Fine Structure Varies !

[avandonk]

Steven where does dark matter and dark energy fit in this nice little closed Universe without Alice?

Bert

[xelasnave]

Is there a "string" in reality. Isnt a string merely a way of representing particles as a wave function? so rather than imagining little loops or lines we are really attempting to describe a particle and how it may move etc... it is a point we seek to describe so is there a string at all....
alex

[avandonk]

Alex all of Physics is mere mathematical construction of theories that fit reality. Some can be felt directly. If I hit you with a rather large club the conservation of momentum holds and the damage is concomitant with the impulse F X delta time. It would be painfully obvious to you when I hit you.

If I irradiate you with very hard alpha rays you would not feel a thing. The damage these ionising particles do would only come out later as you died of some horrible debilitating cancer.

bert

[xelasnave]

Bert you have a way with words thats for sure.
Either option would be a kindness at my stage of the downhill run.

alex

[sjastro]

Originally Posted by avandonk

Steven where does dark matter and dark energy fit in this nice little closed Universe without Alice?

Bert

Bert,

We had a dark matter issue in the 19th century, it was called Neptune. Scientists then applied a perturbation theory to Newtonian physics to predict the existence of Neptune from the deviations in the theoretical orbit of Uranus.

The same principles for dark matter apply today whether it is through the escape velocities of individual galaxies in a cluster to the rotation curves of galaxies.

Dark energy is based on the type II supernova data for distances.

The point is that one of the common misconceptions of dark matter and dark energy is that they are "made up" to support existing theories. For phenomenological theories such as cosmology, dark matter and dark energy are effects that do not require an Alice Universe.

The problem is with non phenomenological theories such as QFT which need to explain what dark matter and energy actually are.

Regards

Steven

[CraigS]

Originally Posted by CraigS

… QFT has its basis in empirical experimentation (phenomenological) …. certainly has firmer ground than that of a string too small to observe and violating the UP.
Cheers

Hmm … I need to correct the above statement … I meant to say QFT has its basis in non-phenomenal theories which are well supported by empirical measurements .. like QM and EM. (Getting my phenomena mixed up with mechanical things ..).

Seeing as I'm on a foot-in-mouth roll, I'll play the dummy and ask what is this Alice Theory business ? What exactly is an Alice theory ??? Is it being used in the sense of 'Alice in Wonderland' ?

Cheers

[sjastro]

Originally Posted by CraigS

Hmm … I need to correct the above statement … I meant to say QFT has its basis in non-phenomenal theories which are well supported by empirical measurements .. like QM and EM. (Getting my phenomena mixed up with mechanical things ..).

Seeing as I'm on a foot-in-mouth roll, I'll play the dummy and ask what is this Alice Theory business ? What exactly is an Alice theory ??? Is it being used in the sense of 'Alice in Wonderland' ?

Cheers

Hi Craig,

String Theory draws quite a bit of mathematics based on algebraic/geometric topology. Your idol Ed Witten is a major contributor in this area.

The infamous Klein bottle is also a product of topology.

An "Alice Universe" is a topological universe which has similarities to a Klein bottle.
http://en.wikipedia.org/wiki/Alice_u...Alice_universe

I need to read the book "The Trouble with Physics" by Lee Smolin which is a scathing criticism of String Theory.

As a result Smolin is public enemy No. 1 amongst String theorists.
Even Leonard Susskind has engaged in a bitter public dispute with Smolin.

http://www.timeshighereducation.co.u...sectioncode=26

Regards

Steven

[CraigS]

Originally Posted by sjastro

I need to read the book "The Trouble with Physics" by Lee Smolin which is a scathing criticism of String Theory.

As a result Smolin is public enemy No. 1 amongst String theorists.
Even Leonard Susskind has engaged in a bitter public dispute with Smolin.

http://www.timeshighereducation.co.u...sectioncode=26

Thanks Steven.
Very interesting ... by following the reference links in the Wiki link you posted about Smolin's book, I found Smolin's following words:

Let me start by saying that I do not think and do not write that that research on string theory should cease or that string theorists should
no longer be funded or hired. As I say in Chapter 12:
“String theory succeeds at enough things so that it is reasonable
to hope that parts of it, or perhaps something like it, might comprise
some future theory. So string theory is certainly among the
directions that deserve more investigation.” So I am not
“against string theory” and any interpretation of my book
as an “attack on string theory” is a misreading.

Methinks there's another journalism beat-up going on in the middle of this one. I'm not sure Smolin is propagating any scathing attacks ... (more reading to do on this one) ...

Cheers

[CraigS]

So, 'Sir Len' (Susskind) says:

Lee Smolin's The Trouble With Physics is another anti-string theory jeremiad. Smolin is a mid-level theoretical physicist, but his popular book-writing activities and the related promotional hustling have given him a platform high above that merited by his physics accomplishments. Smolin is no Chicken Little. He is, if anything, a Don Quixote figure. If physical theories are like ships, then Smolin is a most enthusiastic ship designer.

