[ukmicky (OP)]

Its me again. sorry[]

Is dark energy an easy way out for the scientists when asked to give a possible reason for expansion.

Apart from dark energy or a possible outside force pulling on the universe,are there other possible reasons for the expansion.

Or is it possible that our measurements of distant supernovae are flawed due to the great distances involved, could light effects become distorted over great distances for  reasons we dont know about yet.

Michael                                      

[DoctorBeaver]

It is now being postulated that c being unbreakable is only true on a local scale. Even the fine structure constant is now being questioned. If these "constants" are not, in fact, constant, then that brings into doubt all our assumptions about how things really are.
We can only say that the laws of physics that pertain to our observable universe (albeit as far as we can tell) hold true in our observable universe. Who knows what goes on in parts we can't observe!?
Dark matter is still purely hypothetical. It conveniently fills a hole in a theory. Being slightly whimsical, if I were to propose that the missing mass in the universe is actually angels, who could prove me right or wrong?
The bottom line is that we just don't know.

[Soul Surfer]

The expansion of the universe is generally believed to be a genuine expansion of space itself and not the result of things flying apart as the result of an explosion.  Remember the term "big bang" was the term coined by Fred Hoyle and his mates as a derrogatory term in contrast to his preferred "continuous creation" model.

This expansion of space is as if space itself was making more space.

I have some intersting ideas about visualising this process if anyone is interested.



Learn, create, test and tell
evolution rules in all things
God says so!

[Solvay_1927]

quote:I have some intersting ideas about visualising this process if anyone is interested.

Ian - yes, I'd be interested.

[Soul Surfer]

Please note this is only an idea and not a serious theory and not fully worked through at the moment.

Consider the possibility that a "ground state" black hole exists.  This would be a particle, a bit like a neutrino without any spin but with a tiny mass that only interacts gravitationally.  These particles could form a significant part of the "dark matter" in the universe.  They could be considered as the basic structure of space itself.  These particles would initially have had enormous energy at the time of the initial big bang (a great many millions of times their rest mass)  These particles would interact with each other gravitationally. These particles would have virtually no detectable interactions with normal matter except for the occasional slight disturbance of a perticle bt a close gravitational encounter.  Remote interactions between thew particles would just involve an exhange of gravitational energy between the particles but the occasional close interaction could be more violent and create another of the tiny black holes at the expense of some of the kinetic energy of the other two particles.  this gradual increase in numbers would cause space itself to expand.  (This is not finished yet I've got to do something else now so I'll post it now and edit it again later)

Learn, create, test and tell
evolution rules in all things
God says so!

[DoctorBeaver]

Whilst I accept this is still merely a vague idea, there are just a couple of points I'd like to note.

1) Why would an interaction between the black holes create another black hole? Would it not be more likely that the 2 interacting black holes would merge?

2) Assuming 1) does happen, why would that cause space to expand rather than merely causing a greater concentration of black holes?

[Soul Surfer]

Black holes more complex than the ground state black hole would evaporate by Hawking radiation.  The ground state black holes I am talking about have masses far less than that of an electron and effectively constitute space itself.  This brings me to the answer to the second part of the question.  this "atmosphere" of rapidly moving tiny black holes is in fact the quantum mechanical vacuum itself. clearly interactions between the holes could also produce uncertainty pairs that self anhillate as part of their inteactions just the sort of model that is cirrent for the quantum mechanical vacuum.  The only long lived output that an interaction between two of the tiny holes could have is another one of the same type.

Some quantum gravity types have considered space to be a number of quantized elements like a giant crystal and Roger Penrose visualises it a series of spin networks (which I quite like in its own right) so if you add elements to space it gets bigger.  The process I was desgribing shows how this might be done without contravening the conservation of energy and have a system dominated by "dark energy" using largely classical images.

I am currently pondering the optiond whether the whole of the expansion might be due to the creation of new black holes or just the slight excess of expansion as seen in the supernova expansion but havent put any maths to it yet.  The whole idea is probably far to facile but I do feel that the particle physicists and cosmologists need some new approaches to thinking in this area. and my long experience shows that a return to first principles is often helpful.

By the way If you want a really good and readable book about the mathematical tools you need to start to get a grip on classical physics, quantum physics and cosmology I can thouroughly reccommend Roger Penrose's book  "The Road to Reality"  it starts from sbsolute first principles and gets you all the way to quantum gravity and string theory.

Learn, create, test and tell
evolution rules in all things
God says so!

[DoctorBeaver]

Ian - I think I see what you're getting at now.

 

quote:...a return to first principles is often helpful

I couldn't agree more. It's difficult, if not impossible, to know if the road you're on is a cul-de-sac when you can't see the end of it. Questioning assumptions made previously can be quite revealing.
You seem to think the way I do. To use yet another metaphor, I don't just look at the top of the wall being built. I want to make sure the foundations are sound so I poke & prod at them a bit.

I read 1 of Penrose's books a while back - or rather, I tried to! It was heavy-going to put it mildly! I'll try the 1 you've recommended. Thanks