time-energy uncertainty

[George Herold]

On Apr 7, 3:04 pm, RichD <r_delaney2...@yahoo.com> wrote:

On Apr 5, 1:43 pm, PD <thedraperfam...@gmail.com> wrote:> >the time-energy uncertainty principle,
which seems more obscure
than posiition-momentum.  The books refer
almost entirely to the electron orbital energy

 >>levels in the atom.  That is, the emitted wavelength





dispersion, as the electron drops to a lower
energy, is inversely related to the time emitted,
in a probabilistic manner; the narrower the
spectrum, the wider (more unpredictable) the
time dispersion

But does the formula hold for every energy
measurement?  For example, circuit voltage -
as on a capacitor - is a measure of energy.
Does this uncertainty principle apply there?
Does it place a limit on our time (frequency)
resolution in every circumstance?

It's not clear to me what it means, in these
classical situations.

It applies everywhere.
An interesting application is this:

You can reconstruct a decaying particle's rest
mass by measuring the momenta and identification
of all the daughter particles, and then combining
them in the usual fashion:
m^2 = (sum:E)^2 - (sum)^2.
What you will find, even in a detector with
exquisite momentum resolution, that the
reconstructed mass distribution has a natural
width. That natural width turns out to be related
to the half-life of the decaying particle, in exactly
the way you'd expect from the uncertainty principle.

Sure, but that's typical of all textbook discussions -
a matter of PREDICTION.  We cannot predict the
duration of an event, except statistically.  That's
time uncertainty.

I'm talking about measurement.  The
common misunderstanding is "you can
measure the energy of an event, but you
can't know exactly when it happened!"  Well,
why not?  Why can't I observe the energy,
and look at my watch?  None of the books address
this.

The energy of the event is the uncertainty in the energy of the
particle that is participating in the event. As an electron goes from
one atomic orbital to another what is the energy of the electron? You
don't know, because you don't know which state it's in.

Now an electron can't just go BANG from one orbital to another. If it
did that there would have to be all sorts of high frequency stuff in
the light that came from it. But when you look at the light you see
only one frequency.... well not quite one there a bit of spread... and
that's the time uncertainty.

I'm thinking of electric circuit A/D conversion,
in particular.  I want to arbitrarily crank up both
the # of bits (energy resolution), and the
sample rate (time resolution).  Does QM set a
limit?  I have not seen any such proof.

Another problem is the definition of time uncertainty.  Usually it's
fuzzy, heuristic, dumbed down for the introductory level.

But strictly, it's defined in terms of the energy
operator's statistics.  It is abstruse. The only
place I have seen a rigorous derivation is Albert
Messiah's book.  You could stare at it all day, and
not suss it.  Obviously it is crucial to this question.

For more plebian examples, a transmission signal
chopped to a finite length sample will have a
frequency (e.g. energy) spectrum whose
minimum width is determined by the uncertainty
principle.

But that's just a mathematical corollary
of time-frequency duality, not really physics.

Time-energy uncertainty depends on h /= 0,
in QM.  Consider: if h = 0, we get classical
mechanics, with no such uncertainty formula,
yet the Fourier uncertainty would still hold.
So that is not the answer, though it probably
bears on the answer.

--
Rich- Hide quoted text -

- Show quoted text -

At some point it's more fun to measure e and h, rather than discuss
why they have the value they do.

George H.

 

[BURT]

On Apr 8, 7:39 pm, "Y.Porat" <y.y.po...@gmail.com> wrote:

On Apr 7, 9:04 pm, RichD <r_delaney2...@yahoo.com> wrote:> On Apr 5, 1:43 pm, PD <thedraperfam...@gmail.com> wrote:> >the time-energy uncertainty principle,
which seems more obscure
than posiition-momentum.  The books refer
almost entirely to the electron orbital energy

 >>levels in the atom.  That is, the emitted wavelength

dispersion, as the electron drops to a lower
energy, is inversely related to the time emitted,

-----------------------------
but PD claimed
all along
that photon energy emission
E=h f ----

'IS NOT TIME DEPENDENT   !!

