Download The Universe and Space Travel

The Universe,
Space-Time, and
Space Travel
by
Prof. Lyle N. Long
http://www.personal.psu.edu/lnl
April 25, 2016
April 25, 2016
Topics
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Vastness of space
Relativity
Space-Time
Gravity Waves
Issues in space travel
Missions to Mars
Missions to other
stars and solar
systems
—  Life on Other Planets
—  UFO’s?
Vastness of Space
Humans have great difficulty in understanding the vastness of
space and time.
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Electron:
10-16 meters
Molecule:
10-9 meters
Insect:
10-3 meters
Town:
103 meters
Distance to moon: 108 meters (1.3 sec. light to earth)
Distance to Sun:
1011 meters (500 sec. light to earth)
Solar system:
1013 meters
Alpha Centari:
1016 meters
42 orders
of
magnitude!
(.001 lightyears)
(4 lightyears)
Andromeda Galaxy: 1022 meters (107 lightyears)
Universe:
1026 meters (1011 lightyears)
1,000,000,000,000,000,000,000,000,000,000,000,000,000,000
History and Future of
Universe
—  http://www.sciencealert.com/this-timeline-shows-theentire-history-of-the-universe-and-where-it-s-headed
—  http://www.sciencealert.com/watch-this-3-minuteanimation-will-change-your-perception-of-time?
utm_source=Article&utm_medium=Website&utm_camp
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Distances
1 AU=~93 million miles
1 LY = ~63,000 AU
Launched in 1977
Voyager will
reach this star
in 40,000 years
http://voyager.jpl.nasa.gov/where/
Hawking and Mlodinow (& me) at Caltech
• 
• 
• 
• 
Hawking, A Brief History of Time
Hawking and Mlodinow, A Briefer History of Time
Hawking and Mlodinow, The Grand Design
Mlodinow, Feynman’s Rainbow
The Universe
—  “The Universe can be defined as everything that
exists, everything that has existed, and everything
that will exist.”
—  “Radio messages sent from Earth may never reach
some regions of space, even if the Universe were
to exist forever: space may expand faster than
light can traverse it.”
—  13.8 billion years old (earth is 4.5 billion years
old)
—  About 91 billion light years in diameter
Maxwell’s Equations
Einstein’s Equations
From his notebook
Einstein’s Field Equations
Set of 10 equations in Albert Einstein's general theory of relativity that
describes the fundamental interaction of gravitation as a result of
spacetime being curved by matter and energy. First published by Einstein
in 1915 as a tensor equation.
Reduces to Newton’s law of gravitation when gravity is small and speed is
much less than speed of light.
Led to the prediction of the existence of
blackholes and gravitational waves.
Relativity
—  Speed of light: 300 million meters/sec. (186,000
miles/sec. or 670 million MPH)
—  20% speed of light is 9300 miles/sec. (33 million
miles per hour or 60,000 km/sec.)
—  Nothing can go faster than this
—  As you approach speed of light:
—  time slows down
—  objects appear shorter
—  mass increases
mass =
m
1− (
v
c
)
2
length = L 1− (
v
c
)
2
Relativistic Length Contraction
20% gives 196 ft.
Space-Time
Blackholes
—  Blackholes seem to exist in all
galaxies
—  Massive Blackhole detected
recently:
—  Its diameter is about 80 billion
miles.
—  It would take light 4 days to
travel that distance.
—  And it is 1000 times larger than
the distance from the earth to
the sun.
—  But the effect of the black hole
on other planets is so
enormous, that is effect reaches
out 3000 light years. Thats how
they found it, they saw the
enormous effect it was having
on nearby stars.
Blackholes
Blackholes
Laser Interferometer Gravity-Wave Observatory
(LIGO)
—  LIGO
LIGO
—  Laser Interferometer Gravity-Wave Observatory
—  Measures extremely small changes in space-time
—  https://www.ligo.caltech.edu/
LIGO
—  Detected two black holes colliding
Gravity Waves Detected
The signals came from two merging
black holes, each about 30 times the
mass of our sun, lying 1.3 billion lightyears away.
