Wonderful!
in [Physics]
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From: GogoJF on 16 Dec 2009 22:41 On Dec 16, 9:23 pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) wrote: > GogoJF <jfgog...(a)yahoo.com> writes: > >Michael, can you name me a situation, where there is such a > >phenomenon, which travels at 1/4 c? > > This is a mutation of Albert Einstein's famous train thought experiment > which he used to help explain special relativity. It involves imagining a > train passing a platform at a relativistic speed and when the middle of > the train passes an observer on the platform, the observer sees lightning > bolts strike the front and rear of the train simultaneously. What does a > second observer in the middle of the train (and on it) observe? mpc755 > doesn't understand the thought experiment and think jhe has his own answer > to what happens. > > There is, of course, no such train. Of course there isn't because "light", or at least the effects of light operate as an all or nothing principle- there is no "in between", as far as speed is concerned.
From: mpc755 on 16 Dec 2009 23:01 On Dec 16, 10:32 pm, mpc755 <mpc...(a)gmail.com> wrote: > On Dec 16, 10:08 pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > wrote: > > > > > mpc755 <mpc...(a)gmail.com> writes: > > >On Dec 16, 8:34=A0pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > >wrote: > > > >> >> 1) What is the velocity of the light beam relative to the aether, when > > >> >> it's still travelling through the train? > > >> >Light travels at 'c' relative to the aether. > > > >> OK. Since the angle is so small we can ignore the small effects of > > >> sin/cos of it being different from 0/1. So... the platform observer will > > >> see the light on the train moving at either 1.25 c or 0.75 c > > >The platform observer does not 'see the light on the train'. That is > > >one of the biggest misconceptions of light. You don't watch light > > >propagate like a thrown baseball. What you 'see' is light when it hits > > >your eye. > > > That's why I added the 'dust' to the train. Some of the laser going from > > the back to the front would be scattered by the dust, so that the > > embankment observer could see the laser pulse propagate. > > But the light which is reflected by the dust is still going to travel > through the aether which is at rest relative to the embankment. You're > still not 'seeing the light propagate on the train'. What you are > 'seeing' is light reflected by dust particles traveling at 'c' > relative to the aether. > > > Or, to put it another way. A 1 light year long train, travelling at c/4. > > When the front of the train is 1/4 light year away, the rear of the train > > is 1 1/4 light year away. At that time, a laser is fired from the rear to > > the front. One year later, the front of the train reaches the embankment > > observer since it was travelling at c/4 and was 1/4 light year away. At > > the same time, the laser pulse reaches the front of the train since it was > > travelling a distance of 1 light year for one year. Therefore, as far as > > the trackside observer is concerned, the light travelled 1 1/4 light year > > in 1 year, or 1.25 c. > > Again, this is incorrect. In your gadenken, I'm assuming the aether is > at rest relative to the train. When the light reaches the Observer on > the embankment, the light has traveled from where the back of the > train *is*. The light has traveled 1 light year from where the back of > the train *is* to where the Observer on the embankment is. > > Since the aether is at rest relative to the train, where the lightning > strike occurred in three dimensional space relative to the Observer on > the embankment is meaningless. > > Light travels at 'c' relative to the aether. > > I don't know how else to explain this but with flashes of light in > water. > > There is a round pool on the train. The side of the pool is made of > glass. There are Observers on the train with their faces pushed up > against the glass. > > There is an Observer on the embankment. > > A flash goes off in the middle of the pool. > > It just so happens when the flash travels through the water, travels > through the glass, and is about to reach the Observers on the train, > the pool is right next to the Observer on the embankment. > > The Observer on the embankment presses his face against the glass just > like the Observers on the train do. > > The light travels the same distance to ALL of the Observers. > > The light has traveled from where the center of the pool *is* to where > the Observers on the train *are* when the Observers on the train see > the light. > > The light has traveled from where the center of the pool *is* to where > the Observer on the embankment *is* when the Observer on the > embankment sees the light. > > The light has traveled relative to the water which is at rest relative > to the train. > > In your gadenken, since I am assuming the aether is at rest relative > to the train, the light has traveled at 'c' relative to the aether > which is at rest relative to the train. > > In you gadenken, if an Observer on the embankment and an Observer on > the train are standing side by side when the light reaches both of > them, the light has traveled the same distance to each of them because > the light is traveling relative to the aether, and besides the last > instant where the light is no longer on the train but on the > embankment right before it reaches the Observer on the embankment, the > light had traveled through the aether which is at rest relative to the > train. I have a better gadenken. A modified version of your gadenken. The 1 light year long train is full of water. The laser is fired at the back of the train in the water. The Observer at the front of the train has his face pushed up against a plate glass which separates them from the water. Right when the light exits the glass and is about to reach the Observer on the train, an Observer on the embankment stands right next to the Observer on the train. Now, obviously the train is moving 1/4 the speed of light, so the Observer on the embankment is in trouble, but right before the train hits the Observer on the embankment the light from the laser reaches both Observers. The light has traveled the same distance through the water to both Observers.
