Difference between revisions of "Talk:Essay:Quantifying Order"

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(Reply about making GPB article.)
(If you find the math in relativity fun, great, but relativity is not going to help anyone. It never has. Pick up a Bible in between some equations.)
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::::::On the contrary.  You are exactly the right girl to write this.  But not yet.  Do GR first, OK?  And you'll have to take off your instructor hat, and put on your explainer-for-lay-people hat, so that it won't be 200 pages long.  Whenever you reach the point where you think "You guys this is so ''awesome''", don't go into "and so I have to write the awesome equations".  Go into "how can I convey the awesomeness to my reader?".  [[User:PatrickD|PatrickD]] 11:32, 15 November 2009 (EST)
 
::::::On the contrary.  You are exactly the right girl to write this.  But not yet.  Do GR first, OK?  And you'll have to take off your instructor hat, and put on your explainer-for-lay-people hat, so that it won't be 200 pages long.  Whenever you reach the point where you think "You guys this is so ''awesome''", don't go into "and so I have to write the awesome equations".  Go into "how can I convey the awesomeness to my reader?".  [[User:PatrickD|PatrickD]] 11:32, 15 November 2009 (EST)
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:::::::I don't want to perpetuate this debate, but I don't want a lack of response to be misinterpreted.  Relativity has quasi-religious status for many; they'll defend regardless of what the evidence is, regardless of its absurd inconsistencies, and regardless of its far-fetched assumptions and non-falsifiability.  I don't mind relativity, and look forward to reviewing the updated entry.  But open-mindedness is not a trait of many relativists, who will demonize anyone who points out its fairly obvious flaws.
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:::::::One way to evaluate religions, or quasi-religions, is to look at the fruit it bears.  What has it helped achieved?  In the case of relativity, it has produced nothing.  Nil.  Zippo.  After nearly 100 years and a ton of money.  If you find the math in relativity fun, great, but relativity is not going to help anyone.  It never has.  Pick up a Bible in between some equations.--[[User:Aschlafly|Andy Schlafly]] 18:31, 15 November 2009 (EST)

Revision as of 18:31, 15 November 2009

"Subsequently, however, more accurate measurements with more sophisticated technology have determined this precession to be 55 arc-seconds per century, nearly 30% off the number provided by relativity."

Please provide a citation in the article for this. I'm shocked that I somehow missed the news. Thanks much. --KSorenson 17:48, 14 November 2009 (EST)

I'm urging you to look beyond what you're taught. I went through the same physics curriculum as others, and it is what isn't taught that matters. Earnestly.--Andy Schlafly 17:53, 14 November 2009 (EST)
Okay. Let's find a way of making that point without quoting an incorrect value for the Mercury anomaly then? Cause putting in a number that's not actually supported by observations just to make a philosophical point seems kind of … I dunno. Deceptive? --KSorenson 17:58, 14 November 2009 (EST)
Kate, if I can call you that, I have no reason to lie about this. I'm not applying for any grants. I'm not trying to get a PhD from liberal professors. I'm not worried about what my colleagues might say. Like the Bible, I'm just telling the truth, and trying to learn more of it.
The physics journals all seem to require payment for access. But type this into a Google search: 5599.7 Mercury. You'll then see what the liberal physics professors won't tell you, as Google returns fragments from limited-access journals. Then, please, pause for a moment and ask yourself: why didn't they tell you this so you could decide for yourself, rather than being told what to think?--Andy Schlafly 18:40, 14 November 2009 (EST)
Oh, okay. I see where you made an honest mistake.
There are two numbers at play here: there's the observed precession of Mercury's orbit, and then there's the anomaly. The anomaly is the amount by which the observed precession differs from the mathematically predicted precession. What you did was quote a figure for the anomaly using the figure for the observed precession. Hang on, lemme splain.
The precession of an orbit is the sum of several effects. Newton's approximation for gravity predicted three different effects: axial precession of 5,025 arc seconds per century, 530 additional arc seconds per century from the gravitational effects of the other planets, and a tiny amount, less than one arc second per century, due to the fact that the sun isn't a perfect sphere. (Those numbers are all rounded off; the precise figures are trivially googlable.)
If you add up the precession predicted by Newton's approximation, you get exactly 5,557.02 arc seconds per century.
But if you run the numbers using the Einstein equations instead of the Newton equations — using the same constants for things like the mass and shape of the sun — you get a precession of exactly 5,600±0.04 arc seconds per century. It's really weird that it would be a round number like that, but that's how the math works out.
The observed precession of Mercury's orbit? It's 5,599.7 arc seconds per century. Which is where you got your number from. And that means the general relativity prediction was accurate to within (deep breath) one half of one one hundredth of one percent.
That's like shooting an arrow from Los Angeles and hitting the bullseye in Melbourne.
Would you be a dear and remove the incorrect anomaly figure from your essay now? I know it's a work in progress and I hate nitpickers, but somebody could stumble across that and be misinformed.--KSorenson 19:11, 14 November 2009 (EST)
Your point is an excellent one. Thank you. The 30% figure was wrong for the reasons you provide.
But the underlying point in this entry remains correct: due to advances in precision in measurement, the prediction of relativity no longer matches the data on the precession. The discrepancy is much greater than the margin of error, which is all that matters from a logical perspective. The entry has been updated accordingly, and I welcome further comments you may have.--Andy Schlafly 19:44, 14 November 2009 (EST)

