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Can anyone explain what f(R) theory is?

An alternative theory for gravity.

Originally posted by jaden101
An alternative theory for gravity.

Got that. So far, it is holding it's own against general relativity when tested against observations of the universe.

I simply could not find any detail on the theory.

Detail!

Originally posted by Shakyamunison
Got that. So far, it is holding it's own against general relativity when tested against observations of the universe.

I simply could not find any detail on the theory.

Not really. Aspects of it conflict with the standard model and the standard model has hundreds of high energy experiments that are consistent with the theory and back it up. f(R) doesn't.

Originally posted by jaden101
Not really. Aspects of it conflict with the standard model and the standard model has hundreds of high energy experiments that are consistent with the theory and back it up. f(R) doesn't.

Check it out:

http://www.space.com/scienceastronomy/general-relativity-confirmed-100310.html


Symmetric Chaos
thanks, but unfortunately, my math skills are not good enough.

Just because it hasn't been proven as thoroughly as relative theory, doesn't mean it is false.

"so far" being the key term in Shaky's post.

Originally posted by Shakyamunison
http://www.space.com/scienceastronomy/general-relativity-confirmed-100310.html "The new work also helps rule out a competing theory of gravity that seeks to do away with the need for bizarre concepts like dark matter and dark energy that have irked some scientists. This research indicates those pesky ideas may be here to stay."

I need dark energy to exist, otherwise a story I wrote goes down the ol' tube-aroo.

If f(R) theory is supposed to do away with the need for dark matter, this might be old news...

http://home.slac.stanford.edu/pressreleases/2006/20060821.htm

Originally posted by Shakyamunison
...So far, it is holding it's own against general relativity...

Ah.

f(R) = f***(Relativity).

Those brazen iconoclasts.

Originally posted by Shakyamunison
Can anyone explain what f(R) theory is?

instead of posing "dark" energy and matter to account for the differences between our theories and our observations (mass of the universe, acceleration, etc) f(R) proposes that other systems are at work at macro-levels that are not relevant to the observation of gravity on earth, from my extremely limited understanding, like quantum effects and Newtonian gravity.

I don't really understand the "non-flat variants" stuff, other than to say I think it means that something other than the curvature of space time is responsible for gravity, and that this thing, or things, are also curved in their interactions with space-time. Suffice to say, one of these "non-flat variants" probably mathmatically explains expansion and another (or a variant in the curve of one) that explains the mass differences.

It strikes me a lot as string theory, its got a good story that I think people could love, but its not really testable. Observational stuff is cool, and good, but astrophysics, and most theoretical physics imho, has eyes way bigger than its tummy.

EDIT: got that from the "History" section of this article: http://arxiv.org/PS_cache/arxiv/pdf/0805/0805.1726v3.pdf
minus of course the skeptical editorializing

Originally posted by Mindship
Ah.

f(R) = f***(Relativity).

Those brazen iconoclasts.

That would be pretty cool. Does anyone know where the name really comes from?

I'd look more into this, but I'm afraid of getting MIND-RAPED.

Originally posted by Symmetric Chaos
That would be pretty cool. Does anyone know where the name really comes from?

R: http://en.wikipedia.org/wiki/Scalar_curvature

comes from an equation for this: http://en.wikipedia.org/wiki/Einstein-Hilbert_action

f(R) makes the R a function

Originally posted by inimalist
instead of posing "dark" energy and matter to account for the differences between our theories and our observations (mass of the universe, acceleration, etc) f(R) proposes that other systems are at work at macro-levels that are not relevant to the observation of gravity on earth, from my extremely limited understanding, like quantum effects and Newtonian gravity.

I don't really understand the "non-flat variants" stuff, other than to say I think it means that something other than the curvature of space time is responsible for gravity, and that this thing, or things, are also curved in their interactions with space-time. Suffice to say, one of these "non-flat variants" probably mathmatically explains expansion and another (or a variant in the curve of one) that explains the mass differences.
Are they implying other fields? Are they implying extradimensional influences? Offhand, it doesn't sound any simpler than dark matter/energy. And the thing is, "dark energy" is just a phrase; it's not like some new form of energy has actually been discovered. What's to "refute"?

Originally posted by Mindship
Are they implying other fields? Are they implying extradimensional influences? Offhand, it doesn't sound any simpler than dark matter/energy. And the thing is, "dark energy" is just a phrase; it's not like some new form of energy has actually been discovered. What's to "refute"?

Ya. It sounds like (and I really don't have a good understanding of the theory) they are relabeling dark matter.

Originally posted by Shakyamunison
Ya. It sounds like (and I really don't have a good understanding of the theory) they are relabeling dark matter.

Well they already relabeled aether, it's a proud tradition in physics.

Originally posted by Symmetric Chaos
Well they already relabeled aether... Yeah, they did, didn't they.

Originally posted by Mindship
Are they implying other fields?

I honestly couldn't operationally define the term 'field'

Originally posted by Mindship
Are they implying extradimensional influences?

I would assume no, as the fields are supposed to only affect macro (relative to us) level phenomenon, whereas I have only seen reference to extra-dimensional interactions at micro levels (string theory)

They may be proposing new dimensions in macro space in the same way that string theory proposes them in micro space, but I don't know

Originally posted by Mindship
Offhand, it doesn't sound any simpler than dark matter/energy. And the thing is, "dark energy" is just a phrase; it's not like some new form of energy has actually been discovered. What's to "refute"?

I agree entirely, though I must admit, I don't understand the theories in the first place, so there may be valid experimental tests and observations being done that I wouldn't be able to comprehend.

Like, in perception research, to support that the "redness" of an object caught someone's attention, you have to prove that the brightness, curvature and a number of possibly counter-intuitive (to the lay person) issues aren't capturing attention. So, there probably are observations that are better explained by the one rather than the other, but they do remain untestable by my imagination (as I am totally a lay person here).