LQG, SF: Kicking Tyres, Adding Sawdust, and More

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In summary, the conversation revolves around the concept of LQG, or loop quantum gravity, and the potential limitations and criticisms of the theory. There is a discussion about whether LQG is just a fancy mathematical poetry or if it will yield concrete results. There is also talk about the possibility of a theory of spacetimematter that incorporates LQG and other theories, and what that would mean for the field of physics. The end goal is to have a workable and testable model of spacetimematter, but opinions differ on what that would look like. Ultimately, the conversation highlights the ongoing search for a complete understanding of the universe and the different perspectives and approaches within the scientific community.
  • #1
wolram
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Is this all that LQG, SF is, kicking tyres and adding saw dust to differentials,
putting some pluss gas in your engine, to keep it running, how about giving
the buyer some grantee.
 
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  • #2
wolram said:
Is this all that LQG...is, kicking tyres and adding saw dust to differentials,
putting some pluss gas in your engine, to keep it running, how about giving
the buyer some grantee.

:biggrin:

no guarantee, wolram.
 
  • #3
Please give some assurance that this is not all mathematical poetry, that
some thing will give an end result, that you are not waxing lyrical with
our destiny, and maybe a photon of light will be perceived from all this
conjecture.
 
  • #4
Wolram, God has chosen to remain a conjecture to us limited, created beings. We are finite and can never encompass the All. It is our role to be thankful for whatever little light we get, not ours to demand the whole thing in a chunk. All of our systems are clunky make-do wire and spit constructions, none of them approaches the beauty of the Absolute. That is all we have. For the rest, there is a thing called faith, which we who practice scepticism must finally take as bitter dregs.

My advice, do what you can to make the path beautiful, and don't rush the ending. It will come anyway.

Be well,

Richard
 
  • #5
To add a thought, it would not be the first time mathematical beauty has appeared in nature. Beauty doesn't make it right, but ugliness is always suspect.
 
  • #6
Chronos said:
To add a thought, it would not be the first time mathematical beauty has appeared in nature. Beauty doesn't make it right, but ugliness is always suspect.

You are right Chronos, there may be some beauty in Hopf fibrations or
tubular tetrahedrons, the ugliness comes from the hydra that some scientist
can input into his computations,
 
  • #7
nightcleaner said:
Wolram, God has chosen to remain a conjecture to us limited, created beings. We are finite and can never encompass the All. It is our role to be thankful for whatever little light we get, not ours to demand the whole thing in a chunk. All of our systems are clunky make-do wire and spit constructions, none of them approaches the beauty of the Absolute. That is all we have. For the rest, there is a thing called faith, which we who practice scepticism must finally take as bitter dregs.

My advice, do what you can to make the path beautiful, and don't rush the ending. It will come anyway.

Be well,

Richard

I admire your view NC, but i see beauty in waterfalls, babbling brooks
herbaceous meadows, not stagnant pools or arid land, in reality the
tortoise did not win race, "he used trickery", in the end i guess i will
just have to sit an wait for the rain to come.
and hope that you Marcus or some other, will predict the end of the
drought.
 
  • #8
wolram said:
...
and hope that you Marcus or some other, will predict the end of the
drought.

that seems like a fair request, any of us can speculate, that is to say GUESS :smile: as to what cosmologists will saying 10 years from now
or whenever they get a decent model of spacetimematter.

first off, why don't we each say what would constitute "the end of the drought" for us?

for me, I suppose the "end of the drought" would be a theory of spacetimematter that shows how matter can curve space and time and that shows how space can melt together with matter at the pit of a hole where things get very compressed and hot and where space and matter become the same stuff. and likewise it would show conditions at the cosmological bounce. and it would be a model that had the cosmological constant and the immirzi paramter built into it as perturbation variables, like in Freidel and Starodubtsev January 05 paper "Quantum Gravity in terms of topological observables" that got John Baez so excited.