These are waves in the very fabric of
space and time.
Measurements agree with Einstein’s
theory, computed on supercomputers.
Feb. 11, 2016
Issues in Space Travel
—  Distance to nearest star (Alpha Centauri): 41
trillion km (4.35 lightyears)
—  Time to get there at 40,000 km/hr (25,000
MPH):
—  117,000 years
—  Time to get there at 20% speed of light (216
million km/hr):
—  22 years
—  If there really are UFO’s, they’d have to deal with
these realities also.
Issues in Space Travel
—  Distance to nearest habitable planet
(Kepler-186f): 4700 trillion km (500
lightyears away)
—  Time to get there at 40,000 km/hr (25,000
MPH):
—  13 million years
—  Time to get there at 20% speed of light (216
million km/hr)):
—  2500 years
—  If there really are UFO’s, they’d have to deal with
these realities also.
Apollo & Saturn V Rockets
Cancelled
Saturn V Rocket
—  1966 – 1973
—  Launched 13 times with no loss of crew or payload
—  Still holds record for biggest payload: 310,000 lb
—  Designed under the direction of Wernher von Braun
and Arthur Rudolph at the Marshall Space Flight
Center in Huntsville, Alabama, with Boeing, North
American Aviation, Douglas Aircraft Company, and IBM
as the lead contractors.
—  A total of 24 astronauts were launched to the Moon,
three of them twice, in the four years spanning
December 1968 through December 1972.
Saturn V Rocket
Saturn V
https://www.youtube.com/watch?v=FzCsDVfPQqk
Apollo Spacecraft
Apollo Command Module
DOD Spaceplane: X-37B
X-37
DOD Spaceplane: X-37B
DOD Spaceplane: X-37B
—  Started at NASA 1999
—  Transferred to DARPA 2004,
and became classified
program
—  First launched into orbit 2010
—  Launched using an Atlas V
rocket
—  Was in orbit for 675 days,
ending in 2014
—  Was launched in May, 2015
and is still in orbit (USA-261)
—  Not known what its purpose is,
but probably reconnaissance
or as a space weapon
—  Can land autonomously at
Vandenberg AFB
http://www.n2yo.com/satellite/?s=40651
You can track X-37B’s location
Energy Requirements
Energy in 45 cal. Handgun
—  45 cal. bullet: mass = ~15 grams
—  Kinetic Energy: ½ m V2
—  Speed: 300 m/sec (speed of sound 343 m/sec)
—  Energy:
—  ½ * 0.015 * (300)2 = 675 Joules
—  Browning 50 cal.
machine gun has
15,000 Joules
Energy of Saturn V rocket
from “How Apollo Flew to Moon,” by W.D. Woods
Energy Requirements
—  Kinetic Energy: ½ m V2
—  Apollo 7 Command Module weighed 12,000 lbs
(5600 kg)
—  Speed: 25,000 MPH (40,000 km/hr or 11 km/sec)
—  Energy:
—  ½ * 5600 * (11,000)2 = 300 billion Joules
—  Speed: 20% speed of light [60,000 km/sec]
—  Energy:
—  ½ * 5600 * (60,000,000)2 = 1019 Joules
(you’d need 34 million Saturn V rockets !!)
Energy in Grain of Sand
—  What if we had a grain of sand (0.03 g) travelling
at 20% speed of light?
—  Kinetic Energy: ½ m V2
—  Speed: 20% speed of light [60,000 km/sec]
—  Energy:
—  ½ * 0.00003* (60,000,000)2 = 54 * 1019 Joules
—  About same energy as a Saturn V rocket
How about Sustained Acceleration
over many Years using Sun?