From: mpc755 on 16 Dec 2009 23:04 On Dec 16, 11:01 pm, mpc755 <mpc...(a)gmail.com> wrote: > On Dec 16, 10:32 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Dec 16, 10:08 pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > wrote: > > > > mpc755 <mpc...(a)gmail.com> writes: > > > >On Dec 16, 8:34=A0pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > > >wrote: > > > > >> >> 1) What is the velocity of the light beam relative to the aether, when > > > >> >> it's still travelling through the train? > > > >> >Light travels at 'c' relative to the aether. > > > > >> OK. Since the angle is so small we can ignore the small effects of > > > >> sin/cos of it being different from 0/1. So... the platform observer will > > > >> see the light on the train moving at either 1.25 c or 0.75 c > > > >The platform observer does not 'see the light on the train'. That is > > > >one of the biggest misconceptions of light. You don't watch light > > > >propagate like a thrown baseball. What you 'see' is light when it hits > > > >your eye. > > > > That's why I added the 'dust' to the train. Some of the laser going from > > > the back to the front would be scattered by the dust, so that the > > > embankment observer could see the laser pulse propagate. > > > But the light which is reflected by the dust is still going to travel > > through the aether which is at rest relative to the embankment. You're > > still not 'seeing the light propagate on the train'. What you are > > 'seeing' is light reflected by dust particles traveling at 'c' > > relative to the aether. > > > > Or, to put it another way. A 1 light year long train, travelling at c/4. > > > When the front of the train is 1/4 light year away, the rear of the train > > > is 1 1/4 light year away. At that time, a laser is fired from the rear to > > > the front. One year later, the front of the train reaches the embankment > > > observer since it was travelling at c/4 and was 1/4 light year away. At > > > the same time, the laser pulse reaches the front of the train since it was > > > travelling a distance of 1 light year for one year. Therefore, as far as > > > the trackside observer is concerned, the light travelled 1 1/4 light year > > > in 1 year, or 1.25 c. > > > Again, this is incorrect. In your gadenken, I'm assuming the aether is > > at rest relative to the train. When the light reaches the Observer on > > the embankment, the light has traveled from where the back of the > > train *is*. The light has traveled 1 light year from where the back of > > the train *is* to where the Observer on the embankment is. > > > Since the aether is at rest relative to the train, where the lightning > > strike occurred in three dimensional space relative to the Observer on > > the embankment is meaningless. > > > Light travels at 'c' relative to the aether. > > > I don't know how else to explain this but with flashes of light in > > water. > > > There is a round pool on the train. The side of the pool is made of > > glass. There are Observers on the train with their faces pushed up > > against the glass. > > > There is an Observer on the embankment. > > > A flash goes off in the middle of the pool. > > > It just so happens when the flash travels through the water, travels > > through the glass, and is about to reach the Observers on the train, > > the pool is right next to the Observer on the embankment. > > > The Observer on the embankment presses his face against the glass just > > like the Observers on the train do. > > > The light travels the same distance to ALL of the Observers. > > > The light has traveled from where the center of the pool *is* to where > > the Observers on the train *are* when the Observers on the train see > > the light. > > > The light has traveled from where the center of the pool *is* to where > > the Observer on the embankment *is* when the Observer on the > > embankment sees the light. > > > The light has traveled relative to the water which is at rest relative > > to the train. > > > In your gadenken, since I am assuming the aether is at rest relative > > to the train, the light has traveled at 'c' relative to the aether > > which is at rest relative to the train. > > > In you gadenken, if an Observer on the embankment and an Observer on > > the train are standing side by side when the light reaches both of > > them, the light has traveled the same distance to each of them because > > the light is traveling relative to the aether, and besides the last > > instant where the light is no longer on the train but on the > > embankment right before it reaches the Observer on the embankment, the > > light had traveled through the aether which is at rest relative to the > > train. > > I have a better gadenken. A modified version of your gadenken. > > The 1 light year long train is full of water. > > The laser is fired at the back of the train in the water. > > The Observer at the front of the train has his face pushed up against > a plate glass which separates them from the water. > > Right when the light exits the glass and is about to reach the > Observer on the train, an Observer on the embankment stands right next > to the Observer on the train. > > Now, obviously the train is moving 1/4 the speed of light, so the > Observer on the embankment is in trouble, but right before the train > hits the Observer on the embankment the light from the laser reaches > both Observers. > > The light has traveled the same distance through the water to both > Observers. The light from the laser has traveled the same distance through the water which is at rest relative to the train to both the Observer on the embankment and the Observer on the train.