I am stealing from, or tuning into, other people's intuition. When I say spacetimematter all melting together I am copying how Abhay Ashtekar talks about the "quantum regime" at the pit of a black hole, or at the moment before expansion (where the singularity used to be in earlier models of big bang). When I point to possible importance of Freidel Starodubtsev work I am using the intution of not only John Baez (and Lee Smolin) but also even Cumrun Vafa (an aggressive and with-it string theorist who is chairman of the Harvard physics department)

You can see what are the aspects of LQG that Vafa wants to absorb. you can see from his words and actions what facets make him hungry, so that he wants string/M to make contact with them and assimilate them.

One day, if Vafa stays chairman of the Harvard department, I think he will make a handsome offer to Laurent Freidel. And Freidel might not take him up on it.

So when I try to say what would constitute "the end of the drought", I am using what I see of other people intuitions, using them as my compass needles.
 
  • #9
what do some other people think would be "the end of the drought"

we should have a meaning for that, before we start speculating or fantasizing how it might come about.

for me it would be the appearance of a workable testable model of spacetimematter

(I don't care if it includes all the detail of the Standard Model, but it should have at least some rudimentary matter fields because matter is part of spacetime and may even be a root cause of it)

(I am not talking about a "Theory of Everything" which sounds to me like an impractical goal, maybe even a foolish daydream at this point. At a detail-level I am willing to let the Standard Model look after itself----I want a quantum theory of spacetime and that must include interaction with at least some token matter fields)

So now i have said a workable testable model of spacetimematter, but I have not speculated or GUESSED for you how that model might look. I have not said if it uses the spin foams or spin networks of LQG, or if it uses differential forms like "EF" theory, or simplexes like in "dynamical triangulation" models, or some fancy hypersophisticated algebraic geometry forever inaccessible to the layman, or what-all. So I have not told you my guesses as to how a theory of spacetimematter might look.

but I would like first to hear how other people would describe what the historical objective is, and what would seem to them like "the end of the drought"
 
  • #10
I suspect that the end of the drought will be a bit like what you see when you get to close to a mirage. A result that is more plain and ordinary than you had expected it to be.

As we make more progress, I suspect we will find that the universe is less weird than the bulk of the conjectures that are floating around at the moment.
 
  • #11
wolram said:
I admire your view NC, but i see beauty in waterfalls, babbling brooks
herbaceous meadows, not stagnant pools or arid land, in reality the
tortoise did not win race, "he used trickery", in the end i guess i will
just have to sit an wait for the rain to come.
and hope that you Marcus or some other, will predict the end of the
drought.


Well, science isn't done for our amusement, wolram. It goes down as it goes down. And frankly I don't see any drought. Are you over-focussing on the landscape kerfluffel? That's just a sideshow. Witten has shown that Penrose's twistors, when triangulated through string theory, are directly and productively related to the standard model physics seen in today's colliders. That's not the TOE, but it's not chopped liver either!

Don't watch the headlines, watch the workers.
 
  • #12
By MARCUS
(I don't care if it includes all the detail of the Standard Model, but it should have at least some rudimentary matter fields because matter is part of spacetime and may even be a root cause of it)

It seems that only the producers have there heads in the clouds, and the
grounded buyers have there feet on the ground, but produce goes stale,
rancid, if it is kept to long, if the dough does not raise you will not be
eating bread on the morrow, so is it a change of ingredients or sack the
chef?
 
  • #13
By SA.

Don't watch the headlines, watch the workers.

excellent advice SA, headlines can be just so not relevant.
 
  • #14
Ohwilleke
You are now one of my three, four, most worth listening to.
 
  • #15
wolram said:
I admire your view NC, but i see beauty in waterfalls, babbling brooks
herbaceous meadows, not stagnant pools or arid land, in reality the
tortoise did not win race, "he used trickery", in the end i guess i will
just have to sit an wait for the rain to come.
and hope that you Marcus or some other, will predict the end of the
drought.

