Jun 14, 2021
You have to learn to think about the simplest possible thing in the simplest possible best way, and then things proceed. General fact about life in Physics
Nima Arkani-Hamed talking about the importance of understanding three-point gluon scattering amplitudes in order to understand higher order amplitudes.
Jun 30, 2019
As an undergraduate at Hampshire College, I did a lot of physics and some philosophy courses. Then when I went to Harvard for graduate school, I intended to do a double Ph.D. in physics and philosophy, but I got disenchanted with philosophy pretty quickly. I mean, the physicists were arrogant enough. But the philosophers even more so.
Lee Smolin in an interview with quanta magazine, explaining the sociology of physicists and philosophers.
Mar 11, 2019
It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.
Teddy Roosevelt in the speech “Citizenship In A Republic“, delivered at the Sorbonne, in Paris, France on 23 April, 1910.
Dec 31, 2018
Gerard ‘t Hooft’s opinion [1] of causal sets, loop quantum gravity and causal dynamical triangulations as plausible approaches towards a theory of quantum gravity:
Numerous other schemes have been proposed, over time. As is often the case in situations such as these, there [has] been an abundance of completely wild concoctions that serious researchers have come up with. Lack of phantasy is not our problem [9][10][11].
where the references “[9][10][11]” are to the works [2, 3, 4, 5].
Warren Siegel in his text [6], commenting on the high energy levels required in order to be able to study String Theory:
Chapts. 2-5 can be considered almost as an independent book, an attempt at a general approach to all of field theory. For those few high energy physicists who are not intensely interested in strings (or do not have high enough energy to study them), it can be read as a new introduction to ordinary field theory, although familiarity with quantum field theory as it is usually taught is assumed.
Dec 30, 2018
Joe Polchinski [7] on the significance of String Theory in the preface of Vol 1 of his magnum opus “String Theory“:
String theory (and the entire base of physics upon which it has been built) is one of mankind’s great achievements, and it has been my privilege to try to capture its current state.
Dec 15, 2018
Peter Goddard [8] on the use of “modern” mathematics in theoretical high energy physics in the early days of string theory:
A senior and warmly admired physicist gave some lectures on the Regge theory of high energy processes. With great technical mastery, he was covering the board with special functions, doing manipulations that I knew from my studies with Alan White (who was also at the School) could be handled efficiently and elegantly using harmonic analysis on noncompact groups. Just as I was wondering whether it might be too impertinent to make a remark to this effect, the lecturer turned to the audience and said, “They tell me that you can do this all more easily if you use group theory, but I tell you that, if you are strong, you do not need group theory.“
![[doi]](https://i0.wp.com/www.quantumofgravity.com/blog/wp-content/plugins/papercite/img/external.png?resize=10%2C10&ssl=1){kind=small}
G. {‘t Hooft}, “Nature’s Book Keeping System,” Arxiv preprint arxiv:1605.00027, p. 127–135, 2017. [Bibtex]
@article{t-Hooft2017Natures,
abstract = {Establishing how one should describe and study natures fundamental degrees of freedom is a notoriously difficult problem. It is tempting to assume that the number of bits (or qubits) needed in a given Planckian 3-volume, or perhaps 2-volume, is a fixed finite number, but this ansatz does not make the problem much easier. We come not even close to solving this problem, but we propose various ingredients in phrasing the questions, possibilities and limitations that may serve as starting points.},
archiveprefix = {arXiv},
author = {{'t Hooft}, Gerard},
date-modified = {2024-08-25 13:14:15 +0530},
