Mysteries of Time

Does Time Run Backward in Other Universes?

One of the most basic facts of life is that the future looks different from the past. But on a grand cosmological scale, they may look the same

By Sean M. Carroll -Scientific American

Key Concepts

• The basic laws of physics work equally well forward or backward in time, yet we perceive time to move in one direction only—toward the future. Why?
• To account for it, we have to delve into the prehistory of the universe, to a time before the big bang. Our universe may be part of a much larger multiverse, which as a whole is time-symmetric. Time may run backward in other universes... -(more)
  

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Q & A

Mysteries of time, and the multiverse

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Gary Friedman / Los Angeles Times

In his studies of entropy and the irreversibility of time, Caltech physicist Sean Carroll is exploring the idea that our universe is part of a larger structure.

By John Johnson Jr., Los Angeles Times Staff Writer
June 28, 2008

Caltech physicist Sean M. Carroll has been wrestling with the mystery of time. Most physical laws work equally well going backward or forward, yet time flows only in one direction. Writing in this month’s Scientific American, Carroll suggests that entropy, the tendency of physical systems to become more disordered over time, plays a crucial role. Carroll sat down recently at Caltech to explain his theory.

What's the problem with time?

The irreversibility of time is sort of the most obvious unanswered question in cosmology.
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