—  Solar sails:
—  A solar sail in space works almost like a ship sailing on
the seas. Engineers can use photons emitted by a star
to both propel and steer a spacecraft. –
— 
http://www.space.com/22442-solar-sail-starship-interstellar-spacecraft.html
—  For a 30x30 square meter sail, the light force from
sun is only about 0.01 Newtons (0.002 Lb-f)
—  For a nano-spacecraft of 50 g (about ½ of iPhone 5):
—  acceleration = 0.01 / .05 = 0.2 m/s2
—  To reach 20% of speed of light would take 9 years (but
as it travelled away from sun the force would get
smaller and smaller)
How about Sustained Acceleration
over many Years using Lasers from Earth?
—  Lets say you want your 0.05 kg spacecraft to reach
20% of speed of light in 1 week
—  You’d need acceleration of about 100 m/s2
—  So you’d need a force of about 5 Newtons
—  This is about 500 times more photons than from
the sun
Proposed Mission to Nearest Star: StarShot
—  Milner, Hawking, and Zuckerberg
—  $100M project to travel to nearest star
—  Nearest star is 25 trillion miles away (4.3 lightyears)
—  Using traditional rockets would take 30,000 years to get there
—  If they could reach 20% of speed of light, it would only take 20
years and 4 years to get data back
—  Nano-spacecraft powered by laser beams from earth
—  http://www.nytimes.com/2016/04/13/science/alpha-centauribreakthrough-starshot-yuri-milner-stephen-hawking.html?_r=0
—  https://www.youtube.com/watch?v=U2zCo6MCcCA
—  https://www.youtube.com/watch?v=c7VPHGjT8A4
Proposed Mission to Nearest Star: StarShot
Yuri Milner
mail.ru $5.6 billion company
Physicist turned investor
How about Sustained Acceleration:
Ion Thrusters
—  Chemical rockets are
great for breaking from
earths gravitation, but
they require an
emormous amount of
fuel, not useful for
interstellar travel
—  Ion thrusters very high
specific impulses
(thrust per mass rate)
—  Very small thrust but
they can can run for
very long time
—  Small amount of mass
but particles leave with
very high velocity
•  Konstantin Tsiolkovsky in 1911
•  Robert H. Goddard's notebook, September
6, 1906.
•  The first experiments by Goddard at Clark
University from 1916–1917.
Hubble Space Telescope
Similar in design to KH-11 spy satellite
Edwin Hubble
1889-1953
American astronomer who
played a crucial role in
establishing the field of
extragalactic astronomy and
is generally regarded as one
of the most impor tant
observational cosmologists of
the 20th century. Hubble is
known for showing that the
recessional velocity of a
galaxy increases with its
distance from the ear th,
implying the universe is
ex p a n d i n g , [ 2 ] k n ow n a s
"Hubble's law" although this
relation had been discovered
previously by Georges
Lemaître, who published his
work in a less visible journal.
https://en.wikipedia.org/wiki/Edwin_Hubble
Hubble Telescope
Hubble Space Telescope
—  $2.5 billion, Launched April 24, 1990
—  1.2 million observations since its mission began in 1990.
—  More than 12,800 scientific papers, making it one of the
most productive scientific instruments ever built.
—  It takes pictures as it whirls around Earth at about 17,000
mph at 340 miles altitude, has traveled more than 3 billion
miles
—  24,000 pounds at launch
—  Hubble's primary mirror diameter is 2.4 meters (7 feet, 10.5
inches)
—  13.3 meters (43.5 feet) long – size of a large school bus.
—  Very similar to Keyhole spy satellites (KH-11)
—  http://hubblesite.org/
Johannes Kepler,
1571-1630
•  Known for his three laws of
planetary motion
•  Kepler’s work formed the
basis for Isaac Newton’s
theory of gravity.
•  Devised the eyeglass for
farsightedness and
nearsightedness (founder
of modern optics).
•  Invented the Keplerian
Telescope, an enhanced
version of the refracting
telescope.
