Re: Another Question They Cannot Answer
- From: "PD" <TheDraperFamily@xxxxxxxxx>
- Date: 4 Feb 2006 06:17:39 -0800
Henri Wilson wrote:
On 3 Feb 2006 07:26:34 -0800, "PD" <TheDraperFamily@xxxxxxxxx> wrote:
Henri Wilson wrote:
On 2 Feb 2006 05:52:23 -0800, "PD" <TheDraperFamily@xxxxxxxxx> wrote:
That's a generality. Explain precisely, using an example, of what the
deviation from the truth is.
You must be acting dumb.
..get a bloody telescope and look at a star 500 LYs away.
What do you see?
A 500 yo willusion of that star, of course.
I'm sorry, I was under the impression that "history" and "illusion"
meant different things.
Are you saying that the star was NOT that way 500 years ago?
Well the star WAS that way but you are still seeing a willusion of it. For one
thing YOU have moved. Its light will be doppler shifted differently than it
would have been if you had remained where you were 500 years ago.
But basically the willusion is all about how, where and what the star is really
doing NOW rather than 500 years ago.
You have the willusion of it then, the problem is to determine what it is like
NOW.
Nonsense. No one ever claims they have knowledge about what a star is
doing NOW. Heck, we don't even know what our Sun is doing NOW. If you
think anyone is making that claim, then you simply don't understand
physics.
Or are you saying that when I measure a moving object's length, I'm not
measuring the length as it is NOW but as it was a little while ago?
That depends on the accuracy of your measurement. Basically, the closer it is,
the more accurate will be the measurement.
Every observation you make is D/(c+v) seconds behind your own 'present'.
And this observational delay changes the *length*? How?
Surely you know that.
Luckily this doesn't have much practical significance on Earth...except maybe
the delay in TV satellite hookups.
It isn't there, where you a looking, any more...and it might have changed
colour or brightness.
The question is to try to determine the current position and state of the star
from the willusion you see.
2. Length is defined in terms of a measurement procedure.
Only measurements carried out in the object's frame can be accepted as being
100% correct.
And yet...
1. The laws of physics are identical, regardess of the frame chosen.
The laws might be but parameter values aren't. That's only a postulate anyway.
Yes, you're right, there's a careful distinction between laws and
parameter values. Note that length is a parameter value, and an
observer-dependent one, not a law.
No, the actual length is NOT observer dependent.
Observers simply make mistakes in their measurements of it.
While Einstein elevated for the sake of his paper the invariance of
physical laws to a postulate, it is a *highly tested* postulate. The
invariance of the laws of electrodynamics and mechanics are thoroughly
tested in experiment. The invariance of the laws for quantum field
theory (including all interactions in the Standard Model) was built in,
and the frame-invariance of those laws are *extremely* well-tested.
Preach to yourself as much as you like but you wont be impressing ME.
There is NO evidence in support of SR.
This assertion reminds me of those who simply do not believe the
evidence that dinosaurs roamed the Earth 125,000,000 years ago, because
that notion is incompatible with their conviction that the Earth was
not around 125,000,000 years ago, and therefore the experiments are de
facto suspect. It is also usually true in those cases that they have
not examined the evidence of dinosaurs 125,000,000 years ago. Why would
they? They don't believe it even before looking at it.
2. You don't hold the same restrictions when it comes to measurements
of velocity, acceleration, force, momentum, kinetic energy, potential
energy, and so on and so forth. This restriction ONLY applies to length
and time. Why?
I have told you. It is obvious.
No, I'm sorry, it's not obvious. You simply say the numerator and
denominator of a ratio each must be measured only in the rest frame,
but the ratio can be measured reliably in any frame. You say this fact
is "interesting", but you don't defend it at all.
Well my statement above about 'dx' explains it.
Movement is about the position of a POINT on the object, not about its length.
The path of a muon in the atmophere, which is the movement of position
of a POINT on the muon, is also one of the lengths that Lorentz
contraction applies to. Are you saying that it is perfectly
well-defined (and observer-dependent) in that case?
These statements are not
contradictory, as I've said over and over again. HW, however, cannot
fathom how physical length can NOT be an intrinsic property of the rod,
though he has no problem accepting this for velocity or momentum or
kinetic energy.
Don't lie.
Length IS an intrinsic property of the rod. It occupies an absolutely constant
interval of space no matter how or where it is taken.
I'm not lying. No, it doesn't. That's precisely the point.
Your assertion that it does doesn't make it fact.
But you and your friends have agreed that nothing happens to the rod when it is
moved. Have you changed your mind again?
No. That's because length is not an intrinsic property of the rod.
Observing a change in the length does not imply a change in the
intrinsic physical properties of the rod. I don't know why you would
have thought I had reversed my statement about this. I've been
absolutely consistent.
'OBSERVING' a change when you know there hasn't been one is evidence of a
willusion.
I'm sorry, I don't KNOW there hasn't been one. That erroneous
conclusion stems from an improper *assumption* that length is an
intrinsic property of the object, and that since nothing physical
happens to the object, no intrinsic property of the object can change.
Unfortunately, the assumption is incorrect, and so the conclusion is
also faulty.
Look, if one thousand observers were equipped with identical measuring rods and
clocks and then subsequently fired at different speeds past a metre rod - the
length which they are required to measure - would and should they all get the
same answer?
No, they would not. No, they should not.
They SHOULD because they were measuring the same object
This would be true if every measurement of a physical object should be
the same if viewed by different observers. I don't know where you get
the idea this should be the case.
......but they WOULD NOT
because they would be dependent on light's finite travel time.
Therefore their measurements would all be wrong be different amounts...but the
rod didn't change one iota.
PD
HW.
www.users.bigpond.com/hewn/index.htm
.
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