-)   -)

------------------------------------------> > >in a probabilistic manner;''''''

end of quote
---
probabilistic or not probabilistic does not matter to our issue
the bottom line is that EXPERIMENTALLY :--

---energy emission IS TIME DEPENDENT !!
and so   the formula
E=h f is time dependent !!!

but most people STILL  do not understand even until now
 HOW AND WHY !! IT STEMS OUT  directly  FROM THAT
 E=hf    formula !!!
WITH   NO NEED TO ANY ADDITIONAL
ASSISTANCE !!
AND MOST PEOPLE DO NOT UNDERSTAND THAT
THIS FORMULA
IS A PROVE THAT THE PHOTON ENERGY
**HAS MASS*!!!
AND THAT MASS IS THE ONLY KIND OF MASS THAT EXISTS !!
(not relativistic )!!
and that    insight is another copyright
insight    of mine !! (Y.P)
2
there **is** a bottom limit to photon energy
that can be clalled scientifically relevant
that bottom limit for photon emission is
defined by the
plank time
(5.38 Exp -44 seconds )
less than that** is unmeasurable**
even according to
dt dE ~h !!! (H H P)
because if
dt is zero
dE becomes INFINITY !!!!
another  prove that PD s  pompous  idiotic claim that
*there is no bottom limit to photon energy'''-
is refuted !!
but PD will   never admit being wrong !!

(especially while his mistake is shown by
a' no one'   called Y.Porat....)

ATB
Y.Porat
------------------

A neutron star is younger in its slow clock than the rest of the
universe is in its faster clock.

Mitch Raemsch

 

[BURT]

On Apr 8, 5:16 pm, George Herold <ggher...@gmail.com> wrote:

On Apr 7, 2:39 pm, RichD <r_delaney2...@yahoo.com> wrote:





On Mar 31, George Herold <ggher...@gmail.com> wrote:

the time-energy uncertainty principle,
which seems more obscure
than posiition-momentum.  The books refer
almost entirely to the electron orbital energy
levels in the atom.  That is, the emitted wavelength
dispersion, as the electron drops to a lower
energy, is inversely related to the time emitted,
in a probabilistic manner; the narrower the
spectrum, the wider the time dispersion

But does the formula hold for every energy
measurement?  For example, circuit voltage -
as on a capacitor - is a measure of energy.
Does this uncertainty principle apply there?
Does it place a limit on our time (frequency)
resolution in every circumstance?

I find the energy - time uncertainty relation
perhaps easier.  After all energy is proportional
to the frequency.

Only for a photon.

 And if I have a longer time to count the frequency
of something I can 'know' it
with a smaller uncertainty.
My favorite energy uncertainy in electronics
example is the quantum contact.  Imagine a contact
between to metals where the volume of the
contact is so small that only one elctron can fit in
it at a time.
Now if I apply a voltage (V) across the contact I
can get electrons to move from one side to the
other with a current (I).  What is the resistance? (V/I)  
Well the enegy uncertainty is eV, and the time
uncertainty is e/I (I = charge/time)

I don't follow this, can you elaborate?

According to QM, energy is an operator, which
generates a random variable.  Its standard
deviation is the uncertainty.  I don't see how
you get eV.

I'm assuming all the voltage drop is across the very small contact,
with no resistance in the metal that is next to the contact.  Then the
uncertainty in the energy of the electron as it crosses the contact is
the voltage drop V time the charge e.  Where V is the voltage drop
acorss the contact.  It's not too hard to see this 'in real life' by
the way.  Google quantum contacts and gold wire.



Time is not an operator, 'time uncertainty' is
not defined as a standard deviation.  It derives
from an esoteric formula, which I will not
reproduce.  Please define your notion of this quantity.

