—arthur c. clarke universe or we are not. both are equally...
Post on 01-Apr-2018
214 Views
Preview:
TRANSCRIPT
Listening in the DarkThe search for extraterrestrial intelligence
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”
—Arthur C. Clarke
Why search for life?
● To prove whether life is unique● To answer scientific questions about the nature of life● We may be able to learn from other intelligent life● To discover whether we are alone
How do we search?
Methods for finding life:
● Listen for “noise pollution”
● Search for intentional communication
● Look for modification of the Universe
● Send a message
A feeble light in a vast sea
→ Radio waves are a form of light. Thus, they propagate at the speed of light, but also get weaker the farther they travel.
Distance traveled
Speed of light(299,792,458 m/s)
Time traveled
Starting brightness
Distance traveled
Observed brightness
A feeble light in a vast sea
→ In 1936, a TV broadcast of Adolf Hitler opening the Berlin Olympics became the first radio signal to leave the Earth.
In 1937, that signal was 1 lightyear from Earth.
In 2016, that signal is 80 lightyears from Earth, but it is 6,400 times weaker than in 1937.
SETI today
→ The Allen Telescope Array is engaged in a search for radio signals of extraterrestrial intelligence.
So far, it has found nothing.
A cosmic telegram
Pros
● A strong signal would be easier to detect
● Would give exact source of message● Message more likely to be
unambiguous
Cons
● ET would have to be directly contacting us
● We’d need to know which color to look for
→ A laser generates a beam of highly-focused light. Lasers require relatively little energy to be extremely bright in a single direction. Lasers are monochromatic, which means they contain light of only one color.
Go big or go home
Pros
● Megastructures give a strong indication of the advanced nature of a species
Cons
● Structures built with our current understanding of materials would block only a little of the star’s light
● The signal of a megastructure is easily confused with a natural process
→ A Dyson sphere is a hypothetical structure that encompasses much or all of a star in order to harvest its energy. It’s theorized that it may be
common for advanced species to construct them.
A glimmer in the dark
Pros
● Would give us information about the behavior of an extraterrestrial species
Cons
● Artificial light is likely extraordinarily dim in comparison to the star
● The light may not be in the visible spectrum
→ A key human innovation was the development of artificial light. If other species have also developed it, light may still be visible from the
nightside of a planet.
A message for the stars
→ In 1977, NASA launched the Voyager 1 and Voyager 2 spacecraft. Their mission was to explore the outer Solar System for the first time.
They also carried a message.
Each message was designed to last for a billion years.
Small group discussion
You are sending a message to intelligent life in the Universe. You may only include images and sounds.
What do you send?
Contents of the Golden Record
Sounds
● Greetings in 55 languages● Sounds from nature
○ Wind, birds, volcanos, a train, a kiss
● 90 minutes of world music○ Mozart, Chuck Berry, others
● An hour-long recording of brain waves
Images (116)
● The visited planets● Structure of DNA● Human anatomy● Snowflakes● Jane Goodall and chimps● Supermarket● Taj Mahal● Sunset
“To the makers of music – all worlds, all times”
“This record represents our hope and our determination and our goodwill in a vast and awesome universe.”
– Jimmy Carter
The universal language
→ The principles of mathematics are believed to be constant across the Universe. They may offer a connection between species.
How would we know?
→ Explicit contact from another lifeform would require the expression of knowledge unique to intelligent life.
Fibonacci sequence
→ The Fibonacci sequence is the sequence of numbers generated by starting with 0 and 1 and adding pairs from there.
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...
The golden ratio
→ The golden ratio Φ is a number found throughout mathematics and nature.
Two numbers are said to be in the golden ratio if:
Φ = 1.6180339887…
Pi
→ The ratio of the circumference of a circle to its diameter is called π
π = 3.14159265358979323846264338327950288419716939937510...
The Kardashev scale
→ The Kardashev scale is a hypothetical classification system for how advanced an intelligent species is.
Type 1: The species is capable of harnessing all their host star’s energy that strikes their planet.
Type 2: The species is capable of harnessing all of their host star’s energy
Type 3: The species is capable of harnessing the energy of all the stars in their galaxy
top related