Quantum space and real universe..

[bojan]

This is very interesting article, talking about the simulations starting from couple of simple rules, that at the end result in something very similar to real universe...

http://www.sciam.com/article.cfm?id=...sc=WR_20080701

[sheeny (Al)]

I agree! Thanks for posting!

Al.

[renormalised (Carl)]

Thanks for the link!!

[xelasnave]

Thanks for the link Bojan.
I can not say it does much for me in the context that all their talk about gravity ..even "quantum" gravity... is in my view merely an observation of the Universe expressed as geometry... I still see nothing "tangible" to explain the machinery as to how it works.. all seem preoccupied with the math ..which is reasonable to a degree but the math applied seems little better than holding a tape measure up to the subject of gravity...and having drawn some measurements and tools to aid the recording of relationships the explanation of gravity is avoided... and so does all this new work take us to a place where we can,as better informed humans, say gravity is indeed a force that can be explained other than by Newton's determination that gravity is due to the force of God... and although such an explanation may seem quaint to all of us today I note that Dr A did not in his giant leap forward did not disagree..the one point he left in the mix as first presented by Newton is that of an explanation of how the force of gravity can be explained..all will chuckle at my observation but dont dismiss it until you grasp the point I make...General relativity leaves the question as to force residing in God's hands for Dr A conveniently avoids "a force"...and if it does I need to be corrected ...
The reason why things will not move forward from the current state of learning is the refusal to accept all is simply measurement of "gravity" that provides no machinery with which we could understand all other things...

I did like the fact the cosmological constant is recognised as this hints at where a machinery may be understood.

alex

alex

[bojan]

Alex,
The problem here is that we perceive the gravity as a force. This is not necessarily the "mechanism" you are talking about.
The mechanism here actually is curvature of space, which just manifests itself (to us in our everyday life) as what we perceive as "force".
Mathematically, the force as a "mechanism" can be completely abandoned, and yet we can still have a consistent model which explains and predicts various observable phenomena..

[xelasnave]

Originally Posted by bojan

Alex,
The problem here is that we perceive the gravity as a force. This is not necessarily the "mechanism" you are talking about.
The mechanism here actually is curvature of space, which just manifests itself (to us in our everyday life) as what we perceive as "force".
Mathematically, the force as a "mechanism" can be completely abandoned, and yet we can still have a consistent model which explains and predicts various observable phenomena..

Yes I know what the approach currently is and I still think it fails to grab the issue... it sounds nice to say space is curved but I think folk believe it is the magic of the math on the papeer that actually does the bending..I think there will be found a tangible explanation as to why we get what we get when we use the math of general relativity to make predictions..the math works there is no doubt there..there is no problem with the math being able to predict etc but I still say the current approach leaves everyone happy not to look further at a question begging for an answer....the things we arrive at dont happen by magic ..which is really what we say if we dont look past general relativity..in my humble opinion of course...

I think to leave the "force" as a manifestation of space curvature avoids placement of the "force" with anyone other than God... for my money I dont think God is the force that curves space and unlike those pioneering the science of gravity think we need to move way way past such a cop out of an explanation...

Looking to general relativity as the complete answer leaves so much to be desired in terms of a mechanical explanation which I feel is needed to move the matter forward.

Thanks for your input Bojan

alex

[bojan]

Well..
If physicists were sticking to what feels right, we would have still been at the Aristotle's level of understanding the physical world. Like, heavier things fall quicker than lighter ones... and so on.
I know, it is not a good attitude to accept just everything from "big guys because they know better", but it is not good either not to try to understand why they say things are what they are... However, what we can grasp (if we can not fully understand the mathematical models they are playing with) is the process, how they come up with their conclusions, this is not beyond average person's understanding, if the fine details and tools (math) are.. There are plenty of reading on the web, which can help here. The main thing is not to dig in our own ways of understanding things. Because there must be something in the fact that "big guys" thik otherwise...