He then goes on to promote Gerard T'Hooft's view of String Theory … I should add that T'Hooft is one of Susskind's long term mates. He helped Susskind in the War against Stephen Hawking about information loss in a black Hole.

All these guys are all great scientists in my view.

Sounds like good, healthy brawling .. all necessary to make something productive of it all!

Good on 'em !

Cheers

[sjastro]

Craig,

Smolin was a former string theorist.

The Nobel laureate (for his work on Electroweak theory) Sheldon Lee Glashow is certainly not as conciliatory as Smolin. He refers to String Theory as a tumour and as campaigned to have String theorists banned from the Physics department at Harvard Uni.

Regards

Steven

[CraigS]

Originally Posted by sjastro

Craig,

Smolin was a former string theorist.

The Nobel laureate (for his work on Electroweak theory) Sheldon Lee Glashow is certainly not as conciliatory as Smolin. He refers to String Theory as a tumour and as campaigned to have String theorists banned from the Physics department at Harvard Uni.

Regards

Steven

Isn't the Electroweak also looking 'troublesome' if symmetry doesn't turn up at the LHC/CERN?
Glashow is certainly a hard-liner ... but his objections seem to be philosophical ones ... which, as Sir Len points out, can be set aside temporarily, in order to seek the true 'value propositions' also wrapped up in String Theory. I kinda like that approach ... especially as everyone seems to acknowledge that String Theory does have a lot going for it .. in spite of the falsifiability issues .. (I mentioned in some previous thread that some tests were under development .. I wonder what the status of those are ... I'll have to do some more searching on that front).

Also, Sir Len is a Princeton man and Glashow is only a Harvard man isn't he?

Cheers
PS: No !!! Sir Len is a Cornell and Stanford man ! (Wrong again, Craig ...although, the whole debate might very well have origins in which Physics departments these guys hail from.)

[CraigS]

Ok ... so for all those String Theory doubters out there ... here's a five part Youtube of Ed Witten's story behind the development of String Theory ...

Part 5/5 outlines his conclusions and personal views for why he sees String Theory as important and is well worth listening to.

Its great to see Ed in action ... it isn't very often one gets the opportunity .. a pity, really. An amazing lecture (unscripted also, I think). Not one 'err' or 'um' in the whole five parts ... I think he's going entirely from memory of the history part of it all also. Unbelievable actually !

Cheers

[sjastro]

Originally Posted by CraigS

Isn't the Electroweak also looking 'troublesome' if symmetry doesn't turn up at the LHC/CERN?
Glashow is certainly a hard-liner ... but his objections seem to be philosophical ones ... which, as Sir Len points out, can be set aside temporarily, in order to seek the true 'value propositions' also wrapped up in String Theory. I kinda like that approach ... especially as everyone seems to acknowledge that String Theory does have a lot going for it .. in spite of the falsifiability issues .. (I mentioned in some previous thread that some tests were under development .. I wonder what the status of those are ... I'll have to do some more searching on that front).

Also, Sir Len is a Princeton man and Glashow is only a Harvard man isn't he?

Cheers
PS: No !!! Sir Len is a Cornell and Stanford man ! (Wrong again, Craig ...although, the whole debate might very well have origins in which Physics departments these guys hail from.)

Electroweak symmetry is not a supersymmetry.
When the symmetry is broken, the massless boson or photon is formed for the electromagnetic force, where as the W and Z bosons which have mass form the weak nuclear force.

The problem with the electroweak theory is that it relies on the existence of the Higgs boson to explain why the W and Z bosons have mass.

Regards

Steven

[CraigS]

Originally Posted by sjastro

Electroweak symmetry is not a supersymmetry.
When the symmetry is broken, the massless boson or photon is formed for the electromagnetic force, where as the W and Z bosons which have mass form the weak nuclear force.

The problem with the electroweak theory is that it relies on the existence of the Higgs boson to explain why the W and Z bosons have mass.

Ok .. but it seems in particle physics, one thing leads to another ?
Spontaneous symmetry breaking seems to be referred to as a 'framework' for introducing bosons into relativistic quantum field theories. As you say, its introduction in EW theory, then leads to the quandry of how massive particles come about. Is there any empirical evidence that EW symmetry is necessarily the rule (or Law) in particle physics? (I don't know the answer here .. this is just a straightforward knowledge seeking question ..)

Surely the hunt for Supersymmetry evidence is just another enquiry into whether symmetry can be viewed as one of the fundamental laws of nature (or not)? Ie: if there's more evidence of symmetry, then it moves closer to being a fundamental Law, applicable for EW Theory as well as everything else?

Also, its interesting, (from what Witten says), that the originally 'unwanted' multitude of massless particles generated by String Theory, turn out to be exactly what is necessary to explain mass, gravity etc. He also points out that String Theory 'forces' into existence a quantum field theory of gravity from the outset, and is the only theory which does that. (I presume he is referring to the native unification aspects of String Theory here).

