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Astronomy is the scientific study of celestial objects in the universe. It covers a wide range of topics, including stars, planets, satellites, asteroids, comets, galaxies, and more. Astronomy examines the entire cosmos, from the smallest particles to the largest structures. It investigates the laws that govern celestial phenomena and their interactions.
Astronomers collect data through remote sensing (using telescopes and other instruments) and sometimes replicate celestial phenomena in laboratories. Astronomy extends to understanding the origin, development, and ultimate fate of the universe. Cosmology explores questions about the Big Bang, dark matter, and dark energy.
Launched jointly by NASA, the European Space Agency, and the Canadian Space Agency, the James Webb Telescope is beaming back incredible images of planets and nebulas from the outside. From the knowledge of dark matter or the discovery of numerous discoveries: an exoplanet that has a hydrogen-rich atmosphere and is an aquatic world, the discovery of places in space with all the conditions for human life or even the detection of signs of space life…
But while all this is happening, the scientific community is beginning to wonder if the origin and development of the universe should not be reconsidered. From the existence of galaxies formed earlier than is possible according to the standard model of cosmology, to other surprising discoveries, they only generate more doubts, in addition to needing a vision that goes beyond science itself.
To talk about all these issues, it is a pleasure to interview today a great expert in the field such as Mr. Avi Loeb – Director of the Department of Astronomy at Harvard – who with his special knowledge answers a series of questions about a fascinating world that does not seem to have limits such as that of Astronomy.
Avi Loeb, Curriculum
Abraham (Avi) Loeb is the Frank B. Baird, Jr. Professor of Science at Harvard University and a bestselling author (listed in the New York Times, the Wall Street Journal, Publishers Weekly, Die Zeit, Der Spiegel, L’Express, and others). He is the author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and co-author of the textbook “Life in the Cosmos,” both published in 2021. His new book, titled “Interstellar,” was published in August 2023.
At age 24, he earned a PhD in physics from the Hebrew University of Jerusalem (Israel), led the first international project supported by the Strategic Defense Initiative (1983-1988), and was subsequently a long-term fellow at the Institute for Advanced Study in Princeton (1988-1993).
Loeb wrote eight books and more than 800 articles on a wide variety of topics, including black holes, the first stars, the search for extraterrestrial life, and the future of the universe. He was the longest-serving chair of Harvard’s Astronomy Department (2011-2020), founding director of the Harvard Black Hole Initiative, and director of the Institute for Theory and Computation (2007-present) within the Harvard-Smithsonian Center for Astrophysics.
He is an elected fellow of the American Academy of Arts and Sciences, the American Physical Society, and the International Academy of Astronautics. Loeb is a former member of the President’s Council of Advisors on Science and Technology (PCAST) at the White House, former chair of the Board on Physics and Astronomy of the National Academies, and a current member of the Advisory Board for Hebrew University’s “Einstein: Visualizing the Impossible.”
He also chairs the Breakthrough Starshot Initiative Advisory Committee (2016–present) and serves as Director of Scientific Theory for all Breakthrough Prize Foundation Initiatives. In 2012, TIME magazine selected Loeb as one of the 25 most influential people in space. He is also the director of the Galileo Project.
PhD, Hebrew University of Jerusalem, Israel
https://www.cfa.harvard.edu/people/avi-loeb
INTERVIEW
What are the main lines of research that you are carrying out at the Harvard Institute of Astronomy?
To talk about these topics we have the pleasure of interviewing a very special astronomer. Today we have the pleasure of interviewing Avi Loeb – Director of the Institute for Theory and Computation at Harvard.
First of all we ask him about the Institute that successfully directs and leads some projects, and then we delve into some of the most important topics that are part of this science, such as dark matter, black holes, meteorites, space debris. In particular, we would like to ask you about extraterrestrial life, your concerns, trends based on the latest discoveries in this science and your vision of the future regarding a subject that seems to never have a proven and conclusive answer, such as the existence of other beings in the Universe.
