Known physics defeated by simple puzzle?
in [Relativity]
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From: Sue... on 9 Apr 2010 20:30 On Apr 9, 8:04 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 10 Apr, 00:46, "Inertial" <relativ...(a)rest.com> wrote: > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >news:b55913f6-a3d0-401c-878b-4d0ec3677fa3(a)11g2000yqr.googlegroups.com... > > > > On 9 Apr, 22:24, PD <thedraperfam...(a)gmail.com> wrote: > > >> On Apr 9, 3:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > >> > > But that is not what happens. > > >> > > For example, if I see a car traveling west at 10 kmh, and a car > > >> > > traveling east at 35 kmh, then you have the expectation that, to a > > >> > > passenger riding in the car traveling east, the other car is > > >> > > traveling > > >> > > 45 kmh west. > > >> > > But in fact, it is not traveling at 45 kmh west to a passenger in > > >> > > that > > >> > > car. > > >> > > It is traveling at something close to that, but only approximately. > > > >> > > The bottom line is, the basic sum rule you've been taught for > > >> > > relative > > >> > > velocities is a LIE. > > > >> > i would expect the combined speed to be a real 45kmh, yes, although > > >> > it's quite possible that none of them will any longer agree on the > > >> > definition of "hour" or "kilometer". > > > >> Oh, no, they agree on the definition of hour and kilometer, alright. > > >> Something that is measured locally to be a km will still be measured > > >> locally to be a km. And a standard process that locally takes an hr > > >> will still locally take an hour. > > > > Indeed, the question is whether their respective measures of "an hour" > > > are truly identical. > > > What do you mean by 'truly identical' > > In other words, whether they are measuring the same periods of time - > whether the interval of each tick of each clock would be the same as > each other. The coordinate time of SR is derived from light signal exchange. E-sync. Real clock mechanisms don't "measure" time they mark it. Tape a metre stick to gun barrel. The graduations on the metre stick become units of time. joule /==> gram K.E. = 1/2 mv^2 http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications Sue...
From: Ste on 9 Apr 2010 20:34 On 10 Apr, 01:24, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:a3f09b2c-2003-4d33-bf42-25606b0e4118(a)u31g2000yqb.googlegroups.com... > > > > > > > On 10 Apr, 00:46, "Inertial" <relativ...(a)rest.com> wrote: > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >>news:b55913f6-a3d0-401c-878b-4d0ec3677fa3(a)11g2000yqr.googlegroups.com.... > > >> > On 9 Apr, 22:24, PD <thedraperfam...(a)gmail.com> wrote: > >> >> On Apr 9, 3:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > >> >> > > But that is not what happens. > >> >> > > For example, if I see a car traveling west at 10 kmh, and a car > >> >> > > traveling east at 35 kmh, then you have the expectation that, to a > >> >> > > passenger riding in the car traveling east, the other car is > >> >> > > traveling > >> >> > > 45 kmh west. > >> >> > > But in fact, it is not traveling at 45 kmh west to a passenger in > >> >> > > that > >> >> > > car. > >> >> > > It is traveling at something close to that, but only > >> >> > > approximately. > > >> >> > > The bottom line is, the basic sum rule you've been taught for > >> >> > > relative > >> >> > > velocities is a LIE. > > >> >> > i would expect the combined speed to be a real 45kmh, yes, although > >> >> > it's quite possible that none of them will any longer agree on the > >> >> > definition of "hour" or "kilometer". > > >> >> Oh, no, they agree on the definition of hour and kilometer, alright.. > >> >> Something that is measured locally to be a km will still be measured > >> >> locally to be a km. And a standard process that locally takes an hr > >> >> will still locally take an hour. > > >> > Indeed, the question is whether their respective measures of "an hour" > >> > are truly identical. > > >> What do you mean by 'truly identical' > > > In other words, whether they are measuring the same periods of time - > > whether the interval of each tick of each clock would be the same as > > each other. > > If we are talking about SR .. then (assuming the clocks are accurate), yes > they do measure the same amount of time. But they only measure time for > things at rest wrt them. Then they can't be measuring the same amount of time as each other! Incidentally, if you have two clocks a certain distance apart, synchronised (obviously, accounting for propagation delays), and stationary relative to each other, what happens when you accelerate them towards each other. Does the distant clock appear to slow down, or speed up? And do their times match when they meet up and are brought back to stationary again?