•  Kepler’s book
"Stereometrica Doliorum"
was the foundation of
integral calculus
Kepler Space Telescope
http://kepler.nasa.gov/
http://ssd.jpl.nasa.gov/horizons.cgi
Kepler Space Telescope
—  To find terrestrial planets (i.e., those one half to
twice the size of the Earth), especially those in the
habitable zone of their stars where liquid water
and possibly life might exist.
—  When a planet crosses in front of its star as
viewed by an observer, the event is called a
transit. Transits by terrestrial planets produce a
small change in a star's brightness of about
1/10,000 (100 parts per million, ppm), lasting for
1 to 16 hours. T
—  Launched Mar. 6, 2009 using Delta II rocket
http://kepler.nasa.gov/
http://ssd.jpl.nasa.gov/horizons.cgi
Planets Discovered So Far
Goldilocks Zone
—  An important part of this research is the continuing
investigation into exactly where a star's habitable zone starts
and stops.
—  The habitable zone is the belt around a star where
temperatures are ideal for liquid water -- an essential
ingredient for life as we know it -- to pool on a planet's
surface.
—  Earth lies within the habitable zone of our star, the sun.
Beyond this zone, a planet would probably be too cold and
frozen for life (though it's possible life could be buried
underneath a moon's surface). A planet lying between a star
and the habitable zone would likely be too hot and steamy.
—  That perfect Goldilocks planet within the zone wouldn't
necessarily be home to any furry creatures. But it would
have the potential for some type of life to abound, if even
microbes.
Discovery of Other Planets
—  Kepler-186f, the first validated Earth-size planet to orbit a distant
star in the habitable zone—a range of distance from a star where
liquid water might pool on the planet's surface.
—  Less than ten percent larger than Earth, but its mass, composition
and density are not known. Previous research suggests that a
planet the size of Kepler-186f is likely to be rocky.
—  Orbits its star once every 130 days and receives one-third the
energy that Earth does from the sun, placing it near the outer edge
of the habitable zone. If you could stand on the surface of
Kepler-186f, the brightness of its star at high noon would appear
as bright as our sun is about an hour before sunset on Earth.
—  Kepler-186f resides in the Kepler-186 system about 500 lightyears from Earth in the constellation Cygnus. The system is also
home to four inner planets, seen lined up in orbit around a host
star that is half the size and mass of the sun.
Kepler-186f
—  As part of the SETI Institute's search for
extraterrestrial intelligence, the Allen Telescope Array
had listened for radio emissions from the Kepler-186
system for about a month as of 17 April 2014.
—  No signals attributable to extraterrestrial technology
were found in that interval,
—  However to be detectable such transmissions, if
radiated in all directions equally and thus not
preferentially towards the Earth, would need to be at
least 10 times as strong as those from Arecibo
Observatory.[7]
—  Signals would be 500 years old if they were detected
SpaceX
“SpaceX designs,
manufactures and
launches advanced
rockets and spacecraft.
The company was
founded in 2002 to
revolutionize space
technology, with the
ultimate goal of
enabling people to live
on other planets.”
www.spacex.com
Elon Musk
SpaceX
SpaceX could reveal plans for a Mars mission
sometime in 2016, CEO Elon Musk has said.
He said he hopes to introduce commercial
spaceflights that will essentially transport
people to Mars by 2025.
He said he plans to travel to the International
Space Station (ISS) on board one of his own
SpaceX aircraft by 2020. The firm will also be
focusing on exploring space travel to and
beyond Mars and might make its plans public
by September.
www.spacex.com
Blue Origin: Astronaut Experience
(Jeff Bezos, of amazon.com)
https://www.blueorigin.com/
Missions to Mars
—  U.S.: ~2030
—  https://www.nasa.gov/
content/journey-tomars-overview
—  http://www.nasa.gov/
sites/default/files/
atoms/files/journey-tomars-nextsteps-20151008_508.p
df
Missions to Mars
—  Distance to Mars
(closest approach): 35
million miles (56
million km)
—  But spacecraft don’t
travel in straight lines
between planets
—  Previous spacecraft
have taken 128 – 333
days
—  Hohmann Transfer
Life on Other Planets?
