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TRANSCRIPT
2-Nov-12
The Physics of UFOs
Kevin Pitts
University of Illinois
World of Science - UFOs 1
2-Nov-12 World of Science - UFOs 2
• Why UFOs?
• It all starts at Fermilab…
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Phys 192: Science & Pseudoscience
• What is good science? bad science? pseudoscience?
• Topics covered
– Alternative medicine, UFOs, ghosts, cold fusion, statistics, logical fallacies, lie
detectors, climate change, creationism, …
• Last semester we performed extrasensory perception experiments, all
results negative! This semester, we‟re making videos!
Things aren’t always as they seem
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A Face On Mars
Credit: The Viking Project, NASA
APOD: 1998 April 6
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The Face on Mars
Credit: NASA,Viking Project,
APOD: 1995 July 22
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Mars Express Close-Up of the Face on Mars
APOD: 2006 September 25
2-Nov-12 World of Science - UFOs 13
Polling Numbers
Gallup 1996. In your opinion, are UFO‟s something real, or
just people‟s imaginations?
Real just people‟s imagination don‟t know
48.5% 31.0% 20.6%
Gallup 1996. Do you think that UFO‟s have ever visited the
earth in some form, or not?
Yes no don‟t know
45.1% 40.0% 15.9%
In this same poll, 71% of those surveyed believe that the
government knows more about UFOs than it is telling.
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Extraordinary claims require extraordinary evidence
“Dr. Pitts,
I noticed that you will be presenting a lecture entitled „The Physics of
UFOs.‟
I am not attending the lecture, but would like to know if you have written
an article on this topic and, if so, whether it is available for people to read.
On the basis of what I have read, there seems to be a fair amount of
evidence based on (a) reports from highly reliable witnesses (including
former military people, police officers, and pilots) (b) physical trace
findings, and (c) radar recordings, which support the hypothesis that at
least some reported UFOs are highly technologically advanced craft that
may have an extraterrestrial origin. The „Extraterrestrial Hypothesis‟
seems plausible for explaining at least some reported UFO sightings.
No testimony is sufficient to establish a miracle, unless
the testimony be of such a kind that its falsehood would
be more miraculous than the fact which it endeavors to
establish… -David Hume‟s maxim
“Extraordinary claims require
extraordinary evidence”
-Carl Sagan
Questions about UFOs
• Basic question
– Is there life anywhere other than Earth?
• If yes:
– Is there “intelligent” life anywhere other than Earth?
• If yes:
– Could we communicate?
– Could they come and visit us?
– Could we visit them?
– Have we communicated?
– Have we visited?
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Questions/Topics
1. Distances
2. Nature‟s speed limit
3. Acceleration
4. Radiation
5. Is there anybody out there?
6. How would they know we‟re here?
7. Making contact
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Speed of light
• 186,000 miles/second = 299,792,458 m/s
• 7x around Earth in one second
• Sun to Earth in about 8 minutes
• Earth to Mars in 3−22 minutes
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Distance Scales
• Measurement unit:
1 light-year = distance light travels in one year
1 ly = 5,843,190,000,000 miles 6 trillion miles
It takes Earth about 10000 years to travel 1 ly
around the Sun
Mars Rover Landing
• Landing called “7 Minutes of Terror”
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2-Nov-12 World of Science - UFOs 22 from Atlasoftheuniverse.com
You are here
(approximately)
100,000 light years
The Milky Way Galaxy
2-Nov-12 World of Science - UFOs 23
Distances
• Nearest star is Alpha Centari, 4.3 ly away.
• About 14,000 stars (3500 visible) within 100 ly
• Sun about 25,000 ly from center of milky way.
• To travel to planets orbiting other stars, aliens
(or humans) need
1. to travel near the speed of light
2. to be able to handle long-duration flights
even with these criteria, can probably only visit
a few nearby stars.
