Posted on 10/18/2004 12:27:05 PM PDT by roaddog727
Imagine the weight of a nagging suspicion that what held your world together, a constant and consistent presence you had come to understand and rely on, wasn't what it seemed. That's how scientists feel when they ponder gravity these days.
(Excerpt) Read more at msnbc.msn.com ...
3 metric tons.....thanks
LOL...you just lost the women's vote amigo.
But only relatively....
At the Griffith Observatory in Los Angeles, there is a display, constructed to show the effects of satellite orbital velocities based on distance from the object that they orbit about. A large, but shallow funnel about 10 feet in diameter or so, is used. Metal balls are released into the top of the funnel tangentially to show how the orbital velocities increase as they spiral in toward the center. In this case, the analogy is not dependent upon 'real' gravity to supply the depression caused by the bowling ball, but obviously it is required in order for the ball bearings to move inward toward their eventual disappearance from view. I have a question about gravity: are gravity 'waves' constrained by "c", i.e., the speed of light? My hunch is that they are, but I wonder. If we had an accurate way to measure the gravitational pull of an object travelling at relativistic velocities, would the point of measurment coincide with the point of observation?
gravitically-challenged placemarker
Yes, although there are lunatics and cranks who will tell you otherwise. This was discussed extensively in a recent thread here.
I believe they are constrained by c, the trouble I have is that I do not believe there is such a thing as "gravity waves" because I do not believe that gravity is a thing in its own right. I believe that which we call gravity is actually caused by other interactions, and those other interactions are constrained by c.
If we had an accurate way to measure the gravitational pull of an object travelling at relativistic velocities, would the point of measurment coincide with the point of observation?
I would be lying if I said I understood your question. When you say relativistic velocities, do you mean exactly c or some velocity less than c but higher than what we are used to? And when you are measuring gravitational attraction of a body, are you separated from the body (such as measuring the Earth's gravitation from Mars vs. on the ground)? Finally, I would argue that "point of measurement" and "point of observation" are always the same point by definition because a measurement is an observation, so I am also having some semantic trouble with the question.
However, in order to account for dark matter as I understand it, There would have to be a lot of them. Consider what would happen if a little tiny black hole impacted a normally massive body. It would seem reasonable to me that in that situation, the black hole would quickly devour the entire mass of the normal body, becoming a slightly larger black hole. My guess is that this event would be rapid and dramatic. In all our celestial observations, have we ever noted a star simply vanishing? If not, I would argue that little black holes do not exist, at least in the quantity required to account for dark matter.
Nope, not a blessed thing, except that they are theoretical (I think). That is one of the problems I am wrestling with when I ponder gravity, particle physics, thanks to quantum mechanics, is a vastly complex subject. Sometimes I think all these particles are a bit rediculous, a herculean effort to explain something not yet well understood, and sometimes I retreat to occam's razor....
I won the lottery in another dimension.
Perhaps. But somehow the planets themselves, which are certainly responsive to gravity, always seem to orbit the sun in very predictable paths. Whatever is affecting the probes is very odd indeed. Unless there are anomalies I'm not aware of.
Question: What is the orientation of the solar plane to the sun's present velocity vector? Is it parallel, perpendicular, or some angle in between?
If it is precisely perpendicular, then I am wrong. If it is not perpendicular, then I may be right, but knowing the angle could go a long way towards determining specifics more accurately.
The sun is orbiting the galaxy, more or less, so I guess your question boils down to whether the plane of the solar system is in roughly the plane of the galaxy, or whether we're tilted. I'm not sure, but the fact that we can see the band of the Milky Way in the northern hemisphere indicates to me that we're tilted.
Not only is the plane of the solar system (the ecliptic) tilted with respect to the plane of the Milky Way (galactic equator) but the Earth's axis is also tilted with respect to the ecliptic. The north pole of the solar system (north ecliptic pole) lies about 23.5 deg away from polaris in the constellation Draco (18h 00m R.A.) and the North pole of our Galaxy (north galactic pole) lies about 27 deg away from polaris in the constellation Coma Berenices (12h 51m R.A.).Whatever that means. Maybe RadioAstronomer will step in to help.
Thanks for the research. However, my question was more aimed at the condition at this specific time. Even if the angle varies over time, what is it right now? I will study the link you provided and see if it answers my question.
In my Googling around, I found a site which says that the planes are tilted 60 degrees from each other. I'm not able to give an opinion on this.
Hmmm. I'll have to put some thought into this. Did you find anything that compared the solar plane to the sun's present velocity vector? At any rate, it is probably safe to assume that what ever the vector is at the moment, that it is parallel to the galactic plane, making the solar plane skew to the galactic plane, and thus skew to the vector I seek.
The galaxy is a flat disk (roughly speaking) so the sun is definitely orbiting within the plane of that disk. Are you asking the time it takes for the sun to complete a galactic rotation? That's a "galactic year" I think. Easily found, along with the sun's velocity. I'm pretty much googled out at the moment, but you'll find it easily enough. Anyway, I'm not aware of any reason why the solar system's plane, which corresponds to the sun's equator (if that's the term) needs to be in the same plane as the galaxy's disk. Stars rotate with their poles pointing in various directions.
bump for later
Actually, the Galactic plane is almost 60 degrees offset from our equatorial plane which is offset by 23.5 degrees from our orbit plane.
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