# Re: aiming to complete Everett's derivation of the Born Rule

`On Mon, Apr 25, 2022 at 7:31 PM John Clark <johnkcl...@gmail.com> wrote:`
```
> On Sun, Apr 24, 2022 at 9:09 PM Bruce Kellett <bhkellet...@gmail.com>
> wrote:
>
> * > The trouble with Sean's glib response to the question is that in each
>> branch of the multiverse, we can measure the energy both before and after
>> the supposed split.*
>>
>
> Neither before or after the split are you measuring the absolute total
> energy in anything, in any energy measurement you're measuring the relative
> energy of something against a standard measure. If you say a particle has X
> units of energy calibrated against some standard measure, then after a
> measurement (and thus after a split) if you want to measure the energy in
> the decay products of the particle you do it by comparing them against the
> same standard measure, but *that's impossible* because any act of
> measurement splits a universe. So both the energy in the decay products and
> the energy of the standard measure of energy are decreased by 1/2 (or by
> however many times the universe splits), so you still get  X units of
> Energy and the world still looks the same to you despite it having only
> half the total absolute energy. It all comes down to the fact that you
> never measure the absolute energy of something, you always measure the
> relative energy.
>

You appear to be assuming that one measures energy against some reference
energy. So that if both your reference and the thing you are
measuring change by the same factor, you do not see any difference. That is
true enough, but we do not always measure energy by comparison with some
reference energy. Sometimes we use other laws of physics. For example, most
of the energy in our immediate environment is mass energy, coming from the
relation E = mc^2. So we can consider mass as a surrogate for energy. Mass
can routinely be measured by weighing, assuming that the gravitational
constant does not change. So if all energies halve, say due to a spin
measurement, and we weigh our object before and after the split, in order
to get the same result on the scales, the force due to gravity has to
double in order for half the mass to give the same reading as before. But
the force due to gravity depends on the local acceleration, g, and that
depends on the mass of the earth, which also halves in this scenario. So,
rather than the force of gravity doubling, it also halves, and the reading
on our scales after the split is only 1/4 what it was before. If you think
that such a change in the mass energy around us would not be noticeable,
then you are not looking closely enough.

> *If I want to check energy conservation in neutron decay, I compare the
>> mass-energy of the original neutron to the sum of the mass-energies of the
>> decay products plus any kinetic energy of these decay products.*
>
>
> You left out a few steps. You compare the mass-energy of the original
> neutron against a standard calibration measure, and then you measure the
> mass-energies of the decay products plus any kinetic energy of these decay
> products against a standard measure.
>

But that standard measure may not simply be another energy or mass. It
could be the force on a charge in an electric field, or the measure on a
spring balance in the gravitational field. If the local change in energy is
to go unnoticed, then all the laws of physics must change in concert. It
does not seem that the Schrodinger equation itself is able to accomplish
this.

Bruce

>

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