Re: Spaceship Question
- From: "PD" <TheDraperFamily@xxxxxxxxx>
- Date: 25 Jan 2006 03:16:55 -0800
Henri Wilson wrote:
> On 24 Jan 2006 13:32:21 -0800, "PD" <TheDraperFamily@xxxxxxxxx> wrote:
>
> >
> >Henri Wilson wrote:
> >> On 24 Jan 2006 05:50:01 -0800, "PD" <TheDraperFamily@xxxxxxxxx> wrote:
> >>
>
> >> >> I gather you are also saying that the spaceship both lengthens and shortens
> >> >> simultaneously, when it fires its engine.
> >> >
> >> >Rather, it lengthens for one observer, and it shortens for another
> >> >observer, yes.
> >>
> >> So it follows that nothing actually happens to the ship or anything on it.
> >
> >No physical agent is doing anything to change the ship or anything in
> >it. If that's what you meant, that's right.
>
> God. I'll move you up another rung....
>
> >> >> ....this is most difficult to comprehend.
> >> >
> >> >Why? Length is not an intrinsic property of the spaceship.
> >>
> >> Why do you think that? The ship occupies a length of space. ...as does a metre
> >> rod.
> >> For convenience, we can define the ship's length as ONE length unit and use it
> >> as a universal length standard.
> >
> >That standard would only apply in a particular reference frame (one
> >where the ship is at rest). Length is the result of a *procedure* that
> >is inherently observer-dependent. There is nothing about the ship that
> >you can call spatial length that is independent of the observer.
>
> Of course it is. I would say the opposite.
You would be wrong. Experiment, by the way, indicates otherwise.
>
> No physical attribute of any object is observer dependent. How could it be?
I agree. Except that length is not a physical attribute of the object.
>
> >> I think you will now agree that this standard remains the same no matter how
> >> the ship negotiates space.
> >
> >No, I quite disagree. See the above.
>
> Why are you people so obsessed with observers?
Because length is the result of a procedure that is inherently
observer-dependent.
>
> Are you all exhibitionists, nudists or something?
>
> >
> >>
> >> >There is no
> >> >reason why the same measurement cannot result in different values for
> >> >two observers looking at the *same* spaceship at the *same* time.
> >>
> >> You seem obsessed with observers and their measurements. Observers don't change
> >> physical properties of observed objects, you know.
> >
> >That's right, but length is not a physical property of the ship.
>
> I have explained elsewhere that the ship INTRINSICALLY occupies a length of
> space and that this length can, for convenience, be defined as one standard
> unit.
> Let's perform an experiment.
>
> Let's produce billions of identical platinum-iridium 1 metre rods and fire them
> all into space in all directions.
>
> Do you think any of them actually changes due to that experience?
No, but then again, the change in length does not amount to a physical
change in the rods.
> Do you think that if two of them are reunited in remote space, their lengths
> will be different?
No, but if two of them pass a single observer at different speeds, they
will be have different lengths.
>
> >> >If, however, you cannot free yourself from insisting that length is an
> >> >inherent property of the spaceship, then indeed I can understand why
> >> >this would be most difficult to comprehend.
> >>
> >> The ship's length is defined as ONE SPACE UNIT.
> >
> >That definition would not work for all reference frames. (Or if you
> >mandated that it does, then the length of everything else would change
> >in space units.)
>
> Where is your proof of that...or are you just preaching again?
The proof is in experiment, HW.
>
> We have already established that physical properties do not change with
> velocity. (they cannot both increase and decrease simultaneously)
But length is not a physical property.
>
> >
> >>
> >> It doesn't alter with velocity changes.
> >
> >Sure it does. Length is not a physical property of the spaceship that
> >is observer-independent. Length is the result of a *procedure* that is
> >inherently observer-dependent.
>
> 'Occupation of space' is the physical property. Length can be quantitatively
> assigned by definition.
> We are defining the standard length unit as the amount of space between one end
> of our spaceship and the other end.
Crappy definition. The problem is that two copies of the same standard,
traveling at different speeds and observed by the same fella, will have
different lengths.
>
> >> >> >Observers inside the spaceship observe that outside lengths,
> >> >> >for instance the distance to a remote star, are Lorentz
> >> >> >contracted.
> >> >>
> >> >> Are you claiming that the distance between the asteroid and the star
> >> >> miraculously changes when the ship takes off?
> >> >>
> >> >> ....this is most difficult to comprehend.
> >> >
> >> >Again, you have the preconception that the distance between the
> >> >asteroid and the star is an inherent physical property of the pair. It
> >> >is not.
> >>
> >> Theoretically, the distance between the two can be measured by connecting a
> >> large number of standard rods between them.
> >> That is certainly not going to change just because a moving observer goes past.
