A Ray of Light: The Timeless Life of a Photon
Yours is the day, yours also the night; you have established the heavenly lights and the sun. (Ps. 74:16, ESV)
If you know anything about the speed of light, it’s probably this: Light travels at 186,000 miles per second in a vacuum.
So if you step outside, the sunlight that hits your body left the sun almost 8 minutes ago.
But here’s the thing: From the light’s perspective, no real time has elapsed.
Einstein’s theory of relativity tells us that time is different at different speeds and gravitational pulls. So, when light is traveling at its maximum speed, time is perceived differently. When a photon travels at the speed of light, that photon is massless and, from the perspective of the photon, timeless.
It’s not just true of the relatively short distance from the sun to Earth. If a photon leaves a star and maintains the speed of light, from the photon's perspective no time transpires from its creation to its decay.
On a dark night in a suitably dark area, we can see the Andromeda galaxy, whose light has taken 2.5 million years to arrive at the back of our eye. But its journey of 15 quintillion miles would seem instantaneous to the light if it had some sort of consciousness.
“Time stands still for an object moving at the speed of light,” astrophysicist John Gribbin wrote. “From the point of view of the photon, of course, it is everything else that is rushing past at the speed of light. … You can either say that time does not exist for [a photon of light], so that it is everywhere along its path at once; or you can say that distance does not exist for [a photon].”
Essentially, when we discuss a photon of light, we are diving into a quixotic realm—the ...
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- Editor's Note from October 15, 2015
Issue 33: Martian gardens, making choices in Colombia, and a relatively instantaneous trip. /
- Can We Farm Mars? Should We?
We’ve found evidence of flowing water. Next up: Planting crops? /
- The Breaking with Dawn
Can I have the meteor shower and the sunrise? Must a moment cost me? /
- The Autumn
‘For every breath that stirs the trees, /Doth cause a leaf to fall.’ /
- Wonder on the Web
Issue 33: Links to amazing stuff.
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