Offline SteelyBob

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Re: Cavendish experiment
« Reply #180 on: May 10, 2021, 08:41:09 PM »
If the results can be polluted by other non-gravitational effects, then they can also be created by non-gravitational effects.

Evidence, please, that the second half of that sentence follows from the first. Quote me a physicist (because you're just a random internet person, you see) who actually say that the existence of an error source in an experiment could mean that the totality of the result is in fact something other than that which they thought was being measured.

They just don't know what they are measuring, as stated by Quinn above.
Where does Quinn say he doesn't know what they are measuring? He certainly says, as do his colleagues, that they can't account for all of the errors, but there is no doubt in any of their extensive work that they doubt the existence of G. The wildest assertions anybody is making outside of this forum is that G might in some way be slightly variable, but even that is generally viewed as a fairly wild opinion.

Since you only listen to physicists (apart from when they describe the shape of the earth or the existence of gravity), here's our man Quinn introducing the very Royal Society event that you have bizarrely used to imply that G doesn't exist:

Quote
A misunderstanding of the metrology of weak force physics may in turn imply that the experimental tests that have established the inverse square law and the universality of free fall thus far are flawed in some subtle fashion. This makes for a potentially exciting situation and perhaps explains the general interest shown in our apparently mundane and painstaking work on G.

It's great read - lots of detail from Quinn, and numerous papers outlining many fascinating ways of measuring G. No mention of anybody believing that G doesn't exist, or that the earth might be flat, but to fair I didn't read them all. Do let us know if you find any juicy quotes Tom.

https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0253?cookieSet=1

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Offline Tom Bishop

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Re: Cavendish experiment
« Reply #181 on: May 11, 2021, 12:11:46 AM »
If the results can be polluted by other non-gravitational effects, then they can also be created by non-gravitational effects.

Evidence, please, that the second half of that sentence follows from the first. Quote me a physicist (because you're just a random internet person, you see) who actually say that the existence of an error source in an experiment could mean that the totality of the result is in fact something other than that which they thought was being measured.

The analogy we looked at earlier by the astrophyscist earlier shows that the non-gravity effects can create the recorded effects:

Quote
Therefore, when trying to measure it, the other forces can cause systematic errors. It is akin to trying to measure the weight of a feather, outdoors, in a slight breeze, with an old pair of scales.

In the above example the breeze makes up the majority of the effect, creating systemic errors.

Quinn doubts that he is measuring gravity in his statement "We should be able to measure gravity." Obviously if he is not measuring gravity he is measuring something else.

In the link you posted Quinn also suggests that it could be that gravity isn't universal and that it only applies on astrophysical scales:
https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0253

Quote
What matters then is not the actual value of G itself (give or take a percentage or so) but its uncertainty. The real importance of the accuracy of G is arguably that it can be taken as a measure, in popular culture, of how well we understand our most familiar force: the discrepant results may signify some new physics, or they may demonstrate that we do not understand the metrology of measuring weak forces. Owing to the lack of theoretical understanding of gravity, as alluded to earlier, there is an abundance of respectable theories that predict violations of the inverse square law or violations of the universality of free fall. In fact, a growing view is that G is not truly universal and may depend on matter density on astrophysical scales, for example. A misunderstanding of the metrology of weak force physics may in turn imply that the experimental tests that have established the inverse square law and the universality of free fall thus far are flawed in some subtle fashion. This makes for a potentially exciting situation and perhaps explains the general interest shown in our apparently mundane and painstaking work on G.

This clearly shows a suggestion that he is not measuring gravity in the Cavendish Experiment; that it doesn't apply at smaller scales in the laboratory.

The "new physics" Quinn refers to is that gravity doesn't exist in the Cavendish Experiment test because it only mainly applies at larger scales in that suggestion.

