Thirteen tools. Which one asks your question?

PhysWallThe Physical-Logic Gateway

home the extension the tools about which tool do I need? support

basics a number somebody handed you Three checks, no jargon — and it says when it cannot help. bounds an S11 sweep, or a target How far from the physical limit you are, and what no topology can fix. gauge a stage reading Discharge from four published rating curves, 3.4 ft apart at the flood mark. waves period and depth Which shortcut applies — and the band where both are wrong. basketball a shooting percentage Whether the streak is real, or the sample size. climbing a speed-climbing time Power per kilogram against gravity alone. light time a round-trip delay Distance from the signal alone — and one way is not two. engine any measurement Does it make physical sense, and which law says otherwise. finance a share price The growth the market already assumes. Not a forecast, not advice. adjudication several possible causes Which the evidence eliminates — and it will not pick a winner. sampling switch counters and a sampled flow Whether the two can agree at all. carnot a plant efficiency The most it could reach — from the effective temperature, not the peak. energy feeder losses Held back, and the reason is written down.

Twelve tools, and each one asks the same question in a different subject: what does this measurement support, and where does it stop?

START HERE IF YOU ARE NOT SURE

basics — somebody gave you a number and something does not sit right. Three checks, no jargon, and it says when it cannot help.

FOR A NUMBER SOMEBODY HANDED YOU

finance — a price is a measurement. Inverting it gives the growth the market already assumes. Not a forecast and not advice.

error-propagation — for accredited laboratories. An uncertainty budget, and three questions from one table. Free.

adjudication — whether evidence supports a conclusion, graded by the kind of reason rather than by a number.

FOR A PATTERN THAT MIGHT BE CHANCE

basketball — does a streak mean anything, or is it what chance looks like? Free.

FOR AN INSTRUMENT YOU ARE NOT SURE ABOUT

gauge — a stream gauge read two ways. Did the instrument drift, or did the world change? Free.

waves — where the shallow-water approximation stops being true. Free.

lighttime — a spacecraft's distance from the time light takes to reach it and return.

climbing — speed and power against gravity, from a height and a time.

AND THE FRAME ITSELF

bounds — the seven physical domains and the status of each. Two are marked waiting on a laboratory, in the open.

engine — how the inversion works, and why it refuses.

router — describe what you have and it points at one of these.

⚠ AND ONE THAT IS HELD

sampling — every switch counts bytes exactly and the security layer sees a sample. The engine runs and no measurement has been taken, so there is no form on it — only the calculation worked through on numbers we invented, and said to be ours.

energy is held for a different reason: there is no agreed constant to invert.

Puzzles, and the answers

Four questions with a real source behind each, and the arithmetic is never the hard part. Somebody solved the first one and found the figure was smaller than the uncertainty on it — which is the answer, and not a number.

The four puzzles — a temperature scale that disagrees with itself, a star whose temperature will not settle, a kick that misses where nobody expects, and one that has an answer.
What the clean answer leaves out — carbon dating, and the spacecraft where every number was correct and it burned up anyway.

Why it refuses, and when

The refusal is the product, and it has a name. These pages say which one fired and why.

The refusal, and its name — exists, unique, stable: a problem failing any of the three is ill-posed, and every refusal here is one of those three.
Ruling out, rather than choosing — what a window does that a best fit does not.

The ideas behind the tools

Each of these is one idea, written out. None needs the tool beside it, and none of them is long.

Streaks, and the bias nobody saw for thirty years — Miller and Sanjurjo, 2018.
Sampling, and what folds back — Nyquist, and the frequency that was never there.
Doubling time — and why the rule of seventy is a rule and not a law.
The reciprocal — what happens to an error when you invert it.
Error propagation — one percent in, and anywhere from a quarter of a percent to two out.
The one we are holding back — a tool that exists, does not ship, and the reason is written down.

PhysWall was developed and architected by Gadi Zion.

Built on PhysWall — the same engine reads antenna bandwidth, conductor loss, bit erasure and heat limits. It answers what the measurement implies, and refuses when the measurement cannot say.

Click to see the seven → And one with no physics at all

⚠ Check this instead of believing it. Every number here reproduces from a source that is named, and the claims that turned out wrong are still printed next to what replaced them. The same engine runs all of these — it asks how much a measurement allows you to conclude, and refuses the same way in every field. The same engine runs all of these — it asks how much a measurement allows you to conclude, and refuses the same way in every field. How to check each one →