Neutrino oscillation observed

[sjastro]

One of the early problems with the solar nuclear fusion model was that the observed neutrino flux reaching Earth was only one third the theoretical amount.

This was explained by neutrino oscillation where a neutrino could change "flavours" and oscillate between an electron, muon and tau neutrino.

While neutrino oscillation has been observed in solar neutrinos, it has never been observed in experiments..... until now.

http://news.discovery.com/space/fermilabs-minos-experiment-confirms-neutrino-quick-change-110704.html

Regards

Steven

[renormalised]

Very important discovery, now that neutrino oscillation has been experimentally confirmed (well, at least to 3 sigma).

[CraigS]

Correct me if I'm mistaken, but 3 sigma means that there is about a 1 in 1,000 chance that the result can be attributed to a statistical fluctuation in the data, right (??)

It seems that in particle physics, 3 sigma creates 'interest', but everywhere else (generally), 5 sigma, (~ 1 in 1 mill chance that the result is a fluke), is needed to claim a discovery.

Recently, (in June), Femilab reported a possible new particle had been discovered but when checked by a second detector, they found slightly less than the 5 sigma level, so the new particle announcement was deemed not valid.

So in these guys' words:


Hmm … maybe …
5 sigma seems to be what they need in order to make the ultimate claim of 'discovery' ..

Cheers

[sjastro]

Justification for 5 sigma level.



Regards

Steven

[renormalised]

The problem with being so stringent in the level of confidence is that nature itself doesn't work in that way. Scientists maybe missing discoveries simply because they don't meet the required levels of statistical analysis. Nature can be very quirky and never plays by the book. Things can crop up unexpectedly and then disappear off the charts. All the experiments in the world may not show another result.

However, in playing it safe with such stringent conditions of acceptability, it does negate to some extent the possibility of false positives and the like. But, how far do you have to go, especially when even higher levels of confidence have been rejected in the past. Where/when do you call a discovery 100% certain??. Especially in particle physics, where a spray of particles at the detector of an accelerator can number in the billions, what are your chances of finding anything even at 5 sigma??!!. Then again you may find something right off the cuff. Or repeat your experiments and not find it again. If you follow chaos theory, it would be almost impossible to repeat your experiments exactly, in any case. So how do you rate the results then??. The statistics would be meaningless.

You can see why they use such a high confidence level for the confirmation of a discovery, but it's still not the ideal way of going about it. What's needed is a symposium on this matter and a set of guidelines ruled upon that can be used across all disciplines. That way, at least we could be more confident of smoothing things out a little better than what is being experienced at present.

[CraigS]

Hmm .. great article, Steven .. many thanks for that.

A fascinating topic (although, somewhat off-topic .. apologies).

I've been pondering all this stuff over the last few days.

The sigma levels (and other considerations) are important, as they do lead us to regard things as having the status .. of say: 'a primitive physical object', (requiring demonstration that they exist in the lab), as opposed to something having the status of say: 'a concept', which allows us to continue thinking that the Standard Model is still Ok. For eg: the Higgs boson still doesn't have the status of a primitive physical object yet, eh?

I think that this is yet another aspect where much confusion exists outside of scientific circles, and creates a lot of trouble when scientific 'discoveries' hit the mainstream media.

Relativity doesn't have the same status as say an electron .. but it is still a big enabler of extended scientific thinking …

Coming back to the original topic though, if these neutrino oscillations turn out to be agreed as being physically real, then I'd imagine this would put the onus on those who refute fusion as the source of the Sun's energy, to come up with a viable alternative, eh?

Cheers

[renormalised]

In relation to my last post, yes, you could use Bayesian analysis but what would be the point. Considering its inherent subjectivity, your results would be biased right from the start. Assuming the prior conditions of the statistical set is just as accurate as saying "the milkman did it". Given that the number of assumptions one can make about the priors of any analysis, you might as well use "the milkman did it" because everyone with an opinion on what initially happened could make an analysis and get what they wanted out of it. And, that's with exactly the same set of values!!!.

That's why I believe we have to be careful with using statistics. It can be made to say or justify anything. If it were as unambiguous as algebra or calculus, for example, then there would be no problem. But it's not.

[renormalised]

That wouldn't worry them in the slightest, especially the EU nutters. They'd more than likely have a "solution" for the "problem" even as we speak. Probably that the neutrino doesn't exist and/or some hair brain idea about electrical charge of subatomic particles.