(Unindent) I'm not sure you're going to welcome these comments, sir. Because you're just flat-out, provably, unequivocally wrong on this one. The observed value of the precession of Mercury hasn't been changed in a hundred years, because it's a direct observation. We measured it with telescopes, and those were just fine at that scale a century ago.

I'm afraid your edit made the offending section paragraph even more misleading than it was. Predicted value of the precession (via Newton) in 1915: 5,557. Observed value in 1915? 5,600. Difference? 43. Predicted value from the Einstein equations? 5,600. Observed value today? Still 5,600. Difference? Ridiculously small. I know you're actively working on this essay, and I feel really bad about beating you up over this, but you wouldn't have the paragraph in there unless you thought it had value.

Just so you know, I've got some feedback on your paragraph on quantum mechanics as well. For starters, the position and momentum of a particle is exactly as uncertain after an observation as it is before, because reducing uncertainty of the position increases uncertainty of the momentum and vice versa. They're intrinsically linked. Maybe that's not your point; measuring a particle does, I suppose, bring about a sort of philosophical order that was previously absent — we know where the particle is now — but at the cost of reducing our knowledge about another aspect of the particle's motion. But your essay isn't fleshed out enough for me to really see yet what you're getting at, so that might be irrelevant to your point. --KSorenson 20:00, 14 November 2009 (EST)

Kate, I don't have an ax to grind about this. General Relativity was developed to explain the Mercury precession, so the theory certainly should fit the data. I expected that it would. But the fit isn't there anymore, due to more precise measurements. It's beyond the margin of error, and logically that's all that matters. You're using rounding above that obscures what the margin of error is. Professor Will does not even include this test in his recent summary of all the evidence for GR, and we can now see why. Those are the facts, and logic applied to the facts. Anyone has free will to accept or deny it. I accept the facts and logic as they require.
You make an interesting point about position, but I don't think the essay is incorrect because it says nothing about momentum. Observation can pin down the position, which is relevant to establishing order. But without observation there is disorder. That is the basic point.--Andy Schlafly 20:11, 14 November 2009 (EST)
Right, but there's an error of fact buried in there. It's a totally innocent one, I'm sure; I'm not accusing you of axe-grinding. It's just that the precession of the perihelion of Mercury has not changed since 1916 when the theory was published. It's not that we measured it with telescopes before 1916 and got a rough estimate, and now we measure it with better telescopes and have a much more precise figure. We measured it before 1916 and got a very accurate figure because measuring the motion of Mercury just isn't that hard, and the measurements we make today with better telescopes say only that yup, the older measurements were pretty much spot on.
What we have done since then is to much more precisely measure the oblateness of the sun. There was a big controversy about that back in the … hmm … 80s I think it was? Goldberg and Dicke claimed that the sun was much "fatter" than previously thought, which would have made the predictions from general relativity different from the observed precession. Maybe that's what you're thinking of? For a while there was a lot of disagreement about what shape the sun actually is, but that's been pretty much put to bed with both more accurate ground-based observations in the 90s and helioseismography.
Anyway, saying that the prediction matched the observation in 1916 and doesn't today is simply flat-out false. If your argument depends on it, then you're hurting your argument with this point. If it doesn't, then what's the harm in fixing it?
Thanks for clarifying your point about quantum mechanics. --KSorenson 20:35, 14 November 2009 (EST)
Kate, as I said, I don't care either way, but I am going to tell the truth. GR fit the observed data in 1916 (indeed, GR was developed to fit it), but now (due to more sophisticated measurements) the GR prediction is wrong by more than the margin of error. None of your comments above address the margin of error, which must be the scientific focus. A difference between theory and observation is not "ridiculously small" if it is more than the margin of error, as in this case.--Andy Schlafly 20:47, 14 November 2009 (EST)
Perhaps this is what Mr. Schlafly is referring to. The article states that 5599.7 arc-seconds is the observed value. KSorenson is quoting a value of 5,600 (±0.04). 5600-.04=5599.96. From just those values then yes the relativity value is higher by .26 arc-seconds even factoring in the error. The only thing I ask is what is the error range for the observed value? ameda 21:08, 14 November 2009 (EST)
Presumably the error range for the observed value is no more than .1. Again, note that Professor Will conspicuously omits this famous claim of evidence for GR from his recent comprehensive summary of the evidence for GR, as cited in this entry.--Andy Schlafly 21:12, 14 November 2009 (EST)

