If aliens were located 10 billion light years away from Earth, it would mean that the light we receive from them would have traveled for 10 billion years to reach us. In this scenario, we would be observing the light that was emitted by them 10 billion years ago.
However, it's important to note that the question of whether aliens would be able to see Earth from that distance depends on several factors:
Expansion of the Universe: Over vast distances, the universe is expanding, which means that the objects we observe from Earth today may have moved significantly farther away over time. The light from Earth that was emitted 10 billion years ago may have passed by the aliens' location due to the expansion of space.
Alien Observational Capabilities: We cannot determine the technological capabilities of hypothetical alien civilizations. It is uncertain whether they would have advanced telescopes or other instruments that could detect and observe Earth from such a distance.
Signal Interference: Even if the light from Earth reached the aliens' location, the signal would be extremely weak due to the vast distance traveled. Interstellar dust, cosmic background radiation, and other cosmic phenomena could further attenuate or interfere with the signal.
Considering these factors, it is difficult to determine whether aliens located 10 billion light years away would be able to observe Earth. The vast distances and complexities of the universe make it challenging to draw definitive conclusions about extraterrestrial observations.