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cliffes
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Light from distant stars is doppler shifted. Is the measured speed of light from these stars lower than the speed of light from the sun? Would one expect the permativitity of free space to vary over the universe?
No. In addition, this would require a spherical symmetry, and there is no reason why Earth should be in the center of such a variation.Would one expect the permativitity of free space to vary over the universe?
cliffes said:Light from distant stars is doppler shifted. Is the measured speed of light from these stars lower than the speed of light from the sun? Would one expect the permativitity of free space to vary over the universe?
Would one expect the permativitity of free space to vary over the universe?
cliffes said:Many thanks for the replies.
I am puzzled by frequency shift which I think relates to change in energy of a photon -however the doppler effect is normally explained as a frequency change in the light wave(not the energy of a particle). Intuitively I would expect photons to loose energy as they travel the huge distances in space. Is there evidence for this? Does it show up as a frequency shift if c remains constant?
I am puzzled by frequency shift which I think relates to change in energy of a photon -however the doppler effect is normally explained as a frequency change in the light wave(not the energy of a particle).
Intuitively I would expect photons to loose energy as they travel the huge distances in space.
Does it show up as a frequency shift if c remains constant?
of (photons) are redshifted by being observed in a different frame ...Now as t ticks along, the scale factor a(t) increases. Therefore two observers who are both at rest wrt to the CMB, but who have different times t, will therefore be in different frames (have different metrics). This is what leads to photons being redshifted when observed and emitted at different times.
Local observations trump distant ones.A photon has constant frequency relative to a static coordinate system, but an observer at a higher or lower potential will see it to have a different frequency compared with a photon created locally by means of an identical process, for example, a particular transition between energy levels.”
They DO lose energy due to the redshift / traveling though an expanding universe.
The speed of light from distant stars is approximately 299,792,458 meters per second, which is the same as the speed of light in a vacuum. This is known as the universal speed limit and is a fundamental constant in physics.
The time it takes for light to travel from distant stars to Earth depends on the distance between the two objects. Light travels at a constant speed, so the farther away a star is, the longer it takes for its light to reach us. For example, it takes about 4.3 years for light from the nearest star, Proxima Centauri, to reach Earth.
The speed of light is crucial in studying distant stars because it allows us to measure their distance from Earth. By measuring the time it takes for light to travel from a star to Earth, we can calculate how far away the star is. This is known as the method of parallax and is used in astronomy to determine the distance to objects in space.
No, the speed of light from distant stars cannot change. It is a constant in the universe and has been measured to be the same in all directions and at all times. This is one of the fundamental principles of Einstein's theory of relativity.
The speed of light from distant stars plays a crucial role in our understanding of the universe. It allows us to study objects that are billions of light-years away and to observe the universe as it was in the past. This has helped us gain insights into the origins and evolution of the universe.