[TrevorW]

I'm a great believer in the principle that man tends to over complicate things that he cannot explain in a vain attempt to explain the unexplainable. Paraphrasing albiet in bad taste "time will tell" whether one is right or they are both right depending on the observer and the point in time space when that observation takes place, maths alone cannot explain the complexities of the vista we know as the Universe.

[bojan]

Originally Posted by TrevorW

I'm a great believer in the principle that man tends to over complicate things that he cannot explain in a vain attempt to explain the unexplainable. Paraphrasing albiet in bad taste "time will tell" whether one is right or they are both right depending on the observer and the point in time space when that observation takes place, maths alone cannot explain the complexities of the vista we know as the Universe.

Quite the contrary... Scientist are trying to find the most simple explanations. Everywhere you can read that this-and-that-scientist is talking about simplicity=beauty.. Just because this explanation seems complicated to the rest of us who are not into those problems, does not mean the things are over-complicated. Maybe we lack the tools (math) to understand what they are talking about. I know, because when I was good in math (and that was a long time ago) everything seemed so simple :-)
What I do since and now for living (electronics engineering) does not require even 1/100 of what I learned at school then.. but the "feeling" still remains...

[renormalised (Carl)]

It all really boils down to your definition of simplicity and beauty. What most of these theoretical physicist call simplicity, would for most of us be a completely jumbled complex mess. Mostly unintelligible. However it's not too difficult to appreciate the beauty in many of their equations, especially when you reduce the workings down to the final answer. It's those answers, like E=MC^2, that hold the beauty within them. The simplicity of an equation like that, yet it holds so much power (literally) in describing reality. Fractals...what could be more beautiful than those equations. Nothing to them, yet they describe such complex patterns. Patterns that you can find anywhere in nature. They are the outcomes which you can appreciate, although the workings behind the equations are anything but simple...witness string theory. Simple and elegant in it's description of reality, yet so complex mathematically.

[sjastro]

Originally Posted by renormalised

It all really boils down to your definition of simplicity and beauty. What most of these theoretical physicist call simplicity, would for most of us be a completely jumbled complex mess. Mostly unintelligible. However it's not too difficult to appreciate the beauty in many of their equations, especially when you reduce the workings down to the final answer. It's those answers, like E=MC^2, that hold the beauty within them. The simplicity of an equation like that, yet it holds so much power (literally) in describing reality. Fractals...what could be more beautiful than those equations. Nothing to them, yet they describe such complex patterns. Patterns that you can find anywhere in nature. They are the outcomes which you can appreciate, although the workings behind the equations are anything but simple...witness string theory. Simple and elegant in it's description of reality, yet so complex mathematically.

Yes the mathematics is very complicated and messy, even to a theoretical physicist. This highlights one of the major problems with modern day physics, is the increasing intrusion of pure mathematics into that discipline.

String theory and Gauge theory require algebraic topology as a minimum prerequisite.
In my days at Uni algebraic topology was taught in third year and honours Pure Maths.

These days it's common for theoretical physicists to work in conjunction with mathematicians as the physicists do not have the necessary mathematical knowledge.

Regards

Steven

[renormalised (Carl)]

You know, Steve, I think Hitch-hiker's got it right. The answer's 42. Who gives a rat's what the maths guys think!!!!

It's all transcendental numbers

[sjastro]

Originally Posted by renormalised

You know, Steve, I think Hitch-hiker's got it right. The answer's 42. Who gives a rat's what the maths guys think!!!!

It's all transcendental numbers

I'm not sure how to take this.

I did Applied Maths at Uni. The Pure Maths guys thought of Applied Mathematicians as sub human, we on the other hand thought that Pure Mathematicians were drugged up weirdos with no concept of reality.