Hi Wolram

You are quite right about the waterfalls, babbling brooks, and herbaceous meadows, but of course I am sure you know there is beauty in the high desert also, and even in the stagnant pool. Knowing where and how to look for it is the trick. I like the budhist view that life is painful to the extent that we hold onto things, become attached. Things come and go. It is the process of coming and going that is real, the things themselves are just temporary manifestations.

This doesn't really make me feel better about my dog being injured or my world racing to self-destruction, but it gives me something else to think about when flushing out the wound or ... well, what can I do about the suicidal wreckage anyway?

My friends here are trying to learn to raise horses and pigs and chickens, how to grow gardens and use the bounty nature provides. It's a lot of work and our grandfather's chose the supermarket and superhighway, but now we are wondering if they didn't choose too soon, and for the wrong reasons. The old homesteads are fallen down, and we pick up the rusted tools and try to fit new handles to them.

Science? Well I believe there is a lot more coming. I study the math and try to figure out the concepts because I want to understand it, not because it helps me raise chickens. Maybe I am wasting my time. I should be chopping firewood, carrying water, building chicken coops. I should be working alongside my friends, enriching the earth.

But I figure science and technology got us in this mess, it will probably be up to them to get us out of it, if we don't blow up first. Maybe I read too much science fiction as a child, but I would be proud to see humankind take the road to the stars. If I can make the way easier with some little trick of understanding, so much the better.

Meanwhile there are gardens to plant, and it is a sunny day in spring. Don't despair, Wolram. There will be a harvest. That is the faith you must have to push a seed into the soil. That is the faith you must have, as an old man who plants acorns.

Be well, Wolram, and all. Something good is coming.

Richard
 
  • #16
I am in tears, you rotten philosopher :smile: but i doubt if the dawn will
come in my lifetime, i have just made ginger biscuits, one of my favorites,
twenty minutes to cook and gone in five, i hope friendship lasts longer.
But the fact that the people that guide us are just people ,with brains no
bigger than yours or mine,have just some "take", of what its all about, should
not overwhelm us, it is just one fantasy v another, facts are scarse, if you
find one lock it up in a box and keep it for future use,
 
Last edited:
  • #17
wolram said:
...facts are scarce, if you find one lock it up in a box and keep it for future use...

Dear wolram

The truth is always more interesting than it appears at a glance. But then the closer one looks, the more elusive it becomes. Facts may not be densely scattered through the verbage of so many, but locking them up in a box is not science, no matter how many tenured professors tell you to do just that.

Cheers
Kea :smile:
 
  • #18
wolram said:
But the fact that the people that guide us are just people ,with brains no
bigger than yours or mine,have just some "take", of what its all about, should
not overwhelm us, ...

Hi wolram

Sometimes the people that guide are right in front of you (mirror included). Here, on Physics Forums, the discussions reach further than current research at times, without everyone fully realizing it.

Best Regards,

Mike
 
  • #19
wolram said:
... i have just made ginger biscuits, one of my favorites,
twenty minutes to cook and gone in five,...

if you wouldn't mind sharing it, what is the recipe for ginger biscuits?
 
Last edited:
  • #20
As the veiled prophet said.. "once I pushed the veil aside, it was all so easy". Is that not the point of doing science? The beauty of philosophy rests upon the pillars of science.
 
Last edited:
  • #21
Marcus

if you wouldn't mind sharing it, what is the recipe for ginger biscuits?

NO hard rules for this one you need, Sr flour, butter, treacle, ginger, salt.
add butter to sifted flour add a pinch of salt, mix until you have a rough
crumb ,add treacle ginger and splash of milk, mix well, you should end up
with a slightly sticky mixture that holds its shape when formed into
1 1/2 round balls, into over 180 for 10 15 mins, the biscuit will have a
crisp outer and soft light center. enjoy.
 
