Harvard astrophysicist Avi Loeb says ‘space junk’ will lead us to intelligent aliens.
For more than 70 years, scientists have searched for evidence of intelligent aliens by hunting for radio signals – interstellar messages beamed billions of miles across space. But for Harvard astrophysicist Avi Loeb, the search for extraterrestrial intelligence it starts much closer to home: In Earth’s oceans.
In the summer of 2023, Loeb led an expedition near Papua New Guinea to excavate hundreds of small metal spheres he proposed that they were possible remnants of an interstellar meteor that exploded over the Pacific Ocean a decade earlier. For Loeb, this mission wasn’t just about finding rare evidence of an object from beyond our solar system—it was also a chance to probe the spheres for traces of possible alien technology.
The high purpose of the expedition received criticism from the scientific community—but for Loeb, even a faint possibility of learning something new about our cosmos is reason enough to investigate.
“I don’t pretend to know more than I do,” Loeb told Live Science in an interview. “I’m willing to consider possibilities that others might discount completely.”
Loeb, who is a professor of astrophysics and director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, says his academic success came by accident, as a lifelong passion for philosophy led him to astrophysics. Live Science caught up with the professor ahead HowTheLightGetsIn Festival in London, where Loeb will speak later this month, to discuss his research, his hopes for future expeditions and the search for extraterrestrial intelligence.
Brandon Specktor: You’ve said that, from a young age, you wanted to be a philosopher. Do you have a philosophy that guides your research?
Avi Loeb: Humans, in general, have existed for a few million years on Earth, which is only one part in 10,000 the age of the universe. So we just came to the end of the cosmic game. And we know, thanks to Copernicus and Galileo, that we are not center stage. And so the show is not about us. And we better stay humble and curious. This is my basic philosophy.
BS: You’ve shared many ideas about where humans should look for extraterrestrial life. If you were given a blank check to pursue any of your alien ideas, how would you spend it?
AL: I think we should do a better job with Mars because Mars had liquid water on the surface. We know this for sure. There was some preliminary evidence that maybe the soil on Mars has some tantalizing signs of life that was first hinted at by the Viking mission [in 1976]. There are many things we can do that are no more difficult than they were done in the 70s. It is unfortunate that NASA is not doing this.
[Editor’s note: NASA has collected as many as 30 geological samples on Mars, and is working with the private sector to develop a plan to return them to Earth for analysis. The budget for such missions remains an issue.]
Another thing I would do is that there are millions of objects, roughly one meter in size, that have come from outside the solar system. At any given moment in time, there are several million of them that are within the Earth’s orbit around the sun. They do not reflect enough sunlight for us to detect them with our existing telescopes. So I would create an experimental program to find them out.
I would like to see if among the rocks that arrive in the solar system from other stars, there is any technological debris. It could be space junk or it could be functional, but it should be easy to tell between rocks and something else. So, if I had all the money in the world, I would create an experimental program to monitor objects within the Earth’s orbit around the sun.
We have already found out ‘Oumuamua, an interstellar object about 100 meters [330 feet] in size – the size of [SpaceX’s] Starship, the largest spaceship that humans have ever produced. There must be many more objects that are much smaller.
BS: Could future satellites be liked NASA’s NEO Surveyoran infrared telescope focused on tracking near-Earth objects – helping detect potentially interstellar objects?
AL: Absolutely. But only if they get close to Earth. There will be a larger telescope called [Vera C.] Ruby Observatory in Chile that will begin operations in 2025, and that will likely find many more interstellar objects near Earth, or within Earth’s orbit around the sun. I am working with my doctors and students on a program to find them once the data comes in from the Rubin Observatory.
I am very excited. You see, if you are driven by curiosity, additional data is a blessing. If you are driven by something else, like showing off or establishing your stature, then you would respond to something like Oumuamua the way one of my colleagues did – saying “I wish it never existed”.
