Science is Seeing

Biology

Life has Order

Life uses Energy

(c) Response to the environment

(a) Order

(d) Regulation

(g) Reproduction (f) Growth and development

(b) Evolutionary adaptation

(e) Energy processing

Properties of Life

1 The biosphere

Hierarchy From biosphere…

…to organisms

Cell

8 Cells

6 Organs and organ systems

7 Tissues

10 Molecules

9 Organelles

50 µm

10 µm

1 µm

Atoms

Figure 1.3

…to cells and molecules and atoms

But the reductionist approach fails; biological systems cannot simply be understood in terms of components.

• Water is special (and it

is a common molecule

throughout the universe).

• Carbon is special (and it’s

the second most abundant

element made in stars).

• With a versatile chemical toolkit, the possibilities of

information storage and biological function are almost infinite. Alternate biologies are definitely possible! We just have to look for them. But the question is how…?

Unity of Life

In traditional tress of life based on species, we are usually placed at the top. We are special, the natural end point of all evolution up to this point.

Molecular Tree of Life

• The Modern Tree of Life

– Maps evolution via the gradual deviation of the base pair sequences in DNA or RNA.

– Does not depend on identifying or recognizing distinct species.

– Can track evolution back to the dawn of life but not with good time precision.

– Places us as a minute twig on the tree of life in an overwhelmingly microbial world.

Evolutionary Linkage through Cytochrome C

Organism # Deviant nuclic acids (in 110)

Human 0

Rhesus Monkey 1

Dog 13

Chicken 18

Rattlesnake 20

Tunafish 21

Moth 36

Wheat 43

Yeast 45

Next time you look into your beer glass,

acknowledge that there is kinship.

RNA

phenotype

replication

expression

The Central Dogma

…greatly simplified

DNA

RNA

proteins

Structure and function

of organism

replication

processing

processing

DNA

RNA

proteins

Structure and function

of organism

natural

selection

The Book of Life

Biology uses a four-letter “alphabet” of base pairs, coding proteins in a cell.

The delicate spiral ladder of DNA holds information equal to an encyclopedia.

The Genetic Code

The “Book” of DNA

Base pair 10 1 Letter

Codon 100 6 Word

Gene 10,000 1000 Sentence

Bacterium 10,000,000 1,000,000 Short book

Human 3,000,000,000 6,000,000,000 Encyclopedia

Level Atoms Bits Language analog

The “Tape” of DNA

Base pair 0.00000003 mm 0.03 mm Letter

Codon 0.0000001 mm 0.1 mm Word

Gene 0.05 mm 0.5 m Sentence

Chromosome 5 cm 500 m Short book

Human 2 m 20 km Encyclopedia

Level Actual Scale model Language

In biology, there is metabolic complexity.

In biology, there is structural complexity.

Extremophiles

Extreme Dryness

Extreme Cold

Extreme Heat

Extreme Radiation

Extreme Toxicity

Extreme Isolation

0.1mm Meet the amazing tardigrade, with its own phylum and many species, it’s got four pairs of legs, a digestive system, a single gonad, and it can go into a very dry suspended state (cryptobiosis) for over a thousand years, moving by being carried on the wind and also in fur of animals.

Exobiology

Life on Other Worlds

Epicurus “Letter to Herodotus” There is an infinite number of worlds, similar to ours, and an infinite number of different worlds…One must agree that in all these worlds, without any exception, there are animals, plants, and all the living things we observe.”

Thales Epicurus Lucian Democritus

But the primacy of Aristotle’s geocentric cosmology mostly squashed a discussion of the plurality of worlds until the Copernican revolution.

Evidence that ingredients for life

are widely available in time and space

Evidence that planet and moon

habitable locations are abundant

Pale Blue Dot

Earth, backlit against a gossamer ring of Saturn, is almost certainly not a unique host for biology.

What might be, but isn’t

Majority of the biosphere is

still unexplored.

Over 99% of microbes have

not yet been cultured.

Only remote sensing through

most of the Solar System.

A small fraction of habitable planets/moons discovered.

A tiny fraction of SETI search space explored.

What We Know

(and don’t…)

Isn’t

Is

Imaginable

Possible

WHAT IS AND ISN’T

Using Carbon

Using Planets

EXOBIOLOGY

Recognizable Life

Unrecognizable Life

DNA-Based

Origin of Life

• The “life in a bottle experiments of Miller and Urey in the 1950’s didn’t create life; they just showed how plausible early Earth conditions could have led to amino acids and other building blocks of life. • More recent lab experiments show how vesicles or simple cell precursors could have formed and concentrated and amplified RNA fragments inside. • Chemical complexity can build on itself and some form of chemical “natural selection” may have preceded biology.