From: Inertial on 9 Apr 2010 21:10 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:6a682982-c761-41e1-b146-64cdaaca44c1(a)v20g2000yqv.googlegroups.com... > On Apr 9, 8:04 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> On 10 Apr, 00:46, "Inertial" <relativ...(a)rest.com> wrote: >> >> >> >> > "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >news:b55913f6-a3d0-401c-878b-4d0ec3677fa3(a)11g2000yqr.googlegroups.com... >> >> > > On 9 Apr, 22:24, PD <thedraperfam...(a)gmail.com> wrote: >> > >> On Apr 9, 3:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > >> > > But that is not what happens. >> > >> > > For example, if I see a car traveling west at 10 kmh, and a car >> > >> > > traveling east at 35 kmh, then you have the expectation that, to >> > >> > > a >> > >> > > passenger riding in the car traveling east, the other car is >> > >> > > traveling >> > >> > > 45 kmh west. >> > >> > > But in fact, it is not traveling at 45 kmh west to a passenger >> > >> > > in >> > >> > > that >> > >> > > car. >> > >> > > It is traveling at something close to that, but only >> > >> > > approximately. >> >> > >> > > The bottom line is, the basic sum rule you've been taught for >> > >> > > relative >> > >> > > velocities is a LIE. >> >> > >> > i would expect the combined speed to be a real 45kmh, yes, >> > >> > although >> > >> > it's quite possible that none of them will any longer agree on the >> > >> > definition of "hour" or "kilometer". >> >> > >> Oh, no, they agree on the definition of hour and kilometer, alright. >> > >> Something that is measured locally to be a km will still be measured >> > >> locally to be a km. And a standard process that locally takes an hr >> > >> will still locally take an hour. >> >> > > Indeed, the question is whether their respective measures of "an >> > > hour" >> > > are truly identical. >> >> > What do you mean by 'truly identical' >> >> In other words, whether they are measuring the same periods of time - >> whether the interval of each tick of each clock would be the same as >> each other. > > The coordinate time of SR is derived > from light signal exchange. E-sync. That describes how synchrnoized clocks should behave (ie that they give the same reading for what must be identical times, and show identical time durations as identical). > Real clock mechanisms don't "measure" time > they mark it. A not terribly relevant semantic difference > Tape a metre stick to gun > barrel. The graduations on the metre stick > become units of time. joule /==> gram > > K.E. = 1/2 mv^2 > > http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > Sue... > > >
From: Sue... on 9 Apr 2010 21:16 On Apr 9, 9:10 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote in message > > news:6a682982-c761-41e1-b146-64cdaaca44c1(a)v20g2000yqv.googlegroups.com... > > > > > On Apr 9, 8:04 pm, Ste <ste_ro...(a)hotmail.com> wrote: > >> On 10 Apr, 00:46, "Inertial" <relativ...(a)rest.com> wrote: > > >> > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > >> >news:b55913f6-a3d0-401c-878b-4d0ec3677fa3(a)11g2000yqr.googlegroups.com.... > > >> > > On 9 Apr, 22:24, PD <thedraperfam...(a)gmail.com> wrote: > >> > >> On Apr 9, 3:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > >> > >> > > But that is not what happens. > >> > >> > > For example, if I see a car traveling west at 10 kmh, and a car > >> > >> > > traveling east at 35 kmh, then you have the expectation that, to > >> > >> > > a > >> > >> > > passenger riding in the car traveling east, the other car is > >> > >> > > traveling > >> > >> > > 45 kmh west. > >> > >> > > But in fact, it is not traveling at 45 kmh west to a passenger > >> > >> > > in > >> > >> > > that > >> > >> > > car. > >> > >> > > It is traveling at something close to that, but only > >> > >> > > approximately. > > >> > >> > > The bottom line is, the basic sum rule you've been taught for > >> > >> > > relative > >> > >> > > velocities is a LIE. > > >> > >> > i would expect the combined speed to be a real 45kmh, yes, > >> > >> > although > >> > >> > it's quite possible that none of them will any longer agree on the > >> > >> > definition of "hour" or "kilometer". > > >> > >> Oh, no, they agree on the definition of hour and kilometer, alright. > >> > >> Something that is measured locally to be a km will still be measured > >> > >> locally to be a km. And a standard process that locally takes an hr > >> > >> will still locally take an hour. > > >> > > Indeed, the question is whether their respective measures of "an > >> > > hour" > >> > > are truly identical. > > >> > What do you mean by 'truly identical' > > >> In other words, whether they are measuring the same periods of time - > >> whether the interval of each tick of each clock would be the same as > >> each other. > > > The coordinate time of SR is derived > > from light signal exchange. E-sync. > > That describes how synchrnoized clocks should behave (ie that they give the > same reading for what must be identical times, and show identical time > durations as identical). ============== > > > Real clock mechanisms don't "measure" time > > they mark it. > > A not terribly relevant semantic difference <<Elements of a Clock Before we continue describing the evolution of ways to mark the passage of time, perhaps we should broadly define what constitutes a clock. All clocks must have two basic components: * a regular, constant or repetitive process or action to mark off equal increments of time. ...