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

`On Mon, Apr 25, 2022 at 6:42 PM Bruce Kellett <bhkellet...@gmail.com> wrote:`
```
>> The only reason we think the gravitational constant does not change is
>> because when we measure the potential gravitational energy in something
>> today against a standard calibration energy we find that we get the same
>> number of energy units that we got yesterday when we measured the potential
>> gravitational energy it was in against a standard calibration energy.
>>
>
> *> Sure, a spring balance needs to be calibrated against some standard
> mass. But we do not calibrate every day. Once the scale is set, we assume
> that the spring constant or whatever remains the same, so that
> recalibration is not necessary.*
>

You're right, it's not necessary because as long as the test mass and the
mass standard decrease by an equal percentage you're always gonna get the
same result and you'll never notice that anything has changed.

*> So if all energies (including mass) drop by 90%, we will be able to
> detect this as long as the spring constant does not also change by this
> amount. Springs tend to rely on the electromagnetic properties of metals,
> and these will not change just because we measure a spin component in the
> next room.*
>

If Many Worlds is correct then of course the spring constant will change
because the world will split due to ANY measurement, and the absolute
non-relative amount of energy of EVERY type will decrease.

* > I used a spring balance to compare a mass against the gravitational
> field, where I assumed that Newton's constant does not change on a spin
> measurement. If all energies (and masses) drop by 50% in each branch of the
> spin measurement, then the mass of the earth decreases by 50%, and the
> local acceleration due to gravity, g, also drops by 50%. Now consider a
> simple pendulum: the period of swing is T = 2*pi*sqr(L/g), where L is the
> length of the pendulum. If g drops by 50%*,[...]
>

But g does NOT drop by 50% and I never said it did, I said the
gravitational potential energy drops by 50%, and that will happen if the
mass/energy of a gravitationally bound system drops by 50% even if g
remains constant. If yesterday I measured the mass/energy of a pendulum and
of the entire earth against an energy standard and I measure those things
again today against today's energy standard, and if the mass/energy of the
pendulum and the earth and today's energy standard have all decreased by
50%, then I will get the same measured value that I got yesterday even if g
really is the same as it was yesterday.

And yes the force that the earth is pulling down on that pendulum would
only be half as strong as it was yesterday, HOWEVER  the inertia (which is
proportional to the mass/energy) of the pendulum would only be half as much
as it was yesterday, so the two changes with cancel out and the pendulum
would fall with the same acceleration that it did yesterday, and the period
of its swing would be the same too.

John K Clark    See what's on my new list at  Extropolis