Login Register

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
The premises of general relativity theory and BB
#1
What are the premises, the axioms of GR and BB theories? What they think as granted when followers start to making equations and interpreting empirical findings? Are they aware of them?

The premises of science in general are self correcting. So of course  also in physics and cosmology. If we for example find that God does exist, then we take his influence as possible in the development of the universe. Since that it is problematic.
Reply
#2
GR's premise is that gravity is due to curvature of spacetime, more or less. Of course there are a huge number of underlying unstated premises. One of them is, God has nothing to do with it. Big Bang is based on GR, so that spacetime can start very small and expand. But it doesn't really have unique premises of its own, it's based on observational evidence.

Of the dozens of premises, or underlying assumptions, you can be sure some of them will be considered wrong in a few decades. Which ones, I don't know.
Reply
#3
The choice of axioms of physical theories is an exercise which does not make much sense. That is more useful and interesting for mathematicians. For physicists, what counts is the theory itself. In GR, you have a manifold, a spacetime metric on it, and the Einstein equations. Which are defined as Euler-Lagrange equations of the Einstein-Hilbert Lagrangian. There are also other, not specified matter fields, and there is the requirement that the part of the Lagrangian for these matter fields has to be covariant. This leads to the Einstein equations of GR, with the energy-momentum tensor for matter fields on the rhs, so that this equation already depends on matter.

The spacetime metric defines clock time for a clock travelling along a trajectory - a worldline in the spacetime. But this is not really an independent axiom, because if you have a description of a clock in terms of highly localized matter fields, you can derive this as an approximation for this clock.

The BB is not really a theory. It is a class of particular solutions of GR, which have an expansion, and where the expansion is extended into the past in such a way, that the overall density in the universe becomes as large as inside a neutron star and larger. You can name the hypothesis that this solution of GR approximately describes our universe the "BB theory" if you like, but it is not really a theory.

Modern physics does not start with some general axioms or premises or principles or so an then derives something from them. It starts with whole theories, which are not derived, but always remain hypothetical.
Reply
#4
(10-29-2016, 09:22 AM)Schmelzer Wrote: The choice of axioms of physical theories is an exercise which does not make much sense.  That is more useful and interesting for
The spacetime metric defines clock time for a clock travelling along a trajectory - a worldline in the spacetime.  But this is not really an independent axiom, because if you have a description of a clock in terms of highly localized matter fields, you can derive this as an approximation for this clock.

The BB is not really a theory.  It is a class of particular solutions of GR, which have an expansion, and where the expansion is extended

Very much thanks for both replies. They make me understand much more than before.

It seems to me that the problem in GR is the time. Is it a dimension? Does the Universe have time at all? The glusters of galaxies, the galaxies, the stars, planets and moons definitely have times. Depending of their speed as GR says. The space of the Universe is 3- dimensional, and maybe it has no time at all, because it is not a moving particle. Only the parts have time, beginning and end. If there is other dimensions, they are not space dimensions but something else: time dimensions, different matter dimensions,  spirit world, wormholes, ether or else.

GR supposes some kind of Universe and it is maybe not like the Universe there really is. If it comes from empirical research, some unknown premises and mathematical conclusions, it is only an interpretation of the empirical findings, not necessary a true interpretation of them.

The God problem has not very much to do in cosmology. As in all science. If the Universe has always existed, God has not created it. It has always existed without any creation, only to its nature can there be creation but not to its existence.

God comes here because of the creation hypothesis, but even the creation can be interpreted as the creation of the structure of the planets and the species, not the creation of the Universe from nothing. What is impossible. All power does not mean power to make impossible things or things against the formal logic. Miracles if they really do happen are miracles only because we don't know the laws of nature which make them to happen.

Of cause the GR is best we have. But the investigation of its premises might help in developing it. Seems that I don't have enough competence to analayse them. Maybe some philosophers, who have deep knowledge of physical sciences and mathematics have made something like that.
Reply
#5
At your level of knowledge the best what you can do is to learn. Without some basic knowledge about the established theories, speculations about what are the problems of these theories will remain fruitless.

Don't worry, you don't have to learn string theory or so. But what you certainly need are the basics of GR as well as quantum theory.

Once you are interested in philosophy, it would be helpful to learn also about different interpretations of these theories. For quantum theory, you need at least some idea about the Copenhagen interpretation, as well as the de Broglie-Bohm theory. There are many others, but these two I would name obligatory. For GR, there is only the spacetime interpretation which you will find in textbooks. But the Lorentz interpretation of SR is also useful. Its extension to GR is what you can find only here.

With a philosophical interest, you would also have to read Popper.
Reply
#6
Seems to me that the whole problem here is that the mainstream cosmologist do not popularise their theories in the right way. The problem is maybe not in the theories but in the way you tell them for us.

But after thorough thinking: It is not necessary to understand the cosmology better than an average philosopher does. In fact you are so indoctrinated with your mathematics that you don't see any new possible paradigm for cosmology. History has a good parallel. Ptholemaios wanted that the planets and the sun circulate the earth in the round orbits. Every empirical findings could be put in this framework, but in the long run the calculations did became too complicated. This clearly has happened with the BB-theory and GR. Every empirical findings can be put in this framework but better is to chance the whole framework.

