Re: Is "malfunctioning" absolute or relative?

papa_rios@xxxxxxxxxxx wrote:
On 14 oct, 11:38, Uncle Ben <b...@xxxxxxxxxxx> wrote:
On Oct 14, 10:15 am, papa_r...@xxxxxxxxxxx wrote:



On 14 oct, 10:38, Uncle Ben <b...@xxxxxxxxxxx> wrote:

On Oct 14, 8:42 am, papa_r...@xxxxxxxxxxx wrote:

On 14 oct, 08:48, Uncle Ben <b...@xxxxxxxxxxx> wrote:

On Oct 14, 7:12 am, papa_r...@xxxxxxxxxxx wrote:

On 14 oct, 02:23, Uncle Ben <b...@xxxxxxxxxxx> wrote:

On Oct 14, 12:46 am, shuba <tim.sh...@xxxxxxxxxxxxx> wrote:

Uncle Ben wrote:
I guess we have to leave it that in your view the "bending
of the stick" immersed in a glass of water is real. And in
my view, the bending of the stick is a misinterpretation of
what we see in the real bending of light rays from the scene.

I wouldn't actually use the term 'real' to describe the bent
stick, but neither would I use it for the length contraction
and time dilation of relativity, except perhaps to say they
are real geometric projections.

If we cannot agree on this little demonstration, then we are
doomed to disagree.
That's OK.

(But it still bothers me a little that if the bending of the
stick is real, why doesn't it break?)

Same reason that the same stick can be (really) Lorentz
contracted to any arbitrarily small length without breaking.

---Tim Shuba---

I don't think so. A lorentz contraction merely shortens the
stick. If its ends are not constrained, there is no stress
involved. Whereas the stick in water is bent sharply at one
point. If it is a rubber stick, OK, but if it is a dead stick
and were really bent, it would certainly break.

I am perhaps only illustrating what I mean by "real", as you
are using your definition. I gather that we have a "real"
disagreement about the relativistic effects. Let's agree on
that, anyway. I don't want to get hung up on cute ideas about
what is meant by being real.

Notice that I am not appealing to any one frame as giving real
lengths or times. They are all real; they are just
frame-relative. This is just as simple as the compass needles'
"north" in London and New York pointing in directions defined
relative to their locations. You will grant, I presume, that
the needles are not parallel, but they both point "north"
w.r.t. their locations without contradiction.

Uncle Ben

Indeed. I'm sitting here at my office and every thing I see
around confirms me that I'm totally still. This is my
"reality". But we all know my chair, with my office, together
with my whole city and the continent is moving at around 1600
km/hour while, at the same time, Earth is moving around the Sun
at 30km/sec and the Solar System is moving at 240km/sec
towards...etc, etc.
So, what is the real "reality" or even does it makes sense to
speak of a "universal reality"?

Miguel Rios- Hide quoted text -

- Show quoted text -

Miguel, you are leaving out the essential factor: relativity,
i.e., these facts are relative to the frame of reference. I say
you "really" are at rest w.r.t. your room. And you "really" are
in motion w.r.t. a non-rotating heliocentric frame.

This is so simple. An even simpler example: distance. Can we say
that Chicago is really "farther"? No, it depends on the reference
point. "Fartherness" is not absolute. Chicago is farther than
Buffalo w.r.t. Albany. It is not farther w.r.t. Evanston. Both
distances are real, not illusory, but they are relative to a
point of reference.

It seems not so clear when we turn to rates of clocks, because
for all of human history since clock have existed, we have
thought of time as absolute. Now Einstein tells us that time is
not absolute; it, too, is defined only w.r.t. a frame of
reference. This defies our common sense, but SR tells us that it
is just as real as distance being defined relative to a point of
reference.

