic objects is currently beyond our technological capabilities, and the behavior of particles at such speeds is still an area of active research. The effects described here are based on our current understanding of physics, but in extreme scenarios, where objects approach or exceed the speed of light, the behavior of matter becomes highly complex and would require a more advanced understanding of physics to fully describe.