Speed of Time
in [Relativity]
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From: Inertial on 5 Jan 2010 17:15 "Androcles" <Headmaster(a)Hogwarts.physics_r> wrote in message news:lHO0n.2263$BK3.1597(a)newsfe16.ams2... > > "PD" <thedraperfamily(a)gmail.com> wrote in message > news:99e431a3-c7f1-481e-afe1-56d8c796852a(a)35g2000yqa.googlegroups.com... > On Dec 24 2009, 2:51 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> I was just wondering, can anyone tell me at what rate time advances on >> earth? > > Time doesn't really advance. What happens is that what we call "now" > by observing an event advances through time. > =============================================== > The plane doesn't really arrive at the airport. What happens is that > the pilot and passengers observe an airport arriving at their plane > and call it an "event". > In the Newtonian world the plane meets the airport when the > airport meets the plane and the time is "now". > In the relativistic world the plane meets the airport "now" and > the airport meets the plane "then", because the plane and the airport > are different frames of reference and are not simultaneous, which > is why Phuckwit Duck often misses his flight. Androcles shows here he has NO IDEA what relativity actually says.
From: Androcles on 5 Jan 2010 17:45 "PD" <thedraperfamily(a)gmail.com> wrote in message news:99356665-8b4a-4bcd-a406-a73da017e117(a)35g2000yqa.googlegroups.com... On Dec 25 2009, 9:12 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 26 Dec, 00:30, "Androcles" <Headmas...(a)Hogwarts.physics_q> wrote: > > > > > > > You should read Dork's twin paradox analysis. He can > > pick up the origin of frame of reference and move it, > > so if you go from London to New York you can do it > > twice without ever going from New York to London. > > > He says > > quote/ > > "We use 3 inertial reference frames. > > S: The frame of the "stay at home" twin. > > S': The frame of the "outbound part of the trip". > > S": The frame of the "inbound part of the trip". > > http://users.telenet.be/vdmoortel/dirk/Physics/TwinsEvents.html > > > So if T = 5 years and v = 0.8c, then the stay at home twin will > > have aged 10 years while his travelling twin sister will have aged > > 6 years. > > /unquote > > I'm afraid I don't understand how he arrives at that conclusion. It > rubbishes relativity. Relativity says that both twins will perceive > the same effects, relative to their own frame of reference. Be careful here. That is not what relativity says. ============================================ That's cool, but it is what Dork says. Of course none of you local village idiots can agree on what relativity says anyway.
From: Inertial on 5 Jan 2010 18:40 "Henry Wilson DSc" <..@..> wrote in message news:2mf7k5tcen3g635n1rmss6s3vh033f3s68(a)4ax.com... > On Wed, 6 Jan 2010 09:15:01 +1100, "Inertial" <relatively(a)rest.com> wrote: > >> >>"Androcles" <Headmaster(a)Hogwarts.physics_r> wrote in message >>news:lHO0n.2263$BK3.1597(a)newsfe16.ams2... >>> >>> "PD" <thedraperfamily(a)gmail.com> wrote in message >>> news:99e431a3-c7f1-481e-afe1-56d8c796852a(a)35g2000yqa.googlegroups.com... >>> On Dec 24 2009, 2:51 pm, Ste <ste_ro...(a)hotmail.com> wrote: >>>> I was just wondering, can anyone tell me at what rate time advances on >>>> earth? >>> >>> Time doesn't really advance. What happens is that what we call "now" >>> by observing an event advances through time. >>> =============================================== >>> The plane doesn't really arrive at the airport. What happens is that >>> the pilot and passengers observe an airport arriving at their plane >>> and call it an "event". >>> In the Newtonian world the plane meets the airport when the >>> airport meets the plane and the time is "now". >>> In the relativistic world the plane meets the airport "now" and >>> the airport meets the plane "then", because the plane and the airport >>> are different frames of reference and are not simultaneous, which >>> is why Phuckwit Duck often misses his flight. >> >>Androcles shows here he has NO IDEA what relativity actually says. > > In this case he does. > > Now here is NOW everywhere. But it is always 'now'. 'now' is not just a single point in time. I am typing this 'now'. And you are reading it 'now'. But different times will show on our clocks when we do. Of course it is going to be 'now' in the plane, and 'now' at the airport when it arrives. Just as it was 'now' for the plane and airport when it took off. That does not mean the same amount of time has elapsed for both plane and airport. All observers agree that there is a single event when the plane lands, ie all agree that "A meets B" happens at the same time as "B meets A". The observers may simply disagree as to what that time is showing on their clocks when it happens. Androcles assertions that that does not happen in SR are either from ignorance or deception.
