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We still don't have a more precise value for "Big G"

arstechnica.com

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Re: We still don't have a more precise value for "Big G"

#31

Earlier quoted context omitted.

The theistic schism? I had to look it up, and was not cleverer after. Nobody can ever know an ultimate why, for obvious and well established philosophical reasons. At least the scientists are trying to squeeze the knowledge gap down as small as possible instead of making up stories.

> Nobody can ever know an ultimate why, for obvious and well established philosophical reasons Yes we can, you are just presupposing that philosophy is ultimately ineffective. For example Hegel gave a presuppositionless development of all metaphysics among other things. It’s not some kind of philosophical consensus that ultimate justification is impossible

Philosophy can be perfectly effective as a tool of thought while still being unable to resolve self evidently unsolvable “ultimate questions”

Re: We still don't have a more precise value for "Big G"

#32

> Cavendish painstakingly recorded those oscillations to measure the gravitational force of the larger spheres on the smaller ones, and from that he could infer Earth’s density. I can't wrap my head around this sentence. How is the force between two objects, none of which is the earth, related to any property of the earth (its mass or density)? Wouldn't Cavendish's experiment have worked - even better - in zero g and…

By ascertaining an approxiamte value of G , perhaps? After that, you know M_earth, and already knowing Earth’s geometry, one arrives at average density rho.

Laying out the math (assuming earth is an homogeneous sphere) just in case it's not clear:

F_gravitational = G m1 m2 /r^2

g = G Mass_earth / r_earth^2

Mass_earth = r_earth^2 * g/G

Density_earth = r_earth^2 * g/G / V_earth

Density_earth = 3*g / (4*Pi*G*r_earth)

Prior to Cavendish we already new g and r_earth, just missing G.

Re: We still don't have a more precise value for "Big G"

#33

> Cavendish painstakingly recorded those oscillations to measure the gravitational force of the larger spheres on the smaller ones, and from that he could infer Earth’s density. I can't wrap my head around this sentence. How is the force between two objects, none of which is the earth, related to any property of the earth (its mass or density)? Wouldn't Cavendish's experiment have worked - even better - in zero g and…

By ascertaining an approxiamte value of G , perhaps? After that, you know M_earth, and already knowing Earth’s geometry, one arrives at average density rho.

Oh so the earth density is merely the motivation for the experiment? I read it as the earth mass actually being used somewhere in the formulas within the setup itself which was what confused me.

He uses his experiment to calculate G based only on the test masses and spring and then the _result_ of the calculation was just used as a final step to calculate the mass of the earth, and then from that the density?

Re: We still don't have a more precise value for "Big G"

#34

Earlier quoted context omitted.

The theistic schism? I had to look it up, and was not cleverer after. Nobody can ever know an ultimate why, for obvious and well established philosophical reasons. At least the scientists are trying to squeeze the knowledge gap down as small as possible instead of making up stories.

> Nobody can ever know an ultimate why, for obvious and well established philosophical reasons Yes we can, you are just presupposing that philosophy is ultimately ineffective. For example Hegel gave a presuppositionless development of all metaphysics among other things. It’s not some kind of philosophical consensus that ultimate justification is impossible

Interesting word soup. Ultimately, no, you cannot build a valid representation of the universe from nothing and you need observation and validation. You can presupposition whatever you want when you are talking about unproveable models, but it says more about you than the universe. Until we have a reason to think that there is a "why", discussing what it is is completely unnecessary and futile because 1) it does not change anything about our understanding or the predictions we can make, and 2) it is not something we can observe, measure or prove.

Re: We still don't have a more precise value for "Big G"

#35

I appreciate the scientists’ honesty. When asked about big G and time invariance, he says he just takes it on faith that it has been the same forever. If more people would admit their leaps I think the theistic schism would be far more shallow.

> he says he just takes it on faith that it has been the same forever

It’s not faith, it’s a working assumption. There are in facts Physicists working on figuring out what would change if some fundamental constants changed with time. Our best measurements and understanding right now is that they do not. If we show tomorrow that it’s wrong, then we’ll build better theories and move on. There is absolutely no faith involved.

Re: We still don't have a more precise value for "Big G"

#36
post #14

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Big_Bang > The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. .. A wide range of empirical evidence strongly favors the Big Bang event, which is now widely accepted. ... > The Big Bang models offer a comprehensive explanation for a broad range of observed phenomena, including the abundances of the light elemen…

In reality it's just that the output of the procedural generation routines doesn't quite match that of the primary simulation loop. A classic worldbuilding inconsistency.

Even if your observation were 100% correct, it's also 100% irrelevant to the point.

We still refer to Maxwell's theory of electromagnetism as a theory even though we know quantum electrodynamics is a more precise match to the primary simulation loop.

I suppose a few might have decided to rename it Maxwell's hypothesis of electromagnetism, but I would consider them crackpots or dilettantes with little understanding of the meaning underlying those terms.

Re: We still don't have a more precise value for "Big G"

#37
post #12

Earlier quoted context omitted.

It might also be nice if cosmologists stopped claiming their Big Bang "Theory" wasn't more accurately termed a mere Hypothesis. IIRC, 12 out of 13 predictions failing and necessitating "model" "tweaks" is not a fantastic track record for a Theory, which are supposed to robustly survive investigation.

The model failing is a question of how accurately you want it to model the world. Many laypersons have absolutely no conception of how accurate those "failing" models were. A good example is Newtonian physics. Strictly speaking it is a failing model, after all, under certain conditions and if you look very closely ot falls apart. Yet, every bridge you ever walked on and the most precise mechanical watches ever made w…

See the relativity of wrong by Asimov for a simple development of this theme.

Re: We still don't have a more precise value for "Big G"

#38
post #12

Earlier quoted context omitted.

