General Question

ragingloli's avatar

If you lived on a planet on which time passes faster than in the rest of the universe, would the starlight you see on the surface be redshifted or blueshifted?

Asked by ragingloli (51974points) September 28th, 2019

Or would it appear the same?

Observing members: 0 Composing members: 0

16 Answers

stanleybmanly's avatar

Blue loli. The gravity well responsible for the time dilation imparts more energy to the incoming photons. Observers outside the well see redshifted light coming from the surface.

ragingloli's avatar

Are you sure it would not be the opposite?
Remember, time runs faster on this planet, as opposed to slower on a regular planet.

flutherother's avatar

I would agree with @stanleybmanly but for a different reason. If time passes faster more light waves will be received per unit time and that represents a blue shift. Increased gravity itself causes time to pass more slowly.

stanleybmanly's avatar

It can’t be the opposite loli if things moving away from us are red shifted (like galaxies).

stanleybmanly's avatar

@flutherother the shift is relative. An observer from outside sees the light shifted red. A man on the ground sees the same light as shifted blue.

flutherother's avatar

I think I understand now, correct me if I am wrong. Increased gravity causes time to move more slowly when observed by a distant observer. From the point of view of an observer on the planet increased gravity causes time to move faster so the starlight will be blueshifted.

stanleybmanly's avatar

They’re all different ways of saying the same thing. Only I think it best if any observer, wherever they’re situated should view themselves as “normal” just to keep things easily explainable.

ragingloli's avatar

Increased gravity causes time to move slower.
I am asking about the opposite effect.
So, if in a normal situation, gravity, and thus time dilation, causes light to be blueshifted, would in the opposite case of negative time dilation, not a redshift occur?

flutherother's avatar

No, increased gravity causes time to move faster from the viewpoint of someone on the planet which is what the question assumes.

stanleybmanly's avatar

See? You 2 exhibit the problem exactly. When you say time moves faster or slower, you must ALWAYS include the frame of reference. Time doesn’t move faster for the viewer on the planet. Faster than what? His time (for him) is normal & HIS clock proves it. And loli, increased gravity causes time to move slower for whom? The man experiencing the increased gravity-his time is just fine and he can prove it with HIS stopwatch.

flutherother's avatar

@stanleybmanly I get that and we are comparing two frames of reference with respect to each other. A distant observer far out in space and someone on the planet.

filmfann's avatar

Blue shifted. Light would appear to move faster.
That is unless the reason you are experiencing time different is because the planet is moving super-rapidly. Then, light from one direction would be blue, and the opposite would be reddish

stanleybmanly's avatar

All expressions of the basic fact. You might say the light shifts blue or red because it can’t move any faster.

ARE_you_kidding_me's avatar

Nothing changes, blue shifted and red shifted stars would just be more dramatic in their intensity. Remember time is the variable here.

kritiper's avatar

Neither. The light would be dimmer. The light would only redshift if you were moving away and blueshift if you were moving towards it.

kritiper's avatar

My post above is assuming the viewer is moving parallel to the light source. If viewed in normal time, the light would be normal. but if time was accelerated on the viewer’s planet, the amount of light being viewed would be reduced because the amount of light being received is the same either way, but in fast time, the light is being spread out, thus being reduced in intensity to the viewer on planet.

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