From: Dirk Van de moortel on 6 Jan 2010 11:35 PD <thedraperfamily(a)gmail.com> wrote in message 25da0c47-1cba-4a78-94c8-f95c26904d34(a)26g2000yqo.googlegroups.com > On Dec 28 2009, 6:37 am, Ste <ste_ro...(a)hotmail.com> wrote: > >> >> I was saying that relativity, or at least the interpretations that I'd >> read, all said that all reference frames are equal. > > That is a loose statement that is easily misinterpreted. There is a > more careful statement of the principle of relativity: The laws of > physics take the same form regardless of inertial reference frame. > Note that this does not mean that physical quantities have the same > *value* in all inertial reference frames. It also does not mean that > the accounting of events is the same in all inertial reference frames. > It also does not mean that everything is the same in all reference > frames whether inertial or not (or even "mostly" inertial"). It is > these "does not means" that are the subject of teaching puzzles like > the twin puzzle, the barn and pole puzzle, the rivet and bug puzzle, > and so on. > >> And I know a guy >> with a PhD who suggests to me that the paradox does not exist, because >> the astronaut returns to Earth the same age as his homebody twin. > > A PhD in *physics*? If so, then he should be ashamed of himself. If > his PhD is in psychology or law, then he can be forgiven his > ignorance, though probably not for the arrogance of being sure of an > answer that is wrong. > >> So >> clearly there is a lot of popular misconception about an issue that >> should be incredibly simple to explain (and trust me, I'd trawled the >> internet and couldn't find any easy and intuitive refutation of this >> paradox). > > You haven't looked very well. :) > Have you considered a book? Taylor and Wheeler's book is simple and > thorough. Penrose's book called The Road to Reality dispenses with the > twin puzzle in a half a paragraph. But Penrose assumes at least a masters degree in mathematics to be able to decently work through the introduction, that is, before he even starts talking about physics ;-) Dirk Vdm
From: Dirk Van de moortel on 6 Jan 2010 11:39
Androcles <Headmaster(a)Hogwarts.physics_r> wrote in message NjP0n.5529$mQ.364(a)newsfe01.ams2 > "PD" <thedraperfamily(a)gmail.com> wrote in message > news:99356665-8b4a-4bcd-a406-a73da017e117(a)35g2000yqa.googlegroups.com... > On Dec 25 2009, 9:12 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> On 26 Dec, 00:30, "Androcles" <Headmas...(a)Hogwarts.physics_q> wrote: >> >> >> >> >> >>> You should read Dork's twin paradox analysis. He can >>> pick up the origin of frame of reference and move it, >>> so if you go from London to New York you can do it >>> twice without ever going from New York to London. >> >>> He says >>> quote/ >>> "We use 3 inertial reference frames. >>> S: The frame of the "stay at home" twin. >>> S': The frame of the "outbound part of the trip". >>> S": The frame of the "inbound part of the trip". >>> http://users.telenet.be/vdmoortel/dirk/Physics/TwinsEvents.html >> >>> So if T = 5 years and v = 0.8c, then the stay at home twin will >>> have aged 10 years while his travelling twin sister will have aged >>> 6 years. >>> /unquote >> >> I'm afraid I don't understand how he arrives at that conclusion. It >> rubbishes relativity. Relativity says that both twins will perceive >> the same effects, relative to their own frame of reference. > > Be careful here. That is not what relativity says. > ============================================ > That's cool, but it is what Dork says. Of course none of you local > village idiots can agree on what relativity says anyway. Another phrase you stole from me. Congratulations. Dirk Vdm |