Station's clock with respect to the train
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From: ben6993 on 1 May 2010 04:43 On May 1, 9:16 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "ben6993" <ben6...(a)hotmail.com> wrote in message > > news:29b72afc-f466-4e77-9642-cd5065827e05(a)n15g2000yqf.googlegroups.com... > On May 1, 8:26 am, ben6993 <ben6...(a)hotmail.com> wrote: > > > > > > > On May 1, 5:13 am, John Murphy > > > <london.accommodation.homest...(a)googlemail.com> wrote: > > > On 1 May, 03:08, BURT <macromi...(a)yahoo.com> wrote: > > > > > If the train watches the stations clock go slow then when does it have > > > > the time to age more? > > > > > Mitch Raemsch > > > > It never gets a chance to age comparatively, because by definition > > > neither 'clock' - nor the train, nor the station knows what the other > > > is doing, but it would not help if the train were to visit the station > > > in some metrical sense, since that would entail either time gained by > > > the train or lost by the station and nor would it work the other way > > > around since it would seem to neither 'clock' that they had lost or > > > gained. > > > > All the same, demons are thought to be able to travel at light speed, > > > so could in principle produce a twin-dial clock, available to both > > > station and train, although it is unclear how that could be of help to > > > anyone other than demons themselves unless they could become an > > > interstellar ISP. And if they got a useful role, they might get free > > > from messing things up and win a few prizes here and there. > > > -- > > > Harbinger. > > > Is light speed fast enough for the demons to be able to do that job? > > Wouldn't they need to travel instantaneously, without any time > > elapsing on their own clock or on anyone else's clock, to the station > > and back so they could adjust the auxiliary time dial? And they would > > need to return very frequently, to keep resetting the time on the > > auxiliary dial to the quasi-absolute time. > > > If the demons were to pick a speeding clock, with respect to the > > station, for use as the quasi-absolute time, then the auxiliary dial > > would lag behind the station clock. If the auxiliary clock were to > > run very slow then we would need to display milliseconds or > > microseconds to see any useful passage of quasi-absolute time. > > > Taking more and more decimal places of seconds to be useful for slower > > and slower clocks, at the limit of Planck time, assuming time is > > quantised, the auxiliary dial might in this limit not be able to show > > any passsage of time useful to us. That is because one unit of Planck > > time cannot be subdivided on the auxiliary dial. What use is a dial > > with only one tick every hundred years, say? Just as well the clocks > > will also have the local-time dial.- Hide quoted text - > > > - Show quoted text - > > Post script. Oops. It's much too early in the morning here to think > straight ... not that it will be any better later on ... my logic > about moving clock times is probably wrong. But let the demon instead > take quasi-absolute clocks nearer and nearer to a black hole to get > the effect of slower and slower ticking of time to be applied to the > station clocks. > > ============================================= > Take the train to the black hole... you are right, it must be much too early > in the morning there.- Hide quoted text - > > - Show quoted text - A black hole just outside Deansgate station could maybe explain all that wasted time on local trains there waiting for the signal to go. I wrote my PS before seeing your post. I had assumed that the demon, travelling instantaneously and therefore magically, was able to know the time on all the clocks when stationary with respect to them. But I realised that I was presuming that the demon's stationary clock would run slower that the station's stationary clock, when I knew only that the demon's moving clock appeared, from an observer at the station, to run slower than the stationary station clock.