>> http://physics.nist.gov/GenInt/Time/early.html Sue... > > > Tape a metre stick to gun > > barrel. The graduations on the metre stick > > become units of time. joule /==> gram > > > K.E. = 1/2 mv^2 > > >http://en.wikipedia.org/wiki/Noether%27s_theorem#Applications > > > Sue... > >
From: Inertial on 9 Apr 2010 21:26
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:ea20980d-74e6-4abe-a088-0ec7dfdacb3f(a)r1g2000yqb.googlegroups.com... > On 10 Apr, 01:24, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> news:a3f09b2c-2003-4d33-bf42-25606b0e4118(a)u31g2000yqb.googlegroups.com... >> >> >> >> >> >> > On 10 Apr, 00:46, "Inertial" <relativ...(a)rest.com> wrote: >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >>news:b55913f6-a3d0-401c-878b-4d0ec3677fa3(a)11g2000yqr.googlegroups.com... >> >> >> > On 9 Apr, 22:24, PD <thedraperfam...(a)gmail.com> wrote: >> >> >> On Apr 9, 3:31 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> >> >> > > But that is not what happens. >> >> >> > > For example, if I see a car traveling west at 10 kmh, and a car >> >> >> > > traveling east at 35 kmh, then you have the expectation that, >> >> >> > > to a >> >> >> > > passenger riding in the car traveling east, the other car is >> >> >> > > traveling >> >> >> > > 45 kmh west. >> >> >> > > But in fact, it is not traveling at 45 kmh west to a passenger >> >> >> > > in >> >> >> > > that >> >> >> > > car. >> >> >> > > It is traveling at something close to that, but only >> >> >> > > approximately. >> >> >> >> > > The bottom line is, the basic sum rule you've been taught for >> >> >> > > relative >> >> >> > > velocities is a LIE. >> >> >> >> > i would expect the combined speed to be a real 45kmh, yes, >> >> >> > although >> >> >> > it's quite possible that none of them will any longer agree on >> >> >> > the >> >> >> > definition of "hour" or "kilometer". >> >> >> >> Oh, no, they agree on the definition of hour and kilometer, >> >> >> alright. >> >> >> Something that is measured locally to be a km will still be >> >> >> measured >> >> >> locally to be a km. And a standard process that locally takes an hr >> >> >> will still locally take an hour. >> >> >> > Indeed, the question is whether their respective measures of "an >> >> > hour" >> >> > are truly identical. >> >> >> What do you mean by 'truly identical' >> >> > In other words, whether they are measuring the same periods of time - >> > whether the interval of each tick of each clock would be the same as >> > each other. >> >> If we are talking about SR .. then (assuming the clocks are accurate), >> yes >> they do measure the same amount of time. But they only measure time for >> things at rest wrt them. > > Then they can't be measuring the same amount of time as each other! Each clock measures its own time correctly. When observers mutually at rest with one clock measure the readings of the other moving clock as it passes them, and compare their results, they will calculate it as ticking slower. This is due to clock synchronization being frame dependent. > Incidentally, if you have two clocks a certain distance apart, > synchronised (obviously, accounting for propagation delays), Yes .. that is always assumed. > and > stationary relative to each other, Yes > what happens when you accelerate > them towards each other. Does the distant clock appear to slow down, > or speed up? Acceleration complicates things uncesssarily .. so lets assume no acceleration for simplicity. An equivalent set up is this, with no acceleration invovled, where A, B, A' and B' are all clocks. A'->v B'<-v A o B Let A and B be our mutually-at-rest, synchronized clocks (as you mentioned) Let A' and B' be moving at the same speed (but opposite directions) relative to A and B. As A' passes A and B' passes B (at the same time according to A and B), we copy the reading from A clock to A' clock, and copy the reading from B clock to B' clock. A' and B' keep moving and arrive together at o, where there times are compared. After the pass A and B and have their clock readings adjusted, the an A' observer would measure B' as ticking slowly (as I described above), and a B' observer would measure A' as ticking slowly. They will both also see the other as showing the 'wrong' time (in particular, from what I think (not done the calculations), each frame will measure the other clock as being ahead of their own). > And do their times match when they meet up and are > brought back to stationary again? Yes. |