241–250 of 301 posts
5 sigma results have disappeared (even 6-sigma) upon independent testing, so more testing is needed.
[0] https://www.nytimes.com/2021/04/07/science/particle-physics-...
Earlier quoted context omitted.
From a physicists standpoint, not seeing something unexpected is not a waste at all.
Can you expand on that? I was under the impression that many thought of it as a waste (Sabine Hossenfelder comes to mind, for example).
They keep building bigger machines to fill out the parts that don't have a definition yet.
Anything that specifies what happens at the next band of energy levels is a success, whether it yields new particles, or rules them out at that energy level.
There's some destination of approaching the most energy dense states like describing the mechanics that were active during the big bang period
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As I recall, FTL neutrinos were the result of experimental error, not chance; and so are outside the scope of what sigma screen for.
In scope for the context of this thread though; your GP claimed that 4 sigmas means “it’ll probably pan out as being real”, your parent provided a 6-sigma counter example.
No they didn't; they claimed that 4 sigmas means it will probably turn out to be something other than statistical noise. They made no claims about "it's real" versus "it's a systematic, non-statistical error".
Earlier quoted context omitted.
> Again, this assumes both that there were no errors made in the experiment This is worth repeating a lot when explaining sigma (even in a great and comprehensive explanation such as yours): Statistical anomalies are only relevant when the experiment itself is sound. Imagine you are trying to see whether two brands of cake mix have different density (maybe you want to get a good initial idea whether they could be the…
Nitpick: it assumes that there were no systematic errors. If (say) you switch randomly between steel and glass bowls, you results will still be valid, just with much wider (worse) standard deviation than you could have gotten otherwise (or much greater numbers of measurements needed for a given accuracy, due to Shannon/noise floor issues).
Earlier quoted context omitted.
Just to expand a bit, the sigma symbol is a standard symbol used to indicate the standard deviation of a measurement, and standard deviation is roughly a measure of how much variation there is within a data set (and consequently how confident you can be in your measurement). So when they say that the theoretical result is now 4.2 sigma (units of standard deviation) away from the experimental result instead of 2.7 sig…
> a measurement 1 sigma from the prediction would mean that there is roughly a 84% chance that the measurement represented a deviation from the prediction and a 16% chance that it was just a statistical anomaly. No, this is a p-value misinterpretation. Sigma has to do with the probability that, if the null hypothesis were true, the observed data would be generated. It does not reflect the probability that any hypothe…
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If the theoretical prediction can't be calculated until the experiment is done that motivates the choices of what and what not to approximate, is it really a prediction?
That’s a good (and profound) question, not deserving of downvotes. It turns out that the simplified paradigmatic “scientific method” is a very bad caricature of what actually happens on the cutting edge when we’re pushing the boundaries of what we understand (not just theory, but also experimental design). Even on the theoretical front, the principles might be well-understood, but making predictions requires accurate…
Earlier quoted context omitted.
Just to expand a bit, the sigma symbol is a standard symbol used to indicate the standard deviation of a measurement, and standard deviation is roughly a measure of how much variation there is within a data set (and consequently how confident you can be in your measurement). So when they say that the theoretical result is now 4.2 sigma (units of standard deviation) away from the experimental result instead of 2.7 sig…
> a measurement 1 sigma from the prediction would mean that there is roughly a 84% chance that the measurement represented a deviation from the prediction and a 16% chance that it was just a statistical anomaly. No, this is a p-value misinterpretation. Sigma has to do with the probability that, if the null hypothesis were true, the observed data would be generated. It does not reflect the probability that any hypothe…
The null hypothesis is that there are no new particles or physics and the Standard Model predicts the magnetic charge of a muon. A 4.2 sigma result means that given this null hypothesis prediction, the chances that we would have observed the given data is ~0.0013% (chance this was a statistical anomaly). Since this is a vanishingly small chance (assuming no experimental errors), we can reasonably reject the hypothesis that the Standard Model wholly predicts the charge of a muon.
>the strong force and the weak force. Is there a reason we're leaving "nuclear" off these forces' names now?
I have indeed often seen the names referred to without the term "nuclear".
There was a nice explanation of the finding in comic format from APS & PhD Comics: https://physics.aps.org/articles/v14/47
The creation of new particles, is that bremsstrahlung?? I’m trying to find more info on it.
eg: (a+b)^2 = a^2 + b^2 + 2ab
That 2ab is an interference term so a different process can get mixed in (quantum mechanically speaking). And we may not experimentally be able to disentangle it.
As a particle physicist (no longer working in the field, sadly), this is one of the more exciting results in a long time. Muon g-2 has been there, in some form of another for debate and model building, for many years (taken somewhat seriously for 15+?), waiting for better statistics and confirmation. At over 4 sigma this is much more compelling than it has ever been, and the best potential sign of new (non-Standard M…
tl;dr - electrons and muons are leptons, but what if they don't interact with photons the same way? (ie the rules of physics aren't universal to all leptons)