Another quote from the Scientific American article says that the non-gravity effects could easily overwhelm the experiment and make up the effect:

Quote
Although gravity seems like one of the most salient of nature’s forces in our daily lives, it’s actually by far the weakest, making attempts to calculate its strength an uphill battle. “Two one-kilogram masses that are one meter apart attract each other with a force equivalent to the weight of a few human cells,” says University of Washington physicist Jens Gundlach, who worked on a separate 2000 measurement of big G. “Measuring such small forces on kg-objects to 10-4 or 10-5 precision is just not easy. There are a many effects that could overwhelm gravitational effects, and all of these have to be properly understood and taken into account.
« Last Edit: May 11, 2021, 12:43:57 AM by Tom Bishop »

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Offline stack

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Re: Cavendish experiment
« Reply #182 on: May 11, 2021, 12:31:36 AM »
The analogy we looked at earlier by the astrophyscist earlier shows that the non-gravity effects can create the recorded effects:

Quote
Therefore, when trying to measure it, the other forces can cause systematic errors. It is akin to trying to measure the weight of a feather, outdoors, in a slight breeze, with an old pair of scales.

In the above example the breeze makes up the majority of the effect.

Does the feather not exist?

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Offline Tom Bishop

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Re: Cavendish experiment
« Reply #183 on: May 11, 2021, 12:54:14 AM »
The analogy we looked at earlier by the astrophyscist earlier shows that the non-gravity effects can create the recorded effects:

Quote
Therefore, when trying to measure it, the other forces can cause systematic errors. It is akin to trying to measure the weight of a feather, outdoors, in a slight breeze, with an old pair of scales.

In the above example the breeze makes up the majority of the effect.

Does the feather not exist?

The analogy is clearly such that the feather could not be there and the results would have no significant difference.

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Offline Rama Set

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Re: Cavendish experiment
« Reply #184 on: May 11, 2021, 12:56:18 AM »
 :-X
If the results can be polluted by other non-gravitational effects, then they can also be created by non-gravitational effects.

Evidence, please, that the second half of that sentence follows from the first. Quote me a physicist (because you're just a random internet person, you see) who actually say that the existence of an error source in an experiment could mean that the totality of the result is in fact something other than that which they thought was being measured.

The analogy we looked at earlier by the astrophyscist earlier shows that the non-gravity effects can create the recorded effects:

Quote
Therefore, when trying to measure it, the other forces can cause systematic errors. It is akin to trying to measure the weight of a feather, outdoors, in a slight breeze, with an old pair of scales.

In the above example the breeze makes up the majority of the effect, creating systemic errors.

Making measurement difficult, not impossible.

Quote
Quinn doubts that he is measuring gravity in his statement "We should be able to measure gravity." Obviously if he is not measuring gravity he is measuring something else.

He doesn’t say he is not measuring gravity so your conclusion is arrived at from a faulty premise.

Quote
In the link you posted Quinn also suggests that it could be that gravity isn't universal and that it only applies on astrophysical scales:
https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0253

Quote
What matters then is not the actual value of G itself (give or take a percentage or so) but its uncertainty. The real importance of the accuracy of G is arguably that it can be taken as a measure, in popular culture, of how well we understand our most familiar force: the discrepant results may signify some new physics, or they may demonstrate that we do not understand the metrology of measuring weak forces. Owing to the lack of theoretical understanding of gravity, as alluded to earlier, there is an abundance of respectable theories that predict violations of the inverse square law or violations of the universality of free fall. In fact, a growing view is that G is not truly universal and may depend on matter density on astrophysical scales, for example. A misunderstanding of the metrology of weak force physics may in turn imply that the experimental tests that have established the inverse square law and the universality of free fall thus far are flawed in some subtle fashion. This makes for a potentially exciting situation and perhaps explains the general interest shown in our apparently mundane and painstaking work on G.

This clearly shows a suggestion that he is not measuring gravity in the Cavendish Experiment; that it doesn't apply at smaller scales in the laboratory.

The "new physics" Quinn refers to is that gravity doesn't exist in the Cavendish Experiment test because it only mainly applies at larger scales in that suggestion.

Another quote from the Scientific American article says that the non-gravity effects could easily overwhelm the experiment and make up the effect:

Quote
Although gravity seems like one of the most salient of nature’s forces in our daily lives, it’s actually by far the weakest, making attempts to calculate its strength an uphill battle. “Two one-kilogram masses that are one meter apart attract each other with a force equivalent to the weight of a few human cells,” says University of Washington physicist Jens Gundlach, who worked on a separate 2000 measurement of big G. “Measuring such small forces on kg-objects to 10-4 or 10-5 precision is just not easy. There are a many effects that could overwhelm gravitational effects, and all of these have to be properly understood and taken into account.

