Fine tuning and Fermi’s paradox
David H. Bailey
http://www.davidhbailey.com
Lawrence Berkeley National Lab (retired)
University of California, Davis

1 / 27

A “freakishly” fine-tuned universe
1. The synthesis of carbon depends sensitively on the value of the strong force.
2. The existence of protons and neutrons depends sensitively on the strong and weak forces.
3. If the electromagnetic force were not roughly 1040 times stronger than gravity, the heavier
elements would not form.
4. If the neutron mass were very slightly less, the universe would be entirely protons.
5. The cosmic microwave background is just nonuniform enough (one part in 105 ) to permit
galaxies to form.
6. The positive and negative contributions to the vacuum energy density cancel to within
one part in 10120 (the cosmological constant paradox).
7. The positive and negative contributions of the Higgs boson mass cancel to within one
part in 1019 to give the anomalously low value we observe.
8. Shortly after the big bang, the universe must have been flat to within one part in 1015 .
9. The overall entropy of the universe is “freakishly lower than life requires.”
I G. F. Lewis and L. A. Barnes, A Fortunate Universe: Life in a Finely Tuned Cosmos, CUP, 2016.
I M. J. Rees, Just Six Numbers: The Deep Forces that Shape the Universe, Basic Books, 2000.

2 / 27

Fermi’s paradox
In 1950, while having lunch with colleagues, Enrico Fermi asked, Where is everybody?
I Presumably there are thousands if not millions of othertechnological civilizations in the Milky Way galaxy alone.
I Any technological civilization is, almost certainly, many

thousands or millions of years more advanced than us.
I Within a few million years after becoming technological (aneye-blink in cosmic time), a society could have explored
and/or colonized most if not all of the Milky Way.
I So why don’t we see evidence for the existence of even asingle extraterrestrial (ET) civilization?

Credit: Wikimedia

3 / 27

My thesis
I Recent dramatic developments in technology have all but destroyed the mostcommon and plausible solutions to Fermi’s paradox.
I Fermi’s paradox significantly deepens the conundrum of universal fine tuning.

In the following, we will assume only that:
I The laws of physics, as currently understood, apply over several billion light-yearsof space and several billion years of time.
I Any technological ET civilization consists of a society of individuals, has arisen via
Darwinian evolution, and thus is subject to principles of diversity and natural
selection.
We do NOT assume:
I ET individuals are carbon- or water-based, or that their biology is based on DNA.
I ET societies have invented exotic communication or transportation technologies(e.g., space-warp travel) beyond what we can envision from well-known physics.
4 / 27

The grim mathematics of Fermi’s paradox
Let p be the probability that an individual on a given planet in a given year launches
an interstellar exploration, m be the number of individuals on a typical planet, n be thenumber of planets, and t be the number of years. Then the probability P that a
civilization has explored the Milky Way can be estimated as:
P = 1 − (1 − p)mnt
Conservative estimates for the Milky Way:m > 109 ,n > 1011 ,t > 5 × 109 .

For the universe as a whole, n > 1022 and t > 1010 .
In other words, if the probability of the rise of a space-faring civilization anywhere iseven microscopically nonzero (given the instance of human civilization), then after
billions of years, on many billions of planets, with billions of individuals, ET should beeverywhere. Where is everybody?
5 / 27

Proposed solutions to Fermi’s paradox: The “zookeeper” solution
Solution 1: They exist, but are under strict orders not tocommunicate with a civilization such as Earth.
Rejoinder: In numerous vast, diverse ET civilizations (or even injust one ET civilization), each spanning multiple planets or stars,
and, most likely, consisting of millions of individuals, it is hardly
credible that a galactic society could impose a global ban oncommunication to Earth that is absolutely 100% effective.

Credit: Huffington Post

Once a signal has been broadcast and is on its way to Earth, there is no way to call it
back, within known laws of physics. And for a civilization that is thousands or millionsof years more advanced than us, such communication would be vanishingly cheap.
For the next several viewgraphs, see:
I Paul Davies, The Eerie Silence: Renewing Our Search for Alien Intelligence, Houghton Mifflin Harcourt,
New York, 2010.
I John Gribbin, Alone in the Universe, John Wiley, New York, 2011.
I Stephen Webb, If the Universe Is Teeming with Aliens... Where Is Everybody? Fifty Solutions to Fermi’s
Paradox and the Problem of Extraterrestrial Life, Copernicus Books, New York, 2002.

