Time Travel

The Universe
Season 5
8 episodes
See below for purchasing options
DVD & Blu-ray
"The Universe" episode no. 60 (season 5)
  • written and directed by Darryl Rehr
  • edited by Katie Smith
  • science consultants Clifford Johnson & Alex Filippenko

  • narrated by Erik Thompson
  • Main Title Theme and Original Music by Eric Amdahl
  • Flight 33 Productions, (c) 2010 A & E TV Networks
  • 1 documentary @ 44 minutes

Data Capsule Review

by Martin Izsak

This turns out to be one of the best episodes of the fifth season.

Our physicists' ideas for getting a toe-hold into the abstract theory of time travel are pretty limited - sticking mainly to the forward-only concept of time-dilation that they expect from Einstein's theory of relativity and speeds approaching that of light. I'm still unsure they've thought through the frame-of-reference caveats such that what an observer sees is what is actually happening.

But, you have to give Clifford Johnson a star for sticking with the topic long enough to give it much more depth than usual, and for cleverly adding some wormhole theory in tandem to come up with a good theory for traveling into the past. This produces what may be the most memorable imagery in the episode.

As expected, the good old grandfather paradox is explained and re-enacted in a refreshingly non-violent permutation, while beautifully insisting that the universe must have an elegant way of resolving it. Three elegant solutions are presented, but I'm not sure why Alex Filippenko thinks the best of those - Level 3 alternate universes - is so strange and mind-bending. To me, it's everyday background now. Maybe he'd find it easier if he conceptualized them as branching universes, instead of calling them parallel.

Also quite interesting is the extensive coverage on the Large Hadron Collider in Switzerland, and the big questions of physics that it might help solve.

Alpha Centauri Exoplanets?

What knocks this episode up a huge notch is the last 25%, where we consider the Alpha Centauri triple star system and everything we knew about it up to 2010 including the possibility of detecting planets anywhere in it. Of course, it wouldn't do to explore that without Alpha Centauri expert Greg Laughlin, who shows up on cue and takes us to the Rose Bowl.

Best of all, the new spaceship for the Universe's later seasons takes us on a trip to Alpha Centauri, which for once is done in a more careful and awe-inspiring style than usual, shifting about halfway to a style closer to Carl Sagan's "Cosmos" series. This includes some notably different music - cool!

Ultimately, it seems to me like writer/director Darryl Rehr rocks, as he always seems to produce episodes of "The Universe" that stand above and beyond those of his fellow colleagues on the show.

Alex Filippenko: "Though we think we know a lot about the universe right now, and we do, there have been many times in the history of physics when we've been burned by having too much of a self-assured sense of knowing it all."

Sean Carroll: "There really are laws of physics that we can't violate, but there's also technology. You say, `Well, this is just too hard. We'll never be able to do it.' And there, when scientists say things like that, they're almost always wrong. It's much safer for us to say, `Here are what the laws of physics allow us to imagine doing. Hopefully, someday in the future we'll build the technology that makes it happen."

Participants include:

Clifford Johnson

University of Southern California

Sean Carroll


Alex Filippenko

Astronomer, supernova hunter
University of California, Berkeley

regular science consultant to
"The Universe" series.

Greg Laughlin

University of California, Santa Cruz

creates computer models of solar systems such as Alpha Centauri

Donald Marolf

University of California, Santa Barbara

Richard Obousy


one of the few physicists who have worked on faster-than-light space warp drive

And the "Ask the Universe" question for this episode is... "Can planets exist in a binary star system?"
- Nicole, Oklahoma City, Oklahoma.

from the disc sleeve:

Time Travel:
The laws of physics do not tell us it's impossible, but the bizarre consequences of going into the past and altering the future make for mind-bending science. Explore the possibility of time travel, both to the past and the future, as HISTORY (TM) hunts for an Earth-like planet 4.3 light years away.

Chapter List:

  • Arrow of Time
  • Wormholes
  • Large Hadron Collider
  • Warp Drive
  • Alpha Centauri

This documentary has become available on DVD and Blu-ray.
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The Universe
Season 5 Box Set
8 episodes



Blu-ray U.S.

Blu-ray Canada

Blu-ray U.K.

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Read the data capsule review for the next episode: "Secrets of the Space Probes"

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