Final Exam

Question 1

What is METI?

WEEK 14

Answer 1

Messaging Extra Terrestrial Intelligences

Also called active SETI; actively trying to communicate with ETIs

Question 2

What was important about the Pioneer plaques and the Voyagerrecord?

WEEK 14

Answer 2

The messages will almost certainly never be found but they might outlive human civilization and earths biosphere

Pioneer 10&11 were the 1st probes to leave our solar system

Voyager 1&2 had messages in the form of a record that could play sounds & show pictures

Question 3

Relatively speaking, how far have these probes travelled? How long would it take them to get to another star?

WEEK 14

Answer 3

Pioneers are about 15-18 light years away from earth

If the voyager was headed for the closet star it would get they in about 70,000 years

Question 4

What was the Arecibo message?

WEEK 14

Answer 4

It was used to send message to globular cluster M13 (25,000 lys away)

Binary message of the telescope, Sun/planets, human, DNA, organic molecules, and #s 1-10

Sent bc telescope was upgraded and wanted to celebrate by sending it to a nicely place star(?) at the time M13

Question 5

Why is METI controversial?

WEEK 14

Answer 5

• already broadcasting TV and radio (low power)
• not a message but can be detected as a sign of our civilization

Question 6

What is the “Dark Forest” idea?

WEEK 14

Answer 6

Wondering and Crying out loud for help in a dark forest by yourself

Something good may appear or something band

Better to figure out what’s out there b4 shouting

Question 7

What is a technosignature?

WEEK 14

Answer 7

Any measurable evidence of last or present technology

Question 8

Describe Type I, II & Ill civilizations on the Kardashev scale.

WEEK 14

Answer 8

Karashev scale - suggest that advanced civilizations might be divided into 3 types

Type 1 (planetary) - use the resources of their home planet

Type 2 (stellar) - use the resource of their home star (capture all energy of it)

Type 3 (galactic) - use the resources of their entire galaxy

Question 9

Where is humanity today on the Kardashev scale?
If current trends continue, how long would it take for humanity for become a Type Il civilization?

WEEK 14

Answer 9

Humanity is type ~ 0.75 on kardashev scale

If we limit growth to 23% in 400 years we’ll used all the solar energy that hits earth

Check technosignatures & civl types

Question 10

What is the hallmark technosignature thought to be produced by Type Il civilizations? How might we find them?

WEEK 14

Answer 10

Dyson spheres?

Question 11

What is so unique about “Tabby’s Star”?

WEEK 14

Answer 11

It dimmed 0.34% per 4years & 2.5% in just 200 years

The star is 20% fainter that it was 100 years ago

Dust caused this

Question 12

What is so unique about “Przbylski’s Star”? What might this have to do with aliens?

WEEK 14

Answer 12

Unusual spectrum

All short lived radioactive elements found in star

Suggested in 60s that aliens could per say spike this unusual star per say with heavy elements

Question 13

What is SETI?

WEEK 13

Answer 13

Search for Extra Terrestrial Intelligence

Super unlikely to 4 us to be the only civilization ever to be in universe 1 in 10^22 - one in ten billion trillion)

Question 14

List and describe the terms of the Drake Equation.
<– This is a big one.

WEEK 13

Answer 14

DRAKE EQUATION:
N = R*fp ne fl fi fc L

N - total # of civilizations in our galaxy that we might be able to communicate with

R* - rate of formation of suitable stars in the Milky Way

fp- fraction of suitable stays with planets

ne - number of earth like planets per system

fl - fraction of worlds that develop life

fi - fraction that develop intelligent life

fe- fraction that develop civilizations that we might communicate with

L - lifetime of civilization

Question 15

Why is L such an important factor in the Drake Equation?

WEEK 13
DE 2

Answer 15

May tells us about how long technological civilization lasts/ how they may die

Question 16

How far do humanity’s radio signals extend into the
Milky Way?

WEEK 13

Answer 16

1.420 gigahertz?

Maybe 1.33730

Question 17

How have astronomers been searching for aliens via SETI?

WEEK 13

Answer 17

Through radio technosignatures

Ex: project ozma- 1st search 4 alien broadcasts looking @ 2 sunlike stars

Question 18

What was the “Wow!” signal? Can we draw any firm conclusions from it?

WEEK 13

Answer 18

Moved with the stars & wasn’t something here on earth or satellite/moving w/stars themselves

Never repeated

Observing time is limited resource that has 2 be shared w/other radio ASTR projects

Question 19

What are the problems associated with the traditional SETI searches?