(unindent again because I'm lazy with bullets) We can do a heck of a lot better than "presumably," Andy, and as a person who cares deeply about facts and logic, you darned well know that. I happen to have the Pijpers paper from 94 here; I dug it out when I thought you might have been thinking of helioseismography. In it he cites radar ranging studies from 1976 to 1992. Here's the data, with margins of error. Note that these numbers are for the anomaly, and not the precession total, and remember that the figure from the Einstein equation is 42.98 ± 0.04, okay?

  • 43.11 ± 0.21 (Shapiro 76)
  • 42.92 ± 0.20 (Anderson 87)
  • 42.94 ± 0.20 (Anderson 91)
  • 43.13 ± 0.14 (Anderson 92)

So the Einstein prediction is within the margin of error of those four radar-ranging measurements of the Mercury anomaly. I'm sure there've been more recent studies, but I don't have them literally sitting in front of my face at the moment, so those are the ones I'm citing. Can I see your numbers that say the Einstein prediction is outside the margin? More recent data than what I have in my hand here maybe? (This Pijpers paper is on ARXIV, by the way, if you want to check it out.)--KSorenson 21:17, 14 November 2009 (EST)

Oh, and just incidentally? Will didn't leave Mercury out of his paper; he just talked about it in really jargony physics-paper language.

Three decades of experiments, ranging from the standard light-deflection and perihelion-shift tests to lunar laser ranging, planetary and satellite tracking, and geophysical and astronomical observations, have placed bounds on the PPN parameters consistent with general relativity.

"PPN" is the parameterized post-Newton formalism, a rewriting of the law of universal gravitation to include coefficients derived from general relativity. The Einstein field equations are nightmarish to solve, so PPN was created as a middle-ground approximation between the (good but not good enough in some contexts) Newton approximation and the agonizing pain of having to actually solve the Einstein field equations every time you want to calculate the delta-vee required during a solar slingshot maneuver for a planetary probe. What Will said in that paper is the PPN approximation has been tested against general relativity and supported by 30 years of experiments.

This is really getting into the tall grass, and I know how you hate wasting time. Maybe we can bring this conversation to a conclusion? --KSorenson 21:38, 14 November 2009 (EST)

Kate, I have an open mind about this but, quite honestly, the relativists protest too much. Why do you care so much about defending relativity? Not to pick on you, however, because many trained in math and physics likewise defend relativity like they are defending their own reputation. It's bizarre. Regardless of the reason, protesting too much is not scientific.
Answering the substance of your post, your most recent data is from 1992 (17 years ago, with the data probably older than that), and its margin of error confirms what I said: it's approaching 0.1. Combine that 0.1 (or 0.14 if you like) with the most recent data and it's clear that GR no longer fits the data. Of course, no one is going to dare publish a paper claiming GR is disproved by the data, and even if they tried, no journal would accept it. So the trail goes cold at this point, just as the data diverge from the GR predictions and the margin of error declines to where it can't save GR.--Andy Schlafly 22:37, 14 November 2009 (EST)
"Why do you care so much about defending relativity?" 'Cause teaching physics is something I do for a living. 'Cause I think it's really neat. 'Cause seeing somebody totally misunderstand it, and then go on to draw incorrect conclusions based on his misunderstanding of it, and finally to pass those incorrect conclusions on to impressionable kids who trust him … well, that just breaks my heart. You can call it protesting too much if you want, Andy. But I wish you could understand that it's really just me trying to help.
I wouldn't have fought you on this at all if you'd said something like "A dozen eggs contains fifteen eggs, plus or minus two." That's just obviously wrong, and nobody who reads it would fall for it. But you're hiding your false conclusion behind a wall of data that you know most people won't bother looking up for themselves, and that's just dishonest. That's unworthy of anybody who'd call himself a teacher, and what's more I think you know that in your heart. You seem like a conscientious guy; what does your conscience say to you about this?
Anyway, it's your essay, you can obviously write what you want. But let me just give you a heads up: Next week, when I put your theory of relativity page on the table for major surgery? I don't think you're gonna like it. --KSorenson 23:24, 14 November 2009 (EST)
Kate, you didn't address the substance of my comment about the evidence, but don't worry about it. The bottom line is clear: no physics major, no physics grad student, and no physics teacher should dare criticize relativity, no matter what the data say. The political grip on this issue is intense. In fact, to be honest, I would advise against your criticizing it in any way. It could harm your (or any other teacher's or physicist's) career. There are examples of people who were denied tenure simply because they criticized evolution, and the politics here is just as strong.
I look forward to learning from your entry on the theory of relativity. The math is fascinating regardless of its manifestation in reality.--Andy Schlafly 23:33, 14 November 2009 (EST)