1. What are the main lines of research that you are carrying out at the Harvard Institute of Astronomy?
– My research centers on the first stars and galaxies, black holes, and the search for technological signatures of extraterrestrial intelligence. I pioneered the first topic and have written two textbooks about it; it is currently one of the frontiers in cosmology thanks to new data from the Webb telescope concerning the first billion years after the Big Bang. The data educates u show the first black holes formed and evolved. I was the founding director of Harvard’s Black Hole Initiative where the first image of a black hole slhuette was obtained. Currently, I lead the Galileo Project which searches for technological objects near Earth that might have been produced by alien civilizations!
You chair the Advisory Committee of the Breakthrough Starshot Initiative, a research and engineering project whose objective is to develop a fleet of micro spacecraft that will open up new possibilities for interstellar exploration and that could change our understanding of the universe.
2. Could you tell us what the current status of this project is?
– We made progress on the material design of the lighsail, the laser to push it and the communication between the probe and Earth. But there is much more work to do before the concept Will materialize.
Black Holes
NASA states that “A black hole is an astronomical object with such a strong gravitational force that nothing, not even light, can escape from it.”
3. Could you tell us what is inside a black hole?
– We do not know what happens to matter after it enters the evento horizon of a black hole. One possibility is that it accumulates near the center after reaching the máximum density posible in nature, called the Planck density. The evento horizon of a black hole is the ultimate prison: you can get in but nothing can escape from it, note ven light. Since there is no way to receive information from the inside, we do not know what happens at the center. Einstein’s theory of gravity breaks down there because the curvature of spacetime diverges. We know that quantum mechanics would resolve the problema but we do not have a quntum theory of gravity that gives relaible predictions for black hole interiors
Dark Matter
The existence of dark matter was discovered by Fritz Zwicky in 1933, when he noticed that in a large cluster of galaxies (Coma Cluster), the mass of the stars was not sufficient for the 1,000 galaxies in the group to remain united by gravity. It must therefore be dark matter, whose existence was confirmed by Vera Rubin in a study of the rotation of galaxies. Dark matter is composed of particles that do not absorb, reflect or emit light.
4. Are black holes and dark matter the same thing?
– One possibility is that dark matter is made of small black holes, between the mass of a kilometer size asteroid and the mass of the Moon. They could have formed when the universe was very young and are called `primordial black holess.
Wormholes in space
A wormhole is defined as a hypothetical structure that connects disparate points in space-time and is based on a special solution to Einstein’s field equations. Although at the moment it only exists from a theoretical point of view, different investigations are investigating the scope and contents of these holes.
5. What is the current status of this theory that could become a time machine to travel to the past?
– We do not know if wormholes exist in nature. They require exotic matter which induces anti-gravity that may not exist. In principle, a negative mass can be used for a time machine that would allow travel back in time. The reason is simple. A positive mass cause a time delay for light. A negative mass cause a time advance and with a proper design, can be used to make a time machine. The only problema is that we never detected a negative mass nor a traveller from the future. If we could design a time machine, I would first use it to go back in time and prevent Hitler from geeting to power. He killed 65 members of my father’s family in Nazi Germany. The only Branch of the family that survived was my grandfather’s, Albert Loeb, after whom I am named.
New discoveries
Each discovery that is made causes us more confusion if possible. An example of this is these two investigations. Two planets sharing the same orbit, a discovery published in the journal Astronomy and Astrophysics thanks to the use of the ALMA telescope located in the Chilean Atacama desert. Or the observations of the universe through the James Webb telescope where the age of the universe could be twice as old as previously thought, specifically 26.7 billion years and which has just been published in Monthly Notices of the Royal Astronomical Society. Indeed, astronomy does nothing but surprise us more every day with its discoveries especially through precision instruments such as powerful telescopes that have high sensitivity that allow us to see old, distant objects as is the case of the James Webb telescope and others.
6. From your qualified point of view, what is the most important discovery that the James Webb telescope has made so far?
– The most exciting and unexpected result from the Webb telescope is the existence of bright galaxies at cosmic dawn, less than a billion years after the Big Bang. Among them is an early population of compact red galaxies. The galaxies are redder than expected from their cosmological redshift, indicating additional reddening by a veil of dust. Some of them contain as much mass in evolved stars as our own Milky Way galaxy. Nevertheless, they are a hundred times smaller in size, of order a few hundred light years. These compact galaxies manifest an increase by a factor of a million in the number of stars per unit volume relative to the Milky Way. If we were to reside in such a galaxy, the Oort cloud of the solar system would have been stripped to a percent of its current size by the gravitational tide of passing stars. These tiny red rubies in the sky are commonly dubbed `little red dots.’
