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PX436 reading

This page has been retained unaltered from the previous version of the course. It represents an excellent set of links to relevant and interesting additional material. To clarify something that is written below; I will not incorporate into the examination any material, including that linked to here, that is not also explicitly included in my lecture notes, beyond the standard proportion of 'unseen' material that is supposed to appear in any exam paper. The one exception, although it was also explicitly shown in lectures, is the recent paper from the LIGO experiment on the direct observation of gravitational waves.

Observation of Gravitational Waves from a Binary Black Hole Merger, LIGO Scientific Collaboration and Virgo Collaboration, Phys. Rev. Lett. 116, 061102 (2016).

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence, LIGO Scientific Collaboration and Virgo Collaboration, Phys. Rev. Lett. 116, 241103 (2016).

[Gareth Alexander, 2nd December 2016] 

This page collects together links to extra reading associated with the course. All papers but one here are all concerned with experimental tests of GR. In most cases you will have to click on a link to a PDF file within the links. Note that several of the papers use a generalised "Post-Keplerian" parameterisation which allows GR to be compared against potential alternative (but still metric) theories of gravity. Usually these are scaled so that the various parameters are equal to 1 if GR is right.

You should read these papers as qualitative questions based upon the content of the experimental ones will not be discussed in detail during lectures but may appear in the exam. The papers on the reading list add detail to the course, and may help your understanding and improve your knowledge of things discussed in lectures. You may find this helpful and have additional things to discuss in "describe" or "explain" questions in the exam such as "give examples of observational tests of..." or "describe the relevance of...". However, I am less likely than the previous lecturer (Tom Marsh, who set past exam papers up to and including 2011) to ask questions based solely on the extra reading unless I warn you otherwise in lectures. Wait until relevant material has been covered in the course before reading relevant papers. Please let me know if you have any difficulties accessing them. You may have to be on the campus network, or log in through the library, to have sufficient access rights for several of them.

  1. Historical perspective on testing the Equivalence Principle, Everitt et al (2003), 4 pages. Summary of efforts to test the equivalence principle.
  2. Apparent Weight of Photons, Pound and Rebka (1960), 4.5 pages. The classic, beautiful, experiment to test gravitational time dilation. The experiment was later improved by Pound and Snider (1965)
  3. Test of Relativistic Gravitation with a Space-Borne Hydrogen Maser, Vessot et al (1980), 4 pages. A direct test of gravitational time dilation using atomic clocks on a rocket flight.
  4. A test of general relativity using radio links with the Cassini spacecraft, Bertotti, Iess, Tortora (2003), 3 pages. The best measurement of the "Shapiro delay" in the passage of light near a gravitating object, the Sun in this case. Look at Figure 2 in particular. You will probably need to be on the campus network to access this Nature paper. You should also look at Shapiro's original paper (4 pages) based upon radar echoes from Venus and Mercury. This was the first measurement of the delay, now superceded by the spacecraft tests. The delay is also seen in the binary pulsars (see below).
  5. The total eclipse of 1919 May 29 and the influence of gravitation on light 4 pages, very easy to read paper by Eddington on his (at that time) upcoming expedition to measure the deflection of light by the Sun, and a fascinating insight into the development of physics.
  6. Measurement of the Solar Gravitational Deflection of Radio Waves using Geodetic Very-Long-Baseline Interferometry Data, 1979–1999, Shapiro, Davis, Lebach and Gregory (2004), 4 pages. The best modern measurement of light-deflection by the Sun. Although Irwin Shapiro is again the lead author here, do not confuse this with the "Shapiro delay" of item 4; this is essentially a much better version of the same test that Eddington first carried out in 1919 using photographic observations of stars during a total eclipse of the Sun; see previous item.
  7. Tests of general relativity from timing the double pulsar, Kramer et al (2006), 6 pages. This shows how timing measurements of pulsars in binary stars can lead to precise tests of GR. The system here is a wonderful discovery which not only has the shortest orbital period known for two neutron stars but is also the only one in which pulses are detected from both stars. Just 2 years of measurements of this system have bettered 30 years of timing of the famous "Binary Pulsar" which lead to the award of a Nobel Prize for Russell Hulse and Joseph Taylor in 1993. Particularly note the large GR-induced orbital precession rate (17 deg/year!) and the nice measurement of the Shapiro delay as the pulses from one pulsar pass close to the other. Look at table 2 of the paper to see how GR passes all the constraints from this system with flying colours. Above all, binary pulsars such as this allow one to test the formula for gravitational wave emission, and are a key motivation behind current attempts to detect gravitational waves. See also sections 4.4 and 4.5 in this paper for a more general look at relativisitic tests in binary pulsars.
  8. Data analysis changes in transient gravitational wave astronomy, Chassande-Mottin et al, 2012, 7 pages. A good synopsis of the current state, progress and limitations of gravitational wave detection experiments.

Finally, not an experimental paper but Einstein's 1916 paper should not be missed in a list such as this.This was Einstein's first full exposition of General Relativity. Allowing for some differences of notation, you should be able to follow it from about half-way through the course.

Others

Finally if I come across other papers of interest, I will add them to the list below. These are not required reading, and some are pretty advanced; I just put them here for interest and in case anyone might be thinking of studying for a PhD in gravitational physics and would like to know what they would be getting into:

  1. Gravitational Wave Detection by Interferometry (Ground and Space). Gives good technical details of the use of interferometry to detect gravitational waves.
  2. No Way Back: Maximizing survival time below the Schwarzschild event horizon. What you can do to stave off the inevitable.
  3. Expanding Space: the Root of all Evil?. A look at the concept of "expanding space" in cosmology.
  4. LIGO: the Laser Interferometer Gravitational-Wave Observatory. Full technical background on the leading GRW detector, LIGO.
  5. Searches for continuous gravitational wave signals and stochastic backgrounds in LIGO and Virgo data. Update on current status of observational projects
  6. A Mock Data Challenge for the Einstein Gravitational Wave Telescope. Plans for a planned third generation telescope.
  7. Charactersiation of photoreceivers for LISA. Plans for the space-based GW detector.