# how it works?

Discussion in 'Physics & Math' started by ethernos, Sep 8, 2017.

1. ### hansdaValued Senior Member

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See my post #20.

3. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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And as I said - that is based on the observer. Thus, the actual volume cannot shrink as observed by something in the same frame of reference as the object in question.

Kindly provide some evidence otherwise?

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5. ### exchemistValued Senior Member

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You miss Kitta's point. This is only true from the viewpoint of an observer relative to whom the electron is moving with this speed. To a co-moving observer there is no length contraction. The volume will be measured to be different accordingly as well of course. To the electron itself therefore, there is no change in volume.

7. ### hansdaValued Senior Member

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If the observer is also travelling along with the object, there is no relative velocity between the object and the observer.

8. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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That has nothing to do with my comment.

9. ### exchemistValued Senior Member

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..and thus, to him or her, no length contraction. Agreed?

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10. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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Correct, so it obviously depends on which frame you are in!

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11. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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Here is the point.

Assume there are 2 different inertial frames with an observer in each.
Each will say the other is length contracted.
Each will also say that their own frame is not length contracted.

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12. ### hansdaValued Senior Member

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The observer has to be in the rest frame. Otherwise, how there can be a relativistic speed between the observer and the object.

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13. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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Each of the observers can consider themselves as the rest frame, and can consider the other in the moving frame. Or either of the observers can consider themselves in the moving frame and the other in the rest frame. It makes no difference, we are talking about 2 different inertial frames so it is sort of relative.

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14. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member

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You just agreed that it depends on which frame you are in which was my point!

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15. ### KittamaruAshes to ashes, dust to dust. Adieu, Sciforums.Valued Senior Member

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Exactly -

So, that said, how can the actual volume change, when volume is a measure of the capacity or space of an object - for the volume to change, the actual dimensions would have to change - however, to the object itself, its length has not changed, thus its volume cannot change.

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16. ### exchemistValued Senior Member

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You seem to think there is such a thing as the rest frame. But there isn't.

There is a frame of reference in which the object is at rest and there is another in which it is moving close to the speed of light. And there are innumerable other possible ones too. All are equally valid.

You can choose to imagine observers in any of these frames and they will all see the lengths differently. And they are all of them right.

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17. ### ethernosRegistered Member

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thank you all for this interestingly debate...,

Last edited: Sep 10, 2017
18. ### James RJust this guy, you know?Staff Member

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Volume of what?