Last edited:
  • #22
Kea said:
Dear wolram

The truth is always more interesting than it appears at a glance. But then the closer one looks, the more elusive it becomes. Facts may not be densely scattered through the verbage of so many, but locking them up in a box is not science, no matter how many tenured professors tell you to do just that.

Cheers
Kea :smile:
Yes of course Kea i feel ashamed for saying such a thing, a fact belongs to
no one.
 
  • #23
kneemo said:
Hi wolram

Sometimes the people that guide are right in front of you (mirror included). Here, on Physics Forums, the discussions reach further than current research at times, without everyone fully realizing it.

Best Regards,

Mike
Hello Kneemo, I can only echo your thoughts, Intelligence just oozes out
of PF like a fresh fried sunny side up egg, But my thoughts wander unfocussed,
only touching on some enlightenment by chance, this gives me a different
outsiders view, untrained yes, but able to wonder if a path leads anywhere.
 
  • #24
Chronos said:
As the veiled prophet said.. "once I pushed the veil aside, it was all so easy". Is that not the point of doing science? The beauty of philosophy rests upon the pillars of science.
I can respect and do, this line of thought, but sometimes lifting the veil
reveals a hall of mirrors, Chronos my education is no match for most on
PF, but i have a part of me, the little monkey intuition, that draws me into
the mix, it is kind of you all for tolerating an oopart.
 
  • #25
wolram said:
Marcus

if you wouldn't mind sharing it, what is the recipe for ginger biscuits?

NO hard rules for this one you need, Sr flour, butter, treacle, ginger, salt.
add butter to sifted flour add a pinch of salt, mix until you have a rough
crumb ,add treacle ginger and splash of milk, mix well, you should end up
with a slightly sticky mixture that holds its shape when formed into
1 1/2 round balls, into over 180 for 10 15 mins, the biscuit will have a
crisp outer and soft light center. enjoy.


When reading English stories I always make the mental substitution "treacle = molasses". But in a recipe one might need to be more precise. Can you or anyone provide a usable substitute for the UK substance treacle?
 
  • #26
selfAdjoint said:
When reading English stories I always make the mental substitution "treacle = molasses". But in a recipe one might need to be more precise. Can you or anyone provide a usable substitute for the UK substance treacle?

beyond that there is some obscurity concerning units.
I assume a 180 oven is 180 celsius, but what about a 1 and 1/2 round ball

is that 1.5 inches? is it the diameter?

is the butter melted first, or mashed (as I imagine) into the flour with a fork?

what proportions, butter to flour?
 
  • #27
Marcus, SA.

Treacle = golden syrup , molasses in uk is a less refined
darker produce, but you can use it in this mix.
to blend the butter into the the flour use your fingers,
it is best to use the butter cold.
do you buy butter in 1/4lbs? if so use approx 1/4 of that
to two cups flour, add two table spoons golden syrup.
you need to make 1.5 inch balls of the mix and cook
at 180c on a well greased baking tray .
The ginger must be added to taste, i use a level tea spoon for
this amount.

For the tastiest most succulant beef ever, take a BLOW TORCH
and caramalise all round the joint, and cook slow 140c untill
juices run clear.
 
Last edited:

1. What is LQG?

LQG stands for linear-quadratic-Gaussian and is a mathematical control theory used to design controllers for linear systems with Gaussian noise.

2. How does LQG differ from other control theories?

LQG uses a combination of optimal control and estimation techniques to design controllers, while other control theories may only use one or the other.

3. What does "kicking tyres" mean in the context of LQG?

"Kicking tyres" is a phrase used to describe the process of testing and evaluating a control system before implementing it in a real-world setting.

4. What is the purpose of adding sawdust in LQG?

Adding sawdust is a metaphor for adding noise to a system in order to test and improve the robustness of the control system.

5. Can LQG be applied to non-linear systems?

LQG is specifically designed for linear systems, but there are extensions and variations that allow it to be applied to non-linear systems as well.

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