What is Modified gravity: Definition and 18 Discussions
Alternatives to general relativity are physical theories that attempt to describe the phenomenon of gravitation in competition to Einstein's theory of general relativity. There have been many different attempts at constructing an ideal theory of gravity.These attempts can be split into four broad categories based on their scope. In this article, straightforward alternatives to general relativity are discussed, which do not involve quantum mechanics or force unification. Other theories which do attempt to construct a theory using the principles of quantum mechanics are known as theories of quantized gravity. Thirdly, there are theories which attempt to explain gravity and other forces at the same time; these are known as classical unified field theories. Finally, the most ambitious theories attempt to both put gravity in quantum mechanical terms and unify forces; these are called theories of everything.
None of these alternatives to general relativity have gained wide acceptance. General relativity has withstood many tests, remaining consistent with all observations so far. In contrast, many of the early alternatives have been definitively disproven. However, some of the alternative theories of gravity are supported by a minority of physicists, and the topic remains the subject of intense study in theoretical physics.
I am looking for examples of Modified Gravity theories that have been developed with the aim of dispensing dark matter, besides Milgrom's [MOND][1], Bekenstein's [TeVeS][2], and the recent relativistic version of MOND ([RMOND][3]) by Skordis and Zlosnik.
Are there any other examples of similar...
Let ##\phi## be a scalar field and ##g_{\mu \nu} = \eta_{\mu \nu}+h_{\mu \nu}/M_p## where ##M_p## is the Planck mass (so we assume we deal with perturbations). Let ##\Lambda_2,\Lambda_3## be energy scales such that ##\Lambda_2 \gg \Lambda_3##. These are defined by ##\Lambda^2_2 = M_p H_0## and...
Hello everyone,
I am currently finishing my Masters in Theoretical Physics and looking forward to continue in a PhD.
I always thought I would love String Theory, and now that i am actually doing it I see that my feeling was correct. I do not know why but trying to understand its concepts...
One approach that has been proposed to replicate the description of dark matter phenomena in galaxies with a gravity modification that is set forth in a simplified manner in the phenomenological toy model theory MOND is to do so through a variation on Einstein's General Relativity known as...
In this paper (https://arxiv.org/abs/astro-ph/0603302) the authors derive the field equations for f(R) gravity considering a spherically symmetric and static metric. Now the Ricci scalar only depends on r so you could write f(R(r)) = g(r) for some g. However what it seems the authors have done...
Different things keep popping up in the literature that pose Dark matter and Dark energy are not needed to explain the universe, the latest MOG i have come across is this:
http://arxiv.org/pdf/1510.07037.pdf
What are the chances that a modified gravity theory will replace the standard model?
http://arxiv.org/abs/1508.04641
The body text of the paper ends up calling the "Hybrid metric-Palatini gravity theory" f(X) gravity. From the body text (citations and internal references omitted without notation):
The paper closes by identifying many issues for further study and arguing...
I found a few curious arxiv papers by Alexandre Deur (via Twitter).
Deur works in QCD. He explains QCD strings (flux line between quark and antiquark) as due to attraction between gluon field lines, ultimately due to gluon-gluon interactions. Phenomenologically this adds a linear term to the...
What are your personal opinions ??, Do you guys think gravity is just not fully understood that is why we can't explain certain events or DM is the probable answer to these discrepancies ?
I personally don't think we need to create a somewhat imaginary matter (dark matter and dark energy) to...
Friends:
I have been studying John Moffats Modified Gravity theory. I find it very interesting and I agree with him in that I think Dark Matter and Dark Energy are merely mediums to make our current equations work so we can predict the movements of the cosmos. However I am unclear on what...
http://arxiv.org/abs/astro-ph/0605278
Searching for modified gravity with baryon oscillations: from SDSS to WFMOS
Authors: Kazuhiro Yamamoto, Bruce A. Bassett, Robert C. Nichol, Yasushi Suto, Kazuhiro Yahata
Comments: 16 pages, submitted to PRD
We discuss how the baryon acoustic...
http://arxiv.org/abs/astro-ph/0506692
Title: Cosmological expansion and the uniqueness of gravitational action
Authors: T. Multamaki, I. Vilja
Comments: 4 pages
Modified theories of gravity have recently been studied by several authors as possibly viable alternatives to the cosmological...