Speed of Time
in [Relativity]
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From: Ste on 26 Dec 2009 17:02 On 26 Dec, 03:31, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:b5e0a622-6862-43ec-9f06-1ae8a46b1d1d(a)k23g2000yqa.googlegroups.com... > > > > > > > On 25 Dec, 20:39, snapdragon31 <snapdrago...(a)gmail.com> wrote: > >> On Dec 25, 6:21 am, "Dirk Van de moortel" > > >> <dirkvandemoor...(a)nospAm.hotmail.com> wrote: > >> > Ste <ste_ro...(a)hotmail.com> wrote in message > > >> > ee5c4ca0-faf6-46a8-8565-c830f685d...(a)m16g2000yqc.googlegroups.com > > >> > > I was just wondering, can anyone tell me at what rate time advances > >> > > on > >> > > earth? > > >> > I suspect you won't like this answer, but every clock tells > >> > you how its time advances, and the theory that relates one > >> > clock's time to another clock's, is the theory of relativity. > > >> > Dirk Vdm > > >> The rate time advances is 1 sec per sec. That is true for all clocks > >> including those malfunction clocks in relativity. > > > Let's do the maths with that then. Time advances at a rate seconds/ > > seconds (i.e. 1 second for every second). Any number divided by itself > > is 1. Therefore time advances at 1 second. > > it is nonsense to talk of the 'rate' of time > > > So I'll ask again, at what *rate* does time advance. > > There is only the relative rate at which processes happen > > > Telling me that > > time has a velocity of 1 second per second is as tautologous as saying > > an object has a spatial velocity of 1 metre per metre. > > Indeed it is .. but then, asking the rate of time is similarly nonsensical I'm only asking the question rhetorically. My position is that time does not move *at all*. It is other people who are saying time flows forward (which introduces the nonsensical spectre of time standing still, or flowing backwards).
From: Ste on 26 Dec 2009 17:37 On 26 Dec, 04:03, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:c6d4ea67-9711-4b79-b35f-7bc54e086b76(a)n35g2000yqm.googlegroups.com... > > > > > > > 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. > > He was using the Lorentz transforms of SR But the same transformation applied with the astronaut in the fixed frame of reference (which, according to relativity, is a perfectly legitimate switch of frame) will yield *the opposite* result. Clearly there is something wrong there - and I think the answer is in good ole classical mechanics. > > It > > rubbishes relativity. > > Nope If the argument is correct it does. Of course, really I think the problem lies in the argument, not in relativity. > > Relativity says that both twins will perceive > > the same effects, relative to their own frame of reference. > > No .. it does not. This is something many novices stumble over. The two > twins are no equivalent as one remains at rest in his initial frame of > reference, the other twin changes frames of reference (ie does not remain at > rest in his initial frame of reference). An absurd position. Of course the astronaut remains at rest in his own frame of reference. It is the *universe* that is accelerating around the astronaut, according to relativity. Believe it or not though, this contrivance of "moving reference frames" is closer to the truth than you might think. What changes is not the reference frame. What changes is the astronaut's relative length (i.e. length contraction). And soon in separate post, I'll tell you why length contraction is not the same for the homebody as it is for the astronaut. > In fact he changes inertial frames > three times (given instantaneous acceleration) .. once when he leave his > twin, one when re turns around to come back, and another when he stops when > he gets back to the stay-at-home-twin. The stay-at-home twin stays at rest > in his inertial frame of reference through out. A ludicrous argument, that if true rubbishes relativity! Relativity says that an astronaut accelerating through space, is indistinguishable from space accelerating around the astronaut. If you accept relativity, then you cannot deny this. > NOTE: You can avoid two of the changes by starting the experiment the > instance after the twin starts to move away, and finishing the instant > before he stops .. then there is just one change in inertial frame. > > NOTE: You can also eliminate the instantaneous (infinite) acceleration > altogether by having three 'twins' (triplets then). I'll explain if you > like. What really makes a difference is the change of inertial frame of > reference. But according to relativity, there has been no change of reference frame, because all reference frames are equal. There has only been a change of reference frame relative to the other twin - both will say the other twin's reference frame changed in the middle of the journey (one will say the rocket turned around and came back, the other will say the earth turned around and came back). If both reference frames are equal, then we're left with the paradox. If both reference frames are not equal, then we must discard relativity. The question is, if we retain relativity, then what force or factor does the astronaut suffer to a greater extent, that the homebody suffers to a lesser extent? > > If that is > > true, then the astronaut cannot return younger than the homebody - it > > cannot happen. > > Sorry .. it does And therein lies the contradiction. We observe that the astronaut comes back younger - the observation cannot be denied. We must therefore deny the coherence of the explanation. > > Because if you change the analysis and have the > > astronaut in the fixed frame of reference, and have the universe > > accelerate around him, then by exactly the same logic the *homebody* > > will be the younger twin when the astronaut returns to earth. > > Nope .. you can do the analysis from either point of view, and you get the > same result That is not possible. You cannot possibly do an analysis that involves the earth accelerating away from the astronaut, and still have the astronaut come back younger, because by your own argument the *earth* has changed reference frames at the turnaround, and the astronaut's reference frame has remained constant. Clearly, this "changing reference frame" business is a gratuitous failure to grasp relativity. > > If the astronaut is younger when he returns, then either relativity is > > false, or there is another factor in play that applies differently to > > the astronaut than the homebody. > > > Incidentally, what evidence is there exactly to suggest that such > > twins ages would differ once the astronaut returned to earth? > > Because less time has elapsed for the travelling twin. In other words, my question is "why is the twin younger", and your answer is "because the twin has aged less". Thankyou for that dynamite response. I was actually looking for you to name studies that have proven the effect. I presume astronauts themselves have not come back discernibly any younger than their earth-bound families. > Unlike spatial dimensions, where the shortest distance between two point is > a straight line (and so a twisty path is longer) for the temporal dimension > the straight line is the longest temporal distance (elapsed time). The more > you move in your path from one event to another, the shorter the time taken. Naturally. If I travel at 10mph, 1 mile of distance takes 6 minutes to cover. If I travel at 60mph, 1 mile of distance takes 1 minute to cover. That does not explain why, when I come back from my journey, I will be any younger than my housebound family.