Hubble is a reflecting telescope that works based on optical and ultraviolet wavelengths. The James Webb works with infrared lights; it is of the anastigmat type with three mirrors and a wider field of view, surpassing the capacity of Hubble by up to 100 times.
It seems that Xuntian, the new Chinese space telescope, has a field of view 300 times larger than that of Hubble. In addition, the Five Hundred Meter Aperture Spherical Radio Telescope (FAST), is one of the main technological prides of the Chinese scientific program.
7. Is Chinese technology superior to European and American technology in space exploration?
– China has a very ambitious plan for space exploration. Science is an infinite-sum game where all humans benefits from new knowledge. Therefore, the scientific success of any nation benefits humanity as a whole, as long as the data is shared with all humans. Competition among nations is good as long as it propels scientific discovery and not military hostility. The global military budget worldwide is 2.4 trillion dollars. If this Budget would have been invested in space exploration, humanity could have launched a probe towards every star in the Milky-Way Galaxy, hundreds of billions of them, by the end of this century. I was just invited to serve on the selection committee of the innagurated Miwon Peace Prize from South Korea, intended to promote world peace and prosperity.
Natural Disasters
Natural disasters are responsible for numerous deaths, injuries, displacements… affecting millions of people around the world. These events are mainly of meteorological origin as a consequence of the transfer of water and energy between the Earth’s surface and the lower atmosphere.
That said, we would now like to delve into the disasters that could occur as a result of the impact of an asteroid, meteorite, comet or even space debris. One of the most important challenges is how to anticipate in order to avoid possible impacts. But the question:
8. When do we know that an asteroid or other body of this nature is potentially dangerous? What techniques are currently available to destroy them?
– The damage from the impact of an object on Earth is related to its kinetic energy, namely half its mass times its speed squared. The non-avian dinosaurs were killed by a rock the size of a large city that impacted Earth 66 million years ago. We are smarter than the dinosaurs were and constructed survey telescopes, like Pan-STARRS in Hawai or the Rubin Observatory in Chile, that can alert us of any incoming impactor larger than a soccer field. If such an object is identified far enough from Earth, we could prevent the impact by slightly shifting its trajectory so that it would not hit Earth. One approach is to send a spacecraft that will collide with it, as demonstrated by NASA’s DART spacecraft which collided with the rock Dimorphus on September 26, 2022. Another approach is to shine a lswer beam and ablate one side of the object, so as to propel it away from Earth by the rocket effect of the evaporated gas. Finally, there is a possibility of painting one side so that the reflection of sunlight would push the object away from Earth.
Space Debris
Since the space race began, thousands of satellites and rockets have been put into orbit, and perhaps we do not even know how many there are. Not only have we invaded our planet Earth with garbage and pollution, but we are also doing the same in space. We have seen, for example, how Starkink has had permission to send 12,000, but it intends to increase another 30,000 satellites in the coming years.
9. Is there any control by any institution or state that is responsible for tracking and monitoring objects lost in space?
What is going to happen with all this rubbish?
What are we doing to prevent it?
– In October 1957, Sputnik-1 was launched as the first artificial satellite of Earth. By now, sixty six years later, the European Space Agency reports that there were 6,500 successful rocket launches of nearly 17,000 satellites into Earth orbit. Out of these, about 11,500 satellites are still in space and about 9,000 of them are functioning. But there are many more objects orbiting Earth as a result of broken satellites or discarded rockets. Altogether, there were more than 640 break-ups, explosions, collisions, or anomalous events that resulted in fragmentation. The number of debris objects regularly tracked by Space Surveillance Networks is 35,150. The total mass of all space objects in Earth orbit is more than 11,500 tons.
