TIME TRAVEL!

Lucas O’NeilBrendan Cassidy

Overview

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

Introduction

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.

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?

Spacetime

• Model combining 3D space and 1D time into a single manifold.

• Einstein’s special relativity: Space and Time are not possible to separate.

• New concept of distance, spacetime interval:

Theories

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

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.

• 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)

Wormholes for Time Travel

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.

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.

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.

Paradoxes

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

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

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

Causal Loop

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

Causal Loop

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

Research

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 World’s First Time Machine.”

• 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...

References in Fiction

• 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.

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

Superman (1978 film)

• Superman flies around the world at super-speed in the opposite direction of the Earth’s rotation.

• Momentum from him flying causes Earth to spin backwards on its axis.

• Logically, this causes time to move backwards.

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.

• 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.

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.

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

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

References

• Wired– http://www.wired.com/wired/archive/11.08/pwr_timetravel_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

Questions?