doi = {10.1007/978-3-319-44418-5_10},
eprint = {1605.00027},
journal = {arXiv preprint arXiv:1605.00027},
pages = {127--135},
title = {Nature's {{Book Keeping System}}},
year = {2017},
bdsk-url-1 = {https://doi.org/10.1007/978-3-319-44418-5_10}}[Bibtex]
@article{Sorkin2003Causal,
abstract = {These are lecture notes on causal set theory prepared in Jan. 2002 for a Summer School in Valdivia, Chile. In some places, they are more complete, in others much less so, regrettably. An extensive set of references and a glossary of terms can be found at the end of the notes.},
archiveprefix = {arXiv},
author = {Sorkin, Rafael D.},
eprint = {gr-qc/0309009},
file = {/Volumes/Data/owncloud/root/research/zotero/storage/IZL48W84/Sorkin_Causal Sets_2003.pdf;/Volumes/Data/owncloud/root/research/zotero/storage/3KVECEQB/0309009.html},
journal = {arXiv:gr-qc/0309009},
keywords = {_tablet,Astrophysics,General Relativity and Quantum Cosmology,High Energy Physics - Theory},
month = sep,
shorttitle = {Causal {{Sets}}},
title = {Causal {{Sets}}: {{Discrete Gravity}} ({{Notes}} for the {{Valdivia Summer School}})},
urldate = {2018-12-31},
year = {2003}}[Bibtex]
@article{Rovelli1998Loop,
abstract = {The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. The research in loop quantum gravity forms today a vast area, ranging from mathematical foundations to physical applications. Among the most significative results obtained are: (i) The computation of the physical spectra of geometrical quantities such as area and volume; which yields quantitative predictions on Planck-scale physics. (ii) A derivation of the Bekenstein-Hawking black hole entropy formula. (iii) An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, overcompleteness of the loop basis, implementation of reality conditions) have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.},
archiveprefix = {arXiv},
author = {Rovelli, Carlo},
doi = {10.12942/lrr-1998-1},
eprint = {gr-qc/9710008},
file = {/Volumes/Data/owncloud/root/research/zotero/storage/QHF58TSH/Rovelli_Loop Quantum Gravity_1998.pdf;/Volumes/Data/owncloud/root/research/zotero/storage/N5IULZVV/9710008.html},
issn = {2367-3613, 1433-8351},
journal = {Living Reviews in Relativity},
keywords = {_tablet,General Relativity and Quantum Cosmology,High Energy Physics - Theory},
month = dec,
number = {1},
title = {Loop {{Quantum Gravity}}},
urldate = {2018-12-31},
volume = {1},
year = {1998},
bdsk-url-1 = {https://doi.org/10.12942/lrr-1998-1}}[Bibtex]
@book{Smolin2017Three,
abstract = {"It would be hard to imagine a better guide to this difficult subject." -- Scientific American In Three Roads to Quantum Gravity, Lee Smolin provides an accessible overview of the attempts to build a final "theory of everything." He explains in simple terms what scientists are talking about when they say the world is made from exotic entities such as loops, strings, and black holes and tells the fascinating stories behind these discoveries: the rivalries, epiphanies, and intrigues he witnessed firsthand. "Provocative, original, and unsettling." -- The New York Review of Books "An excellent writer, a creative thinker." -- Nature},
address = {New York},
author = {Smolin, Lee},
date-added = {2024-08-25 13:17:49 +0530},
date-modified = {2024-08-25 13:17:49 +0530},
edition = {3rd edition},
isbn = {978-0-465-09454-7},
langid = {english},
month = aug,
publisher = {Basic Books},
title = {Three {{Roads}} to {{Quantum Gravity}}},
year = {2017}}[Bibtex]
@misc{Ambjorn2014Quantum,
abstract = {"Causal Dynamical Triangulations" (CDT) represent a lattice regularization of the sum over spacetime histories, providing us with a non-perturbative formulation of quantum gravity. The ultraviolet fixed points of the lattice theory can be used to define a continuum quantum field theory, potentially making contact with quantum gravity defined via asymptotic safety. We describe the formalism of CDT, its phase diagram, and the quantum geometries emerging from it. We also argue that the formalism should be able to describe a more general class of quantum-gravitational models of Horava-Lifshitz type.},
