The Fermi Paradox - Ashford Astronomical Society
Transcript of The Fermi Paradox - Ashford Astronomical Society
The Fermi ParadoxThe Fermi Paradox
““what alienswhat aliens””
By David J Styles By David J Styles BA CSci FIBMS SSGBA CSci FIBMS SSG
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guesswork
Educated GuessworkEducated Guessworkin action…in action…
Educated GuessworkEducated Guesswork
Fermi ProblemsFermi Problems
Fermi ProblemsFermi Problems
Fermi was known for his ability to make good approximate calculations with little
or no actual data
http://en.wikipedia.org/wiki/Fermi_problem
Fermi ProblemsFermi Problems
For example:
How many piano tuners are there in Chicago?
Fermi ProblemsFermi Problems
How many piano tuners are there in Chicago?
•There are approximately 5,000,000 people living in Chicago. •On average, there are two persons in each household in Chicago. •Roughly one household in twenty has a piano that is tuned regularly. •Pianos that are tuned regularly are tuned on average about once per year. •It takes a piano tuner about two hours to tune a piano, including travel time. •A piano tuner works eight hours a day, five days in a week, and 48 weeks in a year.
Fermi ProblemsFermi Problems
How many piano tuners are there in Chicago?
From these assumptions we can compute that the number of piano tunings in a single year in Chicago is
(5,000,000 persons in Chicago) / (2 persons/household) × (1 piano/20 households) × (1 piano tuning per piano per year) = 125,000 piano tunings per year in Chicago.
And we can similarly calculate that the average piano tuner performs•(50 weeks/year)×(5 days/week)×(8 hours/day)×(1 piano tuning per 2 hours per piano tuner) = 1000 piano tunings per year per piano tuner.
•Dividing gives (125,000 piano tuning per year in Chicago) / (1000 piano tunings per year per piano tuner) = 125 piano tuners in Chicago.
The Fermi ParadoxThe Fermi Paradox
The Fermi ParadoxThe Fermi Paradox
The size and age of the universe suggest that many technologically
advanced extraterrestrial civilizations ought to exist.
However, this hypothesis seems inconsistent with the lack of
observational evidence to support it.
Observational EvidenceObservational Evidence
Observational EvidenceObservational Evidence
Observational EvidenceObservational Evidence
The Drake EquationThe Drake Equation
Dr. Frank Donald Drake (born May 28 1930)
The Drake EquationThe Drake Equation
N = R* x fp x ne x fl x fi x fc x fL
• N - how many planetfuls of aliens there are• R* - the rate of star formation in our galaxy (Stars per year)• fp - the fraction of stars that have planets around them• ne - the fraction of stars with planets that are capable of sustaining life• fl - the fraction of planets in ne where life evolves• fi - the fraction of fl where intelligent life evolves• fc - the fraction of fi that try to communicate with other planets• fL - the expected lifetime of such a civilization in years
The Drake EquationThe Drake Equation
N = R* x fp x ne x fl x fi x fc x fL
• N - how many planetfuls of aliens there are with whom we could communicate
The Drake EquationThe Drake Equation
N = R* x fp x ne x fl x fi x fc x fL
• N - Dunno• R* - Measureable• fp – Measureable (to a degree)• ne - Guessable• fl - Guessable• fi - Arguable• fc - Arguable• fL - !
The Drake EquationThe Drake Equation
N = R* x fp x ne x fl x fi x fc x fL
• R* - the rate of star formation in our galaxy (Stars per year)
Seven
http://www.physorg.com/news9595.html Other sources quote 5 – 10
Drake said 10
The ESA say 6
The Drake EquationThe Drake Equation
N = 7 x fp x ne x fl x fi x fc x fL
• fp - the fraction of stars that have planets around them
1
Says Me !!! Everything we’ve found in space has something spinning round it.
Drake said 0.5
The Drake EquationThe Drake Equation
N = 7 x 1 x ne x fl x fi x fc x fL
• ne - the fraction of stars with planets that are capable of sustaining life
0.09
Assume all G class stars like our sun have such planets
http://www.peripatus.gen.nz/Astronomy/Sun.html
Including class F & K as well as G class stars might knock this up to 0.27
Assuming NOT all G class stars like our sun have such planets would reduce this number
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x fl x fi x fc x fL
• fl - the fraction of planets in ne where life evolves
0.1
http://www.newscientist.com/article.ns?id=dn4525
“10% of star systems in the Galaxy are hospitable to life, by having heavy elements,
being far from supernovae and being stable themselves for sufficient time”
Drake said 1
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x fi x fc x fL
• fi - the fraction of fl where intelligent life evolves
1
Says Me !!! Define intelligence !!
Drake said 0.01
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x 1 x fc x fL
• fc - the fraction of fi that try to communicate with other planets
0.3
Says Me !!! Neanderthals & dolphins never made radio waves.
I can find no other examples (!)
Drake said 0.01 – where did he get this figure ?
