Astronomer Discovers the Most Distant Stars Ever Observed From Earth 291
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."
What is this light speed thingie? (Score:2, Insightful)
factoring spacetime is silly (Score:2, Insightful)
Re:paraphrasing Douglas Adams (Score:3, Insightful)
(hint - track one starts at the outside edge)
Re:only 1 billion ly? (Score:3, Insightful)
Re:it travels as fast as it travels (Score:5, Insightful)
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
Re:A correction/explanation (Score:2, Insightful)
Re:Looking back in time. (Score:2, Insightful)
Re:only 1 billion ly? (Score:1, Insightful)
Re:Looking back in time. (Score:3, Insightful)
No, you are completely missing the concept.
When you see something you are always seeing the past - what that object looked like when the light left it.
Think of it this way... when you see our sun, you are seeing how it looked 8 minutes ago. If the sun blew up right now (ignoring all the other issues associated with the sun exploding), you wouldn't see the explosion for another 8 minutes even though it already happened.
Re:Looking back in time. (Score:4, Insightful)
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.
Re:Looking back in time. (Score:3, Insightful)
"Once upon a time, the majority believed the Earth was flat"
This is actually much debated. People used to believe that the earth was center, with the sun/moon going around it, but there's huge evidence showing that the idea of everyone (or even most people) believing the world was round is flawed. Evidence includes discovery of coins with king and globes on them (showing people high up believed it to be round, not just some heretic in some village), people realising that for ships to disapear over the horizon must mean there was a curve (otherwise they would keep getting smaller, not disapear). Right back to Eratosthenes, who devised the system of latitude and longitude, and calculated the circumference of the earth around 220BC with an error of around 15% (measuring difference in angles of shadows cast from the sun in Aswan and Alexandria). Early models of the solar system showing the sun/moon going around the earth clearly shows the earth as a ball (makes sense, to believe the sun goes around something implied the something must be round).
Err, I'm getting carried away, was just a little impressed with what people managed to work out 2000+ years ago, distroyed by rumour created by people trying to show "the light" by showing how barbaric and misinformed people in the past were. If only the earth was at the end of the telescope, maybe we could see what really went on.
Re:Looking back in time. (Score:3, Insightful)