NSCI 314

LIFE IN THE COSMOS

19 - LIFETIMES OF TECHNOLOGICAL CIVILIZATIONS

Dr. Karen Kolehmainen Department of Physics, CSUSB

http://physics.csusb.edu/~karen/

RECALL THAT THE LEAST WELL-KNOWN FACTOR IN THE DRAKE EQUATION IS

L = AVERAGE LIFETIME OF A TECHNOLOGICAL CIVILIZATION

ESTIMATING L IS IMPORTANT BECAUSE:

1. IT ALLOWS US TO USE THE DRAKE EQUATION TO ESTIMATE HOW COMMON EXTRATERRESTRIAL CIVILIZATIONS ARE, AND,

2. EVEN MORE IMPORTANTLY, WE WOULD LIKE TO KNOW HOW LONG WE CAN EXPECT THE HUMAN RACE TO SURVIVE!

FACTORS THAT MAY LIMIT THE LIFETIME OF TECHNOLOGICAL CIVILIZATIONS IMPACTS BY ASTEROIDS, COMETS,

OR LARGE METEORITES POPULATION GROWTH CLIMATE CHANGE (GLOBAL

WARMING) POLLUTION DISEASE WAR LOSS OF INTEREST IN

COMMUNICATION

FACTS ABOUT THIS IMPACT

MOVING AT 10 to 30 km/Sec

PASSES THROUGH HOUSE IN 0.01 Sec at 10 km/sec

ENERGY RELEASE = 1 KILOTON BOMB

CRATER DIAMETER = 120 FEET (TYPICALLY AT LEAST 10x THE DIAMETER OF THE

IMPACTING OBJECT)

CRETACEOUS-TERTIARY BOUNDARY

BOUNDARY BETWEEN TWO GEOLOGICAL PERIODS 65 MILLION YEARS AGO

ROCKS DEPOSITED BEFORE THE BOUNDARY CONTAIN DINOSAUR FOSSILS

ROCKS DEPOSITED AFTER THE BOUNDARY CONTAIN NO DINOSAUR FOSSILS

BOUNDARY MARKED BY THE EXTINCTION OF 80% OF LAND AND MARINE ORGANISMS (NOT JUST DINOSAURS)

RECOVERY, AS DOCUMENTED IN THE FOSSIL RECORD, TOOK AT LEAST 5,000 YEARS

EXTINCTION OF THE LARGE DINOSAURS

LUIS & WALTER ALVAREZ DISCOVERED (1980):

LARGE EXCESS OF IRIDIUM, A RARE-EARTH ELEMENT,

LOCATED IN ROCKS DEPOSITED AT THE CRETACEOUS-TERTIARY BOUNDARY.

THIS LAYER HAS BEEN FOUND WORLD-WIDE.

IRIDIUM IS KNOWN TO BE PRESENT IN METEORITES AT MUCH HIGHER ABUNDANCES THAN IN EARTH ROCKS.

TO SUPPLY THE ESTIMATED AMOUNT OF IRIDIUM WOULD REQUIRE A METEORITE 10 km ACROSS.

METEORITE ESTIMATED TO BE 10 km ACROSS (SOMETHING THIS SIZE IS USUALLY THOUGHT OF AS AN ASTEROID)

CRATER ESTIMATED TO BE 150-200 km ACROSS

PEMEX DISCOVERED A BROAD SUBTERRANEAN ARC OFFSHORE YUCATAN PENINSULA (1978)

SUBSEQUENT DISCOVERY OF 180 km CRATER AT CHICXULUB (STRUCTURE IS BURIED)

CRATER HAS BEEN DATED AND IS 65 MILLION YEARS OLD

99% of Atmosphere Below This Level

Asteroid 10 km across moving at

30 km/sec

Mt. Everest8.7 km

Ocean Floor 3 km

ENERGY OF A MOVING BODY

DEPENDS ONLY ON THE MASS (M) AND VELOCITY (V)

(BELOW EQUATION CORRECT ONLY IF V<< c)

