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Flat Earth Theory / Re: Clarifications on UA
« on: July 21, 2019, 08:29:34 PM »
Gravitational mass is determined by the strength of the gravitational field.  Mass will always be static and constant, but gravitational mass will vary with the strength of the gravitational field.

@markjo, I think you are confusing weight and gravitational mass there.  Here is what I learned from physics textbooks in grad school:

Let mg be the gravitational mass of object 1, Mg be the gravitational mass of object 2, G be the gravitational constant, and r be the separation between the masses.  Then the gravitational force on object 1 is Fg = GmgMg/r2.  So, the gravitational mass determines the strength of the gravitational force on an object.  The strength of the gravitational field created by object 2 at location r is g = GMg/r2.  Then the force is Fg = mgg.  (Although many people do it, I think it is confusing to call g the "acceleration of gravity".)  The force Fg is called the "weight" of object 1.  According to this treatment (which is the standard treatment taught in university physics classes), the gravitational mass of an object does not depend on the gravitational field, but the weight does.  Note also that the gravitational mass of object 1 does not depend on object 2 at all.  For example an object's gravitational mass is the same on Earth and on Jupiter, but the weights on Earth and Jupiter are very different because Earth and Jupiter create different gravitational fields.

Let mi be the inertial mass of object 1.  When a force F acts on object 1 its acceleration will be a = F/mi.  The inertial mass determines the relationship between any force (whatever its cause) and object 1's acceleration.

Experiments showing that mg = mi are routinely done in introductory physics laboratory classes.  In my opinion the coincidence that mg = mi is very surprising!!!  For all other types of forces (for example electrical forces) there are other "charges" that determine the strength of the force, but in this way gravity is special.  The theory of general relativity is built in such a way that mg = mi from the foundation of the theory, but it still does not really tell us why gravity has this property that other forces don't have.  This coincidence of mg = mi is the main problem of uniting gravity and quantum theory -- the biggest current problem of fundamental physics.

I have seen these quotes from sources like Encyclopedia Britannica, which says "Gravitational mass is determined by the strength of the gravitational force experienced by the body when in the gravitational field g.", but I think they are confusing because of their use of passive voice.  What they mean is that you can determine an object's gravitational mass by putting it in a gravitational field g and measuring the force Fg.  If you know g and Fg, then you can calculate mg=Fg/g.  Given the way that the Encyclopedia Britannica article discusses weight vs mass earlier in the article, it would not make sense to interpret this sentence in any other way.  The authors assume that the reader has already understood that "mass" always refers to an object's own properties not related to its location or other surrounding objects.


I find your analysis to be thoughtful, accurate and compelling.

Wow, that is high praise for an internet form comment!  Thanks!

You mention Carol uses too blunt an instrument to dissect and discard religion, and suggest value exists it. I am interested to hear more of your thoughts on this matter.

I am an atheist. I believe religion offers communal and society benefits, but also produces much harm. Presently, I cannot identify any benefit of religion that can be found elsewhere which justifies tolerating the harm.

Nevertheless, I am open to challenging my view, and would like to hear your input.

I'm sorry that it took me so long to reply to this.  It deserved some thought.

Carol does a great job of discarding religion as a scientific theory, but that is too easy because it is not a scientific theory.  Craig is arguing that one's belief in God should be strengthened because God's existence would explain the existence of the universe.  (Unlike Craig and Carol, even if the universe had no beginning instant and is eternal, I might still want an explanation for why there is a universe rather than nothing.)  I have some sympathy with the argument that explanatory power is a reasonable cause for belief.  I often believe things for which I do not have scientific proof because of their explanatory power.  For example, I believe that my wife genuinely loves me, meaning that she experiences loving feelings similar to the feelings that I have for her.  To me this seems like a better explanation for her behavior than that she is engaged in a years-long deception or that she is a philosophical zombie.  I can't have direct access to her (or anyone else's) conscious experiences, so I can never prove scientifically that she experiences loving feelings.  I accept "on faith" that she does feel love for me.  I also believe that I am not stuck in computer simulation of reality, that I am not a Boltzmann brain, that people should not hurt each other, and that God exists.  All of these are extremely strong beliefs that I have without scientific evidence.

