cosmology the new theology

[velo]

It is a matter of belief in one theory or the other, maybe you think string theory is right, maybe you think quatum loop gravity is right, the test of these theories are all ways open to dispute, when will we have tests that

show these conjectures are just so right or wrong?

I dare say that the grant system will suppress any new thinking progress

in the understanding of our universe.

[the tree]

It's a matter of hunches and wagers, not belief. No-one actually believes they're right, they just work with the model they like until it gets proven impossible.

[ajb]

It is a matter of belief in one theory or the other, maybe you think string theory is right, maybe you think quatum loop gravity is right, the test of these theories are all ways open to dispute, when will we have tests that

show these conjectures are just so right or wrong?

I dare say that the grant system will suppress any new thinking progress

in the understanding of our universe.

 

It is not a matter of blind belief like in religion. You work on a "theory" based on mathematical and (hopefully) experimental/observational evidence.

[Martin]

It's a matter of hunches and wagers, not belief. No-one actually believes they're right, they just work with the model they like until it gets proven impossible.

 

also there are not just two horses in the race or two boxers in the ring.

 

I think it is human nature to simply situations into a bipolarity

when one hears people arguing. Indeed some of the people arguing seem to want to give this oversimple impression.

 

In his book Smolin gives examples of 3 or 4 different background independent non-string approaches to understanding space time geometry and matter at microscopic level.

 

It is really misleading to lump them all together and call them "Loop Quantum Gravity"

 

But the people that work on these different approaches are called the "LQG community"

 

and to a certain extent they accept this inaccurate name because the main international conference where they will all get together this year is called

LOOPS '07

 

To get a sense of the full spectrum, you should read the list of 20-some invited plenary talks they will have at the June 2007 conference

http://www.matmor.unam.mx/eventos/loops07/index.html (click on PROGRAM and see the list of plenary talks, click on talk title to see abstract summary)

 

THEN, velo, we can talk about the prospects for empirical testing, if you like:-)

 

Velo, your question of "when will there be testing to falsify some of these models" is a very good one!

 

How much do you know about LQC (loop quantum cosmology) as distinct from LQG? If you have some familiarity with Ashtekar and Bojowald LQC work then maybe I can reply to the point.

Are you at all familiar with DSR (deformed special relativity) and the fact that some versions seem to predict an observable dispersion in Gammaray bursts? If the GLAST satellite (launch this year hopefully) does not see the predicted dispersion this will rule out some DSR. It will seriously constrain but not totally kill DSR---a feature in several non-string QG approaches.

Forgetting about GLAST and DSR, there is the possibility of using structure formation data to constrain LQC models. To get a taste of this, see the recent paper of Magueijo and Singh.

http://arxiv.org/abs/astro-ph/0703566 (don't get bogged in technicality!, just sample what they are talking about.)

It is a TECHNICAL article, but you can skim the intro and conclusions and get a taste without delving into detail----it is interesting because Magueijo and Singh are urging the LQC people to stabilize certain specifics and derive certain details which they need in order to be able to test.

 

Magueijo and Singh are here writing as PHENOMENOLOGISTS that is not as theoreticians themselves but as people concerned with the testability of other people's theories. QG phenomenology has become an interesting and active field. The invited talk about QG phenomenology at LOOPS '07 will be given by Sabine Hossenfelder, it is her specialty. She is the person who could best give the overview to answer your question about "when will..."

 

click on http://www.matmor.unam.mx/eventos/loops07/index.html again and on PROGRAM and scan down to Hossenfelder and click on her talk title, to get this abstract summary

===quote===

Sabine Hossenfelder: Phenomenological Quantum Gravity

 

The search for a satisfying theory that unifies general relativity with quantum field theory is surely one of the major tasks for physicists in the 21st century. During the last decade, the phenomenology of quantum gravity and string theory has been examined from various points of view, opening new perspectives and testable predictions. I will give a short introduction into these effective models which allow to extend the standard model and include the expected effects of the underlying fundamental theory. I will talk about models with extra dimensions, models with a minimal length scale and those with a deformation of Lorentz invariance. The focus is on observable consequences, such as black hole and graviton production and modifications of standard-model cross-sections.

==endquote==

She will sound pessimistic but that is normal for phenomenologists---they are supposed to be unenthusiastic, uncommitted, cautious, and a bit of the devil advocate who throws the cold water of reality on the theorists. But hers is the talk you should hear if you could be there, if you ask those phenomenology questions relating to testability.

[Severian]

Anyone can call themselves a phenomenologist, but unless they actually make predictions that can be tested in an experiment, they are not.

[velo]

Martin, Thanks for the reply, it must have took some effort

 

Yes i am aware of the many approaches to QL, it seems there is a new one

every month, it still has a lot of catching up with the string vacua's in number

however.

I am also aware of the difficulty of getting grant money for anything other

than loop or string.

And i am aware of the lack of tests for these conjectures, even if a test is

put forward some one will right a paper on how to get around a null

result.

Martin, what will it take to kill, and put these conjectures out of their misery

once and for all?

[Phi for All]

I am also aware of the difficulty of getting grant money for anything other

than loop or string.

You've mentioned this twice. Were you denied grant money for one of your conjectures?

Martin, what will it take to kill, and put these conjectures out of their misery

once and for all?

Do you feel this is necessary? Do you have an hypothesis you put more faith in?

[foodchain]

It is a matter of belief in one theory or the other, maybe you think string theory is right, maybe you think quatum loop gravity is right, the test of these theories are all ways open to dispute, when will we have tests that

show these conjectures are just so right or wrong?

I dare say that the grant system will suppress any new thinking progress

in the understanding of our universe.

 

I don’t know if its beliefs as in animism as much as it might be different camps testing(hopefully) different hypothesis on something. Its like gravity with Newton, it just leaves something open. It goes from mass and distance, but what real physical force is affecting the other body, such is how is just mass compared to mass somehow gravity? Why is energy easier to find in lower states and not higher, but what frame of reference do you use for all of these judgments really, or perceptions of such.

 

Its like biology really, or something someone in the medical field can probably point out. Every little detail physically overall in an organism can be discerned and have title giving to it, but how does it all relate, what is perfectly healthy skin, what is a perfectly healthy eyelid to look like on the inside, how many different details of the physical reality of an eyelid exist? Biology is probably able to make a unifying theory possible, such as evolution, due to the ability to get more direct with life on earth for instance, why physics for the most part, more so in reference to the universe is currently not privy to being able to directly study such, and with biology the farther back in time you go, such as billions of years, the evidence in a direct tone becomes rare, and indirect methods have to be employed. Physics still has been able to make great strides and has predicted and concluded truth about reality many times from indirect methods, even dealing with the core of our planet. Chemistry is also challenged in many regards by such, such as in geology it would be hard to recreate a naturally occurring chemical reaction that takes millions of year to conduct in a few seconds in a lab.

[Severian]

Saying that cosmology is the new theology is, in my opinion, insulting to both cosmology and theology.

 

No matter how flakey you may think certain cosmological ideas and/or cosmologists are, cosmology is still an experimental science. It can make predictions that can be confronted with data and tested.