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 Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...The Space and Astronomy Agora On Clarity And Meaningless Phrases Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response ToPosted by Timothy Storer on April 25, 2003 10:45:34 UTC

I thought I was the one that needed clarity. LOL

sagefr0g has requested that I clarify statements in my posting. I'll try.

My origional message said:
" But ACTUAL speeds are meaningless. Any object always have a velocity of zero to the frame of referance that follows it, and for any other frame of referance, the speed varies depending of the frame. The object in the above story has many different velocities depending on the frame of referance."

Let's say that an object("Object A") is moving with a velocity "X" reletive to some other object("Object Zero") in space and that a third object("Object B") is moving at velocity "Y" reletive to the first Object A in the same direction. Let's say that I then ask, "What is the ACTUAL speed of the Object B?"

There are at least three perspectives here from which speeds of objects could be measured. The speed of all three objects could be measured from the perspective of an observer traveling with any one of the three objects. Even if all velocities involved are small compared to the speed of light, the phrase "actual speed" has no meaning here. To say "actual speed" or "actual velocity" implies that there is some special perspective that is truly motionless. If there some some perspective that is truly motionless and to which all other perspectives should be compared, then a person need to describe that perspective and let the reader/listener know that all references to "actual" speeds and velocities refer to them being measured as from that particular perspective. Therefore, because the phrase "actual speed" needs to be defined before it has a specific meaning, it is meaningless. Perhaps I should have said vague instead of meaningless. Oh, well. Close enough.

:)
Timothy48342@yahoo.com