6 / 27

The “beach bum” solution
Solution 2: They exist, but have lost interest in scientificresearch, exploration and expansion.
Rejoinder: Darwinian evolution strongly favors organisms thatthink, explore and expand. Thus it is hardly credible that every
individual in every ET civilization has lost interest in scientificresearch, exploration and expansion, or that a global ban on suchactivities is absolutely 100% effective.

Credit: Wikimedia

What’s more, any ET society’s long-term existence crucially hinges on having an
in-depth scientific understanding of all potential perils in its cosmic environment:
I Asteroids, meteorites and solar flares.
I Supernovas.
I Gamma ray bursts.
I Neutron star mergers.
I Potentially dangerous biological systems.
I Potentially hostile neighbors.

7 / 27

The “humans are ants” solution
Solution 3: They exist, but have no interest in a primitive,
backward society such as ours; to them, we are as ants.
Rejoinder: Perhaps 99.99% of an ET society is not interested inprimitive societies such as ours. But, as before, it is hardly
credible that every individual in every ET civilization has nointerest.

Credit: Wikimedia

In our society, perhaps 99.99% of the public has little or no interest in ants. But many
thousands do. There is even a full-fledged scientific field (myrmecology) to study ants,
and researchers have meticulously catalogued and studied every known species.

8 / 27

The “advanced communication” solution
Solution 4: They exist, but have progressed to moresophisticated communication technologies.
Rejoinder: This does not apply to signals that are specificallytargeted to societies such as ours, in a form (optical, microwaves)that could be easily recognized by a newly technological society.

Credit: Australian National Telescope Facility

Again, it is hardly credible that a galactic society could enforce a global ban, over avast array of inhabited planets, each with millions of individuals, on communication
targeted to emerging technological civilizations, that is absolutely 100% effective.
As noted before, once a signal is on its way to Earth, it cannot be called back, within
known laws of physics.

9 / 27

Diversity and Fermi’s paradox
Similar diversity arguments defeat a wide range of other proposed solutions:
I Darwinian evolution is the only known or hypothesized mechanism whereby

high-information organisms and species (carbon-based or not) can form.
I Diversity is a fundamental, inescapable law of Darwinian evolution.
I Diversity is also a law of economics, political science, organizational behavior, and evenphysics (quantum superposition, sum over histories, chaos, anisotropy in the CMB, etc.).
I Highly conformist species, societies and organizations inevitably fail.
I All great figures of history were nonconformists: Albert Einstein, Martin Luther King,

Susan B. Anthony, Nelson Mandela, Steve Jobs. Jobs’ motto was “think different.”
In a vast, diverse society, there will be exceptions to any rule. Thus claims that “all ET are likeX” have no credibility, no matter what “X” is.
It is ironic that while most scientists would reject stereotypes of religious, ethnic or nationalgroups, some seem willing to hypothesize sweeping, ironclad stereotypes for ET societies.
I Stephen Webb, If the Universe Is Teeming with Aliens... Where Is Everybody? Fifty Solutions to Fermi’s
Paradox and the Problem of Extraterrestrial Life, Copernicus Books, New York, 2002.

10 / 27

The “no evidence of humans” solution
Solution 5: They exist, but are not aware of our existence yet — ourfirst TV signals have only passed 80 light years’ distance.
Example: Lawrence Krauss (Canadian physicist/cosmologist), on the
PBS show “The Farthest — Voyager in Space” (aired 26 November
2017 in the U.S.):Over the last four and a half billion years, the only
evidence of intelligent life was in the last 50 to 60 years, bywatching Star Trek or I Love Lucy, or whatever — signals
we sent out. So even if someone told you “look at that star,and look at the third rock from that star, that’s where you
will find life,” even if [you] knew which object to look for,there is only a 50 year period over 5 billion years, almost,where you would be able to find intelligent life.