From: Androcles on 1 May 2010 05:54 "ben6993" <ben6993(a)hotmail.com> wrote in message news:687bc182-c130-495c-be1e-d665fd165373(a)d39g2000yqa.googlegroups.com... On May 1, 9:16 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "ben6993" <ben6...(a)hotmail.com> wrote in message > > news:29b72afc-f466-4e77-9642-cd5065827e05(a)n15g2000yqf.googlegroups.com... > On May 1, 8:26 am, ben6993 <ben6...(a)hotmail.com> wrote: > > > > > > > On May 1, 5:13 am, John Murphy > > > <london.accommodation.homest...(a)googlemail.com> wrote: > > > On 1 May, 03:08, BURT <macromi...(a)yahoo.com> wrote: > > > > > If the train watches the stations clock go slow then when does it > > > > have > > > > the time to age more? > > > > > Mitch Raemsch > > > > It never gets a chance to age comparatively, because by definition > > > neither 'clock' - nor the train, nor the station knows what the other > > > is doing, but it would not help if the train were to visit the station > > > in some metrical sense, since that would entail either time gained by > > > the train or lost by the station and nor would it work the other way > > > around since it would seem to neither 'clock' that they had lost or > > > gained. > > > > All the same, demons are thought to be able to travel at light speed, > > > so could in principle produce a twin-dial clock, available to both > > > station and train, although it is unclear how that could be of help to > > > anyone other than demons themselves unless they could become an > > > interstellar ISP. And if they got a useful role, they might get free > > > from messing things up and win a few prizes here and there. > > > -- > > > Harbinger. > > > Is light speed fast enough for the demons to be able to do that job? > > Wouldn't they need to travel instantaneously, without any time > > elapsing on their own clock or on anyone else's clock, to the station > > and back so they could adjust the auxiliary time dial? And they would > > need to return very frequently, to keep resetting the time on the > > auxiliary dial to the quasi-absolute time. > > > If the demons were to pick a speeding clock, with respect to the > > station, for use as the quasi-absolute time, then the auxiliary dial > > would lag behind the station clock. If the auxiliary clock were to > > run very slow then we would need to display milliseconds or > > microseconds to see any useful passage of quasi-absolute time. > > > Taking more and more decimal places of seconds to be useful for slower > > and slower clocks, at the limit of Planck time, assuming time is > > quantised, the auxiliary dial might in this limit not be able to show > > any passsage of time useful to us. That is because one unit of Planck > > time cannot be subdivided on the auxiliary dial. What use is a dial > > with only one tick every hundred years, say? Just as well the clocks > > will also have the local-time dial.- Hide quoted text - > > > - Show quoted text - > > Post script. Oops. It's much too early in the morning here to think > straight ... not that it will be any better later on ... my logic > about moving clock times is probably wrong. But let the demon instead > take quasi-absolute clocks nearer and nearer to a black hole to get > the effect of slower and slower ticking of time to be applied to the > station clocks. > > ============================================= > Take the train to the black hole... you are right, it must be much too > early > in the morning there.- Hide quoted text - > > - Show quoted text - A black hole just outside Deansgate station could maybe explain all that wasted time on local trains there waiting for the signal to go. I wrote my PS before seeing your post. I had assumed that the demon, travelling instantaneously and therefore magically, was able to know the time on all the clocks when stationary with respect to them. But I realised that I was presuming that the demon's stationary clock would run slower that the station's stationary clock, when I knew only that the demon's moving clock appeared, from an observer at the station, to run slower than the stationary station clock. =============================================== I set my phone/watch to midnight and the alarm for 7:00 am and then put it under the pillow and go to sleep. At 7:00 am the alarm wakes me. I get up, shower, dress, eat breakfast and head off to the station to catch the 9:14 (which will always leave on time whenever the station lift is broken, causing me to stumble down the steps and miss the train) to London Bridge for my 11:00 am appointment at Guys, taking the phone with me, but forgetting my watch. In my frame of reference (the train), as I look out of the window I see the countryside passing by. This is a very real observation, the other passengers do not move relative to me and they too see the world passing by. Eventually I see London come to the train, and I conclude that the principle of relativity states that London Bridge meets the train at the same instant that the train met London Bridge; and that my forgotten wristwatch has moved away from me, it is still under the pillow. Since my wristwatch moved away me, do I conclude that it no longer reads the correct time and ask my specialist if I need additional medication to overcome my relativityphobia which is raising my blood pressure, or additional medication to overcome my psychosis in believing the idiot Einstein was actually a genius and Galileo a fool? I will say this. Whatever he recommends, when home returns to me in my frame of reference I shall check the time of my watch against the time by my phone and make up my own mind whether or not to take additional drugs; and probably select a wee dram of Macallan as a palliative measure against the demon of idiocy, whilst staring at my watch and wondering how it could keep time without me looking at it.