Saying G is not universal is not the same as saying gravity isn’t universal. G is the constant that mediates the relationship between the mass product and 1/r2, not gravity itself. He is definitely saying gravity exists just that it may not be constant like the other forces. He also says nothing about how likely that hypothesis is.
Th*rk is the worst person on this website.

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Offline stack

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Re: Cavendish experiment
« Reply #185 on: May 11, 2021, 01:52:30 AM »
The analogy we looked at earlier by the astrophyscist earlier shows that the non-gravity effects can create the recorded effects:

Quote
Therefore, when trying to measure it, the other forces can cause systematic errors. It is akin to trying to measure the weight of a feather, outdoors, in a slight breeze, with an old pair of scales.

In the above example the breeze makes up the majority of the effect.

Does the feather not exist?

The analogy is clearly such that the feather could not be there and the results would have no significant difference.

How can that be? How do you get that interpretation when he is actually, literally/analogously, saying he is trying to measure a thing, a feather (gravity), but there are other things that make it difficult? The thing exists that he is measuring, it's just hard to measure. Where is it clearly stated that he is trying to measure nothing? Does a feather mean the same to you as nothing?

Re: Cavendish experiment
« Reply #186 on: May 11, 2021, 06:52:33 AM »
Quinn does not talk about being able to measure gravity.

Actually, he does. Maybe you should read the article:

https://www.scientificamerican.com/article/puzzling-measurement-of-big-g-gravitational-constant-ignites-debate-slide-show/



I would ask that whenever you quote me you do not cherry pick to misrepresent what I wrote.
The full quote is:

"Quinn does not talk about being able to measure gravity. He rather talks about the degree of precision to which we can measure it."

The above is consistent to what is written in the article that you posted and also to the one I posted.

Offline Action80

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Re: Cavendish experiment
« Reply #187 on: May 11, 2021, 11:41:37 AM »
Quinn says "Could these unresolved discrepancies in G hide some new physics? This seems unlikely. I believe undiscovered systematic errors in all or some of these new experiments is the answer"
At the top of the article you can see that the "unresolved discrepancies" are "about 400ppm".

It is clear that he believes that it is the differences of up to 400ppm that are caused by the systematic errors. He does not say that the systematic errors give him any lack of confidence beyond these discrepancies.
Quinn does not talk about being able to measure gravity. He rather talks about the degree of precision to which we can measure it.

As I said, you cannot really believe that something that cannot be measured cannot exist. To give you an example, what is the distance from the Earth to the Moon? Can it be measured within FE?

Also to give you an example which is more analogous to the discussion on what Quinn says, can you measure your height in micrometers (μm)? If not, does this mean that you do not exist?
If you have a tool marked in micrometers, then yes, I could do so.

Let me know when you get one.

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Offline Tom Bishop

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Re: Cavendish experiment
« Reply #188 on: May 11, 2021, 11:52:30 AM »
Quinn does not talk about being able to measure gravity.

Actually, he does. Maybe you should read the article:

https://www.scientificamerican.com/article/puzzling-measurement-of-big-g-gravitational-constant-ignites-debate-slide-show/



I would ask that whenever you quote me you do not cherry pick to misrepresent what I wrote.
The full quote is:

"Quinn does not talk about being able to measure gravity. He rather talks about the degree of precision to which we can measure it."

The above is consistent to what is written in the article that you posted and also to the one I posted.

Incorrect.

“It’s not a thing one likes to leave unresolved, we should be able to measure gravity.”

“The Newtonian constant of gravitation, a constant too difficult to measure?”

He is literally talking about the ability to measure gravity there in those quotes.

How can that be? How do you get that interpretation when he is actually, literally/analogously, saying he is trying to measure a thing, a feather (gravity), but there are other things that make it difficult? The thing exists that he is measuring, it's just hard to measure. Where is it clearly stated that he is trying to measure nothing? Does a feather mean the same to you as nothing?

