Harvard Physicist Proposes Sending Time Capsules via Comet 3I/ATLAS

The interstellar comet known as 3I/ATLAS, discovered on July 1, 2025, has captured the attention of scientists and the public alike. In a groundbreaking proposal, Avi Loeb, a physicist at Harvard University, has suggested that humanity could utilize these celestial visitors to send messages—or even “time capsules”—to potential extraterrestrial life. His theory, published on December 21, 2025, encourages a shift in how we think about interstellar outreach.

Loeb’s approach challenges the traditional mindset that prioritizes building faster spacecraft. Instead, he advocates for leveraging the natural high-speed trajectories of interstellar objects like 3I/ATLAS. This method, according to his calculations, could allow humanity to send messages into the cosmos much more efficiently than current efforts.

Currently, initiatives to communicate with extraterrestrial life focus on the Voyager 1 and Voyager 2 spacecraft, which are moving out of the solar system at a pace of approximately 17 kilometres per second. At this speed, Voyager 1 will take an estimated 28,000 years to reach the furthest points of the solar system. In stark contrast, 3I/ATLAS travels at a remarkable 60 kilometres per second, significantly reducing the time it would take to escape the solar system.

Utilizing the speed of interstellar comets, Loeb asserts that a time capsule could reach interstellar space in about 8,000 years, a substantial improvement over the timeframe associated with human-made probes. He stated, “Riding 3I/ATLAS offers the benefit of reaching interstellar space by the year 10,000 CE instead of the year 30,000 CE.” This notable difference underscores the potential advantages of adopting a more innovative approach to cosmic communication.

In his proposal, Loeb also suggests that future missions could attach a record similar to the Voyager Golden Records, which contain sounds, images, and messages from Earth. Alternatively, he explored the possibility of using high-power lasers to carve messages directly onto the surfaces of these celestial objects, creating a more permanent record of humanity’s existence.

While acknowledging the uncertainty surrounding whether these messages would ever be detected, Loeb emphasizes the profound implications of such a discovery. If extraterrestrial beings possess the technology to decode the messages, it could lead to a new field of study, which he terms “Interstellar Archaeology.”

Loeb’s vision not only aims to expand our understanding of the universe but also encourages a broader dialogue about humanity’s place within it. As the quest for contact with extraterrestrial life continues, his proposal opens new avenues for exploration and collaboration in the field of astrophysics. The potential to communicate across the cosmos represents a daring leap for science and humanity, inviting us to consider what it means to truly reach out into the unknown.