The model failing is a question of how accurately you want it to model the world. Many laypersons have absolutely no conception of how accurate those "failing" models were. A good example is Newtonian physics. Strictly speaking it is a failing model, after all, under certain conditions and if you look very closely ot falls apart. Yet, every bridge you ever walked on and the most precise mechanical watches ever made w…

This is what has always made it hard for me to go beyond the Newtonian physics. The only thing I know and use daily that relies on relativity is GPS and having looked into the equations on how it accounts for this it seemed to me that I could not discount that the equations account for some arbitrary consistent (or random) error, not relativity specifically. All experiments I have run never needed precision beyond Ne…

You could well live your whole life without needing anything more than Newtonian Physics. For most of us, relativity is a fun thought experiment. If you want to grapple with it, special relativity is the answer to "how can the speed of light be constant regardless of the speed of whoever is measuring it?" In his "vulgarisation" books, Einstein explains it with nothing more sophisticated than trains and stopwatches.

General relativity is more complex and quickly goes in complicated mathematical weeds but is just as profound from a philosophical point of view, which is that things do not merely affect other things around them, but instead change space-time itself. You can see with a couple of clicks observations of phenomena predicted by it, like black holes and gravitational lenses. It’s interesting to think about even if you are not directly affected.

Re: We still don't have a more precise value for "Big G"

#39

I appreciate the scientists’ honesty. When asked about big G and time invariance, he says he just takes it on faith that it has been the same forever. If more people would admit their leaps I think the theistic schism would be far more shallow.

It might also be nice if cosmologists stopped claiming their Big Bang "Theory" wasn't more accurately termed a mere Hypothesis. IIRC, 12 out of 13 predictions failing and necessitating "model" "tweaks" is not a fantastic track record for a Theory, which are supposed to robustly survive investigation.

What are the 13 predictions? Can you list them or provide a link to that list?

Re: We still don't have a more precise value for "Big G"

#40

Earlier quoted context omitted.

It might also be nice if cosmologists stopped claiming their Big Bang "Theory" wasn't more accurately termed a mere Hypothesis. IIRC, 12 out of 13 predictions failing and necessitating "model" "tweaks" is not a fantastic track record for a Theory, which are supposed to robustly survive investigation.

We can literally observe cosmic microwave background and it fits our prediction that the universe was denser and hotter. It is a scientific theory. You might be confusing the established big bang with the more speculative cosmic inflation model. They're very closely related.

> We can literally observe cosmic microwave background and it fits our prediction that the universe was denser and hotter.

I can't observe that, because I don't have the gear. (Nor the time, budget, inclination nor training, for that matter. :-) But I am happy to admit the possibility that some of those observations, as reported in the literature, are correct.

However, unlike a depressingly large percentage of my former scientific colleagues, I also appreciate just how much of what gets reported in the literature, from the conclusions all the way back to the raw data, is anything from sloppily wrong to flat out lies. Witness the decades-long fiasco in genetics that is only this past month being corrected:

Before: https://www.nature.com/articles/437047a

After: https://www.nature.com/articles/s41586-025-08816

TLDR: The original work by the CSAC reported only a fraction of the actually relevant data and hid the remainder where nobody was going to look. This was not the kind of Reproducibility Crisis mess, where an undergrad isn't paying attention when he grabs the electrophoresis gel off the shelf and then writes down the wrong brand name in his lab book. This was fraud. They intentionally misrepresented the data and hence the conclusions by an order of magnitude, which allowed them to delude the whole world for decades that "humans are 98.8% the same as chimps!"

Many people had their entire worldview swayed by this pronouncement, myself included. I don't like being lied to.

So yeah, you'll have to forgive me if I'm a bit skeptical when it comes to scientific observations and reportage that I'm a few $million shy for confirming myself. And I'll continue to think poorly of those who have been making lucrative careers out of doing "well-established" physics that "everybody" "accepts", only to have to quietly admit under scrutiny that their predictions didn't work out quite as nicely as the popular press has told us.

Furthermore,

> It is a scientific theory.

It is a scientific hypothesis. It has not been subjected to repeated experimental trials or observations and found to be correct.

A hypothesis does not become "well-established" simply because every college professor whose salary depends upon supporting the grant authority's narrative repeats it.

I am fully aware that some people (present company excluded; I'm not placing any blame here) have watered down the definition of these terms. They are wrong. I do not consent to and will not be bullied into accepting changes to my language. Especially nothing as important as the language of science.

> You might be confusing the established big bang with the more speculative cosmic inflation model. They're very closely related.

Perhaps. I was never too terribly interested in things "smaller than an electron"[1] or larger than a whale.

Lerner's arguments[2], particularly on relative elemental abundances, are persuasive to me. That may be because during my formative years I was a bit preoccupied with H vs D, because deuterated compounds for the NMR were too expensive for me to just play around with as I liked, so I had to tinker with spectroscopy/spectrophotometry instead. In any case, he's right. You can't have a cosmological constant be one value to account for the D and another value to account for the He3.

As for the CMB, he addresses that as well, though once again I haven't done the work to confirm either side myself.

Lerner has a whole basket full of other arguments as well, but I'm not a fan of lazy people posting Youtube links to hour long videos and saying "watch this!", so I shan't be a hypocrite. I believe that pdf should give a good flavor of it. It's been a while since I read it and I only skimmed it now, but I believe it a good representative sample of his other work.

[1] PS: Yes, I know, I know. Stop being pedantic. This site is a hobby and I'm not about to cheat and get a chatbot to write me a 12 page essay every time I want to save a few words. I get to abuse quotation marks when I'm feeling lazy.

[2] See sections II and IV in particular: https://web.archive.org/web/20260429053749/https://www.resea...

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