Would Aliens from the Andromeda Galaxy See Earth as It Was 2.5 Million Years Ago?

Imagine the cosmos as vast and unfathomable, where interstellar minds ponder what Earth might look like from the Andromeda Galaxy, some 2.5 million light-years away. If beings from the Andromeda Galaxy had the technology to observe Earth, they would not catch a snapshot of the present. Instead, they would observe the Earth as it was 2.5 million years ago. This peculiar phenomenon is a consequence of the finite speed of light and the vast distances in our universe.

The Physics of Interstellar Observation

To visualize this, let’s delve into the physics of light travel in space. Light, which moves through the vacuum of space at an incredible 299,792 kilometers per second, travels infinitely slower than the theoretical speed required to traverse the distances separating Earth and the Andromeda Galaxy. This colossal delay means that any message or visual transmission from Earth would take over 2.5 million years to reach the eyes of Andromedans, assuming they possess the necessary telescopic technology.

Telescopic Technology: For beings from Andromeda to even observe Earth, they would need telescopes that span multiple star systems. This implies a sophisticated and advanced level of technology far beyond our current understanding. Even with such advanced telescopes, they would still be seeing Earth as it was 2.5 million years ago, since that is the time it would take the light from Earth to reach them.

The Historical Earth 2.5 Million Years Ago

At 2.5 million years ago, Earth was in the Proterozoic Eon, a period characterized by significant evolutionary and geological changes. The Great Oxygenation Event was underway, marking the beginning of the oxygen-rich atmosphere we now enjoy. Plate tectonics were just beginning to shape the continents as we know them today. The only life forms present were bacteria and archaea, and no eukaryotes had evolved yet.

Imagining Instantaneous Travel

Assuming these Andromedan beings could somehow instantly travel from Andromeda to Earth, the effects of the speed of light still apply. They would observe Earth as it was 2.5 million years ago, due to the time it takes for light to travel from Earth to Andromeda. This delay means that the image they see is not a snapshot of the present but a historical one, frozen in time.

Imagine light as tiny pixies that take pictures of the place they bounce from. When these ‘pixies’ leave Earth, they carry a picture of the Earth at the moment they bounce from it. As these light pixies travel across the vast expanse of space, they take over 2.5 million years to reach Andromeda. Therefore, the Andromedan observers would see a picture of Earth from 2.5 million years ago.

The Irrelevance of Human Civilization

Despite the stunning visualization of Earth 2.5 million years ago, it is important to note that this observation would not include the human civilization as it currently exists. Humans did not emerge until around 200,000 to 100,000 years ago. Therefore, if the Andromedans could somehow instantly travel to a distant galaxy, they would likely observe Earth in a state without humans, possibly only the presence of apes and other early animals.

Fast forward to the present day, the Earth has aged an additional 5 million years more than what the Andromedans observe. If they were to return to Earth immediately after their observation, they would find a planet that has aged further, by the exact amount of time their observation took to reach them.

Conclusion

The phenomenon of observing Earth from such a distance as the Andromeda Galaxy highlights the profound implications of light travel time and the finite nature of the speed of light. Our telescopes, even if they could span multiple star systems, would still need to contend with the limitations imposed by the speed of light. This means that any observation of distant objects, including Andromeda itself, would always be a snapshot of the past, tied to the age of the light from those objects as it reaches us.