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Motionlessness

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wurf

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I was reading that there are some individual intergalactic or "lonely" stars that exist outside of any galaxy or cluster. Do these stars revolve around anything? Is there any object known which is motionless in the universe?
 
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MeteorWayne

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Since there is no reference framework, the question would be motionless, compared to what?<br /><br />Yes stars and "planets" exist outside of galaxies.<br /><br />They are not motionless compared to other galaxies. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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wurf

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Planets and comets have speed we can measure in some arbitrary distance moved per hour or second, so I guess that's the framework I'm thinking of. Does every object have a measurable speed or velocity in that way?
 
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MeteorWayne

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Well all those measurements are velocities compared to our sun.<br /><br />That doesn't necessarily apply to objects in interstallar space.<br /><br />If you measure speed relative to our sun, everything moves.<br /><br />In fact if you measure the speed of any object relative to any spot in the Milky Way, it moves. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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nexium

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The lonely stars are likely sort of orbiting something, but the gravity is weak far from any other bodies, so one orbit could take billions of years to make one trip around all or most of our local group of galaxies.<br />A fast lonley star might pass several galaxy groups in a billion years and never repeat the same path twice. Neil
 
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qso1

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I would think they would be in motion. They would drift alongside whatever galaxy they were expelled from...drifting further away with time. Planets would probably remain in orbit around the drifting star assuming their orbits were not severly disrupted during the galactic expulsion event. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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a_lost_packet_

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Gravity doesn't like "non-motion." I would suspect that anything with mass would be in motion relative to something unless there was a force countering that. Then again, maybe we're all standing still and the rest of the Universe is actually in motion... <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
 
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3488

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Good question.<br /><br />They will be moving, probably quite fast too, seeing as they would have exceeded the <br />'escape velocity' of their parent galaxies.<br /><br />It is a very difficult one to answer really, what are they moving against in relation too?<br /><br />If they can be tracked back to source, than the question is answered. <br /><br />Their motion could be measured against the point at which they were ejected <br />from their parent galaxies.<br /><br />My guess is that for now, their motion will be based against ourselves, the observers.<br /><br />On a very related, but somewhat different note, could you imagine an Earth type planet <br />alone in intergalactic space??<br /><br />Very possible, but just imagine it. <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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enigma10

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Motionlessness. Define one single thing in the universe that meets this term properly and i will believe it actually exists.<img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>
 
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kelvinzero

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The manned space program beyond LEO, for about thirty years <img src="/images/icons/wink.gif" /><br /><br />(oftopic again.. sorry, sorry.. <img src="/images/icons/smile.gif" /> )
 
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wurf

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On Earth, if something's at rest, it's at rest in relation to everything else on Earth. Couldn't something in the universe be at rest in relation to everything else in the universe?<br /><br />If something, anywhere in space, could be measured moving at zero miles per hour, the hour measurement would be in relation to our sun, but wouldn't the fact that the distance value is zero mean that it would have zero speed, zero movement, in relation to anything and everything there is, including the movement of the person measuring? If something moved zero distance through space, wouldn't that be described as motionless? (Motion in the sense of travel, not rotation, vibration or such.)<br /><br />I'm not trying to argue something I actually believe, I'm just not getting how I'm wrong.
 
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enigma10

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Find an example. Define any object as being motionless. "If" is not an example. "If" defines nothing.<br /><br /> Think of motionless properties again, and bear in mind the motion down to subatomic level. Now think of Absolute Zero. Now find absolute zero.<img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>
 
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nexium

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Hi Wurf: The idea of motionless works well for short distances, but seems to break down even over distances of thousands of miles. Is Quito, Equador motioless wth respect to Nome, Alaska? Logic suggests Quito is rotating around Nome, but I am far from an expert on frames of refernce. Neil
 
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wurf

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I can think of examples but of course not without "if". They make sense to me but that doesn't mean they make sense, lol. What does seem weird is that when Newton wrote "...an object at rest tends to remain at rest...", a scientific law so important and famous that everybody's heard it, he was referring to something which doesn't actually exist. Thanks for the responses.
 
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nyrath

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As far as I am aware, the concept of something that is "absolutely motionless" is impossible in Einstein's relativity, since everything is, well, <i>relative</i>.<br /><br />If the distance between planet A and planet B is increasing, you can say that A is motionless and B is moving, A is moving and B is motionless, or that both are moving. It just gets worse when you add planets C, D, and E.
 
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heyscottie

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Wurf,<br /><br />Actually, Newton still had it right. Think of it this way.<br /><br />You are in a car travelling at a constant velocity. You have a ball in your lap. Is the ball at rest? According to you, it is. In order to make it move, you have to exert a force upon it.<br /><br />But your friend is by the side of the road, and he watches you and your ball go by. He sees the ball in motion, moving in a straight line. In order to make it divert from that straight line, he has to exert a force upon it.<br /><br />Both you and your friend are in what Einstein called "Galilean frames of reference", where you are both moving at a constant velocity with respect to one another. (Note that I'm simplifying, you are actually accelerating around the earth as it rotates, around the sun, etc.)<br /><br />So is the ball at rest, or is it in motion? Who can say who is right?<br /><br />Let's look at another example. You are in a closed box in space, away from any gravity influences. You are travelling away from your friend, who is in another box, at 100 miles per hour. Which one of you is moving? Which one is at rest? There is NO experiment you can do to determine if you are moving or not.
 
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enigma10

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taking this to a lighter side..<br /><i><font color="yellow">You are travelling away from your friend, who is in another box, at 100 miles per hour. Which one of you is moving? Which one is at rest? There is NO experiment you can do to determine if you are moving or not.</font></i><br /><br /> Sure there is. It's whomever looses their cell phone signal first.<img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>
 
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heyscottie

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I know enigma was joking, but I want to make sure that I stated the problem above correctly. The boxes are completely insulated -- there is no communication with the world outside of the box. If these requirements are met, then what I said was valid.<br /><br />Of course, this means that nobody gets any cell phone at any time! <img src="/images/icons/wink.gif" />
 
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enigma10

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Outside of cellphones(joke), motion is relative. In your experiment, if you were in a completely closed in system(box) with no points of refference. No way of denoting motion relative to anything else, then yes, you couldn't tell you were moving.<img src="/images/icons/wink.gif" /> If you can see your friend moving away, you might have something to work with. <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>
 
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wurf

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In your first example, I, the ball, and my friend are all rotating and revolving with the Earth and so I know that all are moving.<br /><br />But in the second example, in space, what if I'm travelling away from my friend at 0 m.p.h.? That is to say, not travelling. If I'm not moving, then I'm not moving, regardless of his or my perception.
 
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heyscottie

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In the first example, you are right. But I could put the same example in deep space. In that case, which one of you is right about the ball moving?<br /><br />In the second example, if you are not moving with respect to your friend, then you are still in the same Galilean reference frame, and are at rest with respect to each other. But you still might both be moving with respect to something else.<br /><br />The point is, that in our universe, there is no favored point of reference. You are always at rest or in motion with respect to something else. You can't say "with respect to the universe as a whole", because objects in the universe as a whole are all moving with respect to one another, in general. If there were some mythical "center" or "edge" of the universe, we could say we are at rest or in motion relative to that, and everybody could agree on that as a frame of reference, but such things do not exist. Therefore, all motion will always be measured relative to some object or arbitrary frame of reference.
 
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wurf

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So if the universe is infinite, there's no motionlessness, and if it's finite, there could be. I guess in the back of my mind there's an intuitive thought of an edge to the universe, whether it's right or not.
 
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