From: ben6993 on 1 May 2010 06:52 On May 1, 10:54 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "ben6993" <ben6...(a)hotmail.com> wrote in message > > news:687bc182-c130-495c-be1e-d665fd165373(a)d39g2000yqa.googlegroups.com... > On May 1, 9:16 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > > > > > > > "ben6993" <ben6...(a)hotmail.com> wrote in message > > >news:29b72afc-f466-4e77-9642-cd5065827e05(a)n15g2000yqf.googlegroups.com.... > > On May 1, 8:26 am, ben6993 <ben6...(a)hotmail.com> wrote: > > > > On May 1, 5:13 am, John Murphy > > > > <london.accommodation.homest...(a)googlemail.com> wrote: > > > > On 1 May, 03:08, BURT <macromi...(a)yahoo.com> wrote: > > > > > > If the train watches the stations clock go slow then when does it > > > > > have > > > > > the time to age more? > > > > > > Mitch Raemsch > > > > > It never gets a chance to age comparatively, because by definition > > > > neither 'clock' - nor the train, nor the station knows what the other > > > > is doing, but it would not help if the train were to visit the station > > > > in some metrical sense, since that would entail either time gained by > > > > the train or lost by the station and nor would it work the other way > > > > around since it would seem to neither 'clock' that they had lost or > > > > gained. > > > > > All the same, demons are thought to be able to travel at light speed, > > > > so could in principle produce a twin-dial clock, available to both > > > > station and train, although it is unclear how that could be of help to > > > > anyone other than demons themselves unless they could become an > > > > interstellar ISP. And if they got a useful role, they might get free > > > > from messing things up and win a few prizes here and there. > > > > -- > > > > Harbinger. > > > > Is light speed fast enough for the demons to be able to do that job? > > > Wouldn't they need to travel instantaneously, without any time > > > elapsing on their own clock or on anyone else's clock, to the station > > > and back so they could adjust the auxiliary time dial? And they would > > > need to return very frequently, to keep resetting the time on the > > > auxiliary dial to the quasi-absolute time. > > > > If the demons were to pick a speeding clock, with respect to the > > > station, for use as the quasi-absolute time, then the auxiliary dial > > > would lag behind the station clock. If the auxiliary clock were to > > > run very slow then we would need to display milliseconds or > > > microseconds to see any useful passage of quasi-absolute time. > > > > Taking more and more decimal places of seconds to be useful for slower > > > and slower clocks, at the limit of Planck time, assuming time is > > > quantised, the auxiliary dial might in this limit not be able to show > > > any passsage of time useful to us. That is because one unit of Planck > > > time cannot be subdivided on the auxiliary dial. What use is a dial > > > with only one tick every hundred years, say? Just as well the clocks > > > will also have the local-time dial.- Hide quoted text - > > > > - Show quoted text - > > > Post script. Oops. It's much too early in the morning here to think > > straight ... not that it will be any better later on ... my logic > > about moving clock times is probably wrong. But let the demon instead > > take quasi-absolute clocks nearer and nearer to a black hole to get > > the effect of slower and slower ticking of time to be applied to the > > station clocks. > > > ============================================= > > Take the train to the black hole... you are right, it must be much too > > early > > in the morning there.- Hide quoted text - > > > - Show quoted text - > > A black hole just outside Deansgate station could maybe explain all > that wasted time on local trains there waiting for the signal to go. > > I wrote my PS before seeing your post. I had assumed that the demon, > travelling instantaneously and therefore magically, was able to know > the time on all the clocks when stationary with respect to them. But > I realised that I was presuming that the demon's stationary clock > would run slower that the station's stationary clock, when I knew only > that the demon's moving clock appeared, from an observer at the > station, to run slower than the stationary station clock. > =============================================== > I set my phone/watch to midnight and the alarm for 7:00 am > and then put it under the pillow and go to sleep. At 7:00 am the > alarm wakes me. I get up, shower, dress, eat breakfast and head > off to the station to catch the 9:14 (which will always leave on > time whenever the station lift is broken, causing me to stumble > down the steps and miss the train) to London Bridge for my 11:00 > am appointment at Guys, taking the phone with me, but forgetting > my watch. In my frame of reference (the train), as I look out of the > window I see the countryside passing by. This is a very real > observation, the other passengers do not move relative to me and > they too see the world passing by. Eventually I see London > come to the train, and I conclude that the principle of relativity states > that