3 Things ‘Faster Than Light’


These 3 things go “faster” than the speed of light. How’s that even possible?
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More about the experiment:
Marissa Giustina’s research: http://arxiv.org/abs/1511.03190

Advanced scientific note about Doppler: If there is a light moving away from you at constant velocity in static flat (Minkowski) space-time, no matter how red it is, you will never conclude it is going faster than light. But, here I am discussing the conclusions one might come to if you mistakenly use Doppler in the context of the curved space-time of the universe (where there is expansion). Interpreting the huge redshift as a result of the doppler effect, could make one think that galaxies we see are moving away at speeds approaching light speed. And since what we are actually seeing is light from those galaxies from billions of years ago, and given that the universe is expanding, you might be tempted to say that they have since “accelerated” to faster than the speed of light. You might go further and say that there are more distant galaxies that we can’t see which are moving away even faster. So you might conclude there are galaxies moving faster than light in the universe. But the redshift isn’t from doppler and this “acceleration” of the expanding universe isn’t actually causing a true increase in velocity.

Sometimes astronomers do say there is a faster than light “recession speed” by pretending the expansion of the universe is causing distant galaxies to move away from each other at a corresponding velocity, but that’s misleading. In general relativity, you can actually have an increase in space between objects without causing a corresponding increase in the relatives velocities of those objects.


Host, Writer, Animator, Editor:
Greg Kestin

From the producers of PBS NOVA
© WGBH Educational Foundation

Funding provided by FQXi

Special thanks:
Marissa Giustina
Nick Hutzler
Julie Elksy
Byron Drury
Jacob Barandes
Tyler Howe
Lissy Herman
Ari Daniel
Lauren Aguirre
Kristine Allington
Allison Eck
Anna Rotschild


Music provided by APM:

Stars – Rene Barrios
Earth – Eirika
galaxy spiral (by coornio – diviantart)
Squirrel with scissors – 60811670 – Dollarphotoclub
Equations – 91613623 – Dollarphotoclub
Maxresdefault – Sean Stewart
Marissa Giustina – Lammerhuber
Tangled cat – David Swayze
Cat doll – Vicky Somma

Stock footage:
train-exits-tunnel – Pond5
Bin_pulsar_442 – Courtesy of Nasa
Expanding in space (40294) – Courtesy of Nasa
WMAP_archive – Courtesy of Nasa

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