From: GogoJF on 16 Dec 2009 23:06 On Dec 16, 10:01 pm, mpc755 <mpc...(a)gmail.com> wrote: > On Dec 16, 10:32 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Dec 16, 10:08 pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > wrote: > > > > mpc755 <mpc...(a)gmail.com> writes: > > > >On Dec 16, 8:34=A0pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > > >wrote: > > > > >> >> 1) What is the velocity of the light beam relative to the aether, when > > > >> >> it's still travelling through the train? > > > >> >Light travels at 'c' relative to the aether. > > > > >> OK. Since the angle is so small we can ignore the small effects of > > > >> sin/cos of it being different from 0/1. So... the platform observer will > > > >> see the light on the train moving at either 1.25 c or 0.75 c > > > >The platform observer does not 'see the light on the train'. That is > > > >one of the biggest misconceptions of light. You don't watch light > > > >propagate like a thrown baseball. What you 'see' is light when it hits > > > >your eye. > > > > That's why I added the 'dust' to the train. Some of the laser going from > > > the back to the front would be scattered by the dust, so that the > > > embankment observer could see the laser pulse propagate. > > > But the light which is reflected by the dust is still going to travel > > through the aether which is at rest relative to the embankment. You're > > still not 'seeing the light propagate on the train'. What you are > > 'seeing' is light reflected by dust particles traveling at 'c' > > relative to the aether. > > > > Or, to put it another way. A 1 light year long train, travelling at c/4. > > > When the front of the train is 1/4 light year away, the rear of the train > > > is 1 1/4 light year away. At that time, a laser is fired from the rear to > > > the front. One year later, the front of the train reaches the embankment > > > observer since it was travelling at c/4 and was 1/4 light year away. At > > > the same time, the laser pulse reaches the front of the train since it was > > > travelling a distance of 1 light year for one year. Therefore, as far as > > > the trackside observer is concerned, the light travelled 1 1/4 light year > > > in 1 year, or 1.25 c. > > > Again, this is incorrect. In your gadenken, I'm assuming the aether is > > at rest relative to the train. When the light reaches the Observer on > > the embankment, the light has traveled from where the back of the > > train *is*. The light has traveled 1 light year from where the back of > > the train *is* to where the Observer on the embankment is. > > > Since the aether is at rest relative to the train, where the lightning > > strike occurred in three dimensional space relative to the Observer on > > the embankment is meaningless. > > > Light travels at 'c' relative to the aether. > > > I don't know how else to explain this but with flashes of light in > > water. > > > There is a round pool on the train. The side of the pool is made of > > glass. There are Observers on the train with their faces pushed up > > against the glass. > > > There is an Observer on the embankment. > > > A flash goes off in the middle of the pool. > > > It just so happens when the flash travels through the water, travels > > through the glass, and is about to reach the Observers on the train, > > the pool is right next to the Observer on the embankment. > > > The Observer on the embankment presses his face against the glass just > > like the Observers on the train do. > > > The light travels the same distance to ALL of the Observers. > > > The light has traveled from where the center of the pool *is* to where > > the Observers on the train *are* when the Observers on the train see > > the light. > > > The light has traveled from where the center of the pool *is* to where > > the Observer on the embankment *is* when the Observer on the > > embankment sees the light. > > > The light has traveled relative to the water which is at rest relative > > to the train. > > > In your gadenken, since I am assuming the aether is at rest relative > > to the train, the light has traveled at 'c' relative to the aether > > which is at rest relative to the train. > > > In you gadenken, if an Observer on the embankment and an Observer on > > the train are standing side by side when the light reaches both of > > them, the light has traveled the same distance to each of them because > > the light is traveling relative to the aether, and besides the last > > instant where the light is no longer on the train but on the > > embankment right before it reaches the Observer on the embankment, the > > light had traveled through the aether which is at rest relative to the > > train. > > I have a better gadenken. A modified version of your gadenken. > > The 1 light year long train is full of water. > > The laser is fired at the back of the train in the water. > > The Observer at the front of the train has his face pushed up against > a plate glass which separates them from the water. > > Right when the light exits the glass and is about to reach the > Observer on the train, an Observer on the embankment stands right next > to the Observer on the train. > > Now, obviously the train is moving 1/4 the speed of light, so the > Observer on the embankment is in trouble, but right before the train > hits the Observer on the embankment the light from the laser reaches > both Observers. > > The light has traveled the same distance through the water to both > Observers. Well, I certainly like the way you carry on your conversation.