Credit: J. Vangiel

11 / 27

The “no evidence of humans” solution, continued
Rejoinder: Ample evidence of an emerging technologicalcivilization on Earth has been on display for much longer:
I Our atmosphere has contained methane, oxygen and otherchemical signs of life for at least three billion years.
Credit: NASA

I Images of Earth would have shown dinosaurs and countless otherlarge species for at least 300 million years.
I Images of Earth would have shown bipedal hominins for at least 5

million years, and humans for at least 200,000 years.
I Images of Earth would have shown large human structures(Mesopotamia, Egypt, China, Rome) for at least 10,000 years.
I Urban lights have been on display for at least 2,000 years, andespecially in the past 200 years.
I Atmospheric carbon dioxide has been on the rise for 200 years.

Again, it is hardly credible that all of this evidence has been overlooked by all ETs.

12 / 27

The “technological” solution
Solution 6: They exist, but travel and communication are too
difficult.
Rejoinder: Recent dramatic and largely unanticipateddevelopments in technology in the past few years have all but
destroyed this solution:

Credit: SpaceX

I New energy sources.
I New propulsion systems.
I New space exploration vehicles.
I Supercomputers (currently run at 1017 flop/s).
I Artificial intelligence.
I Robotics, 3-D printing and nanotechnology.
I Exoplanet search and imaging technology.
I Gravitational lenses.
I von Neumann probes.

13 / 27

New energy sources
I German physicists have announced that have successfully contained helium

plasma in a stellerator-type fusion reactor.
I Lockheed Martin is developing a 100-megawatt fusion reactor only 2 × 3 meters insize — small enough to fit in a spacecraft.
I TriAlpha Energy of San Diego has been developing a fusion reactor. They havereported heating a plasma of hydrogen fuel to 10 million C.
I Brillouin Energy of Berkeley claims, in a patent application, to generate thermalenergy by “neutron generation and capture.”
I Andrea Rossi of Florida has publicly demonstrated a “low-energy nuclear reactor”

process. The effect has been reproduced by a team of Swedish and Italian
researchers, and has been granted a U.S. patent.
Numerous others could be listed.
Even taking a highly skeptical approach to these individual projects, one way or
another new clean energy sources are coming, with compelling potential applications
for space travel (and thus for Fermi’s paradox).
14 / 27

New propulsion systems
I Ion propulsion: A high-energy electron collides with a xenon

atom, releasing electrons, and the charged atom is thendischarged at high speed (up to 150,000 kph).
I High-power electric propulsion: The xenon ions areproduced by a combination of microwave and magnetic
fields, using electron cyclotron resonance.
I Fusion-driven rocket: A fusion energy source releases its

Credit: NASAenergy directly into a lithium propellant, without converting
to electricity.

For details, see:
http://www.nasa.gov/centers/glenn/about/fs21grc.html
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040139476.pdf
https://www.nasa.gov/directorates/spacetech/niac/2012_phaseII_fellows_slough.html

15 / 27

Yuri Milner’s plan to explore Alpha Centauri
Russian billionaire Yuri Milner, backed by Stephen Hawking andMark Zuckerberg, proposes to send “nanocraft” to explore Alpha
Centauri and its planets:
I Thousands of credit-card-sized spacecraft.
I Launched by giant solar sails, pushed by earth-bound lasers.
I Travel at up to 0.2c, arriving in 20 years.
I Upon arrival, send back images and other data via laser

beams, which will arrive at Earth four years later.

Credit: Bloomberg

For details, see:
http://www.scientificamerican.com/article/100-million-plan-will-send-probes-to-the-nearest-star1/
16 / 27

Elon Musk’s vision for space exploration
I SpaceX is designing a new, more powerful rocket that could

transport humans to Mars.
I SpaceX plans to fly two cargo ships to Mars in 2022, andtwo crew ships and two cargo ships in 2024.
I The ship will feature 40 cabins, each of which would house

Credit: SpaceX

two or three persons, with a capacity of 100 persons per
flight.
The ultimate goal is to create a new society on Mars, making humans a true
multi-planetary species.

