Final answer:
The question is an allusion to a concept in physics where light or any form of matter travels away from a point in space in a straight line and never returns. Notably, light emitted from a black hole illustrates a scenario where light travels in a straight line but can never return due to the intense gravitational pull. This question incidentally explores the effect of gravity on spacetime and light's one-way path.
Step-by-step explanation:
The student has asked a riddle-like question: What goes straight but never comes back? The subject matter hinted in the provided references spans across Physics, exploring the nature of light, spacetime, and the behavior of paths in the context of the universe's structure.
An example of something that moves in a straight line and doesn't return is a beam of light traveling away from a point in space. Once it goes in a straight line, due to the vastness of space and unless interfered with by another object, it does not come back on its own.
Among the examples provided, the idea of the intelligent ant and the black hole's effect on spacetime illustrate these concepts inventively.
Taking the analogy of the ant walking in a straight line over a curved surface, we can relate this to how light travels. However, while the ant could theoretically return, light emitted from a collapsing star that becomes a black hole effectively has no escape, providing an illustration of something that cannot come back once it goes out.
In Physics, the concept that light or matter travels away from a point and does not return is exemplified by the one-way exit from a black hole. Black holes create such a strong gravitational pull that beyond the event horizon, light itself cannot return, and thus, it goes in a straight line according to the curved spacetime but never comes back.
The phrase 'going straight but never coming back' aptly applies to such scenarios in the cosmos, revealing intriguing aspects of our universe's mechanics.