For example, on February 10, 2009, an accidental collision at a speed above 10 kilometers per second occurred between two communication satellites: the active commercial satellite, Iridium 33, and the defunct Russian military satellite, Kosmos 2251. The collision created thousands of debris pieces larger than 10 centimeters, some of which still orbit Earth today. Many pieces followed a decaying orbit towards Earth, and burned up in the atmosphere within a couple of years.
By now, there are of order 130 million pieces of debris that are too small to be tracked, in the size range of millimeter to centimeter. Bigger pieces are rarer. In particular, there are a million orbiting objects in the range 1–10 centimeters and 36,500 pieces larger than 10 centimeters. These fragments orbit the Earth at a typical speed of about 8 kilometers per second, carrying 50 times more kinetic energy than the fastest rifle bullets with the same mass. Collisions between this space debris and functioning satellites on their orbital highway, can cause significant damage. Satellites can be warned of dangerous collisions. The International Space Station maneuvers to avoid such debris.
Space trash is a major problem for the future but there is no international plan to address it effectively as of now.
There are times when the very technology being deployed to investigate and discover new areas of space development only hinders other areas of research. A study by the CPS (International Astronomical Union) published in Nature [1] notes that “Elon Musk’s thousands of Starlink satellites are not only disrupting scientific research by causing streaks in deep space photos; according to a new study, they are also spewing “unintentional electromagnetic radiation” into space, something that could be a major problem for Earth, potentially confusing or even drowning out the signals from deeper space that radio astronomers are looking for. Part of the radiation emitted by satellites falls within a bandwidth designated by the International Telecommunication Union (ITU) to allow radio astronomers to do their work, according to the study.”
10.What do you think about this large-scale deployment of satellites in space?
– The concerns about space trash extends also to astronomy. The chance that one out of 130 million fragments larger than a millimeter would cross a single point in the sky within an orbital time of hours is of order a percent. According to my calculations, sunlight reflected from a perfect reflector of millimeter-size resembles the brightness of distant galaxies or faint supernovae at the edge of the Universe. A 10 centimeters object would be ten thousand times brighter.
As these fragments move across the sky, their glint produces a flare that typically lasts a fraction of a second at a favorable orientation relative to the Sun. The forthcoming Rubin Observatory in Chile will use a 3.2-billions pixel camera to survey the entire Southern sky every four days, starting in 2025. It could employ a novel strategy which sacrifices a small fraction of its observing time in order to avoid large commercial satellites and reduce the occurrence of satellite streaks in its images. Space trash of fragments larger than ten centimeters would contaminate the Rubin Observatory images.
The above numbers summarize humanity’s record in trashing the terrestrial neighborhood so far. But what does our future hold? A recent report from the United Nations forecasts that the number of satellite collisions will increase dramatically after 2025. In particular, the report projects a `tipping point’ to tens of catastrophic collisions within the next decade, which could trigger a dramatic growth in the population of small fragments. The resulting debris would add artificial lights on the sky and provide astronomers with an added incentive for building telescopes on the Moon or in space, where human-made space trash is nonexistent as of now.
Establishing astronomical observatories beyond Earth could be part of humanity’s plan to become a multi-platform civilization.
AI Technology
The commitment to technologies for the benefit of humanity is allowing the application of computing power and data analysis allows anticipation and recovery from natural disasters. This includes earthquakes, floods, tsunamis and hurricanes mainly, but also others such as fires or volcanic eruptions. The data obtained in the observation systems are duly treated in which AI algorithms recognize patterns that provide a certain prediction.
11.What do you think about this large-scale deployment of satellites in space?
What can be the role of artificial intelligence (AI) in the early detection of space bodies?
– Artificial Intelligence (AI) can help us process large amounts of data that the human brain cannot process, and identify rare anomalous objects in the sky. AI is already playing an important role in the analysis of large data sets in astronomy. The second role that AI can play is in decoding communication signals from other civilizations. This includes the possible interpretation of the intention of functional extraterrestrial devices that visit Earth. We may need our AI to help us figure out extraterrestrial AI. Finally, there is the possibility of sending AI to space, which is yet to be attempted.
Who should represent Earth in interstellar space? Humans cannot survive the long trip and so humanity will likely use an AI avatar as its flagship towards a possible encounter with aliens in interstellar space. In that case, which humans should the AI system replicate as a representation of humanity?