Uncle Ben

I agree with you. My main argument is that for many here, the
concepts of "real", "perspective" and other relativity terms are
difficult to grasp.
It like, in other context, the financial problems. Is the
vanishing of trillion of dollars "real" or just an "illusion" due
to market values?. For many that question is also quite difficult
to understand. In the twin paradox, the traveling twin compares
his clock (frame K') with several clocks located along his path
(frame K) and he measures that his clock is running slow. In his
"reality" his watch, he knows, is running OK, so his logical
conclusion is that, through these measurements, he is
experiencing time dilation. He is also observing that he is
moving,m by seeing all those clocks coming in and going out from
his location. If he would not have access to those clocks on the
path, he would not be able to detect any time dilation at all.
While the latter situation is not a different twin "reality", for
the twin himself his perceptions and senses would tell him
nothing is happening! He would not be able to say if he is moving
or is still.

Miguel Rios- Hide quoted text -

- Show quoted text -

Miguel, you said:

In the twin paradox, the traveling twin compares his clock (frame
K') with several clocks located along his path (frame K) and he
measures that his clock is running slow. In his "reality" his
watch, he knows, is running OK, so his logical conclusion is
that, through these measurements, he is experiencing time
dilation. He is also observing that he is moving,m by seeing all
those clocks coming in and going out from his location. If he
would not have access to those clocks on the

I think you would find that the "travelling" twin A (travelling
w.r.t. his brother B) would find that it is the clocks (B's)
whizzing backward (w.r.t. his [A's] ship) that are running slow.
That is because w.r.t. his own ship, he A is "really" not
travelling, and they [B's clocks] are. W.r.t. his brother's frame
of reference, on the other hand, his [A's] clocks are running
slow. Both statements are true and the effects are real.

It helps mightily when speaking of these things to specify the
frame of reference. You would not quote "the distance" to Chicago
without specifing the reference point. Similarly, you should not
speak of a clock's rate without specifying the frame of reference.
The three little letters "w.r.t." can correct most apparent
contradictions in SR.

Would you not agree that w.r.t. A's ship, A is not moving? (I don't
have to say "appears not to move", do I?

Uncle Ben

Dear Ben:

Quoting Landau and Lifshitz, Chapter 1, section 3 on bottom of page
7:

"...To compare the rates of the two clocks in K and K' we must once
more compare the readings of the same moving clock in K' with the
clocks in K. But now we compare this clock with different clocks in
K, by whose location the clock in K' goes at different times. Then
we find that the clock in K' lags behind the clocks in K with which
it is being compared. We see that to compare the rates of clocks in
two reference frames we require several clocks in one frame and one
in the other, and that therefore this process is not symmetric with
respect to the two systems. The clock that appears to lag is always
the one which is being compared with different clocks in the other
system."

Miguel Rios- Hide quoted text -

- Show quoted text -

What L&L are talking about is how to measure the rate of a moving
clock. What I am talking about is how to compare the rates of two
clocks; we suppose the existence of both frames of reference, each of
which is conceptually defined by a whole string of clocks each at
rest w.r.t. one frame of reference or the other. This is a detail of
technique.

The result is always that a clock runs fastest w.r.t. its proper
frame. W.r.t. any other frame it runs slower. So the "travelling
twin's" clock runs fastest w.r.t. the "travelling twin". W.r.t. the
"traveling twin", his brother's clocks run slower, since they are
travelling backwards w.r.t. the "travelling twin"!

If you disagree with this, there is no point in continuing the
discussion.

(Note that we are calling one of the twins the "travelling twin" in
quotes, because he is travelling w.r.t. his brother, but is not
travelling with respect to himself. It would be clearer to refer to
the two individuals as A and B, but anyone in this newsgroup, except
possibly Spaceman, should be able to understand.)

Uncle Ben

That is precisely the point of the cited paragraph (actually what you
say is in the previous paragraph of the Landau book). For sure A will
measure B's clock to run slow with respect to his own local measure,
and B will measure A's clock to run slow with respect to his own local
measure, the situation being totally symmetric and not contradictory.

When the clocks return. they prove to not be symetric.
Hence.. TADA.... A PARADOX.
Sheesh.
Only one clock actually slowed rate.
The clock simply malfunctoned.
How can you say with someting that comes up with years off
is a precise clock at all.
C,mon man.. get a clue.



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