# Tag Info

### Why should a clock be "accurate"?

why it is necessary for a reference clock to worry about this, if the definition of the second itself is a function of the number of ticks the clock makes. The concern is that somebody else (say a ...

### Why should a clock be "accurate"?

For most of human history, we had a single mechanical clock: the spinning Earth. Well, actually two mechanical clocks. The Earth’s spin rate is a good constant, but it’s tricky to measure directly. ...

### How long is a second?

A second is a second long by definition, but if you measure any time in seconds, the number of seconds you infer will be subject to an error of at least $\mathcal O(10^{-15})$ because of the ...
Accepted

### The Electron at the End of the Universe

The calculations are done in Schwartz (2019), Lecture 3: Equilibrium (https://scholar.harvard.edu/files/schwartz/files/3-equilibrium.pdf) Here's a summary of the key equations, using the notation ...

### If a measurement has 5% error, can we say it has 95% accuracy?

Prefer “uncertainty” over “error.” When you say “error” you imply that Someone Out There has determined the Right Answer. This isn’t how it works outside of an introductory lab class. When you say “...

### Why should a clock be "accurate"?

if the definition of the second itself is a function of the number of ticks the clock makes. Why don't we just use a single simple mechanical clock somewhere with a wound up spring that makes it tick,...

### Why should a clock be "accurate"?

Having a central clock system has a lot of drawbacks: broadcasting means the signal takes time, so if I need a clock, it will always be somewhat behind. This cannot be fixed to the precision ...

### What if the resulted error is so large?

This is a case in which the standard statistical tool of Gaussian error propagation fails. When you write a measured quantity as "$\text{quantity} = \text{value} \pm \text{error}$" this is ...
Accepted

### Rules of significant figures, precision, and uncertainty

There is actually no guarantee at all. Although in school students are taught about “significant figures”, they are not used by professional scientists. They are like “training wheels” for ...
$F = \frac{1}{A-B}$ with $A=1.08\pm0.02$ and $B = 1.05\pm0.03$. ...which looks ridiculous. So, is this error analysis problematic? It's not ridiculous. It might be problematic depending on how well ...