Steven

[xelasnave]

I still say general relativity is geometry and tells us little of how it all works and if I understand it even string theory is really geometry...the maht gives us limits but we understand nothing of what it is that can run around in those limits..unless that is the HB's job...I dont know really....now that is probably a simple statement but if either are more someone can say so... I think until gravity is seen as a force other than that of God we will stay in darkness..and therefore need dark matter as such
the force of attraction does not exist that is the stumbling block...well I have been in the bush I have to say something
alex

[sjastro]

Originally Posted by xelasnave

I still say general relativity is geometry and tells us little of how it all works and if I understand it even string theory is really geometry...the maht gives us limits but we understand nothing of what it is that can run around in those limits..unless that is the HB's job...I dont know really....now that is probably a simple statement but if either are more someone can say so... I think until gravity is seen as a force other than that of God we will stay in darkness..and therefore need dark matter as such
the force of attraction does not exist that is the stumbling block...well I have been in the bush I have to say something
alex

Alex,

Dare I say it, but science attempts to explain nature as we see it rather than providing a total picture of the mechanism.

For example elementary quantum mechanics provides an astonishing accurate picture of the energy levels of the hydrogen atom but tells us absolutely nothing about why the energy levels are quantized in the first place. The observation that hydrogen existed in discrete energy levels amongst other things led to the development of quantum mechanics.

The theory of gravity goes down the same lines. The closest we will come to a "mechanistic" theory of gravity is when someone finds the graviton and sorts out the mathematics of quantum gravity with the graviton as the virtual particle of interaction.

The speed of light in a vacuum is 299,792,458 m/s. Do we really need to understand why it doesn't travel at 299,792,459 m/s or 765,897,432 m/s or any other speed for that matter?

Regards

Steven

[bojan]

Steven,
Perhaps the Hydrogen atom is a bad example to highlight your point.
If we assume (or accept the "crazy" idea) that electron is a wave (de Boglie) , then it is very easy to see why we have different energy levels here.. because when the wave goes around the nucleus, the only possible orbits are those where the circumference of the orbit is the integer multiple of the electron wavelength. So the distances (and therefore energy levels, calculated from them, taking into account the electric charge and the attracting force between proton and electron) are strictly determined. And the measurements (spectrum) show excellent agreement with calculation results.
The problem are other, heavier atoms, where things are not so simple and the energy levels calculated using this simple "mechanistic" model are far from what is measured in experiment. This is because many other things affect the results, Pauli's principle is just one of those, which simply does not play any part in Hydrogen atom affairs (because there is only one electron here and we need more electrons for this principle to become a factor at all).
Otherwise, your point is very valid :-)

[sjastro]

Originally Posted by bojan

Steven,
Perhaps the Hydrogen atom is a bad example to highlight your point.
If we assume (or accept the "crazy" idea) that electron is a wave (de Boglie) , then it is very easy to see why we have different energy levels here.. because when the wave goes around the nucleus, the only possible orbits are those where the circumference of the orbit is the integer multiple of the electron wavelength. So the distances (and therefore energy levels, calculated from them, taking into account the electric charge and the attracting force between proton and electron) are strictly determined. And the measurements (spectrum) show excellent agreement with calculation results.
The problem are other, heavier atoms, where things are not so simple and the energy levels calculated using this simple "mechanistic" model are far from what is measured in experiment. This is because many other things affect the results, Pauli's principle is just one of those, which simply does not play any part in Hydrogen atom affairs (because there is only one electron here and we need more electrons for this principle to become a factor at all).
Otherwise, your point is very valid :-)

Thanks for your comments.

What you're describing was an early model of quantum mechanics for the hydrogen atom which was still very much influenced by classical mechanics. It's one of those unfortunate cases of a model that turned out to being completely wrong despite giving the right answers. Due to the Heisenberg uncertainty principle, electrons don't travel in orbits but exist as probability densities. It's not possible to make specific measurements about the position or momentum of an electron.

The success of quantum mechanics for describing the hydrogen atom was based on expressing the electron as a mathematical wave function.
Using this model quantum mechanics was able to reproduce Balmer's formula for the position of the emission and absorption lines in the hydrogen spectrum.

This leads me back to my original point that Quantum mechanics was built on observation rather than a specific attempt to explain mechanisms.

Regards

Steven

[JimmyH155]

Wasn't it the poet Keats, who said "..Beauty is truth and truth beauty. That is all ye know on Earth and all ye need to know."