Re: Time Dilation reduces the Speed of moving Objects

On Sep 16, 9:36 pm, Peter Riedt <rie...@xxxxxxxxxxx> wrote:
On Sep 17, 4:40 am, Darwin123 <drosen0...@xxxxxxxxx> wrote:



On Sep 15, 10:37 pm, Peter Riedt <rie...@xxxxxxxxxxx> wrote:> Time Dilation reduces the Speed of moving Objects

When Lorentz invented time dilation as part of his contraction
hypothesis he did so to allow the speed of light to remain constant.
He realized that if  the length  of a moving object contracted, its
time  had to slow down or the speed of light would not be constant.

     That wasn't why he made up the Lorentz transform. The approach
that you describe belongs to Einstein.> Lorentz however considered only the effect of time dilation on the
speed of light, not the object.

     You have it the wrong way around. He DID consider the motion of
an electrically charged object. He considered the interaction between
the electrically charged object and its own electric and magnetic
fields. He discovered that the interaction inhibits the acceleration
of the charged object in a way that suspiciously resembled inertial
mass. The effective increase in mass caused by this inhibition was the
Lorentz factor for mass.
     Since the effective mass of the particles increases due to the
motion of the particle, the acceleration of the particle decreases. An
entire system made of such particles will also slow down. This,
Lorentz proved also. If you make a clock out of electrically charged
particles, the clock has to slow down with velocity.
    Furthermore, the pressure on an electrically charged sphere will
tend to flatten the sphere in a way consistent with the Lorentz length
contraction formula. An entire system of charged particles will also
do so. If you make a ruler out of electrically charged particles, the
ruler has to contract with velocity.
     Lorentz proved it using standard laws for electromagnetic theory
and Newtons mechanics. However, his proofs were very specific to
charged particles. One can use his formulas to explain the Michaelson
Morley experiment, but only under the condition that each and every
particle in the apparatus was electrically charged. Then one has to
ask oneself what held the apparatus together. Systems with only
electromagnetic forces are intrinsically unstable.
    Einstein made that conceptual leap of treating the speed of light
as an invariant. This generalized the Lorentz transformation to
everything, including uncharged particles. So this explained
experiments like the Michaelson Morley experiment among others.
      In any case, I agree that Lorentz was a big time genius who
deserves more space in the history books. However, you are blaming
Lorentz for making the mistake of Einstein's greatest discovery.
That's two consequetive errors. Neither Lorentz nor Einstein were
wrong, and it was Einstein who looked at the speed of light. Looking
at the speed of light is equivalent to considering particles that
aren't electrically charged.

This oversight renders time dilation
invalid.

     No way. Even if Einstein was wrong in his generalization, Lorentz
would still be right if only for electrically charged particles. Time
dilation would exist for clocks that were made of electrically charged
particles, where no other force was involved. This would make it a
marvelous approximation for certain applications. The Lorentz model
would probably describe time dilation in atomic clocks. The Lorentz
model wouldn't explain time dilation in mesons, because mesons decay
by nonelectrical means.
   So if muons didn't display time delay, but atomic clocks did, the I
would say that Lorentz was right not Einstein. However, muons and
atomic clocks both display time dilation. So I guess Einstein was
right. However, so was Lorentz. The atomic clock displays time
dilation.
     Einstein turned the Lorentz model into a theory.> While it is legitimate to apply double standards in politics,
in physics it is not.

     In politics, I want leaders who consistently follow one moral
standard. They have to make compromises, because the world is a
complex dynamic place. How many oil wells to dig versus windmills is
not a big legitimacy issue. However, there are moral invariants. So it
is not legitimate to wipe out hundreds of men, women and children just
because the adults won't vote for you in an election.
     The speed of light is an invariant. So I want clocks that take
into account that difference. However, the physical invariant is the
speed of light.

Lorentz should not have messed with the relationships v=d/t.

       He didn't. Lorentz played with d and t separately, but didn't
put them together.
    It was Einstein who came up with the addition of velocity formula
in SR. I am glad Einstein messed with it. Otherwise, much of the stuff
we developed wouldn't have been developed.

Darwin,
a very nice answer. A small point however: why do we apply time
dilation selectively to the speed of light, the twin paradox, clocks
and everything else but not to the speed of the moving object(except
muons)?