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Nature’s Speed Limit
• In 1905, Albert Einstein published
the “Special Theory of Relativity”
• One consequence of the theory is the
famous equation:
E = mc2
• Important for this discussion is another
constant: no information or object can
travel faster than the speed of light.
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Fermilab, Batavia, IL
protons circulate around accelerator rings
reminder: speed of light c = 186,000 mi/sec
Testing the speed limit
Speed=0.99c=184,500mi/sec
Speed=0.99999999c=185,999.98 mi/sec
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High Speed travel
• Fastest manned object:
– Apollo 10: speed 25,000 mph = 0.000037c
• Fastest man made object
– Helios 2 space probe: 158,000 mph = 0.00024c
– This speed was attained by orbiting the sun,
not through rocket propulsion.
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Rockets • Rockets work by Newton‟s 3
rd Law
– Burn the fuel, it gets pushed out of the nozzle.
– The fuel pushes back on the rocket, accelerating it.
• Good news
– This works even in outer space
• Bad news
– Have to carry your fuel with you
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Acceleration
• Something accelerating at 1g is speeding up at 10 m/s2
– At 1 second: speed 10 m/s
– At 2 seconds: speed 20 m/s
– At 3 seconds: speed 30 m/s
• F-16 pilots can withstand ~6g‟s for a few seconds. (link)
• People might be able to withstand 2-3g‟s for an extended
period of time.
• Space Shuttle
– "Guidance also governs the main engine throttle command so
that acceleration does not exceed 3 g's …. The main engines
are throttled down at approximately seven minutes 40 seconds
into the mission to maintain 3 g's for physiological and
structural constraints."
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Acceleration
• Imagine we have a spaceship that can reach a
speed of 0.75c
– This is 20,000 times faster than Apollo
• We start at rest on Earth (or near Earth) but we
can only accelerate at 3g‟s or else we‟ll kill all of
the passengers.
• How long does it take for our spaceship to reach
a speed of 0.75c?
• Answer: 116 days
– We need enough fuel to accelerate at 3g‟s continuously
for 4 months!
• Don‟t forget, we must decelerate at the same rate.
– So we need to fire our breaking rockets 4 months prior
to when we want to stop.
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Anything prohibitive so far?
• We need
– Radically new technology to accelerate and
decelerate our space ship
– The ability to undergo long duration space
flight (decades to get to the nearest star)
• What about dangers during space flight?
– Radiation!
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National Research Council, 2008
“At the present time, given current
knowledge, the level of radiation
astronauts would encounter would not
allow a human crew to undertake a Mars
mission and might also seriously limit
long-term Moon activity.”
International Space Station astronauts
receive a radiation dose that is 27 times
higher than we receive on Earth‟s surface.
The ISS is still protected by Earth‟s
magnetic field and upper atmosphere.
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Radiation
• Earth‟s atmosphere and magnetic field
protect us from cosmic radiation.
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Radiation
• Radiation would be sufficient to kill humans in
long duration space flight, unless an acceptable
shielding method was developed.
• Perhaps other beings might be less susceptible
to radiation effects.
Questions/Topics
1. Distances
2. Nature‟s speed limit
3. Acceleration
4. Radiation
5. Is there anybody out there?
6. How would they know we‟re here?
7. Making contact
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Galaxies
• Our sun is a small star toward the outside of the galaxy, the
Milky Way (a spiral galaxy) containing
approximately 200,000,000,000 stars (2 x 1011
)
• A few others (e.g. Andromeda) visible to naked eye
• Telescopes reveal many galaxies, each ~ 1011
stars
Andromeda Spiral Galaxy m100
2-Nov-12 World of Science - UFOs 37 from Atlasoftheuniverse.com
You are here
(approximately)
100,000 light years
The Milky Way Galaxy
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Views from the Hubble Telescope
• Picture of an area
of the sky (the size
of a grain of sand
held at arm‟s length)
in which there are
no stars visible to
the naked eye!
