Known physics defeated by simple puzzle?
in [Relativity]
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From: Sue... on 4 Apr 2010 09:21 On Apr 4, 8:36 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 4 Apr, 12:38, "Inertial" <relativ...(a)rest.com> wrote: > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > I give three people a photographic > > > filter each, all different colours, and they hold it front of their > > > eyes. I ask them to look at the sky, and they each comment that the > > > sky has changed colour. I now ask them "has the sky really changed > > > colour?". Now how would you interpret my question, and how would you > > > answer that question? > ============== > > The light reaching them has different colors, because certain frequencies > > are filtered out. > > So when I ask "has the *sky* changed colour?" you will say "no"? The sky is imaginary just as Newton's light corpuscles are imaginary. If you plot the behaviour on an axis that is orthogonal to what you know is real, you can work with it, whether it is real or not without concern for the view of others getting you into a tail-chase. http://en.wikipedia.org/wiki/Complex_number "~Minkowski space~" http://www.bartleby.com/173/17.html I would suggest practising with something a bit simpler than the "sky" but the tool is certainly up to task for the questions you have asked. Sue...
From: Ste on 4 Apr 2010 10:09 On 4 Apr, 14:15, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:9b9f09c2-c45f-4169-9aa6-ba7a107de57f(a)k19g2000yqn.googlegroups.com... > > > On 4 Apr, 12:38, "Inertial" <relativ...(a)rest.com> wrote: > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >> > I give three people a photographic > >> > filter each, all different colours, and they hold it front of their > >> > eyes. I ask them to look at the sky, and they each comment that the > >> > sky has changed colour. I now ask them "has the sky really changed > >> > colour?". Now how would you interpret my question, and how would you > >> > answer that question? > > >> The light reaching them has different colors, because certain frequencies > >> are filtered out. > > > So when I ask "has the *sky* changed colour?" you will say "no"? > > Just sticking my 2 cents worth in here. > > I'm not sure I understand what you mean by the term "the colour of the sky" > in this context. You seem to want it to mean two different things. > > If you define it to mean the colour seen by an observer looking through > filters, then the colour does change. > > If you define it to mean the colour seen by an observer not looking through > filters, then the colour doesn't change. > > So when you say "the colour of the sky", how are you defining this term in > the context of this experiment? The question of what I mean by the "colour of the sky" is not actually that important - it can be given its everyday meaning. The real question is about the cause of the change, and *what* is changed. Placing a filter in front of one's eyes clearly doesn't cause any measurable change in the colour of the sky (if it did, everybody would be able to see the sky turn red when just one person in the whole world put a red filter over their eyes). And of course, the real question behind this is about "length contraction". I'm trying to get an idea of whether length contraction is real (i.e. the sky has turned red for everyone - the whole universe has contracted), or whether the relativistic speeds cause a sort of lensing effect (i.e. like putting a prism in front of one's eyes, the "contraction" affects only the person with the prism in front of their eyes) that makes everything *appear* contracted, but there is actually no measurable change at all in the rest of the universe.
From: Inertial on 4 Apr 2010 10:14 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:265c67a2-6691-4173-be60-e9e93373bf3d(a)30g2000yqi.googlegroups.com... > On 4 Apr, 14:15, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> news:9b9f09c2-c45f-4169-9aa6-ba7a107de57f(a)k19g2000yqn.googlegroups.com... >> >> > On 4 Apr, 12:38, "Inertial" <relativ...(a)rest.com> wrote: >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >> > I give three people a photographic >> >> > filter each, all different colours, and they hold it front of their >> >> > eyes. I ask them to look at the sky, and they each comment that the >> >> > sky has changed colour. I now ask them "has the sky really changed >> >> > colour?". Now how would you interpret my question, and how would you >> >> > answer that question? >> >> >> The light reaching them has different colors, because certain >> >> frequencies >> >> are filtered out. >> >> > So when I ask "has the *sky* changed colour?" you will say "no"? >> >> Just sticking my 2 cents worth in here. >> >> I'm not sure I understand what you mean by the term "the colour of the >> sky" >> in this context. You seem to want it to mean two different things. >> >> If you define it to mean the colour seen by an observer looking through >> filters, then the colour does change. >> >> If you define it to mean the colour seen by an observer not looking >> through >> filters, then the colour doesn't change. >> >> So when you say "the colour of the sky", how are you defining this term >> in >> the context of this experiment? > > The question of what I mean by the "colour of the sky" is not actually > that important - it can be given its everyday meaning. The real > question is about the cause of the change, and *what* is changed. > Placing a filter in front of one's eyes clearly doesn't cause any > measurable change in the colour of the sky (if it did, everybody would > be able to see the sky turn red when just one person in the whole > world put a red filter over their eyes). > > And of course, the real question behind this is about "length > contraction". I'm trying to get an idea of whether length contraction > is real (i.e. the sky has turned red for everyone - the whole universe > has contracted), or whether the relativistic speeds cause a sort of > lensing effect (i.e. like putting a prism in front of one's eyes, the > "contraction" affects only the person with the prism in front of their > eyes) that makes everything *appear* contracted, but there is actually > no measurable change at all in the rest of the universe. You seem to think that something can only be real if it is the same for everyone .. so the pitch of a train whistle is not 'real', the velocity that an object travels at is not 'real' etc etc. By your definition, very little that we measure in physics is 'real'. I think your problem here is what you mean by 'real'.
