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Comment by welterde | Hacker News Reader

ATLAS, CMS, ALICE, LHCb, etc. are all different experiments that just happen to share the same accelerator. They are done using different detectors, designed, built, operated and the data is analyzed by different groups of people.

If you follow your logic, that the different experiments using the same accelerator negates the whole thing, to the extreme then doing two experiments on the same planet/solar system/universe won't be enough..

And I don't buy your inverse argument that one (good) experiment is good enough either. It is very difficult to tell from outside the group if the experiment is actually good or not (although you probably can tell if it's bad). Screw-ups can happen no matter how many people look at the data if there is some flaw in the experimental setup - only way to make really sure is to use different experiments to measure the same thing.

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I think you've got my argument completely backwards - I'm pointing out that if repetition as implied by the article is everything, then results from e.g. the LHC are discounted.

Similarly, I am not saying that you don't need to repeat - just that it isn't the be all and end all of what defines 'science'. Supporting this interpretation is that I mentioned DAMA. Nobody is accusing them of not taking care, but nobody really believes the result either.

In fact, CMS and ATLAS are sort of same experiment repeated twice, just in parallel rather than serially. Repeatable doesn't imply identical experimental design.

Does it not? If the experimental design is not preserved, don't you open yourself to inconsistent controls between the experiments? Where do you draw the line?

If you think about it, complete replication of any experiment is useless, and impossible.

But that doesn't matter, because it is not the experiment you are trying to replicate, is the effect or the observation.

Carefully changing the design of the experiment can allow to verify that your explanation of the effect or observation is accurate.

Of course, if the change the experiment too much, a failure to replicated will have less useful information.

In hindsight I do think it's true that you want numerous experiments with possibly different controls with the exception of whatever is important for the effect. In that sense you want your experiment to "discover the right abstraction" of details that your principle works over.

So I think what has to occur is a gradual "loosening up" of the controls from strict replication to weak replication, with both types of replication giving information about the effect you are testing: its validity and its generality, respectively.

There is a philosophical assumption underpining astronomy and cosmology, the so-called "cosmological principle."[0] This is an assumption (albeit not completely unfalsifiable) that physics across the universe at large scales is the same for all observers, that here on earth there should be similar to physics in andromeda. Of course, all scientific experiments done have been done on or near earth, and thus, our interpretation of astronomy on earth is tempered by experiments we do here, for example, we assume that the speed of light here is the same as the speed of light elsewhere.

This is, in principle, a problem. We unfortunately have no way to measure the speed of light in andromeda, unlike what we can here on earth, so we really have no idea if our astronomical models are wrong given the non-constancy of the speed of light in andromeda or elsewhere.

So, yes, in principle not being able to repeat science experiments everywhere in the universe is a problem. However, I think if one thinks a little less broadly, testing newtonian gravity in say, Italy and also in China shows at least across the Earth, the phenomenon is similar. Then, at least one can say, "certainly, gravity is the same in Italy and China, and perhaps across the surface of the Earth." That is a stronger statement than "gravity is this way in Italy." Ordering claims by "scientific goodness", we can say that

   Gravity is the same *across the universe* > gravity is the same across the Earth
                                             > gravity is in Italy

My point here is that even if one can't fulfill the extreme of testing theories everywhere in the universe, one can progressively prove stronger and stronger statements regarding the validity of scientific theories.

Somewhere the LHC stands between "the SM is validated across the universe" and "the SM is validated at one detector at the LHC". Yes, it would be "better" if the Higgs was found at other experiments, but the current situation is "better" than if the Higgs was found at one detector there and not in any other. Repeatability, like everything in science, is not a binary step function but is some continuous function over the domain [0,1].

[0] https://en.wikipedia.org/wiki/Cosmological_principle

But we can measure gravity in faraway galaxies. We don't need to actually go there, we have telescopes :)

How can you measure the strength of the gravitational constant if you don't know the masses of the objects in question?

The Chandrasekhar mass depends on G and a bunch of fundamental constants, and that's the mass of a type Ia supernova. Unfortunately this Wikipedia article doesn't talk about astronomy much:

https://en.wikipedia.org/wiki/Gravitational_constant#History...

But it does point at one measurement of G on cosmological timescales and distances from 2006:

https://arxiv.org/abs/1402.1534

There are other papers with similar measurements published in the past two decades.

That's only true if all the other physics involved are the same wherever that supernova is; your own link mentions this. We can't prove that's the case since we can't test the individual parts of that theory - it's possible to construct a different set of physics that produces results identical to the physics we're familiar with.

That isn't a particularly fruitful approach since it doesn't permit any real discovery - it's rather brain-in-a-jar - but it is still something you have to assume away.

There are some phenomena which allow good remote assessments of properties, based on various interactions. Cephid variable brightness, for example, serving to validate the expanding universe theory. The stellar Main Sequence gives a good sense of stellar masses. Spectroscopy works pretty well across a wide span of the Universe (several billions of light years). Etc.

Since these operate in concert across the observable universe, and themselves involve various other interactions (elements, strong and week nuclear forces, gravity, speed of light, rates of hydrogen fusion, etc.), we can conclude that either there is no appreciable change in any of the underlying fundamental constants or that change occurs in a compensated fashion such that no net change is detectable.

The second fails Occam's Razor. The conclusion that the laws of physics appear to be similar throughout observable space seems robust.

I read the article carefully, and was unable to find where it says what you say it says.

In particular, you're making super-strong statements like "be all and end all of what defines 'science'" -- that's not what I see in the article. The article is reasonably pointing out that we have a repetition crisis and that more emphasis should be placed on it. That's not the various super-strong things you're claiming you see in it.

The very title claims that unrepeated results shouldn't be accepted.

The contents of the article are the only thing that ever matters.

The title is picked by editors to get the most people to click on it.

I think the title is all that matters. I'm only here for the discussion, and the title defines the topic.

Your approach will lead you to having an incorrect take quite often. You should reconsider unless you enjoy being wrong for no particular reason.

Well it hasnt, and Ive had this "approach" for years.

That's like going to a book club without having read the book.

You miss all nuance.

It's becomes very quickly apparent to those who've read the article when others comment without having read beyond the title.

Youre wrong

See? There you go again. Man, trolls here are way less funny than on reddit.

Not a troll

Are you under the impression you aren't wrong here?

This is why I don't participate in HN discussions. The level of vapidness is mind boggling.

If the title is click-bait that doesn't match the content, it should be corrected when submitting it on HN.

2nd paragraph.

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