Evolution

When a tall tree grows from a tiny seed where does the mass come from: (a) it was in the seed, (b) soil, (c) water, or (d) air?

Life’s Great Innovation

6H2O + 6CO2 → C6H12O6 + 6O2

Photosynthesis

6H2O + 6CO2 → C6H12O6 + 6O2

water + carbon dioxide + light → glucose + oxygen

Plants take in water and carbon dioxide and rearrange the molecules into organic material (hydrocarbons) like cellulose, respiring oxygen.

In mass units: 10 + 22 → 16 + 16 (water) (air) (plant) (air)

Plants are 2/3 water but 90% of the water is transpired, so only 1 unit from water and 6 from air—carbon gets snatched from the air!

A 200 meter object that hit in northern Arizona 35,000 years ago left a kilometer-wide crater.

A 100 meter object that hit Siberia in 1908, and was luckily far from any population center. The 30 meter object that hit Chelyabinsk in 2013 did not cause deaths either.

A world-wide layer rich in iridium, found most often in extraterrestrial material, covered Earth 65 million years ago.

Clinching evidence for an impact as the cause of the mass extinction came with the discovery of an impact crater of the right age just off the coast of Mexico.

Evolution is contingent. There are so many branching points and random influences to evolution that another set of experiments might give very different outcomes.

Pollard 3 Plants animals fungi

Plants Fungi

Animals

Evolution of all animals in terms of DNA

Science is Seeing

Intelligence

Termite mounds are engineering marvels, higher than our best skyscrapers, scaled to organism size. In their construction five temp control mechanisms.

Social insects have complex behavior, specialized function and communication by chemical means.

Intelligent function is distributed within the colony or hive, rather that individuals. How might this evolve?

Alex the parrot was talkative and playful, coming up with the concept of zero.

Rats are ticklish and curious, personality traits are seen, they can anticipate sex, and reflect on their thinking processes (meta-cognition).

Are we “off the chart” smart?

No natural enemies

Large brains

Complex language

Social animals

Mate for life

Bombs, Internet, Cars

ORCAS HUMANS

× ×

After four billion years of life on Earth, homo sapiens emerged to dominate the planet and venture into space. Was this just a fluke or did something like this happen on distant planets, maybe long ago?

Apes

A recent surge in evolution vaulted us to the top of the tree in terms of brain size.

Weird Life

A Bit Weird:

Fairly Weird:

Mostly Weird:

Totally Weird:

Prokaryotes, eukaryotes, but different cell types Novel symbiosis, gene and organism swapping Non-cellular, networks as opposed to containers Planet-scale architecture, geo-engineering

High Level Architecture Not limited by mutation & selection; Evo-Devo toolkit: genes, organisms

A Bit Weird:

Fairly Weird:

Mostly Weird:

Totally Weird:

Different amino acids, or bases for nucleic acids Not DNA-RNA-Proteins (the “Central Dogma”) Non-carbon, non-water (silicate, ethane/methane) High density biochemistry, molecule-scale organisms

Bacterial Communities Evolution timescale is very rapid; information density ~ 1012 bits/cm3

Companionship

Technology Intelligence

Technology

Multi-celled

Multi-celled: Networked, diverse biological function

Intelligence: High level processing, consciousness

Technology: Control of environment, space travel

Thresholds in Evolution

0 4 8 Gyr

10

20

30 ly

+108 more

Earth

?

?

?

Green = stars with planets

Blue = stars with Earths

The couple of hundred solar systems found so far, nearby, under 30 light years, mostly.

A billion habitable worlds in our galaxy, and 100 billion galaxies…

There are likely to be ~108 Earth-like planets in the Milky Way, 1018 in the Universe, and there’s been 8 billion years for life to evolve before Earth formed.

Drake Equation

DRAKE EQUATION

Stars in MW

Stars in Universe

With Sentience

With Earths

With Life

DRAKE EQUATION

Stars in MW

The Drake Equation

The number N of intelligent communicative civilizations in our galaxy

can be estimated by the Drake equation (note the huge uncertainties!)

where

•R is the yearly rate at which stars form in the galaxy (1 yr-1)

•fp is the fraction of stars that possesses worlds (~0.5)

•n is the number of worlds with environment suitable for life (~4)

•fl is the fraction of worlds on which life actually develops (~0.5)

•fi is fraction of these worlds in which life gets intelligence (10-6-1)

•fc is fraction of intelligent life forms that develops culture capable

of interstellar communication (10-3-0.1)

•L is time that this culture devotes to communication (103-106 yr)

This deductive framework embeds some increasingly well-determined

numbers and some factors that are indeterminate. The elements in the

formalism are probably not independent, so it has limited utility.

