Barbour's "Machian Model" of space time

[36grit]

Einstein's upside down pic on this months discovery magazine caught my eye earlier so I bought it read the article. Does anybody understand what it is that's different about his theory and relativity? And, what do you think?

[DrRocket]

Einstein's upside down pic on this months discovery magazine caught my eye earlier so I bought it read the article. Does anybody understand what it is that's different about his theory and relativity? And, what do you think?

 

 

I think that Discovery Magazine and Julian Barbour are equally ignorable.

[36grit]

I think if I were a quantum physicist trying to find solutions to quantum gravity problems and explanations, I'd find it interseting and hard to ignore.

[ajb]

You can find Barbour's papers here.

 

Mach's principle basically says "Local physical laws are determined by the large-scale structure of the universe."

 

Einstein's general relativity does not fully satisfy this principle, although it did philosophically help Einstein in this development of GR.

 

Mach's principle will come up time and time again in pedagogical introductions to GR, but it does not seem to play any role in the modern formulation. I don't think it is seen as important by the general physics community to rectify GR in some way to fully conform with Mach's principle.

 

Now, I am not familiar with Barbour's work to really make further comments.

[dehilster]

Folks, Einsteins days are numbered. Our doc comes out this year and is heading for Canne, Berlin, Sundance. We have a growing databse of scientists around the world from almost 70 countries who have been all over this and Julian Barbour is simply not afraid to speak up. The movie will break this news wide open. "Einstein Wrong - The Miracle Year".

[D H]

Folks, Einsteins days are numbered.

Utter nonsense, and no, I am not the one who gave you the negative rep.

 

Is general relativity absolutely correct? Of course not. It doesn't jibe with quantum mechanics, and it admits singularities.

 

Are Einstein's days numbered? Of course not.

 

For an analogy, look to Newtonian mechanics. Relativity and quantum mechanics collectively demonstrated that Newtonian mechanics was in a way fundamentally flawed. However, they also showed that Newtonian mechanics was fundamentally correct (but in a limited domain). They had to! There was a huge accumulation of confirming evidence during the 200 years between Newton's publication of his Principia and those late 19th century experiments that showed problems with Newtonian mechanics. Newtonian mechanics is still taught because it is still approximately valid in the limited domain of our everyday world.

 

Any theory that overturns relativity must similarly show that relativity is fundamentally correct in the domain where relativity has been well tested.

 

 

Our doc comes out this year and is heading for Canne, Berlin, Sundance.

Good luck with that. Or should I say "bad luck with that?" Unfortunately, the public gobbles up non-science.

 

 

We have a growing databse of scientists around the world from almost 70 countries who have been all over this and Julian Barbour is simply not afraid to speak up. The movie will break this news wide open. "Einstein Wrong - The Miracle Year".

Barbour is first and foremost a relativistic physicist. If he Barbour is right he will not show that Einstein was wrong. Barbour's principal focus is Mach's principle, a concept that strongly motivated Einstein. "Mass tells spacetime how to curve, curved spacetime tells mass how to move" is a concept straight out of Mach's principle. There are some aspects of general relativity that are at odds with Mach's principle. Barbour is trying to find a slight modification to general relativity that makes it fully compliant with Mach's principle. He is not seeking a complete negation of general relativity.

 

 

Your website (I found it, but I will not provide a link; I don't link to such nonsense websites), on the other hand, appears to reject every aspect of general relativity. Your nonsense includes ...

 

"Where are the flying cars?"

This has nothing to do with relativity. It has everything to do with the trash widely published in science popularization magazines in the 1950s. Just because we don't have flying cards, furniture that one cleans with a hose, cheap plastic dishes that dissolve in water doesn't mean that science has abandoned us. It just means that those 1950s magazines were peddling crap because crap science sells.

 

"Why is Einstein considered the genius of our time yet no one knows anything about him or his theory?"

This website has multiple members who know quite a bit about relativity. So, bzzt, wrong.

 

"Why don't we understand anything theoretical and astrophysicists say yet we give them billions of dollars to build experiments that don't better mankind?"

This is a non sequitur, and it is wrong. Some people do understand what those theoreticians say, and at a very deep level. Others understand it to some extent at a lay level. Just because you don't understand it or like it does not mean it is wrong. As for not benefiting mankind, says who? You? Theoretical physics has benefited mankind quite a bit. Astrophysics, too. You are ignoring that it can take quite a while for science to move from theory to application. More importantly, you are ignoring the huge benefit just in the increase in knowledge. Knowledge is the ultimate wealth in this new millennium.

Edited March 4, 2012 by D H

[michel123456]

I think that Discovery Magazine and Julian Barbour are equally ignorable.

Why do you dismiss J.Barbour?

Is it the "who's talking" that bothers you, or really what he says. Like this: (from the abstract of "Shape Dynamics. An Introduction") arXiv.org > gr-qc > arXiv:1105.0183

 

Shape dynamics is a completely background-independent universal framework of dynamical theories from which all absolute elements have been eliminated. For particles, only the variables that describe the shapes of the instantaneous particle configurations are dynamical. In the case of Riemannian three-geometries, the only dynamical variables are the parts of the metric that determine angles. The local scale factor plays no role.

That's fantastic to me: pure geometry! All based on proportition, if I understand correctly.

 

 

And from here

Shape Dynamics

In the last few years, Niall Ó Murchadha, several students, and I have explored the implications of the relativity of size (current research). If all distances in the universe were doubled over night, nothing would tell us this had happened. We therefore believe that relativity of size should be built into the foundations of dynamics. Strangely, Einstein’s general relativity just fails to implement perfect relativity of size. This is what allows the universe to expand in his theory. The Big Bang violates relativity of size. Most cosmologists accept this without even realising that it is an issue. We created a scale-invariant theory very like general relativity but with perfect relativity of size. However, our construction was not satisfactory, being unable to explain fundamental observational facts in cosmology. Relativity of size is such an attractive principle, I long believed that a dynamics of pure shape would one day be found, but in the last two years my thinking has changed somewhat. The changed perspective is reflected in the final four papers in Papers before the two on maximal variety. These define a theory of gravity that my current collaborators and I call Shape Dynamics. It retains the essential dynamical core of general relativity while removing in a well-motivated way structure that is potentially redundant and may well be responsible for the difficulties in the creation of quantum gravity. My collaborators Henrique Gomes, Sean Gryb, Tim Koslowski and Flavio Mercati are now working actively on Shape Dynamics and have obtained very interesting and encouraging results, the first of which are already published in two of the four papers just mentioned.

 

That looks very interesting.

This excerpt, and his arxiv papers show a genuine scientific approach. Why dismiss him just like that?

Edited March 4, 2012 by michel123456