For details, see:https://news.nationalgeographic.com/2017/09/elon-musk-spacex-mars-moon-bfr-rockets-space-science/
17 / 27

A round trip to Mars with a human crew
Fuel for a return trip from Mars could be produced in situ on
Mars (otherwise transporting fuel to Mars for the return trip is
90% of the outbound payload):
I CO2 can be extracted from Martian atmosphere.
I H2 can be produced by using electricity to electrolyze

Credit: Mars Society

Martian ice (producing oxygen for astronauts as byproduct).
I Then this exothermic reaction can be used to produce fuel:3 CO2 + 6 H2 → CH4 + 2 CO + 4 H2 O.
A fully fueled lift-off vehicle could be ready on Mars before the astronauts leave Earth.

For details, see:
http://www.marssociety.org/home/about/faq/
18 / 27

Artificial intelligence: DeepMind’s AlphaGo Zero teaches itself to play Go
I Until two years ago, observers had not expected computer

Go programs to defeat humans for years, if not decades.
But in May 2017 DeepMind’s AlphaGo program beat Ke
Jie, the world’s highest-rated player.
I In October 2017, DeepMind researchers programmed an AI

computer with the rules of Go, then had the program playitself, teaching itself with no human input.
I After just three days of training, the resulting program

Credit: Wikimedia“AlphaGo Zero” defeated AlphaGo 100 games to 0.
I Ke Jie’s Elo rating is 3661. After 40 days of training,

AlphaGo Zero’s Elo rating was over 5000, as far above Ke
as Ke is above a good amateur.
I “The latest AI can work things out without being taught,” The Economist, 21 Oct 2017,https://www.economist.com/news/science-and-technology/
21730391-learning-play-go-only-start-latest-ai-can-work-things-out-without.
I R. Parloff, “Why deep learning is suddenly changing your life,” Fortune, 28 Sep 2016,
http://fortune.com/ai-artificial-intelligence-deep-machine-learning/.

19 / 27

Gravitational lenses
Gravitational lenses, using the Sun as a lens according to generalrelativity, can be used to produce close-up images of distantplanets and civilizations. Magnifications of 1015 may be achieved.
Since there is no chromatic aberration, gravitational lenses canalso monitor a distant civilization’s microwave communications(or any other form of electromagnetic communication).

Credit: FOCAL project

What’s more, we could send images and communications to them. Such a project
would be quite costly today, but in 20, 50 or 100 years?
Are other civilizations using gravitational lenses to see close-up images of Earth? Oreven to send messages to Earth? Why not?

I G. A. Landis, “Mission to the gravitational focus of the Sun: A critical analysis,” NASA Glenn ResearchCenter, https://arxiv.org/pdf/1604.06351.pdf.
20 / 27

von Neumann probes“von Neumann probes” could be sent to distant solar systems,
which could land and construct additional copies of themselves,using the latest software beamed from the home planet.
Detailed studies of a “slingshot” exploration scheme show that asingle civilization could explore the entire Milky Way within fivemillion years.

Credit: F. Tipler

I A. Nicholson and D. Forgan, “Slingshot dynamics for self-replicating probes and the effect on exploration
timescales,” International Journal of Astrobiology, 2 Jul 2013.
21 / 27

The “self-destruct” solution
Solution 7: Civilizations like us invariably self-destruct before
becoming a space-faring society.
Rejoinder: In 200 years of technological adolescence, we have notyet destroyed ourselves through a nuclear, environmental or
biological catastrophe. Further, we have developed sophisticatedsupercomputer simulations to foresee and control future perils.

Credit: Wikimedia

Thus it is hardly credible that societies such as ours invariably self-destruct before they
become space-faring society, without any exceptions whatsoever.
In any event, within a few years human civilization will spread to the Moon, Mars andelsewhere, and then its long-term survival will be largely impervious to calamities on
the home planet.
As before, galloping technology is destroying this solution to Fermi’s paradox.
22 / 27