Speaking of "status" of objects...I've just come up with a couple of terms:). Those objects which have experimental, empirical proof we could call "pragmatic", and those that are strictly theoretical, "romantic":):)

I pretty certain you're right in saying that the confusion between what science and scientists deem as being proof and what the great unwashed deem as being proof, are two entirely different sets of criteria and that the confusion exists. The main fault in the interpretation here is coming through the journos, simply because it's hard enough for the scientists to arrive at a consensus as to what is proof let alone having complete numpkins like journos then figure out what's proof and report it to the rest of us. Filtering the definition of scientific proof through the express desire of wanting to sell a story, is not the way of going about reporting science. The major irony is that if you were to report the science strictly as is, few in the general public would be able to follow it. Except those that might have some training in science and/or be intelligent enough to figure it out in any case.

[CraigS]

Carl;

Who said anything about Bayesian Analysis or Chaos Theory ?
What does this have to do with this topic ? :shrug:


Cheers

[renormalised]

I mentioned them in passing, w.r.t. the topic. What does it have to do with the topic.....the topic's secondary point as was being spoken about was statistics, wasn't it.

Let's not devolve this topic into a pointless debate.

[CraigS]

Overwhelmingly agreed !
:)
Cheers

[CraigS]

:tasdevil:

:lol:

Cheers

[RB]

We're not discussing signatures here, we like to keep this section of the Astronomy forum (mostly) on topic.

;)

[renormalised]

:tasdevil:= Politician debating science (or anything else for that matter!!)

:screwy: = Journalist debating science

:stupid:= General public debating science

:bashcomp: = Scientist doing science


:):P

[RB]

Yes I konw Carl but Mike's ask that this section be strictly moderated.
Half the time I don't even know what you guys waffle on about, but I do see when it starts to turn into spam.

:lol:

[renormalised]

That's not spam, by its definition. If we didn't have some humour in this section, the posts would become boring and rather tiresome. Or they would devolve into pointless debates with no direction. At least it breaks up the tedious air that sometimes appears here.

Plus, I only like waffle with maple syrup and icecream:):P

[RB]

Yes I agree, a bit of humour is great in this section too.
No worries, just if we can keep it relevant to the topic of the thread and not stray too much.

:thumbsup:

[xelasnave]

Very interesting Steven, my favorite particle:thumbsup:.
Craig I only recently found out about the rating but it was from some link of yours I followed. Thanks.

I visited Thunderbolts and had a good look ..over the last couple of days ( I have to rest and its overcast so no viewing)...but having been infected in the past with a similar morosophic approach to a pet subject myself my first emotion is embarrassement....however with a recognition I have moved on I must say they are determined that everything works because of their view on the U niverse.

I have no doubt they will see any discovery as support of their Universe...gives them an interest makes them feel good...no worries...other than a determination to destroy all other ideas before them:eyepop:
alex:):):)

[sjastro]

How theoretical physicists react to the sigma scale for experimental confirmation.

5 sigma:- :scared3:
4 sigma:- :eek:
3 sigma:- :2thumbs:
2 sigma:- :cool:
1 sigma:- :thanks:

Hopefully this is not too off topic.

Regards

Steven

[CraigS]

What does the 'experiment' confirm, if the results fall into one of these bin categories ?

To me, it confirms the applicability of the Standard Model, as a means for explaining the behaviour of fundamental particles. This may also lead to further predictions/outcomes.

What about the results that don't fit into any of these bins ? What do have these mean about the physical phenomena, and what do these then say about the Standard Model ?

Cheers

[sjastro]

It was mean't to be tongue in cheek Craig.:)
The sigma categories relates to confidence in the experiment not the theory.

One reason why particle physics tests require a high sigma level is that invariably there are few accelerators capable of performing the experiment.

Take an experiment that can be performed by a large number of devices such as the Shapiro time delay of Mercury by radio telescopes. It's quite likely the results are satisfactory at a 3 sigma level as the systematic and experimental errors can be accounted for by using a large number of radio telescopes.

As far as theories being supported by data at less than 3 sigma, it's a case of bribery and corruption.;)

Regards

Steven

[CraigS]

Thanks Steven ... (I wasn't having a go at you … just trying to stay on track).
:)
I agree with your interpretation .. but I'm not sure that's how the broader community will see it, if say, the Higgs boson is reported as 'being confirmed' to say, a 4 sigma level … There's so much expectation surrounding this one, that it surely can't escape a triumphant (and loud) declaration of the existence of the HB and of the Standard Model precisely being the way it all works .. but would this actually be what the results are telling us ? (It would seem not).
The same goes also for humble little neutrinos oscillating amongst their chosen states.

Cheers