112
votes
Accepted
How do you make more precise instruments while only using less precise instruments?
I work with an old toolmaker who also worked as a metrologist who goes on about this all day.
It seems to boil down to exploiting symmetries since the only way you can really check something is ...
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104
votes
Accepted
How do we know the LHC results are robust?
That's a really great question. The 'replication crisis' is that many effects in social sciences (and, although to a lesser extent, other scientific fields) couldn't be reproduced. There are many ...
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65
votes
How exactly do you avoid fooling yourself?
There are lots of different strategies that are employed by the scientific community to counteract the kind of behavior Feynman talks about, including:
Blind analyses: In many experiments, it is ...
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61
votes
How do you make more precise instruments while only using less precise instruments?
The more you measure things and add or multiply those measurements, the greater your errors will become.
Not necessarily. If the errors in a series of measurements are independent and there is no ...
- 40.8k
45
votes
How seriously can we take the success of the Standard Model when it has so many input parameters?
It is inaccurate to think that all of the standard model of particle physics was determined through experiment. This is far from true. Most of the time, the theoretical predictions of particle physics ...
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42
votes
How exactly do you avoid fooling yourself?
My favorite story (which I learned about recently) is about Frank Dunnington and his measurements of electron properties in about 1930.
He was measuring the ratio $e/m_e$. Experiments took quite a ...
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32
votes
How seriously can we take the success of the Standard Model when it has so many input parameters?
The Standard Model may have many parameters, but it also talks about many things, each typically only involving a very limited number of parameters. For example, the muon lifetime$^\dagger$ $$\tau_\mu=...
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31
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How do you make more precise instruments while only using less precise instruments?
One thing I haven't seen mentioned is amplification.
Amplification: Imagine you have a lever that is 10 cm on one side of the pivot and 1 m on the other. Then any change in position on the short side ...
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27
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How do you make more precise instruments while only using less precise instruments?
That's a really nice one! I'm not an expert on experiments and measurements but this is how I see it:
The ultimate calibration tool is always nature. We pick special phenomena which rely on certain ...
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25
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Why don't we use absolute error while calculating the product of two uncertain quantities?
It basically comes from calculus (or more generally just the mathematics of change).
If you have a quantity that is a product $z=x\cdot y$, then the change in this value based on the change of $x$ and ...
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24
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Least squares fit versus averaging
That's a good question. The answer depends on how the data is collected. We will posit two simple models and furnish the best unbiased estimator for each model via the Gauss Markov theorem.
We will ...
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23
votes
Accepted
What does it mean to "bin" in a spectroscopy context
Suppose you are analysing the weights of people in the UK to see what the distribution of weights looks like. Suppose also you can measure the weight to arbitrary precision, so that no two people's ...
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22
votes
Is there any advantage in stacking multiple images vs a single long exposure?
Stacking is something that is done all the time in infrared astronomy. This is done because CCD technology doesn't work for wavelengths in the range of roughly 2 to 10 microns, and beyond, so they use ...
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22
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Accepted
How do scientists determine when to disregard a model that has a higher correlation to data than another model?
For any set of data points, you can comprise a 100% interpolated and fitted curve using a sum of sloped lines all multiplied by their respective Heaviside step functions to form a zig-zag shaped curve....
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21
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How do you make more precise instruments while only using less precise instruments?
Measurement errors can accumulate, yes.
But we are not talking about measurements here, we are talking about processes and tooling. That's another deal.
If you fling off a piece of flint from a ...
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21
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Least squares fit versus averaging
Here is the quantitative (simulation) approach @Dr. Momo was mentioning: we can simulate some points for $x_i$ and $F_i$, give them some Gaussian errors, estimate $k$ with the two approaches and see ...
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20
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Easy to perform quantitative experiments at home
The simple pendulum experiment is very simple to perform, from which a lot of conclusions can be drawn. An object like a ball, like an apple can be used as a weight at the bottom, and a string can be ...
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17
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Accepted
When to average in the lab for indirect measurements?
Averaging destroys information. Do it as late as is practical in your analysis.
A commenter points out that, if you are making many position/velocity measurements of the same object as it moves once, ...
rob♦
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17
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Accepted
Least squares fit versus averaging
As in all things statistical, it completely depends on your assumptions.
Why averages are useful:
If you have a variable x which you can sample, and it comes from a normal distribution with some mean $...
- 4,850
16
votes
Is there any advantage in stacking multiple images vs a single long exposure?
The voice of bitter experience, here, to tell you about a problem that a properly working observatory shouldn't have to worry about. But I did the time I was working on a "serious" astronomy project.
...
16
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How exactly do you avoid fooling yourself?
What Feynman is talking about is not particular to physicists, its particular to human nature and it is called "confirmation bias"
Confirmation bias is the tendency to search for, interpret, favor, ...
- 229k
16
votes
How do you make more precise instruments while only using less precise instruments?
The way I understand it, errors only accumulate.
That is not always the case. Human ingenuity found and systematically selected processes which improved a particular quality.
Two examples:
You can ...
- 878
16
votes
How seriously can we take the success of the Standard Model when it has so many input parameters?
The LHC has produced 2,852 publication as of today: September 24, 2021. Let's say each publication has 5 plots. Each plot has 50 points. We'll round that up to 1,000,000 data points, along with a ...
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15
votes
Accepted
Is there any advantage in stacking multiple images vs a single long exposure?
If your exposures are short enough (a fraction of a second), you can even combat turbulence in the atmosphere. The trick is to do very many short images then pick the ones where a (bright) point ...
- 120k
15
votes
How do you make more precise instruments while only using less precise instruments?
I expect that worm drives are part of the story.
For every rotation of the driven axis the driving axis goes through multiple rotations. I expect that it is mechanically possible to capitalize on that ...
- 18.1k
14
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How do we know the LHC results are robust?
In addition to innisfree's excellent list, there's another fundamental difference between modern physics experiments and human-based experiments: While the latter tend to be exploratory, physics ...
14
votes
How exactly do you avoid fooling yourself?
The Particle Data Group (PDG) which every other year summarizes the knowledge of Particle Physics prefixes their tome with the figure I include below (from the 2016 edition). It shows how our ...
- 1,074
13
votes
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 ...
- 81.5k
12
votes
Easy to perform quantitative experiments at home
I) Acceleration due to gravity on objects of different weight
Aim:
To find a relation between the weight of the object and the time taken for the object to reach the ground from a common height. You ...
- 7,033
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