archiveprefix = {arXiv},
author = {Ambj{\o}rn, Jan and G{\"o}rlich, Andrzej and Jurkiewicz, Jerzy and Loll, Renate},
date-modified = {2024-08-25 13:14:04 +0530},
doi = {10.1007/978-3-642-41992-8_34},
eprint = {1302.2173},
file = {/Users/deepak/ownCloud/root/research/zotero_pdfs/Ambj{\o}rn et al_Quantum Gravity via Causal Dynamical Triangulations_2014.pdf},
journal = {Springer Handbook of Spacetime},
keywords = {asymptotic_safety,b_dittrich,causal_dynamical_triangulations,fixed_point,gorlich_a,horava_lifshitz,jurkiewicz_j,lattice_models,manybody,non-perturbative,phase_transition,quantum_gravity,renate_loll},
month = feb,
pages = {723--741},
title = {Quantum {{Gravity}} via {{Causal Dynamical Triangulations}}},
year = {2014},
bdsk-url-1 = {https://doi.org/10.1007/978-3-642-41992-8_34}}@article{Siegel2001Introduction,
abstract = {The 1988 book, now free, with corrections and bookmarks (for pdf).},
archiveprefix = {arXiv},
author = {Siegel, W.},
date-modified = {2024-08-25 13:14:10 +0530},
doi = {10.1016/0550-3213(93)90388-6},
eprint = {hep-th/0107094},
file = {/Users/deepak/ownCloud/root/research/zotero_pdfs/Siegel_Introduction to string field theory_2001.pdf},
month = jul,
title = {Introduction to String Field Theory},
urldate = {2018-12-07},
year = {2001},
bdsk-url-1 = {https://doi.org/10.1016/0550-3213(93)90388-6}}[Bibtex]
@book{Polchinski1998String,
abstract = {String Theory comprises two volumes which give a comprehensive and pedagogic account of the subject. Volume 1, first published in 1998, provides a thorough introduction to the bosonic string. The first four chapters introduce the central ideas of string theory, the tools of conformal field theory and of the Polyakov path integral, and the covariant quantization of the string. The next three chapters treat string interactions: the general formalism, and detailed treatments of the tree level and one loop amplitudes. Chapter eight covers toroidal compactification and many important aspects of string physics, such as T-duality and D-branes. Chapter nine treats higher-order amplitudes, including an analysis of their finiteness and unitarity, and various nonperturbative ideas. An appendix giving a short course on path integral methods is included. This is an essential text and reference for graduate students and researchers interested in modern superstring theory.},
address = {Cambridge},
author = {Polchinski, Joseph},
date-modified = {2024-08-25 13:14:13 +0530},
doi = {10.1017/CBO9780511816079},
file = {/Volumes/Data/owncloud/root/research/zotero_pdfs/Polchinski_String Theory - Volume 1 - An Introduction to the Bosonic String_1998.pdf;/Volumes/Data/owncloud/root/research/zotero/storage/7YQLGGLB/30409AF2BDE27D53E275FDA395AB667A.html},
isbn = {978-0-521-63303-1},
publisher = {Cambridge University Press},
series = {Cambridge {{Monographs}} on {{Mathematical Physics}}},
shorttitle = {String {{Theory}}},
title = {String {{Theory}}: {{Volume}} 1: {{An Introduction}} to the {{Bosonic String}}},
urldate = {2023-10-23},
volume = {1},
year = {1998},
bdsk-url-1 = {https://doi.org/10.1017/CBO9780511816079}}[Bibtex]
@article{Goddard2008From,
abstract = {A personal view is given of the development of string theory out of dual models, including the analysis of the structure of the physical states and the proof of the No-Ghost Theorem, the quantization of the relativistic string, and the calculation of fermion-fermion scattering.},
archiveprefix = {arXiv},
author = {Goddard, Peter},
date-modified = {2024-08-25 13:14:08 +0530},
eprint = {0802.3249},
file = {/Users/deepak/ownCloud/root/research/zotero_pdfs/Goddard_From Dual Models to String Theory_2008.pdf},
month = feb,
title = {From {{Dual Models}} to {{String Theory}}},
urldate = {2018-12-10},
year = {2008}}