# Two new ways to measure the gravitational constant

A team of researchers affiliated with several institutions in China and one in Russia has devised two new ways to measure the gravitational constant. In their paper published in the journal Nature, the group describes the two methods and how accurate they were. Stephan Schlamminger with the National Institute of Standards and Technology in the U.S. writes a News & Views piece on the work done by the team in the same journal edition.

Gravity is one of the four of nature (the others are the weak and strong interaction and electromagnetism). Despite hundreds of years of concerted effort by scientists around the world, there is still no explanation for how it works. Adding to the frustration is the fact that no one has been able to find a way to measure its actual —scientists have been trying to do that for hundreds of years, as well. In modern times, researchers have come very close, however—the current accepted value is 6.67408 × 10−11 m3 kg-1 s-2. In this new effort, researchers working in China have modified a standard way of measuring the gravitational constant—torsion pendulums. The method was first devised by Henry Cavendish back in 1798, and since then, has been modified many times to make it more accurate.

In the first approach, the researchers built a device consisting of a silica plate coated with metal hung in the air by a wire. Two steel balls provided a . The force of gravity was measured by noting how much the wire twisted. The second approach was similar to the first, except that the plate was hung from a spinning turntable that kept the wire in place. In such an apparatus, the was measured by noting the rotation of the turntable.

In both approaches, the researchers added features to prevent interference from nearby objects and disturbances, including seismic. They report measurements of 6.674484 × 10−11 and 6.674184 × 10−11m3 kg-1 s-2—both of which, the team claims, are more precise than other previous measurements.

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New measure of gravitational constant higher than expected

More information: Qing Li et al. Measurements of the gravitational constant using two independent methods, Nature (2018). DOI: 10.1038/s41586-018-0431-5

Abstract
The Newtonian gravitational constant, G, is one of the most fundamental constants of nature, but we still do not have an accurate value for it. Despite two centuries of experimental effort, the value of G remains the least precisely known of the fundamental constants. A discrepancy of up to 0.05 per cent in recent determinations of G suggests that there may be undiscovered systematic errors in the various existing methods. One way to resolve this issue is to measure G using a number of methods that are unlikely to involve the same systematic effects. Here we report two independent determinations of G using torsion pendulum experiments with the time-of-swing method and the angular-acceleration-feedback method. We obtain G values of 6.674184 × 10−11 and 6.674484 × 10−11 cubic metres per kilogram per second squared, with relative standard uncertainties of 11.64 and 11.61 parts per million, respectively. These values have the smallest uncertainties reported until now, and both agree with the latest recommended value within two standard deviations.

Journal information: Nature

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Aug 30, 2018
Interesting that there errors do not over lap. Still the same problems.

Aug 30, 2018
Like hunting gravitational waves or neutrinos, they are working at the very limit of their instruments, incrementally figuring and correcting interfering factors. Note how 'standard deviation' error bars have become smaller with time...

Aug 30, 2018
Interesting that there errors do not over lap. Still the same problems.

meebe? G may fluctuate? How silly would that be?

Aug 30, 2018
Very silly.

Aug 30, 2018
I don't think it fluctuates. We just don't understand all the parameters. For one, the measurements, could be affected by surrounding charge, magnetism, neutrinos, or any number of things.

Aug 30, 2018
At least all the estimates I see there are within an arbitrarily 'narrow' range between 6.670 and 6.676 which doesn't seem too bad to me as that range is over a lot less than 1% variation.

Aug 30, 2018
Some people would like a much more accurate measurement. It might help figure out the final theory of physics.

Aug 30, 2018
Another perspective.

https://physicswo...rements/

Aug 30, 2018
#g: Thank you for that link.

Aug 30, 2018
Some people would like a much more accurate measurement. It might help figure out the final theory of physics.

Would like to see repeating of experiments at same place and different places and different times. This is good that there are many methods of measuring G.

Aug 30, 2018
Maybe nobody knows what they are doing! Gravity is the cumulative DC Field of every charge in the universe; motion and the near field must be well understood. It's obvious! So the historical best fits require updates per infinitesimal wavelength or T. i.e. A Correction!

Aug 30, 2018
@HF, you clearly don't know what you're doing.
Stop smoking the funny stuff and get back on your medication.
If it was possible to give you 0/5 I would do it.

Aug 30, 2018
I'm pretty sure that we need some darn big balls to measure the gravitational constant accurately. Perhaps 100 ton boron balls with isotope with 5 neutrons.

Aug 30, 2018
@HF, you clearly don't know what you're doing.
Stop smoking the funny stuff and get back on your medication.
If it was possible to give you 0/5 I would do it.

