A puzzle for the SRians
in [Relativity]
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From: Cosmik de Bris on 27 Jul 2010 00:13 On 27/07/10 15:59 , eric gisse wrote: > kenseto wrote: > > [...] > > I got a better puzzle. Why does the kenseto keep posting despite 15 amply- > documented years of not understanding relativity? It's incredible really, if he'd spent 10% of that time actually learning something he'd be a real expert.
From: Androcles on 27 Jul 2010 01:08 "Cosmik de Bris" <cosmik.debris(a)elec.canterbury.ac.nz> wrote in message news:M1t3o.103571$Lj2.96506(a)newsfe05.iad... | On 27/07/10 15:59 , eric gisse wrote: | > kenseto wrote: | > | > [...] [...] | | It's incredible really, if he'd spent 10% of that time actually learning | something he'd be a real expert. | It's incredible really, if you'd spent 1% of that time actually thinking anything you'd be a fake arsehole.
From: Hayek on 27 Jul 2010 05:29 kenseto wrote: > Einstein's train gedanken is modified as follows: > When M and M' are coincide with each other......two lightning strikes > hits the ends of the train and the light fronts arrive at M' non- > simultaneously. > Question for the SRians: does this mean that according to the SR > concept of relativity of simultaneity M will see the light fronts > arrive at him simultaneously? > Since there are an infinite number of pairs of strikes that can cause > the light fronts to arrive at M' non-simultaneously, does that means > that there are infinite pairs of strikes that M will see their light > fronts to arrive at him simultaneously????? I think it is quite pointless to reason about simultaneity at all. Simultaneous means "at the same time". But nobody has defined time. There is no generally accepted view on what time is. Suppose both relativistic twins drop an object on the floor. An ftl transmitter confirms that both objects hit the floor at the same instant. But Ann's clock shows 2015 and Betty's clock 2012. At the same "time" ? In my opinion the question of simultaneity can only be solved if we have universe wide instant messaging, and use a positional definition of events. If we follow the wild dreams of the SRian's, like Paul Davies in About Time, then we have mutual time dilation, where the clock's of both twins run slow, and they are in a different timescape. Then it is even impossible to talk about simultaneity. Davies also gives a twin example were one twin hovers near a black hole. There it is more like in my example, with the ftl transmitter. I think the situations of the one twin traveling and the one hovering near a black hole, are exactly the same, except for the distance between them, of course. Uwe Hayek. -- We are fast approaching the stage of the ultimate inversion : the stage where the government is free to do anything it pleases, while the citizens may act only by permission; which is the stage of the darkest periods of human history. -- Ayn Rand I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them. -- Thomas Jefferson. Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. -- Winston Churchill.
From: Inertial on 27 Jul 2010 05:37 "Hayek" wrote in message news:4c4ea6f0$0$22942$e4fe514c(a)news.xs4all.nl... > >kenseto wrote: >> Einstein's train gedanken is modified as follows: >> When M and M' are coincide with each other......two lightning strikes >> hits the ends of the train and the light fronts arrive at M' non- >> simultaneously. >> Question for the SRians: does this mean that according to the SR >> concept of relativity of simultaneity M will see the light fronts >> arrive at him simultaneously? >> Since there are an infinite number of pairs of strikes that can cause >> the light fronts to arrive at M' non-simultaneously, does that means >> that there are infinite pairs of strikes that M will see their light >> fronts to arrive at him simultaneously????? > >I think it is quite pointless to reason about simultaneity at all. >Simultaneous means "at the same time". Amazing >But nobody has defined time. There is no generally accepted view on what >time is. There is in SR, which is the context of the problem >Suppose both relativistic twins drop an object on the floor. An ftl >transmitter confirms that both objects hit the floor at the same instant. >But Ann's clock shows 2015 and Betty's clock 2012. At the same "time" ? There is no ftl transmitter involved. >In my opinion the question of simultaneity can only be solved if we have >universe wide instant messaging, and use a positional definition of events. No need >If we follow the wild dreams of the SRian's, like Paul Davies in About >Time, then we have mutual time dilation, We do have. We certainly know that time is not absolute, and time dilation is supported by experimental evidence >where the clock's of both twins run slow, and they are in a different >timescape. Then it is even impossible to talk about simultaneity. Of course it is .. it is all well defined in SR >Davies also gives a twin example were one twin hovers near a black hole. That's GR .. and doesn't affect the example given which is all at the same gravitational potential > There it is more like in my example, with the ftl transmitter. > >I think the situations of the one twin traveling and the one hovering near >a black hole, are exactly the same, except for the distance between them, >of course. Nope .. other than you end up with a difference in time in both cases. But not for the same reasons or worked out with the same math. Anyway .. none of that has much to do with the answer to Ken's re-statement of the same old train gedanken that has been dealt with by SR for almost a century.
From: Hayek on 27 Jul 2010 06:32
Inertial wrote: > "Hayek" wrote in message > news:4c4ea6f0$0$22942$e4fe514c(a)news.xs4all.nl... >> >> kenseto wrote: >>> Einstein's train gedanken is modified as follows: >>> When M and M' are coincide with each >>> other......two lightning strikes hits the ends of >>> the train and the light fronts arrive at M' non- >>> simultaneously. Question for the SRians: does >>> this mean that according to the SR concept of >>> relativity of simultaneity M will see the light >>> fronts arrive at him simultaneously? Since there >>> are an infinite number of pairs of strikes that >>> can cause the light fronts to arrive at M' >>> non-simultaneously, does that means that there >>> are infinite pairs of strikes that M will see >>> their light fronts to arrive at him >>> simultaneously????? >> >> I think it is quite pointless to reason about >> simultaneity at all. Simultaneous means "at the >> same time". > > Amazing > >> But nobody has defined time. There is no generally >> accepted view on what time is. > > There is in SR, which is the context of the problem > >> Suppose both relativistic twins drop an object on >> the floor. An ftl transmitter confirms that both >> objects hit the floor at the same instant. But >> Ann's clock shows 2015 and Betty's clock 2012. At >> the same "time" ? > > There is no ftl transmitter involved. > >> In my opinion the question of simultaneity can only >> be solved if we have universe wide instant >> messaging, and use a positional definition of >> events. > > No need > >> If we follow the wild dreams of the SRian's, like >> Paul Davies in About Time, then we have mutual time >> dilation, > > We do have. We certainly know that time is not > absolute, and time dilation is supported by > experimental evidence > >> where the clock's of both twins run slow, and they >> are in a different timescape. Then it is even >> impossible to talk about simultaneity. > > Of course it is .. it is all well defined in SR Davies tells a different story. > >> Davies also gives a twin example were one twin >> hovers near a black hole. > > That's GR .. and doesn't affect the example given > which is all at the same gravitational potential > >> There it is more like in my example, with the ftl >> transmitter. >> >> I think the situations of the one twin traveling >> and the one hovering near a black hole, are exactly >> the same, except for the distance between them, of >> course. > > Nope .. other than you end up with a difference in > time in both cases. But not for the same reasons or > worked out with the same math. So you are saying that the time difference has a different cause, and that it matters by which math it is worked out ? Uwe Hayek. -- We are fast approaching the stage of the ultimate inversion : the stage where the government is free to do anything it pleases, while the citizens may act only by permission; which is the stage of the darkest periods of human history. -- Ayn Rand I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them. -- Thomas Jefferson. Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. -- Winston Churchill. |