> >
> >The moving observer would not agree that those standard rods are the
> >same length as the standard rod he is carrying with him.
>
> But he must know that he is deluded if he measures them to have any length
> other than the one he assigned to them at rest....because knows that they could
> not possibly have been affected by his own movement.
What he thinks he knows is irrelevant, as all such "knowledge" should
be checked against experiment. What he *measures* is what determines
what he knows. What he learns from this measurement is that length must
not be an inherent physical property of the object. (Relativity
explains *why* it cannot possibly be an inherent physical property of
the object.)
>
> >
> >> Why would you think it would?
> >>
> >> A_________rod_________B
> >>
> >> ->O O1<-
> >>
> >> You seem to be under the delusion that the rod changes length because of the
> >> presence of differently moving observers. How strange...
> >
> >Yes, that's right. Note that nothing is happening to the rod per se,
> >though something is happening to its length. That's because length is
> >not a physical property of the rod.
>
> Its length has been given the value ONE by definition.
>
> Are you saying that it becomes something other than ONE just because observers
> move past?
Yes.
>
>
> >> >> The principle is that nothing actually happens to the ship or its clocks when
> >> >> its engine is fired for a period. Obviously the length of the period doesn't
> >> >> matter if nothing happens anyway.
> >> >> Wouldn't you agree?
> >> >
> >> >Yes.
> >>
> >> Hooray!
> >
> >The guy on the ship is not going to measure any difference in the
> >period of the ship's clock, no matter how the ship moves.
>
> Nor is anyone else with proper measuring equipment.
Spaceman also believes that time dilation is due to clock
malfunctioning. Do you believe that too?
>
> >> >Your conflict comes from assuming that the observation that the ship's
> >> >clocks slow down must be because of a physical process affecting the
> >> >clocks. Not so.
> >>
> >> I don't consider such observations at all.
> >> If the ship's rods and clocks don't change after a firing of the engine then
> >> they must be exacrtly as they were beforehand.
> >
> >That depends on what "they" stands for. If you mean the rods and the
> >clocks, then I agree. If you mean the rod's length or the clock's rate,
> >as measured on the ship, then I agree. If you mean the rod's length or
> >the clock's rate, as measured by any other observer, then I don't
> >agree.
>
> But you have no good reason to hold such a belief.
Sure I do. It's called experiment. It's an observed fact.
>
> The rod's 'length' is calibrated against the standard, which is the ship's
> length of ONE unit. If nothing physically happens to the rod as a result of the
> acceleration experience, it must be exactly the same rod and therefore possess
> exactly the same length as before...no matter WHO measures it.
>
> Anyone who get a different value for its length must be using a faulty
> technique.
Not if length is not a physical property of the rod. If one defines a
standard and then finds that the standard is useless and
observer-dependent, then one calls into question the standard rather
than assuming the technique is crappy. Especially if one can accurately
*predict* how much the "standard" changes with the observer,
independent of the method used to measure it.
If there were a problem with the technique, then the answer would vary
by varying the technique or by altering the device. Since the result of
the measurement is *predictably* dependent on the relative speed of the
observer and not on the technique, then the implication is that there
is something else going on.
>
>
> >> >
> >> >Not so.
> >>
> >> Time, like length cannot be affected by remote observer movement.
> >
> >Any quantity that is the result of a procedure that is inherently
> >observer-dependent will naturally be affected by remote observer
> >movement. This isn't true for quantities that are inherent properties
> >of the object, but length of the object and the rate of the process in
> >it are not inherent properties of the object.
>
> I think you are confusing 'length' with 'measured length'.
> Measurement always have limits of accuracy.
Limits of accuracy are estimable, and this effect has been observed to
far exceed the limits of accuracy.
>
> Those people who originally standardized their gear with the ship's while at
> rest with it and who subsequently do NOT measure the spaceship's length to be
> ONE unit, are obviously performing a flawed experiments.
Sorry, that's not obvious. In fact, it's pretty easily ruled out.
>The usual cause is the
> use of EM for communication.
>
>
> >> .....maybe you should take up spoon bending.
> >
> >Maybe you should ask yourself what "length" means.
>
> ...occupation of space between two points.
Let's figure out exactly what that means. How do you measure the length
of a moving object?
PD
>
> Measured length is a comparison with a defined standard.
>
> >PD
>
>
> HW.
> www.users.bigpond.com/hewn/index.htm
.
- References:
- Re: Spaceship Question
- From: Randy Poe
- Re: Spaceship Question
- From: PD
- Re: Spaceship Question
- From: PD
- Re: Spaceship Question
- Prev by Date: Re: Spaceship Question
- Next by Date: Re: We All failed (regarding the definition of a crackpot)
- Previous by thread: Re: Spaceship Question
- Next by thread: Re: Spaceship Question
- Index(es):
Relevant Pages
|