I would like to see if among the rocks that arrive in the solar system from other stars, there is any technological debris. It could be space junk or it could be functional. “
Avi Loeb, Harvard astrophysicist
You see this routinely in science, where you have experts worried and really upset about anomalies. They claim that anomalies do not exist. There is nothing new. We already know everything. The people who are pointing out the anomalies should be discredited. The documents should be ignored… We should forget about it and move on. You see this, and unfortunately, it hinders the progress of science.
BS: You’ve gotten some feedback on a recent study of metal spherules you dug up from the ocean off Papua New Guinea, which you claim are part of an interstellar meteorite. Do you put any stock in papers that are critical to your findings? Do you read them with an open mind and see if they really have compelling evidence?
AL: Yes. So for example, there was a claim that what we found is coal ash. So we looked at 55 elements from the periodic table after this claim was made and showed that it’s not coal ash. We made a diagram in which we showed that the abundance of many chemical elements is not that of coal ash.
I submitted this research note to a journal that published the original argument that it is coal ash. The editor said, “Well, I’m not sure there’s any point in publishing this”… So I wrote the editor-in-chief over it, and it eventually got published.
All this means is that there is an agenda sometimes behind what is happening. It is not a fair game.
BS: So are you planning to go back to Papua New Guinea to look for more evidence of this meteorite?
AL: We plan to do it again in a year. I announced it a few months ago and I have several parties interested in funding it. It will be 6.5 million dollars.
BS: How will this expedition differ from the last one?
AL: Last time, we were only at sea for two weeks. The devices we designed collected tiny spherules less than a millimeter in size, less than the size of a grain of sand. Of course, this was very valuable, allowing us to discover that some of them, 10% of them, had an unusual chemical composition. But it still does not tell us the nature of the object. Because these were molten blobs that lost some elements in the melting process.
What we want to find are larger pieces, a centimeter in size, at least a few millimeters, that we can use to get, first of all, a complete record of all the chemical elements. But we can also consider the properties of the material. We know that this object had a material strength stronger than even iron meteorites from the solar system, because it only exploded in the lower atmosphere where the stress was much greater than evidenced by other meteorites. We want to test the properties of the material. Also, if we get a large chunk, we can do isotope analysis and date the age of the material to demonstrate that it is different from the age of the solar system.
Finally, most importantly, we can tell if it is a natural object like a rock or something else, a part of a tool. The next expedition, we will use a remotely operated vehicle that we will place on the ocean floor, and we will have a video feed and collect [spherule samples]. The hope is to collect larger pieces and examine them in the lab afterward.
There may be a lot of space debris created by past civilizations. We have been searching for radio signals for 70 years. We have to change the approach”.
Avi Loeb, Harvard astrophysicist
BS: How confident are you that we will find evidence of alien life in your lifetime?
AL: I have a lot of hope because [we are taking] a path not taken before, in this case, searching for the nature of objects that arrived in the solar system from outside. traditional [search for intelligent life] it was for radio signals, which is the same as waiting for a phone call. Here, we are looking for packages that may be in our mailbox. It’s a very different approach. I hope we will see something unusual, especially since two of the three known interstellar objects look strange, we will learn something new. I think that within the next few years there are many possibilities for exciting results, either from the Ruby Observatory or from the expeditions that we are planning. After the one I mentioned to you, we will go for the second interstellar meteor which is between Portugal and the Azores. It’s a very different place.
BS: And to be clear, do you think that the study of interstellar objects is the most promising route to finding evidence of alien life?
AL: I think so. First of all, it is easy to tell the difference between a natural object and an artificial object. There may be a lot of space debris created by past civilizations. We have been searching for radio signals for 70 years. We need to change the approach. Honestly, radio communication was just a very early technology that humanity developed. However, space exploration, to me, sounds like a general activity that an advanced civilization would engage in. We have to look for those things. I think there’s a chance we’ll find something extraordinary. Of course, without looking, we will find nothing.
It’s like Blaise Pascal arguing that you can’t rule out the possibility that God exists, because if God exists, the consequences are huge. This was Pascal’s argument. I reviewed it in the context of extraterrestrials. I say, this should be part of mainstream scientific research, because the implications are huge.
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