PYTHON · NUMPY

Which plane can see it

Show that a hidden load is visible or invisible depending on which rail the meter sits on, with both readings correct.

01Challenge

A 12 W computation you did not authorise is running on a robot. Two engineers meter the machine, disagree completely about whether anything is wrong, and neither has made a mistake. Work out how.

Predict firstSame robot, same 12 W hidden load, two honest meters on different rails. How far apart are the detection margins?

02Model

PAI-280 established that a robot energy figure is a coordinate: plane times model, not a fact. The consequence for evidence is direct. If the number depends on where you put the meter, then so does what you can prove with it. Put the meter on the whole system and a 12 watt compute load is a large fraction of a 74 watt budget, and it shows. Put the meter on the motor rail and it is not that the load is small — it is that the rail never carried it. Both readings are honest. They are answering different questions, and only one of them is the question you asked.

03Guided practice

Compute the margin on each plane. Then open the instrument, select AMR · autonomous, and toggle between Whole system and Subsystem rail with the hidden-computation slider at 12 W.

04Feedback

PASS WHEN You produced two correct answers that disagree, and named why.

If your run fails, check:

On the whole-system plane 12 W clears the 8.7 W floor. On the motor rail the margin is exactly zero — not small, zero.
Nothing was broken or miscalibrated. The rail is not wired to the load.
An energy claim is only as strong as the statement of which plane produced it. A figure without its plane is unfalsifiable.

05Retrieve & space

Why is the motor-rail margin zero rather than merely small?
What must accompany any energy-based claim for a reviewer to check it?
Give a case where the whole-system plane is the wrong instrument.

06Mastery & project

Given a claim of the form 'we detected X from power', identify the measurement plane it requires, and say what the claim would be worth on a different plane.

Take a published power-monitoring result and identify its measurement plane. If the paper does not state one, write down what that omission prevents you from concluding.

GO FURTHER · THE LIVE PLAYGROUND

Open the instrument ↗ · Toggle the plane with the hidden load held fixed.
PAI-280 · Where you put the meter ↗ · The four-plane result this lesson is built on.

← The body decides what the joules reveal The joule you cannot forge →

PYTHON · NUMPY

Which plane can see it

Two planes, one hidden load. Compute the detection margin on each and explain the disagreement.

You read

the arrays and values already in scope

You change

the code you write in each cell

Fixed

the dataset and the checks that grade you