Humanity’s ambassador should contain the most complex neural network system that can be launched to space, potentially better than any human who ever lived on Earth. There were 117 billion samples of human intelligence that inhabited Earth over the past ten million years. Assuming a normal (Gaussian) probability distribution of intelligence quotient (IQ), the most intelligent biological brain which ever existed is ~7 standard deviations away from the mean. If we construct an AI system that is more than 7 times better than the average human brain, it would perform better than any human who ever lived.
Based on Moore’s Law, if the number of parameters in our most advanced AI systems will grow exponentially with a doubling time of 1–2 years, then within 2 decades artificial neural networks will be more complex than biological neural networks.
This will allow humanity to launch an AI system more impressive than any human brain that ever existed on Earth by the middle of this century. I will be proud of such a system more than a replica of a human, for the same reason that I am proud of my daughters’ accomplishments even if I cannot replicate them.
However, the space launch of an advanced AI system may take much longer than the time required to produce it on Earth. The root of the hurdle is in the required power supply. Currently, the training of Large Language Models (LLM) consumes gigawatts of electric power. Increasing the number of parameters in them or neuromorphic AI systems by a factor of ten thousand so as to exceed human performance, would require tens of terrawatts given their current architecture. This represents ten times the global electric power consumption on Earth. Providing this much power to a spacecraft is challenging. For comparison, the human brain runs on merely 20 watts.
It is remarkable how difficult it is for our technologies to reproduce what nature does so effectively thanks to billions of years of evolution. Indeed, it is difficult to maintain human hubris in light of our limited scientific accomplishments. Consider nuclear fusion as another example. Experimentalists at the National Ignition Facility (NIF) of the Lawrence Livermore National Laboratory (LLNL), achieved breakeven in the nuclear ignition of 0.2 milligrams of deuterium-tritium fuel over ten nanoseconds whereas the sun achieves hydrogen fusion for billions of years in a fuel reservoir that is 37 orders of magnitude larger in mass.
These two shortcomings of our technologies are related. Once we develop a concept for a compact fusion reactor, it could power our most advanced AI system in space.
Given that most stars in the Milky-Way galaxy formed billions of years before the Sun, it is possible that aliens resolved both technological challenges long ago. In case they already sent their ambassadors out of their home exoplanets to interstellar space, these alien avatars might be smarter than any of the senders. In that case, it would be fun to watch how our ambassador interacts with theirs.
After encountering each other, the two ambassadors might choose to partner and ghost their senders, like teenagers falling in love and avoiding their parents. If that happens, we will keep wondering about their whereabouts, and have no other choice but to connect directly with the aliens instead of delegating this task to our AI avatars. After all, there is nothing more rewarding than a dialogue between a biological brain on Earth and an extraterrestrial brain on an exoplanet.
Universe Theories
The existence of some theories about the origin of the universe only raises the eternal question: What is the origin of the Universe? Of all the theories that exist, from the Big Bang, the cyclical or oscillating universe, multiverses, simulation and steady state.
12.What is your opinion and impression of this very special person?
“The history of astronomy is a history of horizons that are moving away from us.” According to theoretical physicist Lucas Lombriser, professor at the University of Geneva, “the expansion of the Universe could be an “illusion” and hide the fact that in reality the cosmos is static.” favorite theory is that the universe was created by a scientist in a laboratory. We currently do not know what created the Big Bang because we do not have a predictive theory of quantum-gravity. Once we do, I can imagine quantum-gravity experimentalists attempting to create a baby universe in the laboratory.
Anyone who can creating a baby universe is eligible to apply to the job description of God.
“The history of astronomy is a history of horizons that are moving away from us.” According to theoretical physicist Lucas Lombriser, professor at the University of Geneva, “the expansion of the Universe could be an “illusion” and hide the fact that in reality the cosmos is static.”
13.What is your opinion regarding this theory in which the expansion of the Universe could be an illusion?
The expansion of the Universe is supported by a large body of data, including the relic radiation and the light elements (hydrogen, helium, lithium) that were produced in the early hot and dense phase in the history of the Universe, as well as the growth of large-scale structure as a function of distance or look-back time. There is no doubt that the Universe is expanding base don all we learned over the past century.
