Known physics defeated by simple puzzle?
in [Relativity]
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From: PD on 5 Apr 2010 12:34 On Apr 4, 12:17 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > No, what I mean is that there is some inherent attribute to the sky > (it's "colour"), and that attribute is not changed by the placing of a > filter between the eye and the sky. In other words, nothing happens to > the sky (as a concrete object in the external world) when you put a > filter in front of your eyes. > Though you may think it is true that color is an inherent attribute to the sky, it's simply not the case. The sky appears blue because the shorter wavelengths of light from the sun are scattered sideways by tiny things in the atmosphere. This leaves the light that is coming more directly depleted of the blues, which makes it red. The more atmosphere the light scatters through, the more pronounced this separation. It's a common effect known for quite a while -- a sunset. The point is that what color you see in the sky DOES depend on where you are in relation to the illuminating source, how much sky that illumination is passing through, and a number of other factors. Thus it is a false, but common, attribution of an inherent property. Just because something is commonly done does at all indicate that there is any correct physical basis behind it. PD
From: PD on 5 Apr 2010 12:51 On Apr 4, 12:36 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 4 Apr, 15:35, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > 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... > > As I've said before, the easiest definition of "simultaneous events" > is "those events which would have occurred at the same time if > information about their occurrance had travelled instantaneously > across space". This is basically the common sense definition that > people use anyway. This is the common sense definition that YOU use. Please do not presume to speak for "people" who, through different assumptions and perhaps a bit more openness, would arrive at a different definition entirely. Indeed, in my experience, students usually intuitively arrive at a definition that is a lot closer to the one that is used by physicists than the one you use. > > If I sit with family at 7 o'clock the evening and I ask "what time did > you have breakfast this morning", I'm not interested in when the > information is actually conveyed to me (i.e. long after breakfast > time). That is, I would not expect to be told "I've just had > breakfast", and when I query this I would not expect to be told that > "I had breakfast 5 seconds ago, when information of its occurence > first reached your ears". > > What I would expect to be told, when I ask "when did you have > breakfast", is "I had breakfast at 9 o'clock this morning". This has nothing to do with simultaneity. It has to do with comparison of an event against a local clock. If I asked you what time you had breakfast, and you told me at 9:00 this morning, and I asked you how you knew that, you might say "Because I looked at my watch while I was doing it." You would not say, "Because had a signal from the National Bureau of Standards had reached me instantaneously, it would have told me 9:00." > > The problem with this nonsense definition of simultaneity that the > physics community seem to be using is that nothing is held to have > ever happened until you actually measure it, and because it takes time > for information to travel, that means not everyone necesarily measures > the same event at the same time. And according to this definition of > simultaneity, the family member above had breakfast at 7pm in the > evening, because it took until 7pm for the information to reach me! You still don't get it. Simultaneity is determined AFTER accounting for the transit time of the signal. If two signals arrive at the same time, at 17:01:34, one does not say that the events that generated the signal were simultaneous at 17:01:34. One asks, how long did the signal take to get here from the first event? How long did the signal take to get here from the second event? If the answer to both those questions is 00:00:17, then you know the events both occurred at 17:01:17, and since they both happened at the same time, they were simultaneous. On the other hand, if another observer sees a signal from one event at 17:01:34 and a signal from the other event at 17:01:37, then you still need to ask, how long did the signal take to get here from the first event? How long did the signal take to get here from the second event? If the answer to both those questions is 00:00:17, then you know the first event occurred at 17:01:17 and the second event at 17:01:20, and they were not simultaneous. And here is the interesting thing: We have real cases where there are two and only two events, and one observer will see signals from them both at 17:01:34, and another observer will see one signal at 17:01:34 and the other signal at 17:01:37. Then BOTH observers will figure out the time of transit of the signals and deduce that the transit times where 00:00:17 in all cases. The conclusion one draws from this set of circumstances is obvious.
