Re: HOCUS POCUS


PD wrote:
Mike wrote:
PD wrote:
Mike wrote:
Randy Poe wrote:
mluttgens@xxxxxxxxxx wrote:
PD wrote:
mluttgens@xxxxxxxxxx wrote:
HOCUS POCUS

Two electrons E1 and E2 are ejected along a straight line with
opposite velocities v1 and v2 from a device stationary in S,
at t=0 according to S clock.

Assuming that v1 = -0.6 c and v2 = 0.8 c, what is the relative
velocity between E1 and E2 ?

After a time interval t measured on his clock, S will conclude
that the distance separating E1 from E2 is (0.6 + 0.8) ct = 1.4 ct,
hence that E2 is moving away from E1 at V = 1.4 c, or that E1 is
moving away from E2 at V = 1.4 c, meaning that the relative velocity
between E1 and E2 exceeds c.

Yes, and there is nothing wrong with that.


Ein Zwei Ein Stein HOCUS POCUS
E1 = S',
V = (.8 c-(-0.6c))/(1+0.8*0.6) = 1.40/1.48 c = ~.9459 c
E2 moves at 1.4/1.48 c relative to S'
E2 moves at 1.4/1.48 c relative to E1
ABRACADABRA
420000 = ~283784

By assimilating E1 to a frame S' moving away at -0.6 c from a frame S,
Srists claim that the electron E2, which had a velocity V = 1.4 c
wrt E1 measured in S, has only a velocity V' = ~0.9459 c measured in
S'.

Yes.


But the electrons don't bother about which name they are given, nor
does their relative velocity V depend on their velocity wrt the device
by which they have been emitted. Such device -the frame S according
to SRists- should be ignored after their emission, it belongs to
history.

Not at all. You seem to think that relative velocity between two
objects should be a frame-independent quantity. It's not. I don't know
why you think it should be.


I am skeptical about the physical validity of a formula (the
relativistic addition of velocities), which gives an infinity of
solutions for a same velocity V between to objects, for instance
1.4 c, measured in one frame (S in my example).

Because you have divine knowledge that separation rate
is independent of reference frame?

Well, the rest of us without divine knowledge are stuck
with describing what we see in experiment, which
is that the Lorentz transform is valid.

You cannot devise an experiment to validate the velocity addition
formula since that would require measuring the OWSL. The velocity
addition formula is a deduction from the postulate of c invariance in
inertial FoR. So talk about valid deduction, it is ok, b ut do not
bullshut people that this is experimentally verified.

That's simply not true. Relativistic kinematics is confirmed all the
time in particle experiments, where those high speeds and also
observations from two different reference frames are common.

Yes, nobody disputes relativistic kinematics. The problem is that SR is
a particular variation of relativistic kinematics that assumes c
invariance in all inertial FoR.

Since c invariance in all inertial FoR cannot be proven, neither
logically (no universally quantified propositions can be proven) nor
experimentally (since it requires measuring OWSL in a SR way) you then
sound too stupid to me spewing the same crap about particle experiments
verifying velocity addition in SR.

Well, what I sound like to you is not of particular importance to me.

Obviously, because you continue bullshuting me.

There are three facts that remain
- The correct formula for combining velocities (independent of what
assumptions are made to *derive* that formula) has been completely
verified in particle experiments. Call it an empirically confirmed
formula, if you like, and forget about deriving it from any
assumptions. It's nevertheless a confirmed relation.

Since there is no way to establish an observer that would measure
anything from any fast moving particle in an accelerator, the only
measurement possible is from a frame at rest wrt to the accelerator.
There is no way to measure the relative speed betweeen two particles
directly, but only infer it.

Because the above is true and makes sense, everything else you have
said sounds again too stupid to me.

I will re-phrase the questions has anyone ever measured directly the
relative speed between to moving particles at speeds close to c so that
the velocity addition formula can be validated?

The answer is NO. All measurements can take place from the frame at
rest in the frame of the laboratory and relative speed only calculated
using the velocity addition formula.

Mike







- TWLS invariance has certainly been measured, and TWLS and OWLS
isotropy has certainly been measured. This is mathematically equivalent
to a direct OWLS invariance measurement and so the latter measurement
is not required except to make people like you feel better about the
whole thing.
- The invariance of c in *different reference frames* has certainly
been measured, using direct time-of-flight measurement of single
photons in a number of measurements. A pion decay experiment is the
most cited one, but it is also routinely measured at the Advanced Light
Source and Advanced Photon Source facilities.

PD


Mike






PD


Mike



There's nothing I can do about the fact that your
divine knowledge contradicts experiment, that there
is some unknowable "reality" different from my
observable universe and accessible only to you.

So I'll stick with the equations that describe life
in my universe.

Let's consider a planet inhabited by advanced ET's, situated at
x billions light-years from the Earth. Their physicists, from the
redshift of the Earth galaxy A and the Hubble constant, calculate that
the Earth is moving away from them at -0.7 c. Opposite the Earth,
they observe another galaxy B, whose velocity relative to them is
+0.7c.
They conclude, in accordance with the cosmic expansion, that such
galaxy has a velocity 1.4 c relative to the Earth.

No, they conclude that those two points are separating
IN THEIR REFERENCE FRAME at 1.4 c.

As they have mastered FTL communication, they transmit those data to
the Earth SRists, who calculate that B is in fact moving away from
them at 0.7c + 0.7c / 1 + 0.7*0.7 =~ 0.94 c, forgetting that it is
impossible to observe a galaxy moving away at 1.4 c.

On Earth, galaxy B is OBSERVED to be moving
away at 0.94c. Earth scientists easily calculate that
the two points are separating at 1.4c from the point
of view of Planet X. They also can see galaxy C
receding at 0.7c (i.e., separating from Planet X
at 1.4c IN THE EARTH FRAME). They can easily
calculate that IN PLANET X FRAME, the observers on
Planet X would see Galaxy C receding at 0.94 c.
Planet X sends a message confirming that the
redshift of Galaxy C is consistent with a relative
velocity of 0.94c.

- Randy

.

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