Now I would like to ask you about two geniuses of Astronomy such as Einstein and Hawking.
It seems that until now there is nothing that can resist Einstein and Hawking in terms of their predictions and research.
14.Have Einstein and Hawking been wrong about anything in terms of their research?
Of course. Being wrong comes with the territory of working at the frontier of our scientific knowledge. In fact, Albert Einstein made three mistakes between 1935-1940. He wrote papers arguing that gravitational waves do not exist, that black holes do not exist and that quantum mechanics does not have “spooky action at a distance.” All three claims were proven wrong by experimental evidence, and the three research teams that demonstrated Einstein wrong, received the Physics Nobel Prize over the past decade.
Stephen Hawking’s most celebrated discovery that black holes evaporate was made because he wanted to demonstrate that the concept of black hole entropy, originally proposed by a Young PhD student at Princeton, named Jacob Bekenstein, is wrong. In the process of trying to prove that, Hawking realized that Bekenstein was correct and that black holes have a temperatura that causes them to emit radiation and evaporate.
Stephen Hawking said before he died that “there is no God. No one runs the universe.” But rather than denying God, another question arises: “You cannot prove that God does not exist,” he told the American network ABC in 2010. “But science makes God necessary.”
15. What is your opinion and impression of this very special person?
I was very impressed by Hawking’s brilliance and joy of life, despite the arresting disability that he suffered from. His life is an inspiration for al lof us who confront much lower obstacle.
Regarding God, my take is that it would appear to us in the form of an advanced extraterrestrial civilization. We would feel religious awe when we will witness technologies well beyond our level. They would appear like miracles to us. The biblical story about Moses is that he believed in a superhuman entity after witnessing a burning bush that was never consumed. Today, we could have impressed Moses much more by showing him an electronic device that we can buy online. The reason is simple: our present-day gadgets represent the technological future of Moses.
Social Innovation: Collective intelligence
Collective intelligence is a form of intelligence that arises from the collaboration of various individuals or communities to address a common problem by combining both intellectual and technical efforts. We have seen that when the scientific community has shared information about the “Genome” of the SARS-CoV-2 virus, positive results have been obtained in massive sequencing, characteristics or properties, which has allowed its monitoring and evolution. Similarly, when hundreds of scientists from around the world come together to record a supernova, the result is also incredible. The SETI Institute and the smart telescope company Unistellar have joined forces with the “Cosmic Cataclysms” program to unite dozens of users in observing the supernova.
16.What importance do you think collective intelligence has in the science of Astronomy?
Large collaborations are becoming more prominent in astronomy because of the increase in the size of the facilities and the volumen of the data collected. Given this trend, collective intelligence is becoming dominant relative to the role of innovation b yan individual scientist like Einstein or Hawking.
Extraterrestrial life
Finally, I would like to ask you about some questions related to the existence of extraterrestrial life:
Oumuamua, an interstellar object that visited our solar system in 2017 was detected by astronomers and is believed to be a comet. This visitor is a rocky, elongated object with a reddish hue and is the first confirmed object from another star to have passed through our solar system. Although its exact origin remains an enigma, its fleeting passage has left us with many questions.
On the other hand, IM1 is the first recognized interstellar meteorite to have crashed on Earth. It was discovered in the Pacific Ocean and originated outside our solar system. The June 2023 Interstellar Expedition led by you recovered hundreds of metallic spheres believed to be unmatched by any alloy existing in our solar system from the seabed of the Pacific Ocean near Papua New Guinea. This is the first interstellar object recognized that, due to its speed, trajectory and hardness, could be of artificial origin. But as they say, “its mission is agnostic.”
17.Could Oumua be of extraterrestrial technological origin?
Are Oumuamua and the 2023 Interstellar Expedition related?
Could you tell us what the analysis is of the current situation of these metallic spheres found in the 2023 Interstellar Expedition?
We We live at an exciting time. The first large interstellar objects were discovered only over the past decade: the interstellar meteor IM1 in 2014, the anomalous near-Earth object Oumuamua in 2017 and the interstellar comet Borisov in 2019. A fundamental unknown is the likely source for each of these unusual objects from outside the solar system.