I propose Charge Exist, Charge is the Geometrical Center of an E Field and Exist as BiPolar! "Bet u can't do that"
Therefore no other particle or force exist that is not derivative! QED! Silly Wabbits!

Aug 31, 2018
Since Sir Isaac Newton 330years ago
Gravity is one of four fundamental the weak the strong interaction and electromagnetism, despite years in 100s still no explanation for how it works no one has been able to find a way to measure its actual force except approximately 6.67408 × 10−11 m3 kg-1 s-2. by torsion devised by Henry Cavendish back in 1798
By modification of torsion a silica plate coated with metal hung by a wire two steel balls provided a gravitational attraction, the second the same but on turntable of rotation brought interesting results of non rotating 6.674484 × 10−11, whereas rotating brought 6.674184 × 10−11
In the world of gravitation at velocity of light a rotating gravitating force brought a lower gravitational force of 0.004495%

As the spinning axial earth rotates, orbiting its star which orbits its galaxy which orbits in innumerable galactically confined orbital's of galaxies, what is the true force Since Sir Isaac Newton's Gravity of 330years ago

Aug 31, 2018
Quite obviously, there is no force whatsoever between the masses, the measurement taken is the force required to keep them apart (i.e. accelerate them away from each other) as they expand.
EVERYTHING in our universe is expanding, including you, which incidentally we observe as the passage of time, a side effect of which is what we call "gravity". Until we turn the Cavendish experiment round, and measure acceleration rather than force, we ain't gonna get much further, 'cos there are so many other accelerations taking place (e.g. Earth expansion, Earth-Moon system expansion, Solar System expansion, etc., etc.)

Aug 31, 2018
HF sounds far off, but the paradoxes created by Gauss and Maxwell with e-fields and charge make you wonder.

Aug 31, 2018
RegMundy: wrong, space within galaxies is NOT expanding. The theory is; only the space outside the galaxies is expanding. Evidence is; the galaxies are all moving away from one another. Like baking a blueberry cake, the cake expands but the blueberries/galaxies do not.

Aug 31, 2018
RegMundy: wrong, space within galaxies is NOT expanding. The theory is; only the space outside the galaxies is expanding. Evidence is; the galaxies are all moving away from one another. Like baking a blueberry cake, the cake expands but the blueberries/galaxies do not.

The velocity of light: Imagine the equal potential surfaces as the center moves as they update relative to the center at the speed c; then, we how fast that wavelet moves past us! So if we measure T as increasing; in most distant stars; then applying logic, we are in an accelerating stream as necessary and sufficient!

Aug 31, 2018
Since this is Light, i.e. oscillatory; then, the relative speed of the object containing the oscillation .. well basically the wavelength by the measured period or elementary! What Period did you measure that was too fast?

oops, thought we were trying to measure the average DC field of the Universe!

Aug 31, 2018
Delta Lambda f(s) then a(0),..

Aug 31, 2018
Asymptotic or Parabolic? Expectations?

Aug 31, 2018
N Pairs! That's it! The more the merrier! You are trying to measure "compliance" ! imagine two distant pairs. They hug each other, inseparable; however compliant. Each center "Fills" the "Presence" of every other center as superimposed. So the distant like centers are farther apart than the distant unlike centers. So they give a little, because the timing of the centers Late reply; they tend to oscillate; however, attract. This has been going on forever. These centers know each other. That osc, Light!

Aug 31, 2018
If a = f(q, s,t) then we'd know! Well we do know.

Aug 31, 2018
Morning coffee!

Scale?

Aug 31, 2018
Morning coffee!

Scale?

Yeah you see the the intensity as a shape in your head; then add 'em up or superimpose!

Aug 31, 2018
Misinterpretation or end of logic!

Aug 31, 2018
RegMundy: wrong, space within galaxies is NOT expanding. The theory is; only the space outside the galaxies is expanding. Evidence is; the galaxies are all moving away from one another. Like baking a blueberry cake, the cake expands but the blueberries/galaxies do not.

Of course the space within galaxies is expanding. The "theory" you quote does not take account of the fact that we are expanding along with the interior galactic space and therefore do not perceive it.THINK, man, THINK!

Aug 31, 2018
RegMundy: wrong, space within galaxies is NOT expanding. The theory is; only the space outside the galaxies is expanding. Evidence is; the galaxies are all moving away from one another. Like baking a blueberry cake, the cake expands but the blueberries/galaxies do not.

Of course the space within galaxies is expanding. The "theory" you quote does not take account of the fact that we are expanding along with the interior galactic space and therefore do not perceive it.THINK, man, THINK!