N = R · fp · n · fe · fi · fc · L

Product ~1 (~determined)

Product 10-6-105

(indeterminate)

Thomas Wright (1750): 170,000,000 habitable worlds in the galaxy.

Towards a New Framework D

ura

tio

n (

y)

Habitability

1010

109

108

107

106

0 1

P (A | B) = n (AB) / n (B)

P (A | B) is probability of A, given B

n (AB) is # times both A and B occur

n (B) is # times B occurs

In general, P (A | B) ≠ P (B | A)

Bayes Theorem: P (B | A} = P (A | B) x P (B) / P (A)

Probability density f (A | θ), may be normal θ = (μ,σ2), or not

H = f (C,E,S | θ) Chemistry is f (metallicity, world dist) Energy is f (“solar” L, world M) Stability is f (stellar ρ, world ε, debris)

Minimal (microbial) life

Maximal (intelligent) life

Number of “Living” Worlds

In galaxy: 108 In universe: 1016

(and, conservatively, with technology) In galaxy: 102 ? In universe: 1010 ?

Communication

0 1 2 3 410

12

14

16

18

20

0 1 2 3 4

10

12

14

16

18

20

300nm

500nm

700nm

log

10P

(W

)

log10D (pc)

Optical SETI

MAGIC parameters:

Pulsed laser, 1ns, 20 kJ

Pulsed level power ~1011 W

230 m2 reflector area

Photon count, weak excess

↑ closest star Galactic ↑ Center

Soon, all PW pulsed lasers and all Arecibos emitting, detected out to 1kpc (spanning 108 stars)

So far, the search has met with 50 years of silence. But search

capacity increases exponentially

The Fermi Question

As originally phrased by Erico Fermi, it seems a reasonable proposition that: • Our civilization and technology is very young; life forms with much more advanced technology could have remarkable capabilities. • A modest extrapolation of current technology allows us mine asteroids or moons, and create probes that could create replicas of themselves and propagate through the galaxy. • There are many likely sites for complex life, and plenty of time for technology to develop, billions of years before Earth formed.

They’ve Already Visited

Curiously, UFO sightings dominate in rich Western countries, in July and in August, and during geopolitical crisis and activity in the US space program.

A Major Problem: Science literacy is low, around 10%, and pop culture is awash in all kinds of pseudoscience, magical thinking, superstition, and supernatural or irrational belief systems.

They don’t exist

They are very rare

They are unrecognizable

They are inscrutable

They don’t care

They created us

Responses to Fermi

Life as Computation

Origin of Life

Today

Would we be surprised if life beyond Earth: Doesn’t

exist Has the same basis as our life

Doesn’t use DNA

Need not use carbon

Could exist without stars

Is unrecognizably different from us

Doesn’t use cells

Artificial Life

• Theoretical biology (exploring possible or potential biologies)

• Artificial, not unreal (new ways to meet the definition of life)

• Bottom up, not top down (generating complexity from simple parts)

• Synthesis, not analysis (the outcomes are not prescribed a priori)

• Leverages emergence (attributes like symbiosis are emergent)

• Role of computation (computation could be analog or literal)

Despite the fact that all known life is based on one form of organic chemistry, it is worth asking whether or not known mechanisms are the only ways to create life and intelligence.

This emerging and interdisciplinary field is characterized by:

A-life research (and its cousin, AI) have several agendas: 1. Modeling to gain a deeper understanding of biological (thought) processes 2. Simulation to understand the possible forms of biology (brain function) 3. Exploration of pure computation as a basis for life (intelligence)

• Randomness, with predictable macroscopic behavior.

• Solutions to differential equations (e.g. EM, QM)

• Transcendental and prime numbers.

• Turing machines (universal computers).

• Axiom systems beyond traditional mathematics.

• All of this is still true if: there is no grid, no fixed geometry (networks), more than 2D, constraints instead of rules.

Repeated application of simple rules leads to patterns, randomness, complexity. Cellular automata generate:

© Scott Camazine

More than a Game

• Complexity increases dramatically with recursion/feedback.

