# Only Three People Understand General Relativity

1. Dec 28, 2017

### Staff: Mentor

From Verifying the Theory of Relativity by Chandrasekhar

Sir J.J. Thomson, as President of the Royal Society at that time, concluded the meeting with the statement', I have to confess that no one has yet succeeded in stating in clear language what the theory of Einstein's really is'. And Eddington recalled that as the meeting was dispersing, Ludwig Silberstei (the author of one of the early books on relativity), came up to him and said,' Professor Eddington, you must be one of three persons in the world who understands general relativity'. On Eddington demuring to this statement, Silberstein responded, 'Don't be modest Eddington'. And Eddington's reply was, 'On the contrary, I am trying to think who the third person is!'

I have seen that and similar accounts about only three people understood GR. Every time I hear/read it I laugh my head off. Who understood it during the early days - say in the 10 years after its final form by Hilbert and Einstein. BTW Hilbert got it wrong initially - but that is another story that for some reason is not usually discussed - as well as initially wanting to take credit for it - but eventually of course saw sense and gave Einstein priority with many well known sayings about the matter such as 'Every boy in the streets of Göttingen understands more about four dimensional geometry than Einstein .Yet, in spite of that, Einstein did the work and not the mathematicians '

Well here is who I can think of:

Bohr
Born
Eddington (of course)
Kretchmann
Pauli
Hilbert
Schrodinger

I could probably go on. Many of course were not famous yet - but many recall saying its the most beautiful theory in physics. His good friend Bohr never ceased to believe it was the greatest triumph of human thought in the history of man - despite of course the disagreement they had about QM.

Why do people think that myth still persists? BTW I think Eddington was simply being facetious.

Added alter - I updated it a bit getting rid of people like Dirac who while even writing a textbook on it are in doubt with knowing it shortly after. Despite his age Pauli was left in because he wrote a textbook on it at just 21 years of age that even Einstein was amazed at.

Thanks
Bill

Last edited: Dec 30, 2017
2. Dec 28, 2017

Can you cite a source? I have not heard of anyone who believes it, but maybe I hobnob in the wrong circles.

3. Dec 28, 2017

### Staff: Mentor

I gave my source and full story - Verifying the Theory of Relativity by Chandrasekhar.

Its possible his memory was faulty - but its so widely known - although not the exact details which Chandrasekhar gave dont seem to be - I think we can safely say his account is correct.

Thanks
Bill

4. Dec 28, 2017

Ah, I thought you meant the myth of only 3 people understanding GR at the present time. Or do you mean the myth of only 3 people having believed it at the time that Eddington made his quip? (I am assuming that you are not labeling the story about Eddington a myth, since you stated that you thought that Eddington's reply was facetious, indicating that you believed that Eddington's reply existed -- hairless French king and all that.) The question is: are there people who now believe that Eddington was not being facetious? (Since you talked about the myth persisting, I do not write "believed".) You gave your source for the story, not for people presently believing the assertion made in the story.

5. Dec 29, 2017

### Staff: Mentor

I think non physicists actually believe it just from speaking to people - they seem to think its, somehow mystically difficult - but an hour or two of explanation usually cures them of that - physicists know the literal interpretation of what Eddington said is so silly he was obviously just being facetious.

So I suppose the question is why do non physicists believe literally what Eddington said - it's an interesting phenomena.

Thanks
Bill

6. Dec 30, 2017

### epenguin

I suppose there are some people who don’t know

There's a wonderful family called Stein:
There's Gert and there's Ep and there's Ein.
Gert's poems are bunk,
Ep's statues are junk,
And no one can understand Ein.

?

7. Dec 30, 2017

### PeroK

Being British, I recognise archetypal deadpan British humour in that comment. From my experiences on this forum, this sort of humour is confusing and perplexing to Americans and Antipodeans alike. Silberstein was supposed to laugh! But, perhaps he just didn't get it either. For what it's worth, I think it is very funny. I would have burst out laughing.

8. Dec 30, 2017

### strangerep

Not Dirac -- I recall reading one of his essays wherein he credited Eddington's "The Mathematical Theory of Relativity" as helping him (Dirac) to understand GR better.

9. Dec 30, 2017

### TeethWhitener

So did Einstein. Several times. Most famously in his initial formulation of the field equations as $R_{\mu\nu} = T_{\mu\nu}$.

10. Dec 30, 2017

### Staff: Mentor

That's true - he certainly knew it later of course - and even wrote a textbook. If he learned it shortly after the theory - I guess is the issue - from what you said - probably not. Actually the same probably applies to Landau. I will update the list getting rid of those in that may be in doubt.

Thanks
Bill

Last edited: Dec 30, 2017
11. Dec 30, 2017

### Staff: Mentor

Hilbert actually made the same error for a different reason. All he basically had to do was vary the Einstein-Hilbert action (its not named after both of them without reason) - and for reasons explained here got it wrong:
https://www.amazon.com/Einsteins-Mistakes-Human-Failings-Genius/dp/0393337685

Basically Hilbert was after bigger game - a unified theory of gravity and EM and this confused his thinking.

I wish I knew that years ago when I posted a lot on sci.physics.relativity. Cranks were always saying Einstein never discovered GR - Hilbert did. Even if Hilbert initially got it right, which he didn't - they both found it independently - but of course Einstein did all the actual physics needed to arrive at that action, so, correctly, got the credit - eventually. Evidently, as I mentioned, and it's usually not discussed much - Hilbert initially wanted credit for it.

Thanks
Bill

Last edited: Dec 30, 2017
12. Dec 30, 2017

### Staff: Mentor

I don't know about others, or differences in humor - it was always obvious to me it was meant as humor and I wryly smiled at it when I first heard it all those years ago. I don't remember actually laughing though - I did laugh at people taking it seriously.

Thanks
Bill

13. Dec 30, 2017

### OCR

I have no trouble seeing the humor...

Here's another one... it's not " laugh out loud " funny, but I see humor there.
Arthur Eddington:

Last edited: Dec 30, 2017
14. Jan 1, 2018

### PAllen

Your original context was 10 years. Eddington’s book came out in 1923, and was an immediate hit (along with Pauli’s exposition of 2 years earlier). So I suspect Dirac fits within the 10 year time frame. You can also add Klein who reviewed and critiqued Pauli’s exposition.

FYI, Eddington was one of the first books on GR I read, before MTW existed, and I found it quite lucid, perhaps my only claim to similarity with Dirac.

15. Jan 1, 2018

### Staff: Mentor

My first exposure was Ohanian:
https://www.amazon.com/Gravitation-Spacetime-Second-Hans-Ohanian/dp/0393965015

Its different, but a viewpoint that fits more naturally with QM.

Then MTW, then Wald and I have got a few others along the way as well such as Dirac.

My favorite by a long way is Wald. Lost MTW in moving to where I live, but with Wald never found any need to replace it.

Thanks
Bill

16. Jan 2, 2018

### PAllen

The more I think about it, the more absurd it becomes to put together a list of physicists with understanding of GR not too far behind Einstein's within some years of 1916. While obviously a small minority of all physicist, numerically many grappled very quickly with this new theory. For example, all three physicists (J.T. Jebsen, W. Alexandrow, G.D Birkhoff) who independently arrived at Birkhoff's theorem, a central result in GR, did so in the 1921 - 1923 time frame. Then, of course, there is Karl Schwarzschild.

17. Jan 5, 2018