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Astronomer Discovers the Most Distant Stars Ever Observed From Earth
Cryolithic writes to tell us The Vancouver Sun is reporting that a University of B.C. astronomer recently used NASA's Hubble telescope to see a cluster of stars one billion light-years from Earth, the farthest stars ever observed from Earth. From the article: "That's interesting, he explains, because given that light travels at a finite speed -- 300,000 km a second -- the light emitted from the star cluster he and Kalirai saw was emitted one billion years ago. That means the cluster as it appeared to them two months ago was the way it looked one billion years ago. In other words, they were looking one billion years back in time."
...in a vacuum. When not in a vacuum, light can travel at a fraction of the speed of light.
Well no, not exactly. When not in a vacuum it takes rest stops which reduce its average speed, but when not taking rest stops it travels at the designated finite speed; because that's the only speed at which light can travel. There was this Maxwell guy who 'splained it.
You know about the pony express? Well, they had posts along the way to change horses. Let's say, for the sake of simplicity, that these posts were 15 miles apart and that the horses traveled at a finite speed of 15 miles per hour. When the horse is moving it is always going 15 miles per hour, but the average speed of the horses over a full day is 13 miles per hour because of the time it takes for the rider to change them on an hourly basis.
Light is like the Pony Express, only without the horses, which wouldn't be like the Pony Express at all, would it? That would just be some guy taking a walk.
Nevermind.
KFG
Occording to relativity, anything travelling at the speed of light doesn't age, which means that the light doesn't age between it leaving its source and reaching you, which means that it is the same light as the past, so you are observing the past - in the present.
To use your china analogy, it's more like, if someone came from china, bringing a photograph they took before leaving, then when they show it to you, the photograph does show what things were like those 12 (or whatever) hours ago. The photograph itself might be in the present, but it's content - what you're looking at - are of the past. This is the same as looking at light from the past; the light may have reached the present, but we're not looking at the light, we're looking at the image carried in the light, which is from the past. Disagree all you want, you'll find you're in the minority opinion.
The revolution will not be televised... but it will have a page on Wikipedia
Bah! You're both right. Just a difference in semantics.