• DNA base pair sequence is mostly random.

• Random mutation is unlikely to produce optimal organisms.

• Easy to misinterpret evolution or complexity (skins,shells).

• Simple programs readily lead to complexity (genetic

algorithms).

Computation and Evolution

Biological evolution is just one example of a wide

range of computationally equivalent possibilities

(none of these are at all deterministic)

Biology may even just be a stage in our evolution – witness

current and future merger of human/machines/computers.

“Never make predictions, especially about the future.” Casey Stengel, Baseball Manager (ENIAC, from 1944, weighed 30 tons, dimmed Philly when it was running, and was a million times slower than a PC) “I think there is a world market for maybe 5 computers” Thomas Watson, IBM Chairman, 1943 “Computers in the future may weigh less than 1.5 tons” Popular Mechanics Magazine, 1949 “There’s no reason anyone would want a home computer” Ken Olsen, CEO, Digital Equipment, 1977

Futurology

106 105 104 103 100 10 Now 10 100 103 104 105 106

Years Ago Years Ahead

Now

Internet

Car, plane

Medicine

Agriculture

Tools

Humans

Genetics

Cyborgs

Star travel

??

????

??????

Simulation

?

IS TO

AS IS TO

Gaming Analogy

The Simulation Argument

(due to Bostrom, Dainton)

In an argument based on probability theory and logic, one or more

of the following propositions must be true:

1. The chances that a species at our level of development can avoid

going extinct before technological maturity are negligibly small.

2. Almost no technologically mature civilizations are interested in

running simulations of minds like ours.

3. You are almost certainly in a simulation.

• Simulation Hypothesis: for every non-virtual early 21st century human life there are many more subjectively indistinguishable (or broadly similar) virtual lives. The argument assumes substrate independence, or non-carbon based computational forms of life.

REAL VIRTUAL

Possibility 1 is gloomy but might be true. If increasingly advanced technologies are increasingly dangerous, we and others may destroy ourselves before we reach maturity. Possibility 2 requires convergence among all sufficiently advanced civilizations. This seems implausible on the face of it. Suppose 1 is false. Then a significant fraction of all species at our level of development become technologically mature. Suppose, in addition, 2 is false. Then these mature civilizations will use some significant fraction of their resources to run computer simulations of minds like ours. The resources required are not large. If 1 and 2 are false, there will be an astronomically huge number of simulated minds like ours, vastly more than the number of organic brains. By the principle of mediocrity, you probably have a simulated mind. If 1 and 2 are false, you must accept 3, the Simulation Hypothesis. It is not logically coherent to reject all three propositions. There is no reason anyone living in a simulation would be able to detect that fact, unless the simulators permitted it.

100 billion humans x 50 years/human x 3 million secs per year x 1014 – 1017 ops per brain per second

Typical human brain: operations per second = 1014-1017

Ops required for 1 ancestor simulation = 1032-25

(assumption: humankind will be superseded in a few centuries)

10,000 processors working for a year

Around 2050 Quantum computers should continue

the exponential trend of Moore’s law

TECHNOLOGICAL MATURITY?

R

Everyone believes their own lives to be real, non-virtual…

I’m real!

I’m real!

I’m real!

I’m real!

I’m real!

I’m real!

I’m real!

I’m real!

I’m real!

R

• Your conviction that your life is non-virtual is no better founded than anybody else’s.

• So, if the Simulation Hypothesis is true, the odds of your life being non-virtual are low

I’M REAL

Simulation Argument: Conclusion

‘My life is real’

High probability

Low probability

‘SH is true’

High probability

Low probability

Probability assignments (not to scale)

Another Copernican Shift

virtual

real

sum total of conscious lives

?

IS TO

AS IS TO

Evolution Analogy

• Nicolai Kardashev’s classification of civilizations: Type 0: not in complete control of planet’s energy Chemical propulsion, solar sails Type I: harnesses energy output of an entire planet (1011 W) Nuclear propulsion, laser sails Type II: harnesses entire output of their host star (1026 W)

Antimatter drives Type III: colonizes and harnesses output of entire galaxy (1037 W) ??? • To which could be added (with implications for SETI): Type Ib: non-electromagnetic signals with low opacity Neutrino beams, dark matter beams Type IIb: orchestrated stellar cataclysms (visible across universe) Supernovae, gamma ray bursts Type IIIb: signals from manipulation of space-time gravity waves, baby universes

Civilizations: Speculation