From: Sue... on 5 Apr 2010 13:26 On Apr 5, 12:51 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 4, 12:36 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 4 Apr, 15:35, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > 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... > > > As I've said before, the easiest definition of "simultaneous events" > > is "those events which would have occurred at the same time if > > information about their occurrance had travelled instantaneously > > across space". This is basically the common sense definition that > > people use anyway. > > This is the common sense definition that YOU use. Please do not > presume to speak for "people" who, through different assumptions and > perhaps a bit more openness, would arrive at a different definition > entirely. Indeed, in my experience, students usually intuitively > arrive at a definition that is a lot closer to the one that is used by > physicists than the one you use. > > > > > If I sit with family at 7 o'clock the evening and I ask "what time did > > you have breakfast this morning", I'm not interested in when the > > information is actually conveyed to me (i.e. long after breakfast > > time). That is, I would not expect to be told "I've just had > > breakfast", and when I query this I would not expect to be told that > > "I had breakfast 5 seconds ago, when information of its occurence > > first reached your ears". > > > What I would expect to be told, when I ask "when did you have > > breakfast", is "I had breakfast at 9 o'clock this morning". > > This has nothing to do with simultaneity. It has to do with comparison > of an event against a local clock. If I asked you what time you had > breakfast, and you told me at 9:00 this morning, and I asked you how > you knew that, you might say "Because I looked at my watch while I was > doing it." You would not say, "Because had a signal from the National > Bureau of Standards had reached me instantaneously, it would have told > me 9:00." > > > > > The problem with this nonsense definition of simultaneity that the > > physics community seem to be using is that nothing is held to have > > ever happened until you actually measure it, and because it takes time > > for information to travel, that means not everyone necesarily measures > > the same event at the same time. And according to this definition of > > simultaneity, the family member above had breakfast at 7pm in the > > evening, because it took until 7pm for the information to reach me! > > You still don't get it. Simultaneity is determined AFTER accounting > for the transit time of the signal. > > If two signals arrive at the same time, at 17:01:34, one does not say > that the events that generated the signal were simultaneous at > 17:01:34. One asks, how long did the signal take to get here from the > first event? How long did the signal take to get here from the second > event? If the answer to both those questions is 00:00:17, then you > know the events both occurred at 17:01:17, and since they both > happened at the same time, they were simultaneous. > ================= > On the other hand, if another observer sees a signal from one event at > 17:01:34 and a signal from the other event at 17:01:37, then you still > need to ask, how long did the signal take to get here from the first > event? How long did the signal take to get here from the second event? > If the answer to both those questions is 00:00:17, then you know the > first event occurred at 17:01:17 and the second event at 17:01:20, and > they were not simultaneous. > Fine and good for today's audience but in Einstein's time, Newton's light corpuscle moved under the influence of inertia. A simultaneity *defined* outside of the existing notions about light propagation was required. That is why you shouldn't consider the thought experiment as having any real significance to light propagation. We don't use the same model today. Just satisfy yourself that Minkowski correctly represented the speed of light on his calculating space. It seems that he did: http://www.bartleby.com/173/17.html Sue... > And here is the interesting thing: We have real cases where there are > two and only two events, and one observer will see signals from them > both at 17:01:34, and another observer will see one signal at 17:01:34 > and the other signal at 17:01:37. Then BOTH observers will figure out > the time of transit of the signals and deduce that the transit times > where 00:00:17 in all cases. The conclusion one draws from this set of > circumstances is obvious.