I didn't say that the scientists don't think that the feather is there. Most of them do think that they are trying to measure something that exists. The problem is that they can't do it reliably; there are other dominating effects at that range getting in the way, creating results that are in "wild disagreement with each other", to the point that some speculate on "new physics" where gravity's effect only applies on astrophysical scales.

Whether you call it human error, the presence of dominating effects, or claim that the theory of gravity is non-universal and wrong, all of this has the same result: We can't measure gravity in this experiment.
« Last Edit: May 11, 2021, 12:20:16 PM by Tom Bishop »

Re: Cavendish experiment
« Reply #189 on: May 11, 2021, 01:00:27 PM »
They just cannot measure the gravity constant to the accuracy they would expect to be able to.  Plancks constant,  speed of light, pi.  Did he post anything about the shape of the Earth. Utterly ridiculous.  Fact: matter has three dimensions.  The inability to do math does not invalidate science.

Offline Action80

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Re: Cavendish experiment
« Reply #190 on: May 11, 2021, 01:06:31 PM »
They just cannot measure the gravity constant to the accuracy they would expect to be able to.  Plancks constant,  speed of light, pi.  Did he post anything about the shape of the Earth. Utterly ridiculous.  Fact: matter has three dimensions.  The inability to do math does not invalidate science.
I don't think that anyone has accurately measured the speed of light either.

That means all of it is just speculation.

Re: Cavendish experiment
« Reply #191 on: May 11, 2021, 01:14:13 PM »
If you have a tool marked in micrometers, then yes, I could do so.

Let me know when you get one.
Right. But this is the exact point. Micrometres are small and therefore hard to measure.
With a regular tape measure you can't measure them.

That doesn't mean that tape measures don't work or you can't measure distances or that distances don't exist.
It just means with the tools at hand you can only measure things to a certain precision - which is always the case, actually.

And sure, they would like to be able to measure G more accurately, but the values they measure at the moment have a discrepancy of less than 1 part in 2000. Plenty good enough for all practical purposes.

Nothing in these quotes casts any doubt on the existence of gravity. The model we have of gravity is good enough to land rovers on Mars and send probes to Pluto. I reckon that's a pretty successful model.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

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Offline Rama Set

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Re: Cavendish experiment
« Reply #192 on: May 11, 2021, 01:29:39 PM »
If you have a tool marked in micrometers, then yes, I could do so.

Let me know when you get one.
Right. But this is the exact point. Micrometres are small and therefore hard to measure.
With a regular tape measure you can't measure them.

That doesn't mean that tape measures don't work or you can't measure distances or that distances don't exist.
It just means with the tools at hand you can only measure things to a certain precision - which is always the case, actually.

And sure, they would like to be able to measure G more accurately, but the values they measure at the moment have a discrepancy of less than 1 part in 2000. Plenty good enough for all practical purposes.

Nothing in these quotes casts any doubt on the existence of gravity. The model we have of gravity is good enough to land rovers on Mars and send probes to Pluto. I reckon that's a pretty successful model.

More importantly the measurements of the Cavendish experiment agree with practical applications of Newton’s law to a high degree. Whatever failings the experts are complaining about, it’s not as big a deal as the FEers are making it.
Th*rk is the worst person on this website.

Offline Action80

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Re: Cavendish experiment
« Reply #193 on: May 11, 2021, 01:33:23 PM »
If you have a tool marked in micrometers, then yes, I could do so.

Let me know when you get one.
Right. But this is the exact point. Micrometres are small and therefore hard to measure.
With a regular tape measure you can't measure them.

That doesn't mean that tape measures don't work or you can't measure distances or that distances don't exist.
It just means with the tools at hand you can only measure things to a certain precision - which is always the case, actually.

And sure, they would like to be able to measure G more accurately, but the values they measure at the moment have a discrepancy of less than 1 part in 2000. Plenty good enough for all practical purposes.

Nothing in these quotes casts any doubt on the existence of gravity. The model we have of gravity is good enough to land rovers on Mars and send probes to Pluto. I reckon that's a pretty successful model.
I didn't state they were not measuring anything.

I, of course, do not believe any of the malarkey concerning Pluto and Mars, but that is another thread.

I merely pointed out that Quinn states they cannot measure gravity.

They have numbers, not a measurement of gravity.