Well t is the time it takes to cross the contact.  I'm assuming all
the resistance is in the quantum contact.

Putting this together with the Heisenbreg
relation gives eV*e/I = h
or with R=V/I= h/e^2
which is the quantum unit of
resistance.  Pretty cool if you ask me!

That is pretty cool, if true.  I didn't know there's
such a thing as ' quantum unit of resistance'.

--
Rich- Hide quoted text -

- Show quoted text -

Oh yeah and if you get some thin gold wire and battery, make yourself
a voltage source and opamp current to voltage converter, and have a
digital scope then you can see it for yourself.

George H.- Hide quoted text -

- Show quoted text -

What about time uncertainty? What about those random events happening
in a window of time? How will we measure how long it took at the
subatomic level?

Mitch Raemsch

 

[artful]

On Apr 9, 12:39 pm, "Y.Porat" <y.y.po...@gmail.com> wrote:

On Apr 7, 9:04 pm, RichD <r_delaney2...@yahoo.com> wrote:> On Apr 5, 1:43 pm, PD <thedraperfam...@gmail.com> wrote:> >the time-energy uncertainty principle,
which seems more obscure
than posiition-momentum.  The books refer
almost entirely to the electron orbital energy

 >>levels in the atom.  That is, the emitted wavelength

dispersion, as the electron drops to a lower
energy, is inversely related to the time emitted,

-----------------------------
but PD claimed
all along
that photon energy emission
E=h f ----

Planck claimed that .. because experiment showed it to be the case.

All of modern physics claims it.

'IS NOT TIME DEPENDENT   !!

Of course it isn't .. there is no time term in the formula .. so
changing some time duration is not going to alter its value.

-)   -)

------------------------------------------> > >in a probabilistic manner;''''''

end of quote
---
probabilistic or not probabilistic does not matter to our issue
the bottom line is that EXPERIMENTALLY :--

---energy emission IS TIME DEPENDENT !!

No .. EXPERIMENTALLY is it NOT time dependent. The energy for
individual photons is the same regardless of any time durations.

and so   the formula
E=h f is time dependent !!!

No .. it is not,

but most people STILL  do not understand even until now
 HOW AND WHY !! IT STEMS OUT  directly  FROM THAT
 E=hf    formula !!!

It doesn't .. you simply do not understand formulas, or photons, or
anything much of physics at all. And you are totally hostile to the
idea of learning

WITH   NO NEED TO ANY ADDITIONAL
ASSISTANCE !!
AND MOST PEOPLE DO NOT UNDERSTAND THAT
THIS FORMULA
IS A PROVE THAT THE PHOTON ENERGY
**HAS MASS*!!!

No .. it does not

AND THAT MASS IS THE ONLY KIND OF MASS THAT EXISTS !!

It certainly doesn't say ANYTHING about whether or not there are other
'kinds' of mass

(not relativistic )!!
and that    insight is another copyright
insight    of mine !! (Y.P)

Its another lack of understanding of yours. Noone but you would
copyright their own stupidity

2
there **is** a bottom limit to photon energy

Why?

that can be clalled scientifically relevant
that bottom limit for photon emission is
defined by the
plank time
(5.38 Exp -44 seconds )

But photon energy is not time dependent. The energy of a photon
doesn't depend on some time interval.

less than that** is unmeasurable**

But the energy in a photon does not change with duration .. it is
fixed

even according to
dt dE ~h !!! (H H P)
because if
dt is zero
dE becomes INFINITY !!!!
another  prove that PD s  pompous  idiotic claim that
*there is no bottom limit to photon energy'''-

Why should there be?

is refuted !!

No .. you just don't understand. your ignorance is not a refutation
of anything.

but PD will   never admit being wrong !!

Why should he lie?

(especially while his mistake is shown by
a' no one'   called Y.Porat....)

No .. your OWN lack of understanding is all you show