From: PD on 5 Apr 2010 14:22 On Apr 5, 12:26 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > On Apr 5, 12:51 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 4, 12:36 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 4 Apr, 15:35, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > 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... > > > > As I've said before, the easiest definition of "simultaneous events" > > > is "those events which would have occurred at the same time if > > > information about their occurrance had travelled instantaneously > > > across space". This is basically the common sense definition that > > > people use anyway. > > > This is the common sense definition that YOU use. Please do not > > presume to speak for "people" who, through different assumptions and > > perhaps a bit more openness, would arrive at a different definition > > entirely. Indeed, in my experience, students usually intuitively > > arrive at a definition that is a lot closer to the one that is used by > > physicists than the one you use. > > > > If I sit with family at 7 o'clock the evening and I ask "what time did > > > you have breakfast this morning", I'm not interested in when the > > > information is actually conveyed to me (i.e. long after breakfast > > > time). That is, I would not expect to be told "I've just had > > > breakfast", and when I query this I would not expect to be told that > > > "I had breakfast 5 seconds ago, when information of its occurence > > > first reached your ears". > > > > What I would expect to be told, when I ask "when did you have > > > breakfast", is "I had breakfast at 9 o'clock this morning". > > > This has nothing to do with simultaneity. It has to do with comparison > > of an event against a local clock. If I asked you what time you had > > breakfast, and you told me at 9:00 this morning, and I asked you how > > you knew that, you might say "Because I looked at my watch while I was > > doing it." You would not say, "Because had a signal from the National > > Bureau of Standards had reached me instantaneously, it would have told > > me 9:00." > > > > The problem with this nonsense definition of simultaneity that the > > > physics community seem to be using is that nothing is held to have > > > ever happened until you actually measure it, and because it takes time > > > for information to travel, that means not everyone necesarily measures > > > the same event at the same time. And according to this definition of > > > simultaneity, the family member above had breakfast at 7pm in the > > > evening, because it took until 7pm for the information to reach me! > > > You still don't get it. Simultaneity is determined AFTER accounting > > for the transit time of the signal. > > > If two signals arrive at the same time, at 17:01:34, one does not say > > that the events that generated the signal were simultaneous at > > 17:01:34. One asks, how long did the signal take to get here from the > > first event? How long did the signal take to get here from the second > > event? If the answer to both those questions is 00:00:17, then you > > know the events both occurred at 17:01:17, and since they both > > happened at the same time, they were simultaneous. > > ================= > > > On the other hand, if another observer sees a signal from one event at > > 17:01:34 and a signal from the other event at 17:01:37, then you still > > need to ask, how long did the signal take to get here from the first > > event? How long did the signal take to get here from the second event? > > If the answer to both those questions is 00:00:17, then you know the > > first event occurred at 17:01:17 and the second event at 17:01:20, and > > they were not simultaneous. > > Fine and good for today's audience but in Einstein's time, > Newton's light corpuscle moved under the influence of inertia. > > A simultaneity *defined* outside of the existing > notions about light propagation was required. > That is why you shouldn't consider the thought > experiment as having any real significance to light propagation. > We don't use the same model today. The definition of simultaneity doesn't require light. It only requires a signal that is known to be the same in both directions for any observer that is using the definition. Walking could work, with care. Sound tends not to work, because it depends on the breeze. > > Just satisfy yourself that Minkowski correctly > represented the speed of light on his calculating space. > > It seems that he did:http://www.bartleby.com/173/17.html > > Sue... > > > And here is the interesting thing: We have real cases where there are > > two and only two events, and one observer will see signals from them > > both at 17:01:34, and another observer will see one signal at 17:01:34 > > and the other signal at 17:01:37. Then BOTH observers will figure out > > the time of transit of the signals and deduce that the transit times > > where 00:00:17 in all cases. The conclusion one draws from this set of > > circumstances is obvious. > >
From: Sue... on 5 Apr 2010 15:20
