TIME TRAVEL

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TIME TRAVEL!

• Lucas ONeil
• Brendan Cassidy

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Overview

• Introduction
• Theories
• Paradoxes
• Research
• References in Fiction
• Conclusions
• References

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Introduction
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What is Time Travel?

• A concept in which time is traversed in much the
  same way that space is traversed.
• Possibly between parallelrealities and universes
• Once confined to fantasy and science fiction,
  time travel is now simply an engineering
  problem.

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Concept of Time

• The indefinite continued progress of existence
  and events in the past, present, and future,
  regarded as a whole." Oxford Dictionary
• Measurement to quantify duration of events?
• Social phenomenon?

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Spacetime

• Model combining 3D space and 1D time into a
  single manifold.
• Einsteins special relativity Space and Time are
  not possible to separate.
• New concept of distance, spacetime interval

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Theories
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Time Dilation

• Permitted by Special Theory of Relativity.
• Time appears to pass more slowly for faster
  moving bodies.
• Gives rise to Twin Paradox
• Preserves causality as only forward travel is
  possible

Where is Lorentz factor
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Wormholes

• Hypothetical topological feature of spacetime.
• Essentially a shortcut through space and time.
• Analagous to a worm burrowing through an apple
  rather than travelling around the surface.

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Wormholes for Time Travel

• Wormhole created.
• One end accelerated to near speed of light and
  brought back to point of origin.
• Due to time dilation, opposite ends of wormhole
  have experienced different subjective passage of
  time.
• Therefore travelling through the wormhole would
  be travelling to different point in spacetime.
• Would require orders of magnitude more energy
  than sun can produce in its lifetime (according
  to current theories)

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Tipler Cylinder

• Hypothetical object theorized by Frank J. Tipler
  in 1974.
• Sufficiently long cylinder with mass of several
  neutron stars.
• Induced to spin at near speed of light rotation
  rate.
• Creates frame dragging effect, warping spacetime
  in its locality.
• Travel limited to times in which cylinder already
  exists.

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Light Cylinders

• Single continuously circulating unidirectional
  beam of light.
• Produces weak and strong gravitational field.
• Exterior strong gravitational field is shown to
  contain closed time-like lines.
• Presence of such lines indicates possibility of
  time travel into the past.

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Flux Capacitor

• Conceived on November 5, 1955 by Dr. Emit Brown.
• Requires speeds in excess of 88 MPH.
• Energy requirements of 1.21 JigoWatts.
• Stainless steel mounting assists in flux
  dispersion.

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Paradoxes
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Twin Paradox

• Stems from theory of special relativity. Uses
  concept of time dilation.
• One of two twins undertakes long space journey at
  near speed of light.
• Due to time dilation, the amount of time observed
  by the twin moving is less (Lorentz factor) than
  the time observed by the stationary twin.
• PARADOX!!!!!!1

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Grandfather Paradox

• Often used to argue that backwards time travel is
  not possible
• You travel back in time and kill your biological
  grandfather before he met your grandmother.
• One of our parents, and thus you, would never
  have been conceived.
• It is therefore impossible for you to have
  traveled back in time to kill your grandfather.
• Therefore your grandfather would have lived to
  conceive your parent, who would have conceived
  you.
• PARADOX!!!!!!1

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Predestination Paradox

• Somewhat opposite to the grandfather paradox.
• A loop of events in time that predestine a time
  traveler to travel in the first place.
• A closed causal loop.
• Events are both cause and effect of one another.
• PARADOX!!!!!!1

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Causal Loop
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Ontological Paradox

• Used to argue why history can not be changed by
  time travel.
• Backwards time travel is only fulfilling role in
  history, not changing it.
• Whatever has happened was meant to have happened.
• Raises question of where, when, and by whom items
  or information are created.
• PARADOX!!!!!!1

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Causal Loop
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Conservation of Mass/Energy

• Net amount of matter and energy in universe is
  constant at any given time.
• If a person travels back in time, the net
  mass/energy at the origin is lowered while the
  net mass/energy at the destination is increased.
• PARADOX!!!!!!1

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Research
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Ronald L. Mallett

• Received Ph.D from Penn State University at age
  25.
• Professor of physics at the University of
  Connecticut.
• Specializes in quantum gravity, general
  relativity, and time travel.
• Featured in 2003 BBC documentary The Worlds
  First Time Machine.

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• Working on plans for a time machine using Ring
  Laser (Light Cylinder).
• Life dream is to travel back in time to save his
  father who prematurely died of a heart attack at
  age 33.

• Has thus far been unsuccessful...

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References in Fiction
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• Time travel is a popular topic for fiction,
  especially in science fiction movies, television,
  and novels.
• Many stories of time travel have had profound
  effects on pop culture.

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Terminator

• Cyborg travels back in time from post-apocalyptic
  future where robots rule over remnants of human
  race to kill leader of resistance movement when
  he is young.
• Features examples of grandfather,
  predestination, and ontological paradoxes

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Superman (1978 film)

• Superman flies around the world at super-speed in
  the opposite direction of the Earths rotation.
• Momentum from him flying causes Earth to spin
  backwards on its axis.
• Logically, this causes time to move backwards.

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Futurama

• Crew travels 1000 years back in time to 1950s.
• Fry, under the instruction of Professor
  Farnsworth to not do anything to change history,
  like killing your own grandfather,
  inadvertently kills his own grandfather.

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• Due to Grandfather Paradox, Fry should have never
  been born and thus not able to travel back in
  time to kill his grandfather.
• However, in an example of the predestination
  paradox, Fry finds himself overjoyed to still be
  alive and in celebration, end up impregnating a
  local waitress who turns out to be his
  grandmother.

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Back to the Future Trilogy

• Marty McFly and Doc Brown travel throughout the
  past, present, and future in a tricked out
  Delorian.
• Wacky hijinx ensue.

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Paradoxes seen in Back to the Future

• Predestination
• Chuck Berry inspired to write Johnny B Goode
  after hearing Marty play that very song
• Mayor Goldie Wilson inspired to become mayor
  after Marty informs him that he will be mayor
• Grandfather
• Marty prevents his parents from meeting and as a
  result his mom has the hots for him

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Conclusion

• Time travel is awesome
• However, you must be careful not to
• Kill your grandfather
• Become your grandfather
• Cause your mom to have the hots for you
• Reverse the rotation of the Earth

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References

• Wired
• http//www.wired.com/wired/archive/11.08/pwr_timet
  ravel_pr.html
• Special Relativity
• http//hyperphysics.phy-astr.gsu.edu/hbase/relativ
  /tdil.html
• Ronald Mallett
• http//www.phys.uconn.edu/faculty/mallett.html
• Wikipedia
• http//en.wikipedia.org/wiki/Time_travel
• http//en.wikipedia.org/wiki/Time_dilation
• http//en.wikipedia.org/wiki/Wormhole

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Questions?