(unindent) "Kate, you didn't address the substance of my comment about the evidence, but don't worry about it." What was there to address? You made an arithmetic error. Do you want me to send you the Mathematica scatterplot I made just to triple-check that I was interpreting the data correctly? It's pretty. The error bars are blue.

Andy, I wish I could get you to come to my department for a week. Just one week, any week. Our students, grad students, associates, profs, chair, heck, even the janitor criticizes relativity every day. I could get you a meeting with one of our theoretical cosmologist; he's been pulling his hair out for years trying to make some progress on the vacuum energy problem. For a while there he was coming into my office a couple times a week and saying … well, unprintable things about partial differential equations. Even we theoretical physicists think general relativity is a mathematical mess.

But we respect it anyway. Because it works, at least as far as anybody's been able to measure.

Can I ask you a question? What's your beef with relativity? I mean, I know you question the data, but … why? Are you just being iconoclastic? I don't mean that in a dismissive way; I totally understand and respect the impulse to say "Everybody agrees that this is true, so I'm going to question it!" I'd really just like to understand your point of view on this, whatever it may be. --KSorenson 23:44, 14 November 2009 (EST)

GR's predictions are off by more than the margin of error, as we discussed in detail above; it and special relativity have absurd discontinuities; there are logical flaws, as in relativistic mass; it conflicts with QM; and it predicts gravitons that have never been found despite wasting hundreds of millions of taxpayer dollars on it. Relativity pulls people away from reading the Bible and relativity is pushed big-time by liberals. It chills progress by intimidating people against criticizing it. Other than that, the theory is pretty good!--Andy Schlafly 00:05, 15 November 2009 (EST)
Wow, Mr. Schlafly must really like this conversation, he actually made a joke. ;) jk ameda 00:15, 15 November 2009 (EST)
Thanks very much for taking the time to reply; I understand better now. Of course, some of that is unmitigated garbage, and we'll have plenty of chances to deal with it when I fix your theory of relativity article next week, so I'll skip some points for now.
  • You discussed the fact that the predictions are outside the margin of error; I pointed out to you repeatedly that you were mistaken. I even offered to show you a plot. So come on.
  • To be frank, relativity doesn't conflict with quantum mechanics; the two theories don't overlap in any domains we can presently observe. But that's the problem. They don't overlap, so we don't know how we're going to understand systems where both gravity and quantum mechanics have non-negligible effects. It's entirely possible that every such region of spacetime is sequestered behind an event horizon; that's jokingly called the "convenient cosmic censorship hypothesis" by one of my colleagues.
  • General relativity doesn't predict gravitons at all. General relativity doesn't say anything about particles; the Standard Model predicts the existence of particles (like the Higgs). Gravitons are part of the various attempts to reformulate general relativity as a vector gauge theory, none of which have gotten there yet. And, uh, since none of the gauge theories have gotten there yet, Andy, not one dollar has been spent looking for gravitons. Because we don't know where to look. But we do know that if they could be detected by existing particle accelerators, they would've been. So if and when physicists decide to look for them, it's going to have to start with building an accelerator the size of our galaxy[1], and you'll have your chance to lobby the appropriations committee then.
  • Yes, studying relativity does take people away from time they could spend in religious activities. So does reading this site. Just give me a chance to copy-and-paste my contributions out before you shut it down to remove the temptation.
Anyway, like I said, we'll have plenty of time to have these arguments when I start work on theory of relativity. All I ask is that you engage in constructive collaboration with me and whomever else chooses to help out, rather than pouncing on the "undo" button like you did when I rewrote black hole. We've both demonstrated that we're reasonable adults, I think; we can work together. Deal? --KSorenson 00:22, 15 November 2009 (EST)
  1. WARNING: exaggeration for humorous effect, do not take literally.