On Apr 5, 2:22 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 5, 12:26 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > On Apr 5, 12:51 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Apr 4, 12:36 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 4 Apr, 15:35, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > > > > > > 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... > > > > > As I've said before, the easiest definition of "simultaneous events" > > > > is "those events which would have occurred at the same time if > > > > information about their occurrance had travelled instantaneously > > > > across space". This is basically the common sense definition that > > > > people use anyway. > > > > This is the common sense definition that YOU use. Please do not > > > presume to speak for "people" who, through different assumptions and > > > perhaps a bit more openness, would arrive at a different definition > > > entirely. Indeed, in my experience, students usually intuitively > > > arrive at a definition that is a lot closer to the one that is used by > > > physicists than the one you use. > > > > > If I sit with family at 7 o'clock the evening and I ask "what time did > > > > you have breakfast this morning", I'm not interested in when the > > > > information is actually conveyed to me (i.e. long after breakfast > > > > time). That is, I would not expect to be told "I've just had > > > > breakfast", and when I query this I would not expect to be told that > > > > "I had breakfast 5 seconds ago, when information of its occurence > > > > first reached your ears". > > > > > What I would expect to be told, when I ask "when did you have > > > > breakfast", is "I had breakfast at 9 o'clock this morning". > > > > This has nothing to do with simultaneity. It has to do with comparison > > > of an event against a local clock. If I asked you what time you had > > > breakfast, and you told me at 9:00 this morning, and I asked you how > > > you knew that, you might say "Because I looked at my watch while I was > > > doing it." You would not say, "Because had a signal from the National > > > Bureau of Standards had reached me instantaneously, it would have told > > > me 9:00." > > > > > The problem with this nonsense definition of simultaneity that the > > > > physics community seem to be using is that nothing is held to have > > > > ever happened until you actually measure it, and because it takes time > > > > for information to travel, that means not everyone necesarily measures > > > > the same event at the same time. And according to this definition of > > > > simultaneity, the family member above had breakfast at 7pm in the > > > > evening, because it took until 7pm for the information to reach me! > > > > You still don't get it. Simultaneity is determined AFTER accounting > > > for the transit time of the signal. > > > > If two signals arrive at the same time, at 17:01:34, one does not say > > > that the events that generated the signal were simultaneous at > > > 17:01:34. One asks, how long did the signal take to get here from the > > > first event? How long did the signal take to get here from the second > > > event? If the answer to both those questions is 00:00:17, then you > > > know the events both occurred at 17:01:17, and since they both > > > happened at the same time, they were simultaneous. > > > ================= > > > > On the other hand, if another observer sees a signal from one event at > > > 17:01:34 and a signal from the other event at 17:01:37, then you still > > > need to ask, how long did the signal take to get here from the first > > > event? How long did the signal take to get here from the second event? > > > If the answer to both those questions is 00:00:17, then you know the > > > first event occurred at 17:01:17 and the second event at 17:01:20, and > > > they were not simultaneous. > > > Fine and good for today's audience but in Einstein's time, > > Newton's light corpuscle moved under the influence of inertia. > > > A simultaneity *defined* outside of the existing > > notions about light propagation was required. > > That is why you shouldn't consider the thought > > experiment as having any real significance to light propagation. > > We don't use the same model today. > > The definition of simultaneity doesn't require light. It only requires > a signal that is known to be the same in both directions for any > observer that is using the definition. Walking could work, with care. How thoughtless of me. I forgot that I might be trampling on your favourite bedtime story. But now that I have irredeemably hurt your feelings, may as well dispose of the political correctness and check your facts: <<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 I don't see much wiggle-room in that. He means LIGHT and he won't debate it. > Sound tends not to work, because it depends on the breeze. Sound doesn't work AT ALL because the author and his friend Hermann are about to put that relation on an imaginary axis that encodes the speed of light without assuming the inertial motion that accompanies Newton's light corpuscle. http://www.bartleby.com/173/17.html If there is a theory of sound corpuscles maybe they will vanish too. But wouldn't it be easier if we simply don't create the theory of sound corpuscles? Maybe hide it under a rug if you find a copy? ;-) Sue... > > > > > Just satisfy yourself that Minkowski correctly > > represented the speed of light on his calculating space. > > > It seems that he did: http://www.bartleby.com/173/17.html > > > Sue... > > > > And here is the interesting thing: We have real cases where there are > > > two and only two events, and one observer will see signals from them > > > both at 17:01:34, and another observer will see one signal at 17:01:34 > > > and the other signal at 17:01:37. Then BOTH observers will figure out > > > the time of transit of the signals and deduce that the transit times > > > where 00:00:17 in all cases. The conclusion one draws from this set of > > > circumstances is obvious. > > |