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johne1618
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If light travels a metre in a unit of cosmological time now will it travel two metres in the same cosmological time interval when the universe has expanded to twice its present size?
johne1618 said:If light travels a metre in a unit of cosmological time now will it travel two metres in the same cosmological time interval when the universe has expanded to twice its present size?
johne1618 said:If light travels a metre in a unit of cosmological time now will it travel two metres in the same cosmological time interval when the universe has expanded to twice its present size?
There's no simple set relation between the travel time and how far the light has gotten away from its point of origin. It will depend on the expansion history (how much of the expansion occurred early, how much occurred later etc etc).
Another way of saying this is that the local effects of expansion are below negligible, so the short answer to your original question is still no.
Naty1 said:pHindsI would say this differently:
The cosmological model that provides our understanding of large scale expansion is based on a homogeneous and isotropic formalism; there is no evidence it applies locally to a lumpy environment such as a solar system or even a galaxy.
Again, I agree w/ what you say, but it is irrelevant to what I was saying about "local" events in intergalactic space, for which my statement is more appropriate.So sum up, from my balloon analogy page:edit: "It is only over HUGE amounts of time that the tiny differences add up to a noticeable amount."
I disagree. I'd say "It is only over huge distances...that expansion applies."
Naty1 said:johne:
If you look at the first diagram here, you can get an idea how the expansion of the universe varies over time...
http://en.wikipedia.org/wiki/Cosmological_redshift#Interpretation
This is not the actual scale factor but rather the related factor 'z'...Wiki shows the relationship
in the article...
I can't find the link to a plot of the scale factor...anyone have that??
I wish Wiki would illustrate that directly...
Naty1 said:... an idea how the expansion of the universe varies over time...
...
I can't find the link to a plot of the scale factor...anyone have that??
I wish Wiki would illustrate that directly...
I agree with the above but it is irrelevant to my statement which was intended to be discussing "local" as a place in intergalactic space, not inside a bound system.
The expanding universe refers to the idea that the universe is constantly growing and getting bigger over time. This theory is supported by observations of galaxies moving away from each other and the measurement of the cosmic microwave background radiation.
In an expanding universe, light is subject to the effects of cosmic expansion. This means that as the universe expands, the wavelengths of light also stretch and become longer. This is known as cosmological redshift and can be observed in the spectra of distant galaxies.
No, the speed of light is a fundamental constant and does not change in an expanding universe. However, the wavelength of light may change due to cosmological redshift, giving the illusion of a change in speed.
The expansion of the universe plays a crucial role in the formation of galaxies. As the universe expands, matter is pulled apart, causing regions of higher density to form. These pockets of matter eventually collapse under their own gravity, forming galaxies. The rate of expansion also influences the distribution of matter and the size of galaxies.
Studying light in an expanding universe allows us to better understand the evolution and structure of the universe. It also provides evidence for the Big Bang theory and helps us to determine the age and composition of the universe. Additionally, studying light can also help us to learn more about the properties of dark matter and dark energy, which make up a majority of the universe's mass and energy, respectively.