—  Scientists detected an Earth-like planet 14 light-years away.
Its size, orbit, sun, and age provide the "opportunity for life
to arise somewhere on the surface ... should all the
necessary ingredients and conditions for life on this planet
[exist]," one scientist said.
—  Drake equation allows us to estimate how many alien
civilizations might exist in the Milky Way:
N=R*(fp)(ne)(fl)(fi)(fc)L
This predicts anywhere from 0.014 to 140,000 possible
civilizations in Milky Way (using pessimistic to optimistic
numbers).
—  There are roughly 100 billion galaxies in universe. So there
are roughly from 109 to 1016 possible civilizations in
universe?
—  They could easily be thousands of years ahead or behind us
in evolution and technology
Wormholes in Universe
Will very likely win
Nobel prize next
year for detecting
gravity waves with
LIGO
Kip Thorne, Black Holes and Time Warps
Wormholes
—  A wormhole is a theoretical passage through space-time that
could create shortcuts for long journeys across the universe.
Wormholes are predicted by the theory of general relativity. But
wormholes bring with them the dangers of sudden collapse,
high radiation and dangerous contact with exotic matter.
—  “This analysis forces one to consider situations... where there is
a net flux of lines of force, through what topologists would call
"a handle" of the multiply-connected space, and what physicists
might perhaps be excused for more vividly terming a
"wormhole”.” — John Wheeler in Annals of Physics
—  discovered by Ludwig Flamm in 1916
—  Theoretically possible, called an Einstein–Rosen bridge
—  But has never been observed
—  Kip Thorne, “Black Holes and Time Warps”
UFO’s & Alien Visits?
—  Unless we discover wormholes thru space-time, UFO’s will have
same problem we have. (30 years to travel to nearest start at 20%
speed of light and enormous energy requirements)
—  To support life (like us) for 30 years, spacecraft would need to be
quite large, although a large one could also carry small spacecraft
—  many UFO sightings could easily be secret U.S. aircraft or
spacecraft
—  Other life forms could easily be more advanced than us. We’ve only
had spacecraft for about 60 years, and that is nothing compared to
age of planets.
—  Top10 unexplained UFO’s:
—  https://www.youtube.com/watch?v=eq7fecg5K2c
—  http://www.listzblog.com/
unexplained_ufo_sightings_alien_encounters.html
—  https://www.cia.gov/news-information/blog/2016/take-a-peekinto-our-x-files.html
SETI
—  Search for Extraterrestrial Intelligence (SETI)
—  https://en.wikipedia.org/wiki/
Search_for_extraterrestrial_intelligence
—  http://www.seti.org/
SETI
—  On 13 February 2015, scientists (including David Grinspoon,
Seth Shostak, and David Brin) at an annual meeting of the
American Association for the Advancement of Science,
discussed Active SETI and whether transmitting a message
to possible intelligent extraterrestrials in the Cosmos was a
good idea;[1][2]
—  That same week, a statement was released, signed by many
in the SETI community, that a "worldwide scientific, political
and humanitarian discussion must occur before any message
is sent".[3]
—  On 28 March 2015, a related essay was written by Seth
Shostak and published in the New York Times.[4]
—  http://www.seti.org/
Conclusions
—  Very exciting time
—  Distances and times involved are staggering
—  Humans will get to Mars this century, hopefully
—  Might be missions to other stars also
—  Will need new propulsion techniques for
interstellar travel
References
—  Hawking, A Brief History of Time
—  Hawking and Mlodinow, The Grand Design
—  Kip Thorne, Black Holes and Time Warps
—  http://en.wikipedia.org
—  Many many websites…