I was reading up on how Römer discovered the speed of light by watching Jupiter and its moons, and I started wondering. Lets say you're constantly watching Jupiter through a huge observatory, while Earth is closing in due to its orbit. Would the display of Jupiter change in some way, comparing the time where the distanse is as far away possible, and when it is as closest. I hope you understand my question, I can try to express it more thouroughly if you want. Thanks!
Hehe, i think he was trying to measure the speed of gravity (?)... but the observation i think was flawed and he really did just measure the speed of light... Anyway jupiter would just appear bigger and not so long ago... Is that the answer?
how do we know that? i mean its not like we can take the sun away and see how long the earth keeps going around before shooting off
Well, I guess your answer to someone asking how far away from the sun the Earth is would be: "How can we tell, there aren't rulers that large." Quoting your signature: "APATHY, IGNORANCE AND GREEDPlease Register or Log in to view the hidden image!" If you know your Physics, you would know that according to the theory of relativity, the speed of gravity is the speed of light. If you would like some articles to back that up, please feel free to search on google with search terms being something like: "speed of gravity". Hundreds of page should pop up guiding you to enlightenment. Here is a link for you to ponder: http://www.space.com/scienceastronomy/gravity_speed_030107.html
The closer you (the earth) get to jupiter, the larger it will apear,but I think you will need one heck of a good telescope to measure the differnce. Change of subject. Recently (about 3 weeks ago) 2 scientists, I forgot their names, claimed to have measured the speed of gravity, and found it to be equal to that of light. But a few days later several scientists jumped on their findings and said they were not valid, there was something wrong with their methodolidy. so that's how it stands right now. I know that Einstein claimed that the speed of gravity was equal to light. but it was only a postulate, he offered no proof. From what I have read, it seems that half of all scientists claim the speed of gravity is instantaineous and the other half says it can never be measured if it has a speed. Regards M.J.
As always, a few links posting what you've read would be kind, apolo. There are always people who will think the speed of gravity is instantaneous, but then again, the effects of gravity ripples in space-time are so minute, the most sensitive sensors ever created are picking them up finally. There are two sensors working independently in the USA, one in the north-west and one in the south-east. I forget the name of the project so I will update my post as soon as I can. It's just a little menacing to me, when someone (Asguard) with much experience on these forums (3000+ posts worth) posts such a ridiculous statement as: I guess I'm the only one who had a little chuckle out of that. Please Register or Log in to view the hidden image!
my expertiess is in a kitchen most of my posts are in ethics i am INTERESTED in physics and it was a seriouse question
It would be surprising if gravity was found to propagate any speed other than c. All gravitational sources to my knowledge don't have any corrections built in to allow for their current position vs their visual position to us. If gravity were any faster than light, we'd see stars and galaxies in one place, but see their gravitational affect based on their current place, much like how the light and sound observations from an object depends on their position.
This was the topic of discussion recently in, I think, the Maths and Physics forum. There are several detectors planned (Germany, US, Australia, Italy, UK, Japan) but AFAIK no gravity waves have yet unquestionably been detected. See: http://www.physics.gla.ac.uk/gwg/ Most detectors are interferometers that (will) detect the gravity waves emitted when a large mass, eg a distant star, is accelerating, eg as in a binary system. Much the same as a moving charge generates EM waves. There is no need for the Sun to suddenly go out. Cheers, Ron.
My fault, the question was lousy. Lets say that you're watching a planet 3'000 light-years away. What you'd see is what happened there, 3'000 years ago. Lets say you travel by the speed of light (or even half or a quarter), to half the distance to the planet. What 'time' would you see, if you kept you're eye on it while you were travelling?
I think this is right, but I dont know alot: If you are travelling at the speed of light, you would see nothing. This is because you are moving relative to the light surrounding you. I dont know about the divisions of light speed, though.
Travel at the speed of light is thought to be impossible. At any speed less than that, if the planet displayed a giant clock I’d see it running faster than my clock. Initially I’d see a time representing 3,000 years ago. I’d reach the halfway point to the planet in less than 1,500 years on my clock. Suppose I traveled at a speed that got me to the halfway point in 50 years by my clock. In those 50 years I’d see 1,500 years transpire on the planet. An analogy is a video. If you play the video at normal speed, you see it normally. If you fast forward, you see more images per second. Likewise, if you are stationary with respect to a distant clock then images of each clock tick correspond one-to-one to the ticks of your clock; the clocks run at the same rate. When you travel towards the clock the more ticks of it you see per second on your clock. When you travel you pass through streams of images. If the images are those of a distant clock, you see the clock ticking faster. If the images are those of the planet rotating, you see the planet rotating faster. You can’t travel at the speed of light. But if you could, you could expect to see a distant clock running infinitely fast. Which makes little sense if you think about it. It’s like playing the video infinitely fast. For related info see this thread and the Usenet Relativity FAQ.