Formal Logic, begin with the elements; space is not a rubber band you can stretch and bend! Axiomatic Nonsense!

Aug 31, 2018
RegMundy: wrong, space within galaxies is NOT expanding. The theory is; only the space outside the galaxies is expanding. Evidence is; the galaxies are all moving away from one another. Like baking a blueberry cake, the cake expands but the blueberries/galaxies do not.

Of course the space within galaxies is expanding. The "theory" you quote does not take account of the fact that we are expanding along with the interior galactic space and therefore do not perceive it.THINK, man, THINK!

Ahhh, Jeez. Not this eejit again! Sold any books, Reg? Lol.

Aug 31, 2018

Aug 31, 2018
@Reg Mundy.
...EVERYTHING in our universe is expanding,..., a side effect of which is what we call "gravity"....
As you know, I have always been open to being convinced by objective scientific/logical arguments whenever they can be shown to be consistent with extant physical reality. So I would greatly appreciate it if you would consider/comment re my following observations/reservations:

- How do extreme energy-mass bodies (called Black Holes) fit into your 'expansion' scenario if their own gravity-effect causes them to actually 'contract' once their cumulative energy-mass content reaches criticality for such contraction proceeding to 'below Event Horizon' radius?

- How long has your hypothesized 'expansion' scenario been going on; and after how long before our own galaxy expanded at 'lightspeed'?

- How long before angular momentum/velocities produce lightspeed limits/centrifugal force 'extremes' leading to spinning bodies' 'fragmenting'?

I'm open and listening. :)

Sep 01, 2018
@RC Black holes effectively drop out of our universe as they are unable to expand thus "falling out of time" so to speak.
Lightspeed increases as the same rate of expansion as the rest of the universe. Light consists of photons which themselves consist of two or more particles orbiting each other with expanding orbits, Light effectively moves along the long axis of the ellipse of the orbits due to relatavistic effect.
Angular momentum/centrifugal force? See above re lightspeed.

Sep 01, 2018

Oh dear, here we go with the insults. Whenever some old codger can't refute a logical argument, he resorts to verbal violence, the first refuge of an inferior mind....

Sep 01, 2018

Oh dear, here we go with the insults. Whenever some old codger can't refute a logical argument, he resorts to verbal violence, the first refuge of an inferior mind....

Or.....

Oh dear, whenever some old codger cannot make a logical statement that corresponds to reality and refuses to listen to reason (the only refuge of an inferior mind) people get frustrated and resort to mocking and insulting the crackpot.
What else can they do?
Reason and logic just does not work.

Sep 01, 2018

Oh dear, here we go with the insults. Whenever some old codger can't refute a logical argument, he resorts to verbal violence, the first refuge of an inferior mind....

Or.....

Oh dear, whenever some old codger cannot make a logical statement that corresponds to reality and refuses to listen to reason (the only refuge of an inferior mind) people get frustrated and resort to mocking and insulting the crackpot.
What else can they do?
Reason and logic just does not work.

OK, give me some reason and logic which disproves the theory, and I'll desist.

Sep 01, 2018
Actually, there's no real evidence anything is expanding, since it's all based on red shift being proportional to distance. And there are many cases recorded of red shift not making sense, like quasars ejected to the front of their galaxies with very old/distant red shift numbers.

Sep 01, 2018
OK, give me some reason and logic which disproves the theory, and I'll desist.

What 'theory'? I suggest looking up the scientific definition of that term. If you want it tested, then it'll be in the scientific literature, where other scientists can review it. Eh?

Sep 01, 2018
To quote myself "A hamster endlessly running on it's wheel, is the physical manifestation of "Nonempirical Logic".

How about some repeatable, verifiable conclusions drawn from empirical evidence using rational reason?

Anyone insisting upon "Logic" as a scientific tool needs to use "Abductive Reasoning" not "Deductive Speculation".

Though come to think of it? I have always been a sucker for "Seductive Comehither"!

Sep 01, 2018

Oh dear, here we go with the insults. Whenever some old codger can't refute a logical argument, he resorts to verbal violence, the first refuge of an inferior mind....

Or.....

Oh dear, whenever some old codger cannot make a logical statement that corresponds to reality and refuses to listen to reason (the only refuge of an inferior mind) people get frustrated and resort to mocking and insulting the crackpot.
What else can they do?
Reason and logic just does not work.

Disrespect is to give oneself greater respect; nonsense is nonsense; a response should be helpful or absent; if the response is received as disrespect and/or without logic, simply more nonsense. Your trust in the chef is based upon?

