The Universe is Over a Hundred Million Times Older than Each of Us
One of the remarkable insights in the biblical story of genesis is that the observable Universe had a beginning in time, akin to the modern notion of a Big Bang. This idea was not philosophically appealing to scientists like Albert Einstein, who in 1917 added a cosmological constant to his equations of General Relativity, in order to counteract the gravitational attraction of matter and radiation and allow for a static eternal Universe. He later realized that such a delicate balance is unstable and leads to a clumpy Universe. Indeed, today cosmologists explain the emergence of galaxies like the Milky-Way as a natural consequence of gravitational instability in an expanding Universe which contains a cosmological constant.
How can we infer the current age of the Universe?
Locally, we find that the Universe is expanding with the recession speed of distant galaxies being proportional to their distance. The proportionality factor, called the Hubble constant after the astronomer Edwin Hubble, is the ratio between the recession velocity and distance. The time that elapsed since these galaxies overlapped equals to their distance divided by their velocity. Crudely speaking, this would imply that the age of the Universe is simply the inverse of the Hubble constant. For the current value of Hubble constant, about 70 kilometers per second per megaparsec, its inverse is 14 billion years.
The value of the Hubble constant is still uncertain, as different techniques for distances measurements provide values that are discrepant by +/-5%, as summarized here. This ambiguity amounts to an age uncertainty of 0.7 billion years.
A more refined approach is to trace the distance that light travelled since the beginning by studying the Cosmic Microwave Background (CMB), the relic radiation from the Big Bang. The Universe became transparent to the CMB as soon as the cosmic temperature cooled under 4000 degrees Kelvin, allowing electrons to join protons in making hydrogen atoms. This removed the fog associated with electron scattering of the CMB at about 400,000 years after the beginning. The distance that sound waves propagated during that time defines a yardstick for the characteristic CMB brightness patterns. The angle that it occupies in the sky depends on the distance travelled by the CMB since that time which — given the speed of light — reflects the age of the Universe. The acoustic patterns can also be found in the large-scale distribution of matter, as traced by galaxies at recent cosmic times. This approach yields a cosmic age of about 13.8 billion years.
The Sun formed in the last third of cosmic history, 4.6 billion years ago, and our modern technological era is only a century old. We arrived late to the cosmic party.
Most stars formed before the Sun. This offers a second path for measuring the age of the Universe. No star can be older than the Universe for a simple reason. As we go back in time before the first minute after the Big Bang, the cosmic density of matter and radiation was much higher than that found in the interior of stars. No star could have not survived these extreme conditions in the infant Universe. Cosmic archaeology can therefore set a lower limit on the age of the Universe by finding ancient stars that formed in the first hundreds of millions of years after the Big Bang.
Recent data from the Dark Energy Camera (DECam) mounted atop the Víctor M. Blanco 4-meter Telescope in Chile, revealed stars inside the nearby dwarf galaxy Pictor II at a distance of 150,000 light years. This satellite galaxy of the Milky-Way is more than 10 billion years old. One of the oldest of these stars is PicII-503, with only a part in 43,000 of the iron mass-fraction of the Sun, as reported last week here.
Another path for cosmic archaeology involves studies of the materials carried by interstellar objects, born out of the debris of distant stars. They also cannot be older than the Universe. The age of interstellar objects can be inferred by isotope dating. Remarkably, the measurement of deuterium to hydrogen and 12C/13C ratios, as reported here and here last week, implies that the age of the interstellar object 3I/ATLAS is 10–12 billion years, suggesting that it may have formed in the early Universe. As I discussed here, this raises a puzzle regarding the mass reservoir of its parent star population.
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Jeanne Calment of France is the oldest verified person to have ever lived. She died in 1997 at an age of 122.45 years. This is a hundred million times shorter than the age of the Universe. One would expect the fact that we live for less than 0.00000001 of cosmic history to sink in and make us humble. But not so. We prefer to ignore it.
Even though our life is brief, we choose to invest most of it in conflicts with each other. Out there in the sky, there is a giant cosmic message telling us how insignificant we are. And yet, even mainstream astronomers who adopt the job of looking up, maintain the arrogant view that we might be at the top of the cosmic food chain and that the quest for extraterrestrial technological civilizations is an extraordinary claim that should be sidelined in favor of the search for microbes. How else can one interpret the top priority of the Astronomy & Astrophysics Decadal Survey to invest more than 10 billion dollars in the search for microbes and no federal funding in the search for extraterrestrial intelligent beings?