Cheers

[glenc (Glen)]

As I said at the start of this article, no-one believes us yet, and we are in for a long battle.
Some days I doubt I shall be living when the proof comes in. John K. Webb Professor of Astrophysics at University of New South Wales
http://theconversation.edu.au/is-lif...f-physics-4153

[CraigS]

Originally Posted by glenc

As I said at the start of this article, no-one believes us yet, and we are in for a long battle.
Some days I doubt I shall be living when the proof comes in. John K. Webb Professor of Astrophysics at University of New South Wales
http://theconversation.edu.au/is-lif...f-physics-4153

Other than the Cosmological Principle, which is a philosophical assertion having evidentiary/observational support at the fundamental levels, I see no particular reason for ruling out the possibility that life on Earth is due to complex non-linear interactions amongst the fundamental laws of physics. After all, life itself, follows complex process rules, so it would seem logical to speculate that its origins followed the same unpredictable processes.

In this sense, there is no need for a call of 'quirks in the laws of physics', when it comes to the origins of life here.

The particular research topic of this thread, hints at the possibility of variations in the fine structure 'constant' when viewed back in time, and across different areas of the observable universe. Measurement error has not yet been ruled out.

Interestingly, in the String Theory Youtube I posted, Witten also says that the possibility of variations in the fundamental laws of nature across the universe has some support in String Theory (due to the vast solutions available in the mathematical theory underpinning String Theory).

No 'quirkiness' is called for or required, other than as a way of explaining flawed statements/assertions/opinions/predictions, made erroneously.

Cheers

[sjastro]

Originally Posted by CraigS

Ok .. but it seems in particle physics, one thing leads to another ?
Spontaneous symmetry breaking seems to be referred to as a 'framework' for introducing bosons into relativistic quantum field theories. As you say, its introduction in EW theory, then leads to the quandry of how massive particles come about. Is there any empirical evidence that EW symmetry is necessarily the rule (or Law) in particle physics? (I don't know the answer here .. this is just a straightforward knowledge seeking question ..)

The "framework" for introducing bosons is the symmetry itself, not symmetry breaking.
The symmetry is defined when the properties of a dynamical system or the Lagrangian is unchanged under a mathematical transformation. For example if the Lagrangian is shifted in local space-time, bosons are created to preserve the symmetry. This however produces bosons that are massless. Breaking the symmetry gives bosons mass through the Higgs mechanism.
The symmetry is unique for the force being described. For example quantum electrodynamics, electroweak theory and Quantum chromodynamics which describe the electromagnetic, electromagnetic/weak and strong forces respectively are defined by their own symmetry group.

The empirical evidence for symmetry and symmetry breaking is indicated that many of the bosons and fermions that were undiscovered at the time had their properties predicted according to their symmetry. The predictions confirmed by experimental discovery were found to be very accurate.

Surely the hunt for Supersymmetry evidence is just another enquiry into whether symmetry can be viewed as one of the fundamental laws of nature (or not)? Ie: if there's more evidence of symmetry, then it moves closer to being a fundamental Law, applicable for EW Theory as well as everything else?

It's been known since the early 20th century well before QM, that many of the laws of physics are a consequence of symmetry not around the other way. This was proven by the mathematician Emmy Noether. She incidentally helped save Einstein's and Hilbert's bacon over some of the early problems encountered in GR.

Regards

Steven

[Robh (Rob)]

Originally Posted by CraigS

The particular research topic of this thread, hints at the possibility of variations in the fine structure 'constant' when viewed back in time, and across different areas of the observable universe. Measurement error has not yet been ruled out.

Craig,

I would have thought that measurements of spectra would be fairly straightforward these days. The spectra show what they show.
Therefore, the debate goes back to the interpretation of what these variations in spectra imply.

The Cosmological Principle won't be abandoned by the scientific community in a hurry. But, if it is not backed up by all of the observational evidence it must go.

Regards, Rob

[CraigS]

Originally Posted by Robh

Craig,

I would have thought that measurements of spectra would be fairly straightforward these days. The spectra show what they show.
Therefore, the debate goes back to the interpretation of what these variations in spectra imply.

The Cosmological Principle won't be abandoned by the scientific community in a hurry. But, if it is not backed up by all of the observational evidence it must go.

Regards, Rob

Hi Rob;
Yep .. I agree … I meant experimental or systematic errors in the analysis .. not 'measurement error'. Sorry about that.

(I'm not firing on all cylinders in this thread, eh ? Too many distractions, I think (?) .. or maybe Alex's compliments have thrown me ! ).

Cheers

[CraigS]

Originally Posted by sjastro

The "framework" for introducing bosons is the symmetry itself, not symmetry breaking.

Yep another blooper .. I did mean symmetry ! (Man, bad day at the office !)

Originally Posted by sjastro

The symmetry is unique for the force being described. For example quantum electrodynamics, electroweak theory and Quantum chromodynamics which describe the electromagnetic, electromagnetic/weak and strong forces respectively are defined by their own symmetry group.

The empirical evidence for symmetry and symmetry breaking is indicated that many of the bosons and fermions that were undiscovered at the time had their properties predicted according to their symmetry. The predictions confirmed by experimental discovery were found to be very accurate.

So, is it possible that symmetry might not necessarily be ubiquitous for all properties (in spite of symmetry predictions)?

Cheers