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x 1 x 0.3 x fL
• fL - the expected lifetime of such a civilization in years
This is the biggie !!!
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x 1 x 0.3 x fL
• fL - the expected lifetime of such a civilization in years
420 years (lower estimate)
Michael Shermer, Why ET Hasn't Called, Scientific American, August 2002, page 21
Drake said 10 000 years
Me – is there an upper limit ? Let’s try 100 000 years (reasonable figure?)
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x 1 x 0.3 x 420
N = 8
The Drake EquationThe Drake Equation
N = 7 x 1 x 0.09 x 0.1 x 1 x 0.3 x 420
N = 8
Well, we ain’t alone.
More generous figures give us:
The Drake EquationThe Drake Equation
N = 10 x 1 x 0.27 x 0.1 x 1 x 0.3 x 100 000
N = 8100
That’s a lot of aliens!
The Drake EquationThe Drake EquationTo recap:
Using science, wit, guesswork and idiot enthusiasm we have shown there are between 7 and 8099 alien civilisations in our galaxy with which we could communicate.
Hold those thoughts…….
The Milky WayThe Milky Way
Educated Guesswork
The Milky WayThe Milky WayThe Milky Way
Guesswork
The Milky WayThe Milky WayThe Milky Way
Guesswork
Galactic Radius:Galactic Radius:40 000 – 100 000 ly40 000 – 100 000 ly
Central thickness:Central thickness:16 000 – 35 000 ly16 000 – 35 000 ly
Total stars:Total stars:1000 000 000 – 4000 000 0001000 000 000 – 4000 000 000
The Milky WayThe Milky WayThe Milky Way
Quite smallQuite small
Astrophysical Journal 662, p. 322,Astrophysical Journal 662, p. 322,http://arxiv.org/abs/astro-ph/0702585http://arxiv.org/abs/astro-ph/0702585
The Milky WayThe Milky WayThe Milky WayTwo short conesTwo short cones
The Milky WayThe Milky WayThe Milky WayVolume of a cone:Volume of a cone:
The volume of a cone = 1/3(Area of Base)(height) The volume of a cone = 1/3(Area of Base)(height) = 1/3 π r2 h= 1/3 π r2 h
So galactic volume = 2* 1/3(Area of Base)(height)So galactic volume = 2* 1/3(Area of Base)(height)
= 13404128640000 ly= 13404128640000 ly33 (lower estimate) (lower estimate) = 183259571250000 ly= 183259571250000 ly33 (upper estimate) (upper estimate)
The Milky Way
To recap:
Using science, wit, guesswork and idiot enthusiasm we have come up with upper and lower plausible values for:
5. The numbers of alien civilisations in our galaxy with which we could communicate
7. The volume of space containing these alien civilisations
Finding the AliensFinding the Aliens
Best-Case Scenario:
3. Lots of aliens
5. Small galaxy
Finding the AliensFinding the Aliens
Best-Case Scenario: Some assumptions
• Stars are equally spaced throughout the galaxy
(not an unfair assumption where we are)
• Aliens are equally spaced throughout the galaxy
(Absolutely no idea!)
Finding the AliensFinding the Aliens
Best-Case Scenario:
• Lots of aliens (8100 civilisations)
• Small galaxy 13404128640000 ly13404128640000 ly33
Finding the AliensFinding the Aliens
Best-Case Scenario:
• Each alien civilisation is at the centre of a sphere of volume
1340412864000013404128640000 =165483070 ly =165483070 ly33
81008100
Finding the AliensFinding the Aliens
Best-Case Scenario:
• Volume of a sphere is Volume of a sphere is
• A sphere of volume 165483070 ly165483070 ly33 has radius 412.6 ly has radius 412.6 ly
• trust me on the sums…..trust me on the sums…..
Finding the AliensFinding the Aliens
Best-Case Scenario:
So civilizations are 2* 412.6 =about 800 ly apart 412.6 =about 800 ly apart
Finding the AliensFinding the Aliens
Best-Case Scenario:
So civilizations are 2* 412.6 =about 800 ly apart 412.6 =about 800 ly apart
At closestAt closest
To recap:
Using science, wit, guesswork and idiot enthusiasm we have shown that the closest alien civilisation to Earth is probably no closer than 800 ly away.
Finding the AliensFinding the Aliens
800 Light Years800 Light Years
800 Light Years800 Light Years46 days at warp 9.975
http://www.ussdragonstar.com/utilitycore/warpspeeds.asp
800 Light Years800 Light Years46 days at warp 9.975
http://www.ussdragonstar.com/utilitycore/warpspeeds.asp
Two problems:
3. Warp drive is theoretically impossible4. Warp drive is theoretically impossible
800 Light Years800 Light Years
http://www.guinnessworldrecords.com/content_pages/record.asp?recordid=46995
Helios 1 reached 1.4% of light speed
57 000 years at that rate
Which I believe explains the Fermi Paradox
Which I believe explains the Fermi Paradox
(but I could be wrong)
Please don’t clap
Please don’t clap
Just throw money !