The “rare earth” solution
Solution 8: Earth is a unique planet with characteristics
fostering a long-lived biological regime leading tointelligent life (see Ward, Brownlee below).
Rejoinder: Perhaps, although many recent discoveries
point in the opposite direction:
Credit: NASA
I The universe contains over 100 billion galaxies.
I The Milky Way contains over 100 billion stars.
I Thousands of exoplanets have been found; more than 40 in the habitable zone.
I Recent work in biogenesis indicates that the origin of life was not a particularly
unlikely event. This is also indicated by recent fossil finds, which show life arose
almost immediately (over 3.8 billion years ago) after the formation of Earth.
I P. Rincon, “Star’s seven Earth-sized worlds set record,” BBC, 22 Feb 2017.
I K. Chang, “Nearby star Ross 128’s planet may have conditions for life,” NY Times, 15 Nov 2017.
I R. F. Service, “‘RNA world’ inches closer to explaining origins of life,” Science, 12 May 2016.
I J. Cepelewicz, “Life’s first molecule was protein, not RNA, model suggests,” Quanta, 2 Nov 2017.
I P. D. Ward, D. Brownlee, Rare Earth: Why Complex Life is Uncommon in the Universe, Copernicus, 2000.
I C. Zimmer, “Scientists say Canadian bacteria fossils may be earth’s oldest,” NY Times, 1 Mar 2017.
23 / 27

Nick Bostrom’s “great filter”
Nick Bostrom has suggested that a “great filter” may explain theeerie silence. Possible examples:
I The origin of life was extremely improbable.
I The jump from prokaryote to eukaryote cells was extremely

improbable.
I Our combination of stable planetary dynamics and moderatetemperatures, over billions of years, is exceedingly rare.
Credit: Wikimedia

I A catastrophe (gamma-ray burst, neutron star merger, etc.)

invariably ends species like ours before they explore the cosmos.

Rejoinder: Given that no gamma-ray burst or neutron star merger has destroyed Earth
to date (over 4.5 billion years), it seems exceedingly unlikely that this will happen
within the next 20–50 years, during which time we will have ventured to the cosmos.

I Nick Bostrom, “Where are they? Why I hope the search for extraterrestrial life finds nothing,”
http://www.nickbostrom.com/extraterrestrial.pdf.

24 / 27

The “solitary” solution
Solution 9: WE ARE ALONE, within Milky Way if not beyond.
Rejoinder: It hardly seems credible that we are unique even in
the Milky Way (with over 100 billion stars and planets), muchless the entire universe (with over 100 billion galaxies).
Credit: publicdomainpictures.net

Solution 9 may be consistent with Occam’s razor, but it is an extreme violation of the“Copernican principle,” namely the hypothesis that there is nothing special about
Earth or humanity. Has the Copernican principle been completely overturned?
Many recoil at this solution (including the author), but what is the alternative?

25 / 27

Leading scientists on Fermi’s paradox
Even before the recent explosion of technology, many researchers concluded we are alone.
Paul Davies (British physicist-cosmologist):[M]y answer is that we are probably the only intelligent beings in the observable
universe and I would not be very surprised if the solar system contains the only life in
the observable universe.
John Gribbin (British astrophysicist):
They are not here, because they do not exist. The reasons why we are here form achain so improbable that the chance of any other technological civilization existing in
the Milky Way Galaxy at the present time is vanishingly small.
1. Paul Davies, The Eerie Silence: Renewing Our Search for Alien Intelligence, Houghton Mifflin Harcourt,
New York, 2010.
2. John Gribbin, Alone in the Universe, John Wiley, New York, 2011.
3. Peter D. Ward and Donald Brownlee, Rare Earth: Why Complex Life Is Uncommon in the Universe,
Copernicus Books, New York, 2000.
4. Stephen Webb, If the Universe Is Teeming with Aliens... Where Is Everybody? Fifty Solutions to Fermi’s
Paradox and the Problem of Extraterrestrial Life, Copernicus Books, New York, 2002.
5. P. S. Wesson, “Cosmology, extraterrestrial intelligence, and a resolution of the Fermi-Hart paradox,”
Q. J. Royal Astronomical Society, 31 (1990), pg. 161-170.

26 / 27

Fine tuning and Fermi’s paradox
If we are truly alone in the Milky Way or beyond, this greatly
magnifies the paradox of fine tuning — not only do we residein an incredibly fortunate universe, but we occupy anincredibly unique time and place within that universe.
Even if we are “only” extremely rare in the universe, this is amost important finding, with truly cosmic implications.
Credit: NASAWas the universe made for us? Or is our understanding of the laws of physics
fundamentally in error?
Either way, human existence is far more significant than anyone could have imaginedeven a few years ago.
Thanks!
This talk is available at: http://www.davidhbailey.com/dhb-fermi-2017.pdf.

27 / 27