KINETIC ENERGY = (1/2) MV²

FOR A 10 km DIAMETER ASTEROID

M = 2 TRILLION METRIC TONS = 2,000,000,000,000,000 kg

V = 30 km/s = 30,000 m/s

KE = 1024 JOULES OF ENERGY = ONE TRILLION TRILLION JOULES(EQUIVALENT OF 95 DAYS OF SOLAR RADIATION ABSORBED OVER ENTIRE EARTH)

ENERGY RELEASE ON IMPACT

UPON IMPACT, ALL ENERGY EVENTUALLY TURNS TO HEAT. IMPACT PRODUCED A FIREBALL 200 km ACROSS AND WITH A TEMPERATURE OF 100,000 K

RESULTS: GLOBAL EFFECTS

FIRESPOSSIBLE TRIGGERING OF EARTHQUAKES POSSIBLE TRIGGERING OF VOLCANIC ERUPTIONSCLIMATE CHANGESEXTINCTION OF MANY LIFE FORMS

EFFECTS OF LARGE IMPACT

FIRESTORMS ~ DAYS TO WEEKSFIREBALL INDUCED FIRES UP TO SEVERAL THOUSAND

KILOMETERS FROM IMPACT SITEGLOBAL FIRES DUE TO SECONDARY IMPACTS

IMPACT WINTER ~ 1 YEARGLOBAL CLOUD COVER, ACID RAIN, SALT RAIN, HIGH LEVEL OF DUST, REDUCED TEMPERATURE

EXTINCTION OF NUMEROUS LIFE FORMS, ESPECIALLY LARGE ONES MANY PLANTS DIE DUE TO FIRES AND DARKNESSMANY ANIMALS DIE DUE TO INTERRUPTION OF THE FOOD CHAIN

ULTRAVIOLET SPRING ~ 1 - ? YEARSDESTRUCTION OF OZONE LAYERUV INTERRUPTS PHOTOSYNTHESIS UV INCREASES MUTATION RATES, EVEN IN OCEANSFURTHER EXTINCTIONS

MASS EXTINCTIONS

HUMAN-

CAUSED

DINOSURS E

TC.

SMALL

ER ASTEROID

?

MOST L

AND & S

EA

MOST F

ISHES

MANY IN

VERT.

MARIN

E SPECIE

S

0 400300200100 500

MILLIONS OF YEARS AGO

ASTEROID IMPACTS EARTH-CROSSING ASTEROIDS – ASTEROID’S

ORBIT INTERSECTS EARTH’S ORBIT.

ONE OF THEM HITS EARTH EVERY 50 TO 100 MILLION YEARS ON THE AVERAGE.

ORBITS ARE NOW BEING MAPPED, SHOULD BE DONE IN 10 YEARS. THEN WE WILL BE ABLE TO PREDICT FUTURE IMPACTS.

HUMANS MUST THINK ABOUT PROTECTION FROM IMPACTS! BEST METHOD – USE EXPLOSIONS NEAR ASTEROID TO ALTER ITS ORBIT SLIGHTLY. DON’T BLOW IT UP!

POPULATION GROWTH THERE ARE CURRENTLY 6.7 BILLION HUMAN BEINGS

ON EARTH.

HUMAN POPULATION IS GROWING AT A RATE OF: – 1.4% PER YEAR– 88 MILLION PER YEAR– 7 MILLION PER MONTH– 240,000 PER DAY– 18,000 DURING OUR CLASS PERIOD TODAY

IF YOU ARE 20 YEARS OLD, THE WORLD’S POPULATION HAS GROWN BY 1.8 BILLION SINCE YOU WERE BORN.

THE MAJORITY OF ALL HUMAN BEINGS WHO HAVE EVER LIVED ARE ALIVE TODAY!

HOW WILL WE FEED EVERYONE? THE EARTH IS NOT INFINITE! IF GROWTH CONTINUES, AT SOME POINT IT WILL BECOME IMPOSSIBLE TO FEED EVERYONE, EVEN IF FOOD IS DISTRIBUTED EQUALLY TO EVERYONE.