• Shows visible stars
in the Milky Way and
distant “fuzzy looking”
galaxies
• Estimate:
~1011
=100 billion
galaxies in the universe
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Summary
• About 1011
stars per galaxy
2 to 4 x 1011
in the Milky Way
• About 1011
galaxies in the universe
• So we have about: 1011
x 1011
= 1022
=
100,000,000,000,000,000,000,000
stars in the universe.
• More stars in the universe than grains of sand on Earth
• Universe is dominated by light elements (H, He,
Li) but there are plenty of heavy elements that
have been produced by supernovae.
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• Question: How many “Earth-like” planets:
• Requirements:
– Single star system (not binary)
– Star should be sunlike (similar to our sun)
– Must have planets
– Must have Earth-like planet
• Estimates (arguable, but you can change them!)
– ~50% are single star systems (not binary)
– ~10% are sunlike (similar to our sun)
– ~10% have planets
– ~10% have an Earth-like planet
4x1011
x 0.5 x 0.1 x 0.1 x 0.1 = 2x108 =200,000,000
Earthlike planets in the Milky Way galaxy alone!!!
[low estimate]
These two estimates are low, reality possibly much higher.
“Good” Places for Life
These two estimates are pretty solid.
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How Would We Make Contact?
• Einstein says we can‟t travel faster than the
speed of light.
– Experiments say he‟s right.
– This immediately limits the possibilities for space travel
between solar systems that are light years apart.
• Milky Way is about 100,000 light-years wide
• What can travel at the speed of light?
– Electromagnetic waves! Light, x-rays, radio-waves.
• First contact with an intelligent life form would
most certainly be through electromagnetic waves!
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Electromagnetic spectrum
All EM radiation travels at speed of light!
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SETI
• Search for Extra Terrestrial Intelligence
– Scanning the sky for all electromagnetic frequencies
– Looking for non-random patterns indicating a
deterministic source.
• Note: Humans have been broadcasting to the
galaxy since the early 20th
century.
– Our electromagnetic waves now reach out some 80 light-
years away from us.
– Anyone farther than 80 light-years would not yet be able
to “see” our broadcasts!
– About 14,000 stars within 100 light-years of us
(=0.00000004% of the Milky Way)
• For signals originating elsewhere, our sensitivity
depends upon location on time.
– To “see” a civilization on the other side of the Milky Way,
they needed to begin broadcasting 30,000 years ago!
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How Would We Make Contact?
• First contact with an intelligent life form would most certainly be
through electromagnetic waves!
Allen Telescope array, part of
SETI = Search for Extraterrestrial Intelligence Project
– Scanning the sky for all electromagnetic frequencies
– Looking for non-random patterns indicating a deterministic source.
• You can participate in SETI at Home (link)
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• Humans have been broadcasting to the galaxy
since the early 20th
century.
– Our electromagnetic waves now reach out some 80 light-
years away from us.
– Anyone farther than 80 light-years would not yet be able
to “see” our broadcasts!
– About 14,000 stars within 100 light-years of us
(=0.00000004% of the Milky Way)
• For signals originating elsewhere, our sensitivity
depends upon location on time.
– To “see” a civilization near the center of the Milky Way,
they needed to begin broadcasting 25,000 years ago!
How Would They Know We’re Here?
2-Nov-12 World of Science - UFOs 46 from Atlasoftheuniverse.com
100,000 light years
The Milky Way Galaxy
Our electromagnetic
footprint is smaller
than this dot!
The rest of the galaxy
has no idea that we are
here!
Sound channels and Roswell
Sound channels
• Waves will “channel” where the wave speed
is lowest.
• In ocean, channel is about ½ mile in depth
– Atmospheric sound channel about 30 miles up
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Speed of sound
Ocean
d
ep
th
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World of Science -
UFOs 49
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Summary
• Is there life beyond Earth?
– We don‟t know.
• Has extraterrestrial life visited Earth?
– There is no credible evidence that it has.
– “Extraordinary claims require extraordinary
evidence.” We have yet to see that evidence.