From: Ste on 26 Dec 2009 17:41 On 26 Dec, 09:09, ..@..(Henry Wilson DSc) wrote: > On Sat, 26 Dec 2009 14:28:03 +1100, "Inertial" <relativ...(a)rest.com> wrote: > >"Ste" <ste_ro...(a)hotmail.com> wrote in message > >news:ee5c4ca0-faf6-46a8-8565-c830f685d3b9(a)m16g2000yqc.googlegroups.com.... > >> I was just wondering, can anyone tell me at what rate time advances on > >> earth? > > >There is no such thing as a rate of time, as 'rate' implies change over > >time. That is a problem with the English language (and I suspect most if > >not all human languages). > > >But one can compare the rates of ticking of clocks (which measures time) and > >compare the rates in different locations or at different relative > >velocities. > > >There is no absolute measure of 'rate' of time (whatever that means) > > Time flows at 1 second (t1) per second (t2) So in other words, time can only be expressed as a factor relative to some other frame. In other words, it is *impossible* to prove a forward flow of time - the forward flow of time is an axiom of the human mind, not a measurable quality of the physical world.
From: Dirk Van de moortel on 26 Dec 2009 18:02 Ste <ste_rose0(a)hotmail.com> wrote in message e2b39ba1-e151-4bd3-8adb-b5f35af59f8a(a)j4g2000yqe.googlegroups.com > On 26 Dec, 09:09, ..@..(Henry Wilson DSc) wrote: >> On Sat, 26 Dec 2009 14:28:03 +1100, "Inertial" <relativ...(a)rest.com> wrote: >>> "Ste" <ste_ro...(a)hotmail.com> wrote in message >>> news:ee5c4ca0-faf6-46a8-8565-c830f685d3b9(a)m16g2000yqc.googlegroups.com... >>>> I was just wondering, can anyone tell me at what rate time advances on >>>> earth? >> >>> There is no such thing as a rate of time, as 'rate' implies change over >>> time. That is a problem with the English language (and I suspect most if >>> not all human languages). >> >>> But one can compare the rates of ticking of clocks (which measures time) and >>> compare the rates in different locations or at different relative >>> velocities. >> >>> There is no absolute measure of 'rate' of time (whatever that means) >> >> Time flows at 1 second (t1) per second (t2) > > So in other words, time can only be expressed as a factor relative to > some other frame. In other words, it is *impossible* to prove a > forward flow of time - the forward flow of time is an axiom of the > human mind, not a measurable quality of the physical world. In physics and in engineering (and in fact in every day life), time is defined as what is read on clocks, as you can see in http://physics.nist.gov/cuu/Units/second.html Armchair philosophers might have different ideas, but this is a physics newsgroup. Since counting events is what happens in a clock, our clocks are designed to run forward, so time is defined to run forward. So indeed "the forward flow of time is an axiom of the human mind", if you wish. But it *is* a measurable quality of the physical world - by definition. Dirk Vdm
From: Dirk Van de moortel on 26 Dec 2009 18:32
Ste <ste_rose0(a)hotmail.com> wrote in message c6d4ea67-9711-4b79-b35f-7bc54e086b76(a)n35g2000yqm.googlegroups.com > 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. I You see how I arrived at it by looking at http://users.telenet.be/vdmoortel/dirk/Physics/TwinsEvents.html If there is anything unclear about it, let me know - perhaps I can explain. Or if there's a mistake, I can correct it. Dirk Vdm |