# Can some bright spark help me? Colour of Light vs Time

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1. Oct 13, 2015

### AlanMC

I'm writing a Science Fiction story which has one place where time runs at normal speed, and another place next to it, where time runs at a much slower speed. If you stand in the normal place and look into the slow place, you will see people moving around as if in slow motion.

But what would happen to light?
Would photons in the slow zone actually slow down?
When photons leave the slow time zone and enter the normal time zone, would the wavelength of the light expand? Would it then seem that things inside the slow zone are reddish, as if looking through a red filter? Or would it seem normal?

Thanks in advance for any help.

2. Oct 13, 2015

### phinds

If you don't care about the laws of physics then you can make up whatever answer you like. If you do care about the laws of physics then the only way your scenario can work is if the "slow" place is something like a neutron star with a humongous gravitational field. In this case, the inhabitants would have to be pretty unbelievable creatures to exist in a gravity field large enough to exhibit the characteristics you describe. They most certainly could not be anything like humans. If that's how you want to set it up, the light from the "slow" place would be severely red-shifted. That is, it would arrive at the "fast" place traveling at c, as light always does, but its frequency would be shifted.

EDIT: Also, the two places would have to be quite a distance apart, so "right next to each other" would have to be on a cosmological scale, not a human scale. And if you ignore that or ignore the gravity part and just say that the light would be red-shifted, then you would still be ignoring the laws of physics and writing non-science.

3. Oct 13, 2015

### AlanMC

Thank you. That's a great help. I've been trying to figure this out for days, and I thought the light would shift. The huge gravitational field is another issue, which I didn't consider.

4. Oct 13, 2015

### phinds

5. Oct 13, 2015

### AlanMC

That's certainly more to consider. For the scenario to work in the way I described it does seem impossible. Perhaps it's a case of writing it as a fantasy rather than a science fiction story. I do appreciate your response. Thanks again.

6. Oct 13, 2015

### jerromyjon

Why limit yourself? I could easily imagine a superconductive graviton dome which could act to dilate time within it without the "heavy" side effects... causing a singularity or whatnot.

7. Oct 13, 2015

### AlanMC

I've certainly asked my question in the right place.

8. Oct 13, 2015

### phinds

Yes, but that would be just as unscientific as ignoring the gravity. Not bad as gobbledygook, but I just want to be clear to the OP that it's not science.

9. Oct 19, 2015

### newjerseyrunner

Is it imperative to your story that one location ACTUALLY be slower? Laws of physics won't allow for that as we understand them right now, but if a species evolved in a very very cold world, energy would be a premium and creatures would simply move very very slowly. A biology based on liquid nitrogen as opposed to water would be frustrating to communicate with, simply saying "hello" might take hours.

10. Oct 19, 2015