Given the dismal brevity of our cosmic existence, we get comfort from the assumption that the we must be surrounded by lower life forms.
I reject this popular view within present-day academia. Out of a sense of cosmic modesty, I define my goal throughout the remainder of my scientific career to seek evidence for a more accomplished sibling of our family of intelligent civilizations. If such evidence will be found, the next Copernican revolution would be that we are not at the intellectual center of the Universe.
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Before my morning jog at sunrise, I had received the following uplifting email from the Finnish artist, Antti Railio:
“Hello Mr. Loeb.
My name is Antti Railio, I am a Finnish singer/artist. I have been following your work for few years now and I am really happy to see a scientist who practices real science with the correct attitude towards it.
I also have had an interest on the UAP/UFO phenomenon since the 1990’s since I have witnessed along with other people the phenomenon of bright orbs up upon the ocean here in Finland in my home town of Kristiinankaupunki.
Also, I had an experience when I was a child which left me with 7 Stiches on my left palm…
Well, that is beside my letter to you…
I wanted to write to you, since I am not a scientist, but I have a curious mind, and it seems I tend to have Ideas or theories that time and time again seems to be after sometimes decades validated by scientists.
For example, I had a theory that our universe might be inside a black hole and possibly the multiverse is like a bunch of soup bubbles. I had this idea 20 years ago… And since few years ago I read that this is now a well thought theory…
I also have had a theory that life on earth had its origins somewhere else possibly the same life source that has been spread through the universe by panspermia. And I somehow am almost certain that this is the case.
Anyway, my main reason for contacting you is this new theory I have… I just had an idea a few days ago popped to my brain!
What would you think of this? You know the theory of white holes being the theorized flip sides of a black whole, but that we have not yet been able to seen or proven their existence ones…
My theory is this: We are all made of the same material that exists inside the Sun as they say and Sun gives us life and illuminates the whole solar system…
What if stars are the other side of a black holes, a reverse singularity! If I am not wrong a black hole appears in 3-dimensional space as a sphere?
So my theory is that one of the reasons the Sun’s temperature is far more greater farther from its surface, is also driven by the forces pushing through the matter from a far distant black whole that is at the same time at the other side of the sun, so that it is occupying basically the same space as the Sun and at the same time it is connecting our solar system with another one somewhere where the black hole resides… Also the black hole’s immense gravitation would keep the sun at its form, but since it is constantly feeding in from the other side it has to disperse the energy gradually away thus the heat and photons would then be the Sun’s source of light and energy…
The immense gravitation would still bleed through its presence over to this side keeping the planets locked in their places…
Also, that would make sense in another theory connecting to UAP…
It would make sense that higher beings would be aware of this and could use stars as a map of “jump points” to travel vast distances by using portals created by the universe…
You know, sometimes the obvious is hiding right in front of our eyes… ;)
That is my newest theory but I lack the scientific knowhow to even start to calculate the mathematics or the more technical sides of this theory, so I leave it to you as a fun theory or perhaps something to be thinking about … :)
With the most respect and admiration
Thank you so much for your time!
Also, I am super excited about your Galileo Project! And secretly wish to grow up and start my scientific career. But maybe I am better at singing and performing…
Yours truly!
-Antti Railio”
My response was as follows:
“Dear Antti,
Thank you for reaching out to me and for your kind words.
Your idea about panspermia might very well be correct. For the latest update, see my essay from last week:
It is possible that our Universe is embedded inside a black hole but we have no evidence for that. A black hole is characterized by a singularity at its venter (a place where the curvature of spacetime diverges), very different from the nearly uniform conditions in the observable volume of the Universe.
Regarding the Sun and other stars: we can explain their properties, including their internal structure — which is probed by sound waves, as a result of nuclear fusion being their source of energy. Once they consume their nuclear fuel, they die and we see their remnants in the forms of white dwarfs (for Sun-like stars), neutron stars and black holes (for stars more massive than 8 solar masses). A white hole was conjectured as the source of energy for quasars or gamma-ray bursts, but these sources of light are well explained by a model involving the infall of matter into a black hole.
Keep up with your creative work.
Avi”
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
Professional website:
https://lweb.cfa.harvard.edu/~loeb/
Social media:
https://avi-loeb.medium.com/
https://www.youtube.com/@ProfessorAviLoeb
https://open.spotify.com/show/1zhndXkvSY2b8FdjspFpCd
https://x.com/ProfAviLoeb
