Does Light Experience Time?

by | Jun 7, 2019


In the book Death’s End by Cixin Liu (which is the final book of the fantastic Three Body Problem Trilogy) a spaceship called Halo has a special propulsion system that curves space and allows the ship to attain light speed. Halo and its occupants journey to a star 286 light years away at the speed of light. The book states that from the perspective of people in the solar system or at the destination Halo’s journey took 286 years (TRUE!), but for people on Halo the journey took a mere 52 hours (FALSE!).

Why is the 52 hour claim false? Because from the perspective of the people on Halo, the journey of 286 light years while traveling at light speed would have taken no time. ZERO! They would have arrived at their destination instantaneously from their perspective.

This strange result occurs because light does not experience time. We know this due to the theory of Special Relativity which links space and time. As an object goes faster through space it experiences less time relative to a stationary observer. The closer and closer an object gets to light speed, the amount of time experienced as compared to a stationary observer approaches zero. At light speed the time experienced is zero.

Thus, for a photon (a packet of light) generated by a distant star 1 million light years away that travels at light speed to Earth, it will be created and hit the Earth at the exact same moment from its perspective. From our perspective, it took 1 million years for that photon to reach us. Stop and think about that for a second. You are photon and are created inside a star and the instant you are created – wham – you hit the Earth (or wherever).

I am sure that Cixin Liu, an amazing science fiction writer, knows of this characteristic of light speed travel, as such I don’t know why he chose 52 hours as the amount of time to travel 286 light years rather than say it occurred instantaneously. Compared to 286 years 52 hours is incredibly small, but its not zero.

Another issue is that nothing with mass can travel at the speed of light. He gets around this by space curvature propulsion drives – presumably working on the premise that while nothing with mass can travel through space at the speed of light, space itself can expand at or greater than the speed of light.

A related question, is faster than light speed travel possible?

Another related IFOD: The Strange Result of Light Speed being a Constant


  1. As a heads up, Halo doesn’t achieve lightspeed as that is impossible, but it achieved near lightspeed which is why there is a slight amount of perceived time.

  2. What about stowaways? Maybe Scooby and Shaggy would never get back in time to see Daffny and Fred again.
    Also would they be able to take the Mystery Machine on the Time Machine?
    Hope they bring some munchies, because time travel causes hunger, no doubt.

  3. Actually, that’s an easy one. There are two speeds that are faster than the speed of light. Ridiculous Speed and Ludicrous Speed. Once you’ve gone to plaid careful with the re-entry to slow down first.

  4. A Nobel Prize is waiting for the person who answers that question.

    There is of course the “ spooky action” Einstein spike of but could not explain.

    So far the speed of light is the known speed limit for the universe we can experience.

    Of course, there IS hyper space and warp speed of the Star Wars and Star Trek fame


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