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 given the same result? There is something more to his setup beyond two big weights pulling on each other that I'm probably missing?
Before the experiment you can measure the mass of both objects. In the experiment you measure the force and distance to calculate the constant.
The weight either object gives you the force between that object and earth (adjusting for atmospheric buoyancy). Altitude at your location + size and shape of earth gives distance between object and center of earth, you just learned the constant. So you know 4 out of five variables in an equation and can thus calculate the mass of the earth.
Technically that excludes the weight of the atmosphere above your altitude, but you can get that from the air pressure. Similarly the density of the earth isn’t constant but it is very close to symmetrical so you can get a reasonable estimate.
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.
- get the gravitational constant with these two known masses
- then can deduct the mass of the unknown Earth by its interaction with other masses (say the "g" gravitational acceleration value)
- then from the mass and the otherwise measured size of Earth the density pops out
More details in good ol' Wikipedia: https://en.wikipedia.org/wiki/Cavendish_experiment#Derivatio...
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?
Along with a unit of charge that is related to the elementary charge by the square root of the fine structure constant then the conductance quantum is 1/pi units of conductance and the inverse conductance quantum is pi units of resistance. Which is somewhat funny.
I thought this would be obvious from TFA. I should have been more explicit.
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.
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
There’s an important gap here between science as practiced and science communication.
Working scientists will absolutely admit their ignorance, shaky foundations, etc. This is especially important in astronomy and cosmology, as the field is relatively young and experiments are impossible, outside of those that nature has already done for us. (Both evolutionary biology and linguistics have similar problems but cosmology has it especially hard.)
This, however, is a losing strategy for communication. Most people equate confidence with credibility (and by high school we’ve beat children down enough that they do so as well), so if you do not sound confident people will not listen to you. (I could pontificate on how this is one of the greatest societal ills of our time, science or no science, but I won’t.) Even outside social situations, most people frankly cannot deal with holding a position and simultaneously not being confident in it, and absolutely cannot deal with holding an entire network of mutually-supporting positions and different degrees of confidence in each, while also having multiple alternatives with different degrees of plausibility for some of them. (This is somewhat more advanced than the programmer’s skill of relying on a deep stack of supporting services and debugging tools while keeping in mind that any given subset of them could be lying, which I’m sure you’re aware is also fairly difficult to communicate the experience of.)
Then there’s the active (if not always successful) effort towards never ever reasoning backwards from things you would prefer to be true or that would make the world nicer for you. (The “History Plots” section[1] of the biennial Review of Particle Physics is there solely as an admonishment never to go with the herd. And that’s for things that have no implications for anybody’s worldview, morality, or livelihood!) It is very uncomfortable to genuinely not know where you are going and also not be able to aim anywhere in particular. (It might among other things imply that the entirety of your life’s work only serves to seal off a dead end and you might not even live long enough to learn that. And either way you’re consigning yourself to a very lonely sort of life if you veer away from the mainstream.)
On the flip side from the vagueness, there’s the experience of doing everything you can to break something and failing, of your forefathers doing the same at their most imaginative and still failing. (The aforementioned RPP has pages and pages of tests for frickin’ energy conservation, without which most of physics and engineering just falls apart. And cosmologists can only dream of doing the same on the scales that are relevant to them, and indeed they do keep things like “modified Newtonian dynamics” around. Note that time invariance [as much as there is such a thing in general relativity] is energy conservation [ditto].) It is a sort of confidence that few others have justifiably had in their lives. (Few other things will infuriate a physicist more than offhand quoting a number with six significant digits. They know—in some cases from direct experience—that this sort of precision takes generations. And a well-established theory needs multiple times the effort.)
So when, say, a cosmologist says that cosmic inflation is a bit of a speculative crapshoot but probably true, the Big Bang is likely true, general relativity they’re fairly sure is true but it sure would be nice to find some cracks, the Standard Model is true despite everybody doing their level best to break it because the foundational issues are quite serious, the mass of a free electron is nearly certain, and the inability to surpass the speed of light is pretty much absolute—this is a dynamic range of confidence that none of us can adequately feel. Now take one of those statements in isolation and try to make your listener understand what the apparent equivocation in it really means.
(I do not believe the typical theist in a debate is on more than an advanced amateur level in all of this.)
Then you get into the cursed philosophical issues, like the (weak) anthropic principle (a class of “why” questions don’t and can’t actually have much of a meaningful answer) or nonexceptionalism in cosmology (it is possible that everything we can or will ever be able to see around us is in fact wildly atypical as a great cosmic joke, but if so we couldn’t ever know enough to join in and any science we do would be completely meaningless, so we might as well proceed on the assumption that it is not, and happily enough it’s been working out thus far.)
[1] https://pdg.lbl.gov/2025/reviews/rpp2025-rev-history-plots.p...
You might be confusing the established big bang with the more speculative cosmic inflation model. They're very closely related.
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...
People work there, and it will have people's dramas and problems, like everywhere else: fraud, crime, jealousy, simple mistakes, etc.
Despite their imperfections, the reason people with power trust their consensus more is because they are a lot more useful than other groups of people.
