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ZylonBane t1_jcnt1c7 wrote

Reply to comment by jthtiger in Where do photons go if they've been emitted but are destined to never be absorbed, and would these photons traveling ad infinitum define the edge of the universe (even if space itself were still larger)? by mysteryofthefieryeye

Redshift has nothing to do with position. Redshift is the photon equivalent of the Doppler effect. Just as sound sources that are rapidly receding sound lower-pitched due to their waveforms being stretched out, light from sources that are rapidly receding appear shifted toward red in the electromagnetic spectrum. So velocity is what matters.

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jthtiger t1_jcnttul wrote

Position isn't the right word probably. Velocity is more accurate yes, but it's the velocity of the object that emits that cause the wavelength to be stretched.

My point was that the wavelength does not continue to stretch over time. So a photon won't redshift into nothing-ness.

The velocity of the photons does not change over time and therefore will not drift apart.

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ZylonBane t1_jcnv4vx wrote

>So a photon won't redshift into nothing-ness.

It will if the rate of universal expansion is accelerating.

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jthtiger t1_jcnvjfn wrote

Hmmm. As always, physics answers brings more questions. Thanks for imparting some knowledge.

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