London Bridge meets the train at the same instant that the train > met London Bridge; and that my forgotten wristwatch has moved > away from me, it is still under the pillow. Since my wristwatch > moved away me, do I conclude that it no longer reads the correct > time and ask my specialist if I need additional medication to > overcome my relativityphobia which is raising my blood pressure, > or additional medication to overcome my psychosis in believing > the idiot Einstein was actually a genius and Galileo a fool? > I will say this. Whatever he recommends, when home returns > to me in my frame of reference I shall check the time of my watch > against the time by my phone and make up my own mind whether > or not to take additional drugs; and probably select a wee dram > of Macallan as a palliative measure against the demon of idiocy, > whilst staring at my watch and wondering how it could keep time > without me looking at it.- Hide quoted text - > > - Show quoted text - "In 1975 Carol Allie of the University of Maryland synchronized two atomic clocks and placed one on a plane and flew it around for several hours and left the other on Earth. When the airborne clock was returned to Earth, she compared its time with the one that hadn't moved and found that time had moved a fraction of a second more slowly for the clock on board the plane." http://abcnews.go.com/Technology/story?id=98062&page=1 There is a photo of Carroll O. Alley on http://www.physics.umd.edu/people/faculty/alley.html and it is a photo of a male professor. So do you trust the rest of the abcnews item which referred to him as "she"? If you could carry out the above experiment yourself with the two atomic clocks, and found the two clocks' times had diverged, would you think differently about the results of your own experiment? Your own wristwatch and phone aren't accurate enough to show any difference after your train journey. I need another correction to my earlier posts. I had presumed that the stationary clock near a black hole was running slower than the stationary clock in the station, but I only know that the clock near the black hole would appear, from an observer at the station, to run slower than the stationary station clock. I will have to leave it to the demon to choose his/her own slow ticking quasi-absolute clock.
From: BURT on 1 May 2010 13:35 On Apr 30, 9:13 pm, John Murphy <london.accommodation.homest...(a)googlemail.com> wrote: > On 1 May, 03:08, BURT <macromi...(a)yahoo.com> wrote: > > > If the train watches the stations clock go slow then when does it have > > the time to age more? > > > Mitch Raemsch > > It never gets a chance to age comparatively, because by definition > neither 'clock' - nor the train, nor the station knows what the other > is doing, but it would not help if the train were to visit the station It is intirely possible for the station and the train to compare clocks while passing each other is it not? Mitch Raemsch > in some metrical sense, since that would entail either time gained by > the train or lost by the station and nor would it work the other way > around since it would seem to neither 'clock' that they had lost or > gained. > > All the same, demons are thought to be able to travel at light speed, > so could in principle produce a twin-dial clock, available to both > station and train, although it is unclear how that could be of help to > anyone other than demons themselves unless they could become an > interstellar ISP. And if they got a useful role, they might get free > from messing things up and win a few prizes here and there. > -- > Harbinger.
From: Mike_Fontenot on 1 May 2010 08:38
BURT wrote: "When the train is passing the station at high speed and it looks at its clock SR says it will be running slow. But for how long can the station clock be running slow if it is aging faster?" Here's a repeat of an earlier posting of mine, that addresses the same question: ____________________________________________________________________ During the constant-speed legs of the trip, BOTH twins conclude that the other twin is ageing slower. But when the trip is over, they both agree that the stay-at-home twin is older. How is that possible? It's possible because, during the turnaround, the traveler will conclude that the home twin quickly ages, with very little ageing of the traveler. The home twin concludes that neither of them ages much during the turnaround. When you add up all these segments of ageing, you get the result that the home twin is older (and both twins exactly agree on that). Years ago, I derived a simple equation (called the "CADO" equation) that explicitly gives the ageing of the home twin during accelerations by the traveler (according to the traveler). The equation is especially easy to use for idealized traveling twin problems with instantaneous speed changes. But it also works for finite accelerations. I've got a detailed example with +-1g accelerations on my webpage: http://home.comcast.net/~mlfasf And I've published a paper giving the derivation of the CADO equation: "Accelerated Observers in Special Relativity", PHYSICS ESSAYS, December 1999, p629. Mike Fontenot |