To shed new light on this unknown, I offered a summer project to Shokhruz Kakharov, an undergraduate student at Harvard College. My idea was to calculate the trajectories of these interstellar objects back in time in the gravitational potential of the Milky-Way galaxy and figure out where they came from. The Galactic region that their orbits sampled in the past would constrain the properties of their sources. For example, if they originated near a star, one could constrain the age of the star and the physical process that could have produced each of these interstellar objects.
We initiated the past trajectories of these interstellar objects by reversing their measured velocities relative to the Local Standard of Rest — the frame of reference obtained by averaging the random motions of local stars near the Sun. This frame is circling the center of the Milky-Way at a speed of about 240 kilometers per second, ten thousand times faster than the speed-limit on a highway.
Using a computer code, Shokhruz numerically integrated the trajectories of interstellar objects back in time in the gravitational potential of the Milky-Way. For simplicity, we ignored transient gravitational features such as spiral arms and the Galactic bar. This is a reasonable approximation for orbits in the outer part of the Galactic disk.
By integrating the orbits of these interstellar objects back in time, we were able to constrain the spatial region of their putative sources within the Milky Way. These constraints limit the potential birthplaces of different interstellar objects and provide insights into the Galactic environment from which they originated.
Stars near the Sun follow an exponential distribution above and below the midplane of the Galactic disk, with a scale-height that increases with age. We used the vertical excursion of each interstellar object from the Milky-Way disk midplane to constrain the likelihood function for its possible age. Our approach was simple. Given the maximum vertical excursion of each object from the midplane of the Milky-Way disk, we calculated the age distribution of stars that could have given birth to them within that region to infer the probability distribution for the object’s age. Any dynamical effect on the stellar scale-height by gravitational perturbations would also affect interstellar objects as well, since both populations are collisionless. Hence, our age constraints apply directly to the full age of the interstellar objects irrespective of their travel time.
We discovered a small vertical extent of Oumuamua’s past trajectory out of the Milky-Way midplane, about six time smaller than that of the Sun. This suggests that Oumuamua originated near the midplane of the thin disk of young stars. This fact implies a likely age younger than 1–2 billion years. Cosmologically speaking, Oumuamua is an infant, younger by an order of magnitude relative to the age of the Universe. It is even much younger than the Sun, which is a late bloomer in cosmic history.
The past evolution of the distance of the interstellar object Oumuamua from the Sun follows a period of about 2.2 billion years. Oumuamua was on the other side of the Milky Way disk relative to the Sun about 1.1 billion years ago.
The maximal excursion of the comet Borisov is similar to that of the Sun, suggesting a similar age. The meteor IM1 exhibits larger vertical excursions, suggesting an older source.
We also applied the same code to calculate the future trajectories of the interstellar probes launched by NASA decades ago, Voyager 1 & 2 and Pioneer 10 & 11.
We have found that human-made interstellar probes, like Voyager 1 or Pioneer 10, will arrive at the opposite side of the Milky Way disk relative to the Sun in about 2 billion years and will return to the vicinity of the Sun in 4 billion years. This future “return near home” will occur long before the Sun will evolve to become a red giant star in about 7.6 billion years.
The radial and vertical extent of Voyager 1’s trajectory relative to the Galactic plane resembles the corresponding ranges for the Sun.
After the Sun will die, it will leave behind a compact metallic sphere, roughly the size of the Earth and containing 60% of the current mass of the Sun. Such a remnant is called a white dwarf. We know this fate for the same reason that we realize that we are doomed to die after visiting a graveyard. There are numerous white dwarfs from sun-like stars which died by now and are buried in the Milky-Way galaxy.
Based on the measured age of these white dwarfs, one can infer the star formation history of the Milky-Way. The procedure is similar to inferring historic birth rates from dated death certificates. Most of the Milky-Way stars formed billions of years before the Sun, with a peak in the star formation rate at about 10 billion years ago. If civilizations like ours were born around that peak and launched Voyager-like probes more than 2 billion years ago, these probes could have made it by now to the vicinity of the Sun from the other side of the Milky-Way disk.