WEEK 13

Answer 19

Not all radio waves make it through a planetary atmosphere (blocked)

Best place to prob look is from space

Question 20

Have we done enough searching for radio signals to be able to draw any conclusions yet? Why or why not?

WEEK 13

Answer 20

It seems that not yet bc there always seems to a problem with radio telescopes and signals tend to be cut short

Question 21

What’s the basic problem with trying to travel to other stars?

WEEK 15

Answer 21

Our spacecrafts are too slow for the

Limit to how far we can travel

Stars r far apart

Relies on the h we don’t have yet

Question 22

What’s the problem with trying to use chemical rockets for interstellar travel? Approximately how long would it take to travel to another star using chemical rockets?

WEEK 15

Answer 22

They don’t deliver enough thrust for long enough

Unlikely to ever get us going faster than 0.1% the speed of light (not enough power)

Trip to próxima centauri b would take 4,000yrs

Question 23

Describe the Project Orion idea and the problems associated with it.

WEEK 15

Answer 23

Using new nuclear weapons to explore space
- vehicle drops nuclear bombs backed every few seconds
-force of explosions push vehicle forward
Bring space craft to 10% spend of light reach close star in 43 years

International treaty in 1965 banned nuclear weapons in space

Question 24

Describe the Project Daedalus plan for interstellar travel. What is the big problem behind this idea?

WEEK 15

Answer 24

Powered by nuclear fusion
- plan to go to barnards star ; fire engines for 4 years getting to1/10 speed of light

However we still don’t know how to get nuclear fusions to work

Question 25

What is the most efficient fuel that we can think of to power an interstellar vehicle?

WEEK 15

Answer 25

H bombs? Hydrogen as in h?

Question 26

What is antimatter? What happens when antimatter & matter collide?

WEEK 15

Answer 26

Particles with the same mass with the opposite electric charge as ordinary motor

When matter and antimatter collide, they annihilate each other, converting their mass into energy

Question 27

What are the problems associated with using antimatter to power a spacecraft?

WEEK 15

Answer 27

Creation of antimatter is difficult and expensive storage of it is also difficult expensive and dangerous

Question 28

Even if we mastered using fusion or antimatter spacecraft, why can’t we ever send a spacecraft to the speed of light or faster? What theory in physics explains this?

WEEK 15

Answer 28

This is due to newtons second law

When using the same force, a boulder is much harder to accelerate in a soccer ball.

Things are complicated as velocities get close to lightspeed.

As well as he gets closer to the speed of light mass increases making it hard to text celery

At the speed of light mass is infinite 

Question 29

What happens to the flow of time as objects approach the speed of light? What would this mean for a traveler moving at a high percentage of the speed of light?

WEEK 15

Answer 29

Time dilations motion makes time run more slowly

He will age the same years he left for (left 25 years, aged 25years)

Other on earth would be 80 if they were the same age as traveler

Question 30

What is a light sail? How do they work?

WEEK 15

Answer 30

Use no on boarded propellant

Ordinary sunlight can propel a solar sail slowly across the solar system

Uses beamed lasers propulsions - lasers to shine solar sail and they will accelerate the solar sail to velocities

Question 31

What’s the plan for the Breakthrough Starshot lightsail? What are the difficulties associated with it?

WEEK 15

Answer 31

Want to deploy 1,000 light sails into space
-Use ground based lasers accelerating them outwards (20% c)
- each has tiny robotic spacecraft
-marrives in 20 years // cost: $10 billion

PROBLEMS
- a lot of power needed for lasers (100 gigawatts)
- how to fit cameras, computers and thrusters on something so small
-may encounter dust
-how will message return to earth
-won’t slow down enough t to study stars

Question 32

If aliens are using beamed-laser propulsion, would it be possible for us to see this as a technosignature?

WEEK 15

Answer 32

Yes

Question 33

Is it possible to send a lightsail spacecraft to another star without using lasers? What’s the tradeoff in doing that?

WEEK 15

Question 34

What is the idea behind the Fermi Paradox?

Question 35

What are the possible “solutions” to the Fermi Paradox (we are alone, the “zoo” hypothesis, etc.)?

Question 36

What is the argument that suggests that human civilization is very young compared to other (possible) civilizations?

Question 37

What is a Von Neumann Machine? How might they spread across the galaxy & what would they possibly have to do with the Fermi Paradox? What are the possible dangers of Von Neumann Machines?