Sep 01, 2018
Begin with the Universe of Discourse, review modern physics; adherence? Any theory states its axioms or are universally understood, i.e. Define Logic such that Formal Logic is a sub-set in order to use the linguistics not written in the Sacred Text!

Sep 01, 2018
Reg: There's no evidence space within galaxies is expanding. The only evidence we have that space outside galaxies is expanding is because red shift says (most) all galaxies are moving away from one another. That's the only evidence of expansion. You just make s*** up to say space within galaxies expands.

Sep 02, 2018
Reg: There's no evidence space within galaxies is expanding. The only evidence we have that space outside galaxies is expanding is because red shift says (most) all galaxies are moving away from one another. That's the only evidence of expansion. You just make s*** up to say space within galaxies expands.

Everything is expanding, including you. You obviously haven't understood a word I've said. THINK, man, THINK!

Sep 02, 2018
Everything is expanding, including you. !
Reg Mundy

NO NO NO. You have misunderstood the theory of space expanding which does NOT imply all objects are necessarily moving away from each other. Space can be expanding on a cosmic scale (as it is) but without objects or particles moving apart on a relatively local scale. This is because there can be much local relative motions between objects or particles with those motions being such that they completely swamp or counteract the effects of the minute expansion of space there would be on a local scale. The effects of expanding space can only be seen and be significant across the arbitrary extremely 'large' distances.
I am afraid it is you that needs to "THINK" here.

Sep 02, 2018
Some expansion, collapsing galaxies
The galaxies are gravitationally merging into larger galaxies that all the observable galaxies are collapsing into a ginormous galaxy of epic proportions some expansion of collapsing galaxies!

Sep 02, 2018
Some expansion, collapsing galaxies
The galaxies are gravitationally merging into larger galaxies that all the observable galaxies are collapsing into a ginormous galaxy of epic proportions some expansion of collapsing galaxies!
granville583762

Straw man; Nobody who understand the basic theory says the galaxies are expanding. Meanwhile, all the most distance galaxies are moving away from us and thus the universe is very clearly expanding to anyone with half a brain; What's your point?

Sep 02, 2018
@Reg Mundy.
Black holes effectively drop out of our universe..."falling out of time"
'Time' is only an abstract measure of comparative motional rates of things compared to chosen regular motion/oscillation 'reference standard' (as in a clock/orbit); so no 'thing' in reality can actually, as you put it, 'drop out of time'. (Time is merely abstract analytical "timing construct"; not a real physically effective 'entity'; just as Temperature is an abstract analytical "kinetic energy" measure construct for heat/pressure state).
Lightspeed increases as the same rate of expansion as the rest of the universe.
I'm not quite sure what you mean here. Can you give examples of consistent/consequential phenomena/effects?
Angular momentum/centrifugal force..
Would not: (1)loose rocks on surface of an ever-expanding spinning-planet eventually be ejected into space by ever increasing centrifugal effect; or (2)planet spin-down due to 'conservation of angular momentum?

Thanks.

Sep 02, 2018
@humy.
all the most distance galaxies are moving away from us and thus the universe is very clearly expanding
Careful. Your assumption/interpretation (that increasing redshift with distance implies 'universal recessional motion') is just that: an assumption/interpretation in a particular hypothesis which so far has no tenable objective evidence to support it meaning 'exclusively' that. There are many contents/processes now being found across the universal space near and far; which space was previously thought 'empty and boring' until more recent telescopes/instruments were available for new re-observations and hence re-interpretations. So, again, be careful not to just appeal to old naive/simplistic/erroneous authority/hypotheses/interpretations in this fast changing field of astronomy/cosmology, in which new/recent mainstream discoveries/reviews is necessitating much rethink regarding many aspects of past hypotheses/interpretations/claims re BB/Inflation etc. :)

Sep 02, 2018
@humy. which new/recent mainstream discoveries/reviews is necessitating much rethink regarding many aspects of past hypotheses/interpretations/claims re BB/Inflation etc. :)

How'd we miss that? Like using the above logic! Logic is context Free!

Sep 02, 2018
@humy. which new/recent mainstream discoveries/reviews is necessitating much rethink regarding many aspects of past hypotheses/interpretations/claims re BB/Inflation etc. :)

How'd we miss that? Like using the above logic! Logic is context Free!

i.e. Within the UoD! INOTHER WORDS, THE PODUS MODEMS APPLY THEREFORE IF s BLAH, BLAH, all the language may be proven T/F, i.e. nothing un-provable!

Sep 02, 2018
How does everyone else sort the nonsense? By the way there's a lot, it'll take awhile. I'll give you a short cut begin with a premise! Charge Exist Therefore any other particle or force is derivative. Now write your paper; Disproof? or App!