17 MILLION CHICKENS

THEY EAT 40% OF THE WORLD’S GRAIN

HUMANS “CONTROL” ABOUT 90% OF ALL LARGE ANIMALS

4.3 BILLION LARGE DOMESTICATED ANIMALS

IN ADDITION TO FEEDING HUMANS, WE MUST ALSO FEED:

BY MORE SENSIBLE USE OF EXISTING RESOURCES (BETTER LAND USE, VEGETARIAN DIETS, DEVELOPMENT OF NEW CROPS), WE CAN DELAY THE PROBLEM, BUT NOT SOLVE IT!

POPULATION GROWTH GOVERNED APPROXIMATELY BY

“EXPONENTIAL GROWTH” – THIS TERM HAS A PRECISE MATHEMATICAL MEANING.

EXPONENTIAL GROWTH OCCURS WHENEVER THE RATE OF GROWTH DEPENDS ON HOW MANY ARE ALREADY THERE - THE MORE PEOPLE ARE ALIVE, THE MORE OF THEM THERE ARE TO REPRODUCE.

EXPONENTIAL GROWTH IS CHARACTERIZED BY A “DOUBLING TIME”, i.e., THE TIME NEEDED FOR THE NUMBER TO DOUBLE ALWAYS REMAINS THE SAME.

DOUBLING TIMES

DOUBLING TIME

Example: You have $5,000 in savings earning 5% per year.

You will have $10,000 in 14 years.

Example: Inflation is running at 1.5% annually.

In 47 years, the average cost of products will have doubled.

~~70

% GROWTH RATE

Example: The world’s human population is growing at a rate of 1.4% per year. The current population is 6.7 billion.

In 50 years the world population will be 13.4 billion.

HISTORY OF HUMAN POPULATION

YEAR

200AD

1300

1750

1900

1975

2000

DOUBLING TIME (YRS)

1100

450

150

75

50

POP.

200 M

400 M

800 M

1.6 B

3.2 B

6.0 B

ANNUAL GROWTH

0.06%

0.16%

0.47%

0.93%

1.4%

IT TOOK ABOUT 1 MILLION YEARS FOR EARTH’S HUMAN POPULATION TO REACH 1 BILLION .

THE NEXT BILLION TOOK ONLY 100 YEARS.

THE LAST BILLION TOOK ONLY 12 YEARS.

POPULATION GROWTH DOUBLING TIME IS NOT CONSTANT,

BUT RATHER DECREASES WITH TIME!

THEREFORE, POPULATION GROWTH IS EVEN FASTER THAN EXPONENTIAL GROWTH!

PAST AND FUTURE?

YEAR

200AD

1300

1750

1900

1975

2000

2050

2100

2150

2200

POP.

200 M

400 M

800 M

1.6 B

3.2 B

6.0 B

12 B

24 B

48 B

96 B

WHAT IS EARTH’S CAPACITY?

ASSUMING A 50 YEAR DOUBLING TIME FROM 2000 ONWARD

SOLUTIONS TO POPULATION GROWTH

POPULATION GROWTH WILL BE HALTED. THE ONLY QUESTION IS HOW WILL IT BE HALTED.

BY OUR INTENTIONAL ACTIONS (i.e., BIRTH CONTROL), OR…

BY EVENTS BEYOND OUR CONTROL (FAMINE, POLLUTION, DISEASE, WAR). THESE HAVE BEEN THE “TRADITIONAL” METHODS OF POPULATION CONTROL THROUGHOUT MOST OF HUMAN HISTORY.

THE ANSWER IS UP TO US!

CLIMATE CHANGE GLOBAL WARMING DUE TO THE GREENHOUSE

EFFECT HUMAN INDUSTRIAL ACTIVITY AND BURNING OF

FOSSIL FUELS ADDS GREENHOUSE GASES TO THE ATMOSPHERE.– CARBON DIOXIDE– METHANE– WATER VAPOR

THE EVIDENCE THAT GLOBAL WARMING IS OCCURRING AND IS CAUSED LARGELY BY HUMANS IS OVERWHELMING .

THE VAST MAJORITY OF SCIENTISTS AGREE ON THIS.

EVEN IF WE STOP ADDING GREENHOUSE GASES NOW, WARMING WILL CONTINUE FOR A THOUSAND YEARS.

