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52 Years and $750 Million Prove Einstein Was Right (nytimes.com)
134 points by jonburs on May 5, 2011 | hide | past | web | favorite | 31 comments



Here's the wikipedia page on it: http://en.wikipedia.org/wiki/Gravity_Probe_B

One point about it is that the probe had a lot of noise, so much noise that it swamped the signal. It was only by developing computer models of the source of the noise, and then subtracting it from the signal that the result was found.

But I find such "adjustments" distasteful. I mean everyone expects a certain answer, and voilĂ  you get that answer. Is there a bug in your code? Or course not - you got the expected answer didn't you?

(See the section called "NASA review" in the wikipedia article.)

Anyway, now that they learned so much about such probes they should launch another one and get much cleaner data.


For those with 65 minutes of time, here's an excellent presentation about it by Dr. Everitt himself:

http://einstein.stanford.edu/Media/Everitt_Brainstorm-flash....


But I find such "adjustments" distasteful.

Well, you have to deal with it somehow. If you know the source of the noise, there's no excuse for not modelling it.


Sure, but the point is that if there's something wrong with your model of the noise, the result could be completely invalid.

Look at the history of Milliken's oil-drop experiment: http://en.wikipedia.org/wiki/Oil_drop_experiment#Millikan.27...

He got the wrong answer, but subsequent researchers who got different results kind of smoothed their own results to match the "correct" (actually wrong) expected result.

I'm not saying that happened here, but it's always a possibility.

Essentially, how do you know when you've modelled the noise accurately enough? When you get the expected right answer? Why not continue to refine the noise model, or consider other ones?


The role that psychology and social dynamics plays in science ought to be more studied. To ignore it is foolish. One person I knew in commutative algebra said that he always adds references to the famous people in the field in his papers for ass kissing purposes. It's just one anecdote but this sort of stuff, I suspect, is much more common than it is thought.



I like the definition of humility by Eliezer Yudkowsky on less wrong - "To be humble is to take specific actions in anticipation of your own errors."

Given Dr. Everitt's commitment to this experiment, I'd wager he was humble enough according to that definition ... though that assumption of mine would simply be a "halo effect" instance?


What you are describing is a very real danger, but if you are modeling actual noise, it's less of a risk than if you are modeling some small systematic shift that you claim you must subtract from the signal. With noise, it's more unlikely that the model would just by chance give a systematic shift to the data. More likely, if the model is wrong, it just won't decrease the noise level.


It's was actually systematic shift, but a periodic one. It wasn't random noise.


Well, true. If the noise was truly random, you couldn't model it, of course. I just meant "noise" in the sense of "apparently random variations that actually aren't random".


That's not quite true, since a small signal+random noise will certainly give you a prediction that is testable.


For Dr. Everitt, who joined the Gravity Probe experiment in 1962 as a young postdoctoral fellow and has worked on nothing else since, the announcement on Wednesday capped a career-long journey.

There's something so profound about that.

To think of how many jobs I've held in my comparatively short life, how many minor career changes I've had here and there, how many massive shifts in interest and passion I've had over the years, and to hold these up beside someone who has been wholly dedicated to the same singular goal since before I was even born--that's just mind-boggling.

And it was selfless! This one singular goal to which he's dedicated himself, every one of the fifty years of work that went into it, ultimately ended up becoming--at least when boiled down to a headline--a footnote to someone else's greatness.

Five decades. I can't even begin to fathom what sort of drive and passion and commitment that must require.

Bravo.


And it was selfless! This one singular goal to which he's dedicated himself, every one of the fifty years of work that went into it, ultimately ended up becoming--at least when boiled down to a headline--a footnote to someone else's greatness.

Don't forget that we do science because we don't know the answer, not because we do. The best-case scenario would have been that after forty years you prove that relativity is wrong.


It's impressive, but keep in mind that most of our parents and grandparents had a job for life decades ago. Times are much different now. Things change so much faster. Companies die faster. We have many more job options, entrepreneurship, and so on.


Why is this so inspiring? I'm not trying to put down his career, I just don't see why his selflessness is something to be admired. Is it because it's not something you would choose? Does that fact alone make that lifestyle profound?


According to the article below, everything measured by the probe has long since been measured in other ways with greater precision. Based on that, I'd have to say, this probe didn't really prove anything...

http://www.newscientist.com/article/dn20444-beleaguered-miss...


I thought this had been proven long ago by measuring the gravitation pull the sun had on light from stars as it passed by.


[ugh] NYT headline writers again.

Falsifiable scientific experiment -- the gold standard for physics -- cannot prove that something is right. It can only fail to demonstrate that something is wrong.


it's not necessarily a tl;dr i'm requestion, so much as a physic geek deciphering.


RobotRollCall gave an explanation of the thing in the relevant /r/science thread: http://www.reddit.com/r/space/comments/h45c8/nasa_announced_...

(side note: RRC is one of the best commenters to ever happen to /r/science, or more generally Reddit)


Wow. If he/she has any spare time, or interest, at all he should teach mini science courses online to the public. He has a gift.


RRC is an absolutely excellent teacher and explainer of science. I strongly recommend browsing her comments list: http://www.reddit.com/user/RobotRollCall?sort=top


it's a very direct way of measuring the curvature of space. at least in theory. in practice it was such a delicate measurement that, by the time it was done, it was confirming a theory that we not only believe, but are already questioning / extending in other ways.

so it's a beautiful but largely pointless exercise that nasa is spinning in a "romantic" way because, well, astronomy and space science depend hugely on public goodwill for government funding.


And for just three-quarters of a billion dollars.

It took me a second look to realized, but in today's dollars, quite the bargain!


Does this mean that it is no longer the Theory of Relativity, but now the Law of Relativity?


That's not how theories work. A scientific theory is more like a framework and not really the same meaning as what people usually mean by theory (which is closer to hypothesis). Also nothing in science can ever be 100% definite; the term law shouldn't really ever be used.


As an aside to your comment, misuse of the word theory is a big pet peeve of mine.

In day to day conversation, people use it interchangeably with the word opinion (or as you mentioned hypothesis).

"My theory is the government should such and such." This is bogus! So later, when someone hears about the "theory" of evolution, it strikes them as something with which they can disagree.


per Wikipedia:

A common distinction made in science is between theories and hypotheses, with the former being considered as satisfactorily tested or proven and the latter used to denote conjectures or proposed descriptions or models which have not yet been tested or proven to the same standard.


Is there an arXiv paper on that?


Anyone who's feeling like they can't handle the physics here should probably just leave now ...


... its a joke people. relax. http://xkcd.com/849/




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