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Time Travel

That particles might travel back in time, is perhaps one of the most ridiculed aspects of quantum physics. But will time travel ever be possible?

Posted by Tormod Guldvog
01 October, 2002 12:10:28

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The eternal grandfather paradox
If you saw any of the "Back to the Future" movies, you might remember that one of the basic problems of time travel is what some call the "grandfather paradox".

Imagine that you could travel back in time and somehow kill your grandfather. You would never be born, and could never travel back in time to kill your grandfather.

There is still hope...
But although the grandfather paradox is troubling, it might not be the final word on time travel. Some scientists have pointed out that quantum mechanics might hide clues to how we can deal with time as a traversable dimension, just like space.

The problem is usually posed as a mathematical problem, in which we would need an infinite amount of energy to create a time loop. It is important to realize that understanding time is not necessarily something we need in order to travel back in time. If we want to travel to other stars, we might have to find a way to move faster than light if we want to get there in less than thousands of years. To conquer time would mean that we would be able to travel instantly across vast reaches of space.

Paul Davies & Carl Sagan
In the past decades, British physicist and writer Paul Davies has developed very interesting ideas on the possibility of time travel. His writing style is quite accessible, and he has written several of the texts we link to below. Of interest is also the interview with Carl Sagan, one of the most renowned cosmologist of the last century.

If you find the topic of time fascinating, don't miss our Hypography on The Arrow of Time, which deals with the perception of time flowing in one direction only.

Related Links

Time Travel
http://freespace.virgin.net/steve.preston/Time.html
A private web page which discusses the possibilities of time travel in a readable manner.

Time Travel for beginners
http://www.biols.susx.ac.uk/home/John_Gribbin/timetrav.htm
An essay by science writer John Gribbin on various aspects of time travel.

EDGE: Time Loops
http://www.edge.org/3rd_culture/davies/davies_index.html
An interview with Paul Davies about his research into quantum physics, and most notably, time travel.

Carl Sagan on Time Travel
http://www.pbs.org/wgbh/nova/time/sagan.html
An interview with Carl Sagan about his views on time travel. You can hear his voice via RealAudio.

Timespeak
http://www.pbs.org/wgbh/nova/time/timespeak.html
A handy dictionary of time travel words and expressions.

Superspace
http://www.deoxy.org/superspace.htm
An essay by Paul Davies on the dynamics of spacetime, including an in-depth look at gravity waves and a concept of superspace, in which many worlds are weaved together.

Bang goes Einstein's speed of light theory
http://old.smh.com.au/news/0007/21/text/pageone3.html
Paul Davies has written this brief comment on reports from Princeton that the speed of light is not a true constant.

Paul Davies: Biography
http://www.nedkelly.com.au/books/author.asp?author=52
This article presents the scientist and writer Paul Davies.

Promise of Science: Time Travel
http://www.umich.edu/~umfandsf/film/promise/time_travel.html
This is an article about how time travel has been dealt with in movies and literature.

Is Time Travel Possible?
http://www.flash.net/~csmith0/time.htm
A text on the feasibility of time travel, and some of the problems involved, by Michio Kaku.

What Happened Before The Big Bang?
http://www.fortunecity.com/emachines/e11/86/big-bang.html
An entertaining article by Paul Davies, about the problems of causality and some rather interesting points about the existence of the universe.

Time Travel and Modern Physics
http://plato.stanford.edu/entries/time-travel-phys/
A very long page from Stanford University, with lots of background and illustrations, discussing how modern physics is being used to consider time travel.