• If we make contact with another
civilization, it will be by electromagnetic
wave.
How would they know we’re here?
• We are looking for exoplanets
– Planets that orbit stars other than our own
– Any in the Goldilocks zone?
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UFOs?
• Have we been visited?
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UFOs
• Question: Why are they always seen by
untrained observers? Professional
astronomers and astrophysicists observe
the sky daily with sophisticated
equipment have never observed an
extraterrestrial spaceship.
• Question: Why hasn‟t anyone observed
the electromagnetic footprint (radio
waves, gamma rays, light, etc.) of an alien?
The electromagnetic footprint would be
here before the aliens would.
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UFOs: Natural Explanation
Some sources that might be misinterpreted:
• Approaching Aircraft (appear to hover)
• Unconventional Aircraft
• High Altitude Balloons
• Venus
• Artificial Satellites
• Reflections Off Clouds
• Optical Mirages
• Meteors
• Uncommon Atmospheric Phenomena (Aurora, Ball
Lightning)
• Secret Military Objects
• Accidents
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Material for Life
• Earth is teeming with elements:
– Nitrogen, hydrogen, oxygen, carbon, gold, iron, manganese,
uranium, silver, lithium…
• The big bang (and it‟s aftermath) produced no
element heavier than lithium (atomic number=3).
– Hydrogen, helium and lithium only….nothing heavier.
Atomic # = # of protons
H
2-Nov-12 World of Science - UFOs 59
“Heavy” Elements
• Heavy elements are crucial for life.
– Carbon, oxygen, nitrogen, iron, potassium…
• Where did the heavy elements come from?
– Normal stars (our sun) typically produce helium from
hydrogen, but also produce some lithium and beryllium
(Be, atomic #=4)
• Elements heavier than beryllium require a higher energy
process to produce them…a supernova.
• Supernovas occur at the end of a large star‟s life cycle.
– The stuff you are made of: carbon, oxygen, silicon, iron,
etc. are supernova remnants!
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Supernova
• Expels matter - all heavy elements in the universe (in
you!) are formed in supernovae
• Remnant is a neutron star or black hole
• Radiates more energy than an entire galaxy for a brief
period (months):
– Famous supernovae:
•0 -- The Christmas Star ??
•1054 -- in Crab Nebula, Recorded in China, …..
•1572 -- in large Magellanic Cloud, seen by Kepler
•Pulsars (Neutron Stars) observed now as
remnants of the 1054 and 1572 Supernovae!
•1987 -- in Magellanic Cloud - remnants still
observed
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Does Life Develop?
• Experiments show that organic molecules form in
conditions similar to the earliest stages of Earth‟s
development.
– Carbon dioxide, water, nitrogen + energy (heat or
lighting)
• Details of the mechanisms that bring single
celled organisms (like amoeba) from the organic
molecules are under study.
– Let‟s guess that there is only a 1% chance life will
develop on an Earthlike planet. [This is probably a low
estimate. The likelihood to develop life on an Earthlike
planet is probably very high.]
2 x 108 Earthlike planets x 0.01 chance of developing life
= 2 x 106 = 2,000,000 planets with life in the Milky Way.
[this is still a low estimate]
2-Nov-12 World of Science - UFOs 62
Does Intelligence Develop?
• Large uncertainty.
• See Hobson textbook for a discussion.
– Art Hobson, “Physics Concepts and
Connections”
• The Drake Equation attempt to account for
the likelihood of intelligent life to develop,
as well as the lifetime “time scale”.
– See Origins web site.
2-Nov-12 World of Science - UFOs 63
2009 Morristown Hoax • Details here
• “The icing on the cake came when the popular
History Channel show UFO Hunters featured the
Morristown UFO as their main story one week.
Bill Birnes, the lead investigator of the show and
the publisher of UFO Magazine, declared
definitively that the Morristown UFO could not
have been flares or Chinese lanterns.”