This is why it is worth checking whether the anomalous shape and non-gravitational acceleration of Oumuamua or the anomalous material strength and speed of IM1 might be indicative of a technological origin. While some regard this idea controversial and heretic, it sounds like common sense to me. But what can I say … I am just a simple-minded, curious farm-boy, not as high-brow as some journalists might be — those who prefer not to confuse their readers with common sense.
The expedition to retrieve materials from the interstellar meteor IM1 was described in my TED talk recently. For a farm-boy turned scientist who is genuinely curious about nature, bliss comes with new data. This stands in contrast to solar system experts who know the answer in advance, and who told me when the first interstellar object `Oumuamua showed up: “I wish it never existed.” Wishing that facts go away is the trademark of politicians, not scientists. Alas, scientists sometimes behave like politicians
I am currently seeking funds for our planned expedition to retrieve large pieces of Interstellar Meteor 1 (IM1). The meteor impacted Earth on January 8, 2014 with a speed that translated to 60 kilometers per second relative to the Local Standard of Rest of the Milky Way galaxy. It was faster than 95% of the stars in the vicinity of the Sun. Could it have been a Voyager-type meteor?
A year ago, on June 14–28, 2023, we visited IM1’s impact site, localized by sensors aboard satellites of the U.S. Department of Defense, which detected the light from IM1’s brilliant fireball. We conducted an extensive towed-magnetic-sled survey over the seafloor and found about 850 molten droplets in the form of spherules of diameter 0.1–1.3 millimeters in our samples. The samples were analyzed by state-of-the-art laboratory instruments including a micro-X-Ray Fluorescence analyzer, Electron Probe Microanalyzer and an Inductive-Coupled-Plasma Mass-spectrometer. We identified 78% of the spherules as primitive with a composition that resembles the primordial material that made the solar system. When rocky planets like the Earth or Mars form with a hot molten rock (magma or lava ocean) on their surface as a result of bombardment by large bodies, some elements from the periodic table which have a chemical affinity to iron migrate towards the iron core and leave behind a modified abundance pattern, which we labeled as “differentiated”. Our analysis revealed that 22% of our spherules were differentiated.
Among the differentiated spherules, about half, namely 10% of the total number of spherules, had a chemical composition that was never reported before in the scientific literature, characterized by an enhanced abundance of some elements up to a thousand times larger than the standard solar composition. We labeled this special set: “BeLaU”-type spherules. The BeLaU composition is unfamiliar and different from the composition of the crust of the Earth, Mars, the Moon, asteroids and comets and potentially flags an origin from outside the solar system. This origin could be natural or artificial.
Imagine throwing a laptop into a fireplace. By retrieving the residual molten droplets, it would be impossible to conclude whether the original object was artificial. The key is to find a piece of the laptop that maintained its integrity. This is the goal of our next expedition to the Pacific Ocean, planned for summer 2025. Aside from identifying the nature of IM1, a large piece would allow us to date the object’s age from its radioactive isotopes, as well as gauge its material strength and thermal properties, potentially explaining why it maintained its integrity despite witnessing atmospheric stress beyond the tolerance of the toughest iron meteorites known in the solar system.
To find larger pieces of IM1, we intend to use a robot, namely a Remotely Operated Vehicle named Hercules, accompanied by a video feed that would allow us to see what we are picking up.
Both events arouse curiosity and the excitement of exploring the unknown.
18.What importance do you think collective intelligence has in the science of Astronomy??
It is importat to search for alien artifacts among interstellar objects, given the tremendous implications that a related finding will carry for humanity. Even if we recover clues that IM1 was a rock from another star, it would be the first interstellar rock of a type never seen before and we would learn something new about what lies outside the solar system. Of course, finding a tennis ball thrown by a neighbor would be a completely different ballgame. It would imply that we are not alone. Finding a partner would change the meaning of our existence. The cosmos would not appear pointless or lonely. We could learn about technologies that represents tour future. We may be inspired to explore space. But most of all, we would realice that there is much more real estate in. Outer space than we find here on Earth. And so instead of engaging in conflicts on territories on this small rock around the Sun, we should all cooperating in the pursuit of a better future for humanity beyond the limitations of our planet.