CLIMATE CHANGE WARMING ISN'T UNIFORM - SOME AREAS GET

WARMER, SOME GET COOLER PRECIPITATION PATTERNS WILL CHANGE – SOME

AREAS GET WETTER, SOME GET DRIER. RISE IN SEA LEVEL AS GLACIERS MELT

– COASTAL AREAS WILL BE FLOODED MORE SEVERE STORMS SOME SPECIES WILL BECOME EXTINCT AS POLAR ICE MELTS, MORE SOLAR HEAT IS

ABSORBED, INCREASING WARMING EVEN MORE. AS OCEANS WARM, MORE WATER EVAPORATES,

INCREASING THE GREENHOUSE EFFECT FURTHER. (WATER VAPOR IS A GREENHOUSE GAS.)

POLLUTION HUMANS ARE POLLUTING:

– AIR– WATER– FOOD SOURCES

MANY POLLUTANTS PERSIST IN THE ENVIRONMENT FOR VERY LONG TIMES.

OVERPOPULATION EXACERBATES THE PROBLEM:– MORE PEOPLE PRODUCE MORE POLLUTION.– POPULATION PRESSURE FORCES PEOPLE TO MOVE

INTO MORE POLLUTED ENVIRONMENTS.

DISEASE MANY DISEASE-CAUSING BACTERIA HAVE

EVOLVED RESISTANCE TO ANTIBIOTICS.– THE BIGGEST CAUSE OF THIS IS ANTIBIOTICS THAT ARE

ADDED TO ANIMAL FOOD.

– ANTIBIOTICS ARE ADDED IN ORDER TO INCREASE THE EFFICIENCY OF PRODUCTION OF FOOD ANIMALS.

– OVERPOPULATION INCREASES THE PRESSURE TO ADD ANTIBIOTICS IN ORDER TO INCREASE FOOD PRODUCTION.

THERE ARE DISEASES THAT KILL ESSENTIALLY EVERYONE WHO GET THEM AND ARE HIGHLY CONTAGIOUS (EBOLA, FOR EXAMPLE).

NEW DISEASES APPEAR OCCASIONALLY (AIDS, FOR EXAMPLE).– CAN MOVE FROM OTHER SPECIES INTO HUMANS

DISEASE OVERPOPULATION AND POLLUTION

INTRODUCE NEW DISEASES AND MAKE EXISTING ONES WORSE.– OVERPOPULATION FORCES PEOPLE TO MOVE

INTO AREAS WHERE THEY'VE NEVER LIVED BEFORE, EXPOSING THEM TO DISEASES CARRIED BY ANIMALS.

– OVERPOPULATION DECREASES THE AVAILABILITY OF MEDICAL CARE TO MANY PEOPLE.

– POLLUTION CAN DAMAGE PEOPLE'S IMMUNE SYSTEMS, SO THAT THEY BECOME MORE SUSCEPTIBLE TO DISEASE.

WAR HUMANS HAVE ALWAYS ENGAGED IN

WAR, BUT... UNTIL RECENTLY, THIS WAS NOT A

THREAT TO THE ENTIRE HUMAN SPECIES.

WE COULD WIPE OURSELVES OUT VIA ANY OF THESE WEAPONS OF MASS DESTRUCTION:–NUCLEAR WEAPONS–BIOLOGICAL WEAPONS–CHEMICAL WEAPONS

WAR NUCLEAR WEAPONS

– THE WORLD INVENTORY OF NUCLEAR WEAPONS IS SUFFICIENT TO KILL EVERYONE ON EARTH MANY TIMES OVER.

– IF A SUFFICIENTLY LARGE NUMBER OF NUCLEAR EXPLOSIONS TOOK PLACE, IT WOULD TRIGGER GLOBAL EFFECTS, INCLUDING A “NUCLEAR WINTER.”

– SINCE THE END OF THE “COLD WAR,” WE HAVE REDUCED THE NUMBER OF NUCLEAR WEAPONS FROM ABOUT 65,000 TO ABOUT 20,000.

