Harvard Physicist Proposes Using Comets to Send Messages to Aliens

A recent proposal by Harvard physicist Avi Loeb suggests a groundbreaking method for communicating with potential extraterrestrial life. In a paper published on December 21, 2025, Loeb advocates for the use of the interstellar comet 3I/ATLAS as a vehicle for sending messages—or even time capsules—into the cosmos. This innovative approach aims to leverage the natural high-speed trajectories of such celestial bodies to efficiently share humanity’s story.

Loeb’s theory challenges traditional approaches to interstellar communication, notably those relying on human-made spacecraft. Currently, NASA’s Voyager 1 and Voyager 2 spacecraft are the primary means of reaching out to the cosmos. Launched in 1977, these probes carry the Voyager Golden Records, which contain sounds, images, and messages from Earth. However, Loeb argues that this method is excessively slow, referring to it as a “message in a bottle” for aliens.

The speed advantage of interstellar comets like 3I/ATLAS is striking. Voyager 1 travels at approximately 17 kilometers per second and is projected to take another 28,000 years to exit the solar system. In contrast, 3I/ATLAS moves at an impressive 60 kilometers per second, significantly reducing the time required to escape the solar system and potentially reach other civilizations. By utilizing such a natural messenger, the journey time could be shortened by more than two-thirds, allowing a time capsule to enter outer space in just 8,000 years.

Loeb emphasized that riding on 3I/ATLAS could enable humanity to reach interstellar space by the year 10,000 CE, rather than waiting until 30,000 CE. This substantial time difference underlines the potential of using high-speed natural objects for communication efforts with extraterrestrial life.

He proposed two possible methods for sending messages. One approach involves attaching a record similar to those carried by the Voyager spacecraft to future interstellar visitors. Alternatively, messages could be inscribed directly onto the surfaces of these celestial bodies using high-power laser technology, creating a more permanent marker of human existence.

Despite acknowledging the uncertainty surrounding whether these messages will ever be discovered, Loeb expressed optimism about the profound implications of such a breakthrough. If extraterrestrial civilizations possess the technology required to interpret these messages, it could pave the way for a new field of study he refers to as “Interstellar Archaeology.”

This ambitious vision not only highlights the innovative thinking of contemporary scientists but also raises questions about humanity’s place in the universe. As we continue to explore the cosmos, the prospect of communicating with other life forms remains a tantalizing frontier in scientific inquiry.