Sep 02, 2018
I know the why of both inertia and gravity not just the effects. It is common sense. If anyone is interested, I can be reached at mhardin104@aol.com

Sep 04, 2018
It seems that some people think the more complex one's arrangement of words, coupled with a unique (invented) jargon is = to great intelligence. When one "knows" more than the giants of historical science and feels that those geniuses of the past got it all "wrong", then one is suffering from Delusions of Grandeur. That is a mental health issue, not a physics issue. You are right, everyone else is wrong, you have all of the answers, but, for some reason, you are not getting your due is = Narcissism, with a touch of Paranoia. All usually treatable.

Sep 04, 2018
@RC
'Time' is only an abstract measure of comparative motional rates of things compared to chosen regular motion/oscillation 'reference standard' (as in a clock/orbit); so... (Time is merely abstract analytical "timing construct"; not a real physically effective 'entity';).

Agree. But in our universe, we exist in "time" which, to us, flows inexorably on in a steady state. In reality, it probably moves in fits and starts from one quantum to another, a quantum being of the order of a photon moving a planck length. My theory suggests that each quantum of time is chosen from the chaos according to our "laws" of physics, and those laws dictate our path thru "time". I ain't gonna try to explain the whole thing here, you will just have to borrow or buy
https://www.amazo...1HLDY978

Sep 04, 2018
@RC
Lightspeed increases as the same rate of expansion as the rest of the universe.

I'm not quite sure what you mean here. Can you give examples of consistent/consequential phenomena/effects?

Photons are subject to expansion just as everything else in our universe. Again, I don't intend to provide at length what my theory suggests radiation is.
Angular momentum/centrifugal force..

Would not: (1)loose rocks on surface of an ever-expanding spinning-planet eventually be ejected into space by ever increasing centrifugal effect; or (2)planet spin-down due to 'conservation of angular momentum?

Like the man said, times they are a changing. No increase/decrease in angular momentum.

Sep 04, 2018
maybe its not constant

Sep 05, 2018
maybe its not constant

Suggest it is due to the superposition of every charge in the universe. The near field is dominant. So search for a location and periodic time, i.e. an Event Driven Sensor and Device setup that will yield a Constant/Frequency. Now, do you really want to express this as a constant?

So any instability of the Local DC field is very significant. Within the far field? Identifiable Oscillation, Visual match? Causal? i.e. Identify!!

Sep 05, 2018
The First part of identifying Control, i.e. The Control Space. If one can define every point within that set with a set of axiomatic attributes; then, than that space is controllable or its control is understood!

MSEE, Controls one may design a cpu program Identifier using a fuzzy control space based upon logic, i.e. take advantage of impression as an adaptable function.n I begin with the center of the E field. That's all I need.

Sep 05, 2018
@humy.
So, again, be careful not to just appeal to old naive/simplistic/erroneous authority/hypotheses/interpretations in this fast changing field of astronomy/cosmology, in which new/recent mainstream discoveries/reviews is necessitating much rethink regarding many aspects of past hypotheses/interpretations/claims re BB/Inflation etc. :)
Funny to hear this from you! Actually a shocker!

Sep 07, 2018
@Reg Mundy.
Photons are subject to expansion just as everything else in our universe. Again, I don't intend to provide at length what my theory suggests radiation is.
Can you at least give me a hint as to the actual (real, physically effective etc) mechanism(s) via which radiation/photon (however your theory may describe same) is 'caused' to 'expand'; and also what it is that 'determines' the 'rate' of said 'expansion'?
Like the man said, times they are a changing. No increase/decrease in angular momentum.
You agreed 'time' is not an effective agent of change; but merely an accounting/analytical construct for 'timing' (comparing) motional parameters (ie, speed) using some chosen standard (clock or some other regular/cyclic motion) and the motion/change under study. So the only effective factors are the VARYING orbital (ie, inertial) and VARYING centripetal acceleration (eg, gravity/tether) force/gradient 'values'. Wouldn't these variations impact momentum?

Sep 08, 2018
@RC
Can you at least give me a hint
no, he can't
apparently, he can't actually provide any evidence at all to support his claims other than "buy my book"

In point of fact, he also can't answer some of the more basic questions of his delusional beliefs either as proven by furlong, gawad, whyde, nou and myself (among many others like Q-star, Thermo, etc all over PO)
https://phys.org/...ong.html

Sep 12, 2018
I come from China.I don't speak other countries' languages.So the following content should be expressed in Mandarin.Perhaps some content is not very clear. Please forgive me.