WAR BIOLOGICAL WEAPONS

–NATURALLY OCCURRING OR ENGINEERED ORGANISMS

–OFFENSIVE WEAPONS ARE BANNED BY MULTILATERAL TREATY

– THE TREATY ALLOWS DEFENSIVE WEAPONS

–SOME COUNTRIES PROBABLY HAVE OFFENSIVE WEAPONS IN SPITE OF TREATY

WAR CHEMICAL WEAPONS

–BANNED BY MULTILATERAL TREATY–48,000 TONS ARE ESTIMATED TO

EXIST–ARE GRADUALLY BEING

DESTROYED TO COMPLY WITH TREATY (ABOUT 1/3 ALREADY DESTROYED)

–SOME COUNTRIES MAY HAVE SECRET STOCKPILES

ARGUMENTS FOR SHORT L ASTEROID IMPACTS OCCUR REGULARLY. HUMAN POPULATION CONTINUES TO GROW RAPIDLY, BUT

THE RESOURCES OF THE PLANET ARE LIMITED. HUMAN ACTIVITY CONTINUES TO ADD GREENHOUSE GASES

TO THE ATMOSPHERE. HUMANS CONTINUE TO POLLUTE THE PLANET AND POISON

OUR OWN ENVIRONMENT. HUMANS CONTINUE TO KILL EACH OTHER IN WARS, AND VIA

POLITICAL AND ECONOMIC DECISIONS. EXISTING NUCLEAR WEAPONS COULD DESTROY THE ENTIRE

HUMAN POPULATION MANY TIMES OVER. MANY IMPORTANT WORLD DECISIONS ARE MADE BY

POLITICAL, BUSINESS, AND RELIGIOUS “LEADERS” WHO DON’T TAKE THESE PROBLEMS SERIOUSLY .

ARGUMENTS FOR LONG L SOON WE WILL HAVE THE TECHNOLOGY TO PROTECT

OURSELVES AGAINST ASTEROID IMPACTS. EDUCATION CAN HELP CONVINCE PEOPLE OF THE DANGERS

OF OVERPOPULATION, CLIMATE CHANGE, AND POLLUTION. SCIENCE AND TECHNOLOGY CAN HELP US CLEAN UP

POLLUTION, LIMIT GREENHOUSE GAS EMISSION, AND CURE & PREVENT DISEASE.

INTERNATIONAL PRESSURE MAY HELP PREVENT WARS, OR AT LEAST LIMIT THE NUMBER OF DEATHS.

WE HAVE ALREADY DECREASED THE NUMBER OF WEAPONS OF MASS DESTRUCTION ON THE PLANET THROUGH TREATIES, SO THIS CAN BE DONE.

IF WE COMMUNICATE WITH ALIEN CIVILIZATIONS, WE MAY LEARN FROM THEM HOW TO SOLVE SOME OF THESE PROBLEMS.

CLOSING COMMENTSEITHER N = 1, AND HUMANS ARE THE ONLY TECHNOLOGICAL CIVILIZATION IN OUR GALAXY, OR… N > 1, AND OTHER (MAYBE MANY OTHER) CIVILIZATIONS EXIST.

IN EITHER CASE, HUMANS ARE UNIQUE. IF LIFE DOES EXIST ELSEWHERE, IT WILL BE VERY DIFFERENT FROM US. THEREFORE WE ARE WORTH PRESERVING!

WE WILL NEVER FIND OUT IF EXTRATERRESTRIAL LIFE EXISTS IF WE DESTROY OURSELVES (OR ALLOW OURSELVES TO BE DESTROYED) FIRST!

CLOSING COMMENTSBY OUR ACTIONS, WE DETERMINE OUR OWN LIFETIME AS A TECHNOLOGICAL CIVILIZATION, AND OUR CONTRIBUTION TO THE VALUE OF “L.” (L IS THE AVERAGE LIFETIME OF A TECHNOLOGICAL CIVILIZATION. EACH CIVILIZATION, INCLUDING OURS, HELPS TO DETERMINE THIS AVERAGE LIFETIME.)

LET’S CHOOSE TO MAKE THE LIFETIME OF HUMAN CIVILIZATION AS LARGE AS POSSIBLE!