Re: Cavendish experiment
« Reply #194 on: May 11, 2021, 01:47:50 PM »
I merely pointed out that Quinn states they cannot measure gravity.
But you are cherry picking that statement and not looking at it in the context of the article which basically says "measuring G is hard, but we should be able to do better". Nothing in that article casts any doubt on the existence of gravity, it explicitly says that this doesn't change any scientific theories.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

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Offline Tom Bishop

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Re: Cavendish experiment
« Reply #195 on: May 11, 2021, 02:04:50 PM »
I merely pointed out that Quinn states they cannot measure gravity.
But you are cherry picking that statement and not looking at it in the context of the article which basically says "measuring G is hard, but we should be able to do better". Nothing in that article casts any doubt on the existence of gravity, it explicitly says that this doesn't change any scientific theories.

Nope. Saying that they need do do better isn't a statement that they are measuring gravity.

Re: Cavendish experiment
« Reply #196 on: May 11, 2021, 03:32:32 PM »
I merely pointed out that Quinn states they cannot measure gravity.
But you are cherry picking that statement and not looking at it in the context of the article which basically says "measuring G is hard, but we should be able to do better". Nothing in that article casts any doubt on the existence of gravity, it explicitly says that this doesn't change any scientific theories.

Nope. Saying that they need do do better isn't a statement that they are measuring gravity.

When he says "measuring G is hard, but we should be able to do better" what do you think that he is saying that they are measuring?
In what way is it not a statement that they are measuring gravity?

Re: Cavendish experiment
« Reply #197 on: May 11, 2021, 04:01:32 PM »
I merely pointed out that Quinn states they cannot measure gravity.
But you are cherry picking that statement and not looking at it in the context of the article which basically says "measuring G is hard, but we should be able to do better". Nothing in that article casts any doubt on the existence of gravity, it explicitly says that this doesn't change any scientific theories.

Nope. Saying that they need do do better isn't a statement that they are measuring gravity.

When he says "measuring G is hard, but we should be able to do better" what do you think that he is saying that they are measuring?
In what way is it not a statement that they are measuring gravity?
Tom plays these semantic games endlessly to pretend people are saying things which they clearly aren't saying.
As we've seen in this thread, it can go on for pages.
And he's extremely selective about what he will accept from people who are "authorities".
The people he's quoting here clearly think that gravity is a thing and that the earth is a sphere.
Why he doesn't accept their authority on those points remains a mystery.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

Offline Action80

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Re: Cavendish experiment
« Reply #198 on: May 11, 2021, 04:58:39 PM »
I merely pointed out that Quinn states they cannot measure gravity.
But you are cherry picking that statement and not looking at it in the context of the article which basically says "measuring G is hard, but we should be able to do better". Nothing in that article casts any doubt on the existence of gravity, it explicitly says that this doesn't change any scientific theories.

Nope. Saying that they need do do better isn't a statement that they are measuring gravity.

When he says "measuring G is hard, but we should be able to do better" what do you think that he is saying that they are measuring?
In what way is it not a statement that they are measuring gravity?
Quinn explains what he is saying when states, "We should be able to measure gravity."

That clearly means he understands we are not currently measuring gravity, due to the issue of systematic errors in the experiments.

Pretty simple and not so hard to understand.

Offline SteelyBob

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Re: Cavendish experiment
« Reply #199 on: May 11, 2021, 05:11:04 PM »
I didn't say that the scientists don't think that the feather is there. Most of them do think that they are trying to measure something that exists. The problem is that they can't do it reliably; there are other dominating effects at that range getting in the way, creating results that are in "wild disagreement with each other", to the point that some speculate on "new physics" where gravity's effect only applies on astrophysical scales.

Whether you call it human error, the presence of dominating effects, or claim that the theory of gravity is non-universal and wrong, all of this has the same result: We can't measure gravity in this experiment.

That's some vintage word twisting right there. Nobody in any of the sources we've discussed is saying that.

The comment was:

Quote
G is not truly universal and may depend on matter density on astrophysical scales

That is not the same thing. G is the gravitational constant - the point being that some are speculating that it might vary, depending on matter density on astrophysical scales.

Stop it. You aren't very good at this, and everybody can see through it.