# What is Hartle: Definition and 15 Discussions

Hartle is a surname. Notable people with the surname include:

Adam Hartle (born 1979), an American comedian
Barry Hartle (born 1939), an English footballer
Dean Hartle (1931-2018), an American politician
Enid Hartle (1935–2008), an English opera singer
Greg Hartle (born 1951), a former American football player
James Hartle (born 1939), an American physicist
John Hartle (1933–1968), an English professional road racer
John A. Hartle (1891–1979), an American politician
Roy Hartle (1931–2014), an English footballer
Russell P. Hartle (1889–1961), an American army officer
Tom Hartle, an American publisher
Sophie Hartle,
Gabriella Hartle,
Bernita Hartle,
Imogen Hartle,

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1. ### A Hartle-Hawking sum over all possible metrics?

Physicists Stephen W Hawking and James B Hartle 1 proposed that the universe, in its origins, had no boundary conditions both in space and time. To do that, they proposed a sum over all compact euclidean compact metrics. I have heard that they only considered these metrics in order to simplify...
2. ### Relativity Error in Hartle's Fig. 7.11?

A question concerning FIg. 7.11 on page 173. It seems to me, in light of what is said on the preceding page about null surfaces, that he has interchanged "normal" and "tangent" in the third and fourth sentences of the figure caption. I would say: "The tangent to the surface l lies in the...
3. ### A problem with Integration by Parts in Hartle's "Gravity"

Hi guys! I am reading the book "Gravity" by Hartle. I came across this scary-looking integral. The author does integration by parts and I don't get how he does it. Could someone guide me please? Relevant equations: ∫u dv = uv - ∫v du
4. ### Where can I find solutions to the problems in Hartle's Gravity: An Introduction?

I've started learning GR from Hartle's "Gravity: An Introduction ...". It's all going well, but I feel I could benefit from solutions to some of the key problems. I assume Hartle hasn't published a companion solution guide. A few options show up on line. One by Jorge Ramos, for example. Any...
5. ### Understanding Hartle: My Success Story with WannabeNewton

Here was my success with trying to understand Hartle. Thanks WannabeNewton. https://www.youtube.com/watch?v=Fvt-Fc6uQjc
6. ### Hartle too hard Need another suggestion

It started out OK, like a lot of books, but all of a sudden I hit a mass of integrals at page 22 out of nowhere. No build up, no explanation, many solution steps skipped (of course). Sorry to sound weak, but I need to be "nannied" through the maths of General relativity. I'm a right brain...
7. ### Status of Hawking Hartle no boundary proposal

I came across this statement from James Hartle on Stephen Hawking's website, http://www.hawking.org.uk/ and wondered where you see this proposal currrently [Hartle sure seems to think it explains an awful lot] : James Hartle: Wikipedia has a brief discussion here...
8. ### Comparing Hartle, Schutz, and Ohanian for GR Beginner

I'm going to attempt to start a beginner GR book since we're covering it in Modern Physics and I've been covering the material up a notch so far (I did the SR by reading Spacetime Physics by Taylor and Wheeler & I've already read Griffith's for the Qmech section etc.) I don't intend to finish an...
9. ### Hartle: QM of Individual Systems (1968)

In Fredrik's recent thread: https://www.physicsforums.com/showthread.php?t=506326 some questions arose about this paper: J. B. Hartle, "Quantum Mechanics of Individual Systems", Am. J. Phys., vol 36, no 8, (1968), pp704-712. [For other readers, you'll need to have read or be able to...
10. ### Hartle Hawking offer probabilities for observations (eternal inflation picture)

Hartle Hawking suggest probabilities for observations (eternal inflation picture) http://arxiv.org/abs/1009.2525 Eternal inflation without metaphysics James Hartle, S.W. Hawking, Thomas Hertog 4 pages (Submitted on 13 Sep 2010) "In the usual account of eternal inflation the universe is...
11. ### Supplementary Reading for First GR Course: Schutz vs Hartle?

I hope this is the right forum to post this... I'm going through Wald's book in my first graduate level GR course, and am looking for lower level supplementary reading. I have a relatively strong math background, so Wald's language suits me well, but sometimes I feel like I need more...
12. ### Hartle Gravity - Simple basis vector question

Helo all, I have a very simple question about basis Four-Vectors and Components. In Hartle's book, Gravity, he uses the following equation to show the components of the 4-vector, a a =a^t{}e(sub t) + a^x{}e(sub x) + a^y{}e(sub y) + a^z{}e(sub z) Sorry for the half LaTex half something...
13. ### Is Anyone Else Using Gravity by James B. Hartle and Looking for a Study Partner?

I am looking for a study partner (over the internet) I am using Gravity by James B. Hartle. Is there anyone else using this book that would like to study with me. Also, I am teaching myself. Thanks
14. ### Help with Hartle: Calculating Elapsed Time

Help with Hartle! Hello, I find Hartle's working very confusing. I was wondering if someone could help me decode this problem: Three observers are standing near each other on the surface of the Earth. Each holds an accurate atomic clock. At time t = 0 the first observer throws their clock...
15. ### James Hartle online talk 19 April

I just watched this talk by Hartle Generalizing Quantum Mechanics for Quantum Spacetime given at Perimeter on 19 April, just a couple of days ago. http://streamer.perimeterinstitute.ca:81/mediasite/viewer/FrontEnd/Front.aspx?&shouldResize=False in the seminar series near the top of the list...