In my opinion, the idea that one should only believe things that are supported by science is absurd.  As far as I can tell all people have non-scientific beliefs.  They can give meaning to life, organize other beliefs, provide explanations, and serve other beneficial roles.  Of course, one must strive for consistency of one's beliefs.  For me the reliability of science is a very strong belief, and I allow no conflict between my religious beliefs and science.  God gave us brains capable of rational thought, and God expects us to use them.  My God is not squeezing little miracles into the gaps between known science.  I think creationists for example are confused about both God and science.

I believe in God because it gives me a feeling of purpose and meaning, it helps me to act ethically, it contributes to community, I like its explanatory power (not only for the existence of the universe but also for other things), and it is my habit, to give some examples.  I'm confident that my religion brings me more benefit than harm.  Also, I have no evidence that God does not exist.

Does religion cause more global benefit than harm?  I have no idea!  I wish we had a good randomized, controlled trial for that!  I would comment that I think that a large fraction of religious people, of all religions, are and have been doing it wrong.

So, QED, I hope that answers your curiosity.  At least I enjoyed thinking and writing about it.

Sorry, moderators, for straying off-topic.

Flat Earth Theory / Re: Code for earth moon orbits
« on: May 09, 2019, 08:22:25 AM »
Give it another read. The F=ma example is the simplified state to which perturbations are applied; like the example of the simplified (traditional) model of the atom to which perturbations are applied because the simplified model does not represent reality.

Tom Bishop, that Wikipedia article says "Typically, the 'conditions' that represent reality are a formula (or several) that specifically express some physical law, like Newton's second law, the force-acceleration equation, F=ma.".  In that sentence, I interpret "conditions that represent reality" to mean that F=ma can describe reality rather than only a simplification of it.  Do you believe that Wikipedia is saying that F=ma can only be "the simplified state"?  Can you explain in more detail why you interpret Wikipedia to be saying that?  (I'm not sure what you mean when you refer to an equation as a "state".  In physics literature that I have read the "state" is usually the information about the physical system: positions and velocities of the orbiting bodies in this example.)

Of course F=ma can describe a simplified model when some forces are not included in F.  For example, in the full model describing the Moon's motion, F could include all gravitational forces from the Sun, Earth, Mars, Venus, asteroids, and all other objects acting on the Moon.  In that case F=ma would represent reality, but the exact orbit would be difficult to calculate, so one might temporarily neglect smaller forces.  An approximate orbital path can be calculated using only the force caused by the Earth acting on the Moon.  Then a better approximation can be obtained by including effects of the forces that were neglected.  That process of obtaining a better approximation is what we call "perturbation".

Flat Earth Theory / Re: Code for earth moon orbits
« on: May 08, 2019, 08:40:02 AM »
Quote from: The Listener
The perturbations do not correct the theory of orbital motions; they are provided by that theory.

Would this be backed up by your accompanying provided evidence of nothing at all?

That does not appear to be described anywhere. I encourage you to provide a direct citation for your statements.

Considering the huge wealth of citations and software that others have provided in this and closely related threads recently, I don't think that I can add anything useful by providing more citations.  The disagreement seems to be about how to interpret these many sources, and I only intended my comment to help explain them.  I did notice one interesting quote in this thread here:

The issue is that Perturbation Theory is used to gradually add corrections to make data fit the formula of choice:

This general procedure is a widely used mathematical tool in advanced sciences and engineering: start with a simplified problem and gradually add corrections that make the formula that the corrected problem becomes a closer and closer match to the original formula.

Note that the sentence that you quote from Wikipedia says that one uses the perturbations to obtain a "closer match to the original formula", not as you say to "make data fit the formula of choice".  Wikipedia's sentence is describing a situation in which one simplifies a complicated problem and obtains a formula that is the exact solution to the simplified problem but only an approximate solution of the complicated problem.  That formula is then corrected to more closely match the "original formula", which would be the exact solution of the complicated problem.  The corrections are called "perturbations", and they are prescribed by the original complicated problem.  You don't have to take my word for it.  If you read further in the Wikipedia article, it describes an example in which one wants to model the motion of the Earth, Moon, and Sun.  To simplify the problem, you start with the elliptical orbit of the Moon around the Earth.  You then add a perturbation corresponding to the force of the Sun according to F=ma.  If more accuracy is desired over a longer period, you can add more perturbations.