I've been quietly following this conversation today, but Kate beat me to the "Submit" button! Well, I'll just point out that scientists can and frequently do "intimidat[e] people against criticizing" pretty much any theory, because they think it's right and they don't want to waste time. It's quite likely close-mindedness, but it exists, and you can't take that as disproof of the theory. I don't think someone who rejected Mendel or Maxwell would get pretty far today, either. (Yes, I know Mendel has been amended with epigenetic inheritance, but I think you get my picture). It's just a bothersome red herring.
I don't know anything about the Mercury data, but the most recent data I've seen here says general relativity might work; it's at the border of the range of error, and it's too precise for any of us to extrapolate. General relativity could be spot on. Or, a new theory being needed - if you're trying to construct a theory of everything, a new theory definitely is needed to deal with quantum mechanics! But, general relativity does predict a lot of things better than Newton. Newton didn't explain everything, nor does general relativity - but I think you can find better stuff to attack it with than an extrapolation of Mercury orbital data. --EvanW 00:37, 15 November 2009 (EST)
Ugh, I really should be sleeping, but this is just such an engaging conversation I can't seem to break away.
If you make a measurement to test a theory and the measurement doesn't match the prediction, there are three possibilities. Either the measurement is wrong ("That's not Mercury, that's Saturn!") or the theory is wrong ("Turns out gravity isn't really caused by leprechauns!") or both are fundamentally right but you failed to take something into account ("We really shouldn't have assumed the sun is a sphere.")
The thing about the Mercury anomaly is that the observed and predicted numbers are insanely close together. So close as to be declared equal within the margin of error. So either general relativity is absolutely right and we accounted for everything — no physicist believes this, by the way — or general relativity is at least incredibly close to being right, so close that the factors we failed to account for are negligible at the scale of the Mercury anomaly.
But the thing is, Mercury is really thin sauce, as gravity goes. The fields are weak, and the prediction we're testing doesn't say anything terribly interesting about the theory. If you want to get a real feel for how general relativity holds up as a physical theory, and not just a mathematical one, you really need to look at the Gravity Probe B data. (Conflict of interest alert: I worked on that project.) That experiment didn't measure gravitation indirectly by observing the motion of a particle; it measured it directly by parallel transporting a vector in a closed loop around a region of curvature. We empirically measured the curvature of spacetime around a gravitating object (the Earth) and found it to be non-zero. Spacetime is not flat, massive bodies do curve spacetime, and the fundamental idea of general relativity reflects nature.
General relativity doesn't just say that a falling body moves like such-n-such. It tells us why. And to see it dismissed out of hand because Andy doesn't care for the size of the error bars on the results of a radar study? That, I confess, rubs me the wrong way. --KSorenson 00:51, 15 November 2009 (EST)
Great point about experimental error. Before I really do sign off for the night, Kate, I'd like to give you an article suggestion: Gravity_Probe_B. I'm enthusiastically looking forward to hearing how it was done! --EvanW 01:00, 15 November 2009 (EST)
Oh, I'm not the girl to write that one. It'd be 200 pages long and full of equations and whole paragraphs of me going "You guys this is so awesome!" --KSorenson 01:09, 15 November 2009 (EST)
On the contrary. You are exactly the right girl to write this. But not yet. Do GR first, OK? And you'll have to take off your instructor hat, and put on your explainer-for-lay-people hat, so that it won't be 200 pages long. Whenever you reach the point where you think "You guys this is so awesome", don't go into "and so I have to write the awesome equations". Go into "how can I convey the awesomeness to my reader?". PatrickD 11:32, 15 November 2009 (EST)
I don't want to perpetuate this debate, but I don't want a lack of response to be misinterpreted. Relativity has quasi-religious status for many; they'll defend regardless of what the evidence is, regardless of its absurd inconsistencies, and regardless of its far-fetched assumptions and non-falsifiability. I don't mind relativity, and look forward to reviewing the updated entry. But open-mindedness is not a trait of many relativists, who will demonize anyone who points out its fairly obvious flaws.
One way to evaluate religions, or quasi-religions, is to look at the fruit it bears. What has it helped achieved? In the case of relativity, it has produced nothing. Nil. Zippo. After nearly 100 years and a ton of money. If you find the math in relativity fun, great, but relativity is not going to help anyone. It never has. Pick up a Bible in between some equations.--Andy Schlafly 18:31, 15 November 2009 (EST)