If you reject this statement, you can start by joining the Amish, since virtually all modern technology is built on top of the scientific community's consensus and work.
Indeed, I did. I joined expecting it to be above mere politics. I paid for my folly.
> People work there, and it will have people's dramas and problems, like everywhere else: fraud, crime, jealousy, simple mistakes, etc.
Yes, but it's far worse in the scientific communities. In the "real world" the average person is way better at doing their average job than the average scientist publishing their work.
Imagine even a civilizationally incompetent modern society today (without naming any names). Now imagine what it would be like if >50% of the time you got into a taxi something far worse than the expected result occurred. You got: taken to the wrong destination; or cheated by the driver; or woke up in a bathtub missing your kidneys; etc. Extend that behavior to even a tiny fraction of the whole. That society would have collapsed already.
Compare that to any journal you please and let's see what percentage of their published works can be verified. Even for the "better" fields their rates are shockingly bad. Some are below 50%.
I don't know about you, but my standards for the behavior of scientists are considerably higher than that for taxi drivers.
> Despite their imperfections, the reason people with power trust their consensus more is because they are a lot more useful than other groups of people.
Hard disagree. The reason people with power "trust" scientific consensus is because they manufacture that consensus by controlling the funding. This is fact. It's not pleasant, and is far from uncontroversial. But it is what it is.
The people with power today who are telling you that <topic X> is "settled science" are the spiritual (and in some cases genetic!) descendants of the people who were telling Columbus that he was going to sail off the edge of the Earth and locking up Galileo. Eppur si muove!
If you want to naively believe that calling one's self a big-s Scientist makes one, if not immune then perhaps we could say resistant, to that fraud, crime, corruption, etc. then I suppose you're entitled to that opinion. I look at the data on their output and my vote is to trash the lot of them and start over. They've fallen that far from grace.
I'm inclined to trust the ancient Greeks, sure. Modern scientists, not so much.
> If you reject this statement, you can start by joining the Amish, since virtually all modern technology is built on top of the scientific community's consensus and work.
Unfortunately the Amish are automatically suspicious of the academically tainted such as myself. Otherwise I'd love to chill with them. Their lives are blissfully stress-free compared to ours.
The black body distribution of the CMB is the (confirmed, of course) prediction of the Big Bang. The structure, age, etc. all depend on the cosmological model, and the claims that no such model can explain observations is ridiculous, given the counterexample of the \Lambda CDM model, the cornerstone of the field for decades now, that explains them all.
It's almost impressive how obstinately you've convinced yourself of something so blatantly wrong and out of date, using only a reference predating the entire modern era of cosmology that you even admitted to not having read "for a while." A far, far cry from engaging seriously in a topic.
Like with the frontier LLMs, seeing commentary on this site on topics that I'm an expert in makes me seriously doubt whether I should lend any credence at all to what's said about those that I'm not.
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 were all only calculated using newtonian physics. It is still accurate enough for most tasks on earth.
A model can still be useful despite its limitations, you just need to know those. People who are like "Ha! It is not accurate!" often have their own mental models of the world which are magnitudes worse, miss key bits or get other parts completely wrong (despite clear evidence to the opposite). As if a morbidly obese person for whom even walking presents a challenge made fun of an Olympic silver medalist for only getting second place. "Ha! You didn't get it 100% right so now my fringe theory that fails to even explain the most basic observations must be seen as equally valid!"
So if you say it fails, consider how many digits after the comma it was accurate before it failed and how many digits your own theory would manage.
Take for example Lord Kelvin's model of thermal conduction in a solid Earth. He used it to incorrectly predict the age of the Earth, but if he had taken that failure to heart he could have used it to predict mantle convection and plate tectonics.
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.
That said, those effects would have been small, and likely handled in practice as "some arbitrary consistent (or random) error."
As I said in my effortpost above, the pdf I linked is a sample. There's more in his book, which I can't post here. And the videos he has put out are long, slow and some might find tedious, so I didn't bother to link them. (I didn't see your response while I was writing. Now I feel bad so I'm going to have to take a look and see what I can find that will post well.)
A simple search for "big bang predictions" will find plenty of even mainstream press discussing them, albeit in a positive light, usually along the lines of "oh look, some scientists are talking about how they discovered something really interesting!" when what they really ought to be saying is "some scientists discovered that their hypotheses were wrong, their models failed to predict observable reality, and they were forced to make corrections that they shouldn't have to, if their hypotheses were actually a correct theory."
As in so many different kinds of scientific endeavors, if your "theory" is based on a "model" and you have to keep correcting your "constants", they aren't constants, they are variables. And you don't have a theory.
> 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 elements, the cosmic microwave background, large-scale structure, and Hubble's law.
> Precise modern models of the Big Bang appeal to various exotic physical phenomena that have not been observed in terrestrial laboratory experiments or incorporated into the Standard Model of particle physics. Of these features, dark matter is currently the subject of most active laboratory investigations. ... Viable, quantitative explanations for such phenomena are still being sought. These are unsolved problems in physics.
I got your joke and I appreciate the effort you put in to make it. :-)
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.