Flat Earth Theory / Re: Code for earth moon orbits
« on: May 07, 2019, 08:00:12 AM »
@Tom Bishop, the perturbations are derived from the theory and measurements of the planets and other objects.  The perturbations do not correct the theory of orbital motions; they are provided by that theory.  One begins the calculation of an object's orbit with a very rough approximation.  Then one of several standard recipes is used to "correct" that rough approximation so that it better matches the ideal Newtonian theory of orbital motion.

I know of only one exception: Newtonian mechanics is not sufficient for high-accuracy prediction of the orbit of Mercury.  In Mercury's case, General Relativity prescribes perturbations that should be applied to the Newtonian calculation of Mercury's orbit.  (Of course one can also calculate Mercury's orbit directly from GR.) 

@QED: Carol clearly claims that "the evidence is against theism", "science has undermined theism", "there is no longer any reason to take [theism] as your fundamental world view", and theists should "admit they were wrong" and adopt some kind of godless religion.  He says that a religious person has 3 options: 1. deny the evidence, 2. accept the science but deny the implications, 3. admit they were wrong.  All of these sounds like "theistic claims" to me, but maybe I am not clear on your distinction between reaching into theism and making theistic claims.  I think these claims ignore a lot of subtlety, complexity, and versatility in types of theistic beliefs.  Carol is not arguing against a sophisticated theist, and unfortunately Craig lets him get away with it.

I believe that the category error that Carol makes is that he categorizes theism as a scientific, predictive theory when it is not.  I totally agree with Carol when he argues that theism cannot make useful predictions about the natural world and therefore it is not a good scientific theory, but to me that is not a good argument for rejecting it as a religious belief.  At first I was tempted accuse Craig of making exactly the same category error (of classifying theism as a scientific theory), but I think there is a slight difference.  Carol is importing a religious idea (theism) into science and judging is to be bad science, but Craig is importing a scientific idea (the beginning of the universe) into religion and judging it to be good theology.  At least that is my most generous interpretation of what Craig is doing.  In my opinion, Craig's argument is not very convincing as theology, but I would not call it a category error because theists should use observation of God's creation to obtain information about God.  However, such arguments are not likely to be persuasive to non-theists.  On the other hand, because I am a theist, if the universe was shown to have a beginning, the strength of my belief in God might be slightly increased.

Yes, I know there is a difference between a multiverse and a God, but I think that there are parallels in the ways that they are invoked by Carol and Craig respectively in this debate.  Both are used as explanations for our universe by reference to things outside of it.  Both are sufficiently versatile to accommodate many different types of universes.  (Of course some multiverse theories are more constrained, but also some theisms are more constrained.)  Hopefully some day a multiverse theory will make some specific and surprising predictions that we can confirm by measurements, but I am not aware of any multiverse theory having done that yet.

@Rama Set: I agree; Craig was not able to sustain his argument that there is strong evidence for the beginning of the universe.  His argument that a beginning requires an explanation also failed under Carol's attack.

Thanks for this recommendation.  As a theistic physicist (and a physical theist), I found the debate interesting but a little disappointing from both sides.  Craig clearly does not fully understand some of the theorems and other physics that he attempts to use, and Carol does a great job exposing his ignorance.  However, Carol is also speaking outside of his own expertise when he argues against theism as if it is a bad scientific theory.  In my opinion this is just a giant category error.  Of course theism does not make scientific predictions!  Theism, correctly understood, has not been undermined by science because it was never supported by science.  Implicitly Craig makes the same mistake that Carol make here, because he does not call Carol on it.  Basically, I agree with Le Maitre as his views were briefly described in the debate, so it is disappointing that no one here took that position seriously.

Another irritating thing that Carol does is present his own ideas as if they are settled science accepted by most other physicists.  Many of the arguments that he uses are highly controversial among professional cosmologists, including whether the universe is eternal or had a beginning time and whether a multiverse exists.

Here is a question that I wish someone had asked: "Dr. Carol, if you are so confident that the universe needs no explanation, then why are you inventing multiverse theories to explain our universe?  These multiverse theories have no more predictive power than theism because by changing the probability distribution of parameters describing the multiverses (which distribution is completely unobservable) you can predict anything you want about our universe.  Really, what is the difference between the multiverse and God?"   

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