From: Peter Webb on 4 Apr 2010 10:28 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:265c67a2-6691-4173-be60-e9e93373bf3d(a)30g2000yqi.googlegroups.com... > On 4 Apr, 14:15, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> news:9b9f09c2-c45f-4169-9aa6-ba7a107de57f(a)k19g2000yqn.googlegroups.com... >> >> > On 4 Apr, 12:38, "Inertial" <relativ...(a)rest.com> wrote: >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >> > I give three people a photographic >> >> > filter each, all different colours, and they hold it front of their >> >> > eyes. I ask them to look at the sky, and they each comment that the >> >> > sky has changed colour. I now ask them "has the sky really changed >> >> > colour?". Now how would you interpret my question, and how would you >> >> > answer that question? >> >> >> The light reaching them has different colors, because certain >> >> frequencies >> >> are filtered out. >> >> > So when I ask "has the *sky* changed colour?" you will say "no"? >> >> Just sticking my 2 cents worth in here. >> >> I'm not sure I understand what you mean by the term "the colour of the >> sky" >> in this context. You seem to want it to mean two different things. >> >> If you define it to mean the colour seen by an observer looking through >> filters, then the colour does change. >> >> If you define it to mean the colour seen by an observer not looking >> through >> filters, then the colour doesn't change. >> >> So when you say "the colour of the sky", how are you defining this term >> in >> the context of this experiment? > > The question of what I mean by the "colour of the sky" is not actually > that important - it can be given its everyday meaning. The real > question is about the cause of the change, and *what* is changed. > Placing a filter in front of one's eyes clearly doesn't cause any > measurable change in the colour of the sky If by "measurable change in the colour of the sky", you mean the colour measureed by people not wearing glasses, then yes. > (if it did, everybody would > be able to see the sky turn red when just one person in the whole > world put a red filter over their eyes). > > And of course, the real question behind this is about "length > contraction". I'm trying to get an idea of whether length contraction > is real (i.e. the sky has turned red for everyone - the whole universe > has contracted), No, "real" is not the same as "is observed the same by everyone" If you choose to interpret as "real" only those things which are observed the same by everyone, then "lengths" are not "real". And nor are sound frequencies; as they depend on the speed of the observer. And nor for that matter is the colour of the sky real, because different observers see it differently (depending on whether they are looking through filters). > or whether the relativistic speeds cause a sort of > lensing effect (i.e. like putting a prism in front of one's eyes, the > "contraction" affects only the person with the prism in front of their > eyes) that makes everything *appear* contracted, but there is actually > no measurable change at all in the rest of the universe. No, its not an optical illusion, for the 8 billionth time. The travelling twin really is younger. The ladder really does fit inside the barn.
From: Sue... on 4 Apr 2010 10:35
On Apr 4, 10:00 am, Ste <ste_ro...(a)hotmail.com> wrote: =========== > > That is the whole point here. Simultaneity is a function of the > reference frame, because simultaneity is also a function of your > actual position relative to the events being measured. Sound waves > also have a "relativity of simultaneity", that works in exactly the > same way as SR. <<There is only one demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled. That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A > M as for the path B > M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own freewill in order to arrive at a definition of simultaneity.>> http://www.bartleby.com/173/8.html Stipulations and freewill definitions sounds a bit like something that humans rather than electrical charges would enjoy doing. Nevertheless, H. Minkowski found a way to formalise them. http://www.bartleby.com/173/17.html So you have endless fodder for debate about what is real and imaginary 'till you learn enough GR to manage the concepts formally. Sue... |