From: mpc755 on 16 Dec 2009 23:09
On Dec 16, 11:06 pm, GogoJF <jfgog...(a)yahoo.com> wrote: > On Dec 16, 10:01 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Dec 16, 10:32 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > On Dec 16, 10:08 pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > > wrote: > > > > > mpc755 <mpc...(a)gmail.com> writes: > > > > >On Dec 16, 8:34=A0pm, moro...(a)world.std.spaamtrap.com (Michael Moroney) > > > > >wrote: > > > > > >> >> 1) What is the velocity of the light beam relative to the aether, when > > > > >> >> it's still travelling through the train? > > > > >> >Light travels at 'c' relative to the aether. > > > > > >> OK. Since the angle is so small we can ignore the small effects of > > > > >> sin/cos of it being different from 0/1. So... the platform observer will > > > > >> see the light on the train moving at either 1.25 c or 0.75 c > > > > >The platform observer does not 'see the light on the train'. That is > > > > >one of the biggest misconceptions of light. You don't watch light > > > > >propagate like a thrown baseball. What you 'see' is light when it hits > > > > >your eye. > > > > > That's why I added the 'dust' to the train. Some of the laser going from > > > > the back to the front would be scattered by the dust, so that the > > > > embankment observer could see the laser pulse propagate. > > > > But the light which is reflected by the dust is still going to travel > > > through the aether which is at rest relative to the embankment. You're > > > still not 'seeing the light propagate on the train'. What you are > > > 'seeing' is light reflected by dust particles traveling at 'c' > > > relative to the aether. > > > > > Or, to put it another way. A 1 light year long train, travelling at c/4. > > > > When the front of the train is 1/4 light year away, the rear of the train > > > > is 1 1/4 light year away. At that time, a laser is fired from the rear to > > > > the front. One year later, the front of the train reaches the embankment > > > > observer since it was travelling at c/4 and was 1/4 light year away.. At > > > > the same time, the laser pulse reaches the front of the train since it was > > > > travelling a distance of 1 light year for one year. Therefore, as far as > > > > the trackside observer is concerned, the light travelled 1 1/4 light year > > > > in 1 year, or 1.25 c. > > > > Again, this is incorrect. In your gadenken, I'm assuming the aether is > > > at rest relative to the train. When the light reaches the Observer on > > > the embankment, the light has traveled from where the back of the > > > train *is*. The light has traveled 1 light year from where the back of > > > the train *is* to where the Observer on the embankment is. > > > > Since the aether is at rest relative to the train, where the lightning > > > strike occurred in three dimensional space relative to the Observer on > > > the embankment is meaningless. > > > > Light travels at 'c' relative to the aether. > > > > I don't know how else to explain this but with flashes of light in > > > water. > > > > There is a round pool on the train. The side of the pool is made of > > > glass. There are Observers on the train with their faces pushed up > > > against the glass. > > > > There is an Observer on the embankment. > > > > A flash goes off in the middle of the pool. > > > > It just so happens when the flash travels through the water, travels > > > through the glass, and is about to reach the Observers on the train, > > > the pool is right next to the Observer on the embankment. > > > > The Observer on the embankment presses his face against the glass just > > > like the Observers on the train do. > > > > The light travels the same distance to ALL of the Observers. > > > > The light has traveled from where the center of the pool *is* to where > > > the Observers on the train *are* when the Observers on the train see > > > the light. > > > > The light has traveled from where the center of the pool *is* to where > > > the Observer on the embankment *is* when the Observer on the > > > embankment sees the light. > > > > The light has traveled relative to the water which is at rest relative > > > to the train. > > > > In your gadenken, since I am assuming the aether is at rest relative > > > to the train, the light has traveled at 'c' relative to the aether > > > which is at rest relative to the train. > > > > In you gadenken, if an Observer on the embankment and an Observer on > > > the train are standing side by side when the light reaches both of > > > them, the light has traveled the same distance to each of them because > > > the light is traveling relative to the aether, and besides the last > > > instant where the light is no longer on the train but on the > > > embankment right before it reaches the Observer on the embankment, the > > > light had traveled through the aether which is at rest relative to the > > > train. > > > I have a better gadenken. A modified version of your gadenken. > > > The 1 light year long train is full of water. > > > The laser is fired at the back of the train in the water. > > > The Observer at the front of the train has his face pushed up against > > a plate glass which separates them from the water. > > > Right when the light exits the glass and is about to reach the > > Observer on the train, an Observer on the embankment stands right next > > to the Observer on the train. > > > Now, obviously the train is moving 1/4 the speed of light, so the > > Observer on the embankment is in trouble, but right before the train > > hits the Observer on the embankment the light from the laser reaches > > both Observers. > > > The light has traveled the same distance through the water to both > > Observers. > > Well, I certainly like the way you carry on your conversation. If I could only convince others light travels at 'c' relative to the aether we might actually get somewhere. |