Said MrJesse:For an observer on earth at a point in time when Pluto is 6.8 light hours away and the earth rotates 102 degrees in 6.8 hours, when Pluto appears directly overhead, will it really be 102 degrees off - and not even really in the night sky?
Replied LeGrande: You cavalierly say "at a point in time", well, which point in time? When the light reflected off of Pluto or when the reflected light hit your eyeball?
You see, I didn't only say "A point in time" but I also said "For an
observer on earth.."!
An observer observes. And the fact is that when an observer on earth looks up to observe Pluto, there are two bits of information which are both valid at a (the same) point in time - the point of observation: One question is "Where is Pluto really?" and the other is "Where does pluto appear to be?."
It is sort of saying "I see two lights, 12 degrees apart." If that's what I observe then that's what I observe. It doesn't matter how far they are, and it doesn't matter how many degrees they are away from anything else, and it doesn't matter how long it took the light to reach the observer - it is still a valid and complete observation to say "I observed two lights, 12 degrees apart."
If you will remember, we agreed for the purpose of our discussion that a sensitive gravity meter could be used to determine the exact actual current position of a heavenly body. So it is perfectly valid for me to ask along the lines of "For an observer on earth at a point in time, is the angular displacement between Pluto's actual position and apparent position really 102 degrees when it's 6.8 light hours away..."
Any attempt to talk about the different points in time (like when the light bounced off of Pluto or whatever) is besides the point and just an effort to run us off track to avoid answering the real question.
Let us say that you see the reflected light from Pluto on the horizon (0 degrees) and at that precise moment (from your perspective) there is a nuclear explosion that obliterates Pluto. When and how many degrees from the horizon do you need to be looking in order to see the explosion?
Assuming that Pluto is on the horizon and rising, and is 6.8 light hours away, here's what would happen:
Pluto would still
appear to rise like normal for 6.8 hours, and would appear traverse up from the initial horizin about 102 degrees, then vanish from site. But the light during those 6.8 hours would still continue to come from where Pluto had been before it exploded because Pluto just doesn't move much in 6.8 hours relative to the earth.
So you'd have to wait 6.8 hours to see the explosion, and it would
appear 102 degrees "above" the original horizon, not because Pluto moved 102 degrees after exploding, but because the earth rotated 102 degrees after the explosion.
But this is all besides the question of where the gravity/actual position is as compared to the apparent optical position!
I have two questions? Where did all the water go when God created the earth and do you dispute Einsteins Theory of Relativity?
Amazing! What's wrong here? I, the Creationist, want to talk about science, and LeGrande, the Athiest, keeps bringing up religion!
But in answer to your question:
First one: You don't even believe that God created the earth, so you're certainly not going to believe what I might tell you that God did with some water when he created the earth! ha ha ha.
Second question:
I'm not actually highly versed in all the specifics of Einsteins Theory of Relativity. I skimmed through his paper on it as a youngster, and then again a few minutes ago before replying, and I did not see anything that I dispute. Could you be more specific? I hope you're not just trying to change the subject!
As I have explained before, I am not saying that thing's don't appear to move across the sky as the earth rotates. I'm well aware that things appear to move across the sky at the rate of 2.1 degrees per 8.3 minutes. I've also found that by spinning on the merry go around, I can get things to move across the sky at the rate of 360 degrees per second.
But there is a vast difference between spinning and being orbited - and that is this: When spinning, the light takes a path from the source to you in a straight line between the source and you. When you are being orbited, the source moves aver emitting the light, and so by the time the light arrives to your eyes, the source has moved and will no longer be where the light's angle causes it to appear to be.
In other words, the light is a third body!
It would be soooo helpful if you'd answer my color coded
questions!
So I'm well aware that if I turn on a merry go around at the rate of 180 degrees per 8.3 minutes it will cause the sun to appear to go around at that same rate, but it will not cause the sun's gravity to pull east while the sun appears in the west.
Thanks,
-Jesse
mrjesse - “But there is a vast difference between spinning and being orbited - and that is this: When spinning, the light takes a path from the source to you in a straight line between the source and you. When you are being orbited, the source moves aver emitting the light, and so by the time the light arrives to your eyes, the source has moved and will no longer be where the light’s angle causes it to appear to be.”
take a look at this illustration -
http://www.phys.unsw.edu.au/einsteinlight/jw/module1_Inertial.htm
What it is demonstrating is that there is no difference between being orbited or spinning. It is all about inertial frames of reference.
So back to your Pluto question. You seem to understand that if Pluto was orbiting a stationary earth you would need to lead it by 102 degrees to hit it with a missile traveling at the speed of light. Well it so happens that if Pluto is stationary you will need to lead it by 102 degrees if you are shooting that missile from a rotating Earth. There is no difference between the inertial frames as far as the two observers in them are concerned.
Now go back to the animation and carefully step through it. You will notice that the ball appears to travel straight to the receiver (from his perspective) in both examples and the ball appears to curve to the senders left (from the senders perspective) in both examples and the ball takes the same path each time over the base of the merry go round.