Peter Riedt

I am not sure of what you are asking, since the speed of the moving
object is in the formula for time dilation. Further, we do use time
dilation to describe the lifetime of moving muons. However, I'll
answer under the hypothesis that you are asking about the resolution
of the "twin paradox" with respect to the muons.
Some people are concerned that the description of relativity
involves two way measurements only. In the twin "paradox", for
instance, the twin has to come back before their ages are compared. If
extrapolated to muons, one would say that the muon has to go out and
come back before we compare its age to a stationary muon.
I forgot in which essay Einstein said this explicitly. However, I
did read it. Einstein said that in all physics experiments performed
to the date of his article, one always notes coincidences. That is,
what one measures is always two events occurring at the same place and
the same time. He used the example of "checking the time." He said
when you look at a clock to check the time, one is noting the
coincidence between the hand of a clock being at the same place as the
number on the clock face. So one is assuming that the hands of the
clock will be at the same place at a particular time. There are no
experiments where the critical measurement is of measuring two events
at different places at the same time. In all experiments, there is
some component of the experiment where one records the coincidence of
two events occurring at the same place at the same time.
Einstein wrote this before there were digital displays on clocks.
However, you get the idea. Even in a digital clock, somewhere in the
electronics is a mechanism for recording some type of coincidence
between two disparate events. Even when you measure the length of
something, you are measuring the distance between two coincidences.
One end is next to the ruler at a certain time.
The other end is at a different spot on the ruler at the same
time. So a measurement can only be made between two coincidences. All
measurements are therefore relative, in the sense that only these
coincidences matter.
I happen to like Lorentz's analysis of things better than
Einstein's, even if Lorentz is specific to charged particles. He
actually shows how the electromagnetic forces slow things down. So I
advise that you study electromagnetic theory, and then read some of
Lorentz's essays if you want to get a good grip on relativity.
However, what has become popular is Einstein's type of analysis. This
is because his analysis is more general, because it is simpler
mathematically, and because in its own weird way it is extremely
beautiful. However, I want to look at a "resolution" of Einstein
analysis. Since Lorentz praised the Einstein approach, I am defending
both these honorable gentlemen.
The complaint often made in the Einstein analysis, which isn't
so obvious in the Lorentz analysis, is that the traveling twin could
start out far away. He doesn't have to start out at the same location
as his earth twin and come back. If that were true, they couldn't be
twins to begin with. Twins by definition are born from the same mother
at nearly the same time. Just by using the word "twin," you have
implied at least one coincidence. The twins were born in the same
place and the same time. If one twin travels outward, he has to
accelerate backward at a distant place in order to come back. He has
to use a force (i.e., rockets) to come back. The only relevant
measurement is the biological or physical age of the twin when he is
back with his brother.
The cosmic ray muon at first glance looks like a twin experiment.
It differs in a subtle way. The stationary muon and the traveling muon
were never twins. However, the two muons are identical in all physical
respects except their velocity relative to the earth. So the real
issue is where are the coincidences that have to be measured to
determine lifetime. The lifetime of stationary muons have been
measured. I am no expert, so I may have some of the details wrong.
However, the key is four different coincidences.
In the case of a muonic atom, for instance, the muon is held fast
by a nucleus in an atom that is stationary in the laboratory. The
position of the muon doesn't change. One measures two coincidences.
One, the coincidence is between the flash of light generated when the
muon is formed (flash of light recorded at the same time, same place)
and the generation of an electron when the muon decays (electron
detected same time, same place in the laboratory). The time between
them is the "lifetime" of the muon. Two coincidences determine the
"stationary lifetime."
In the case of the traveling muon, which was generated by a
cosmic ray, high in the atmosphere, the muon is changing its position
rapidly with respect to the laboratory that did the "stationary"
measurement. It never "returns," there is no force associated with
"turning around." Their is a flash of light associated with the
formation of the muon which is recorded at a certain height. However,
there is a "ruler" associated with recording the height. One can not
have determined the height at which this flash of light occurs without
having calibrated the height some how. This was done in one of those
go out and come back experiments. So when the muon is formed, there is
coincidence between the light flash and that particular height. The
muon decays in a cloud chamber on the ground, near the laboratory. So
there is a coincidence between the ground being there and the muon
being there.
In the Einstein analysis, when you decided what the
coincidences were you were defining two inertial frames. By deciding
what the frames were, you have done an end run around the question of
what forces slowed one of the clocks down. Forces exist in relativity,
they are very important. However, the details of the force do not have
to be analyzed. With a Lorentz-style analysis, one would have to make
specific guesses as to how the nonelectromagnetic forces are behaving.
These guesses may be a little wrong, but you may get the same answer
anyway because of relativity.
Relativity as Einstein described it was what we now call a
symmetry property. It describes results which don't depend critically
on details of the force. Of course, the details of the force are
interesting. Even though the muon obeys the Lorentz transformation, we
would like to know why the stationary lifetime is exactly whatever was
measured. Why should a stationary lifetime be 2 microseconds versus 2
milliseconds versus 2 seconds, or whatever the lifetime is? Therefore,
we would like to know what forces caused the muon to fall apart, or
what type of quantum interaction. However, the details won't effect
the fact that the lifetime changes with relative velocity exactly as
predicted by the Lorentz time dilation.
The stationary lifetime as measured by coincidences is
different from the in relative motion lifetime. That is a good start.
.

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