(I apologise that I don't know the implications of QM for the cosmology.)

The genuine way is abandon the expanding universe for a steady state, because the movements of the galaxies (from each others) can be explained by the properties of the limitless universe and the gravity as a real force. And having the time, speed, directions, orbits, gravity and so on only for galaxies and other parts of the universe, not for the Universe itself, witch does not have time or movement. It has only the space and all the matter and energy what there is.

One day you will thank me from this. You can get a Nobel praise : ) I have not invented this be myself but in the discussion with you and others.

Astronomy is not only physics. When we go to the life in the Universe we will need all the other sciences too. Geology we already have there. Every happening in the world has its physical, biological, psychological, social and theological causes in the same time. In the astrology they are nowadays only as imaginary possibilities, but philosophy is there always. Luckily.
Reply
#7
(10-31-2016, 10:28 AM)Olli Santavuori Wrote: Seems to me that the whole problem here is that the mainstream cosmologist do not popularise their theories in the right way. The problem is maybe not in the theories but in the way you tell them for us.
Popular science is indeed a big problem. In part because of science journalists, which are, unfortunately, journalists. The other part is a philosophical problem of modern science - the strong influence of positivism on science.

While in the philosophical discussion of the foundations of science logical positivism is dead, as dead as possible for a philosophical idea, since Popper's Logic of scientific discovery 1935, it remains powerful in science, because the founding fathers of the scientific revolution (as the relativistic, as the quantum one) have been heavily influenced by it. The unfortunate consequence is a rejection of metaphysical interpretation - which does not mean that there are none (this would be the dream of a positivist) but that there is only one, the historically first one, which cannot be criticized.
(10-31-2016, 10:28 AM)Olli Santavuori Wrote: In  fact you are so indoctrinated with your mathematics that you don't see any new possible paradigm for cosmology.
LOL, one of the main points of what I do all the time is to put the same mathematical apparatus into another, different interpretation, or paradigm if you like.
(10-31-2016, 10:28 AM)Olli Santavuori Wrote: One day you will thank me from this. You can get a Nobel praise : )
Sorry, but up to now there is completely nothing to thank you.
Reply
#8
(11-02-2016, 04:00 PM)Schmelzer Wrote: Popular science is indeed a big problem.  In part because of science journalists, which are, unfortunately, journalists.  The other part is a philosophical problem of modern science - the strong influence of positivism on science.  

While in the philosophical discussion of the foundations of science logical positivism is dead, as dead as possible for a philosophical idea, since Popper's Logic of scientific discovery 1935,  it remains powerful in science, because the founding fathers of the scientific revolution (as the relativistic, as the quantum one) have been heavily influenced by it.  The unfortunate consequence is a rejection of metaphysical interpretation - which does not mean that there are none (this would be the dream of a positivist) but that there is only one, the historically first one, which cannot be criticized.  

LOL, one of the main points of what I do all the time is to put the same mathematical apparatus into another, different interpretation, or paradigm if you like.  

Sorry, but up to now there is completely nothing to thank you.

OK. I try once more. Now I know better my own idea, after all these discussions here and in other forums and elsewhere with different people.

Lets put the whole thing upside down. There is only one important question:

In what kind of Universe there happens so that the galaxies are moving from each other in an accelerated speed?

We can go to the history of GR and BB and we find that even Einstein was not content when he found that his equations did lead to an expanding universe and else impossibilities. And he put there the cosmological constant to correct the situation. Later he accepted the expanding universe, the beginning of universe, and so on, because everybody else did so and there might be singularities and so on .

But there was an other possibility that nobody did think seriously and thorougly:


Just find in whits kind of Universe this happens !!!!!


Don't think that you already have a right vision of the real Universe when there happens this kind of unexpected things.

So, you who have the competence, why not try to imagine this Universe? This is my very important (sic!) vision and advise.

This made there maybe is not need for so much dark matter either.
Reply
#9
Sorry, but this "idea" does not make any sense to me. The GR solution is in sufficiently nice agreement with what is observed. What would be the point of considering other kinds of universes?
Reply
#10
Well, some others will understand the meaning of this and are already making the more exact model that you want to have. The point is simple, we get ride off of the awful expanding space time universe that the BB and GR together suppose. Just by thinking which kind of universe it is where the galaxies are moving from each others in accelerating velocity, or where it must be looking like that.

My solution is that it is the normal property of the limitless universe which the real universe necessarily is. This comes from philosophy and not from astronomical cosmology.

I have made known some essentials of these thoughts public already since 2004 in my home page http://www.santavuori.com and maybe some day I will get some merit of this.

(11-10-2016, 08:16 AM)Olli Santavuori Wrote: Well, some others will understand the meaning of this and are already making the more exact model that you want to have. The point is simple, we get ride off of the awful expanding space time universe that the BB and GR together suppose. Just by thinking which kind of universe it is where the galaxies are moving from each others in accelerating velocity, or where it must be looking like that.

My solution is that it is the normal property of the limitless universe which the real universe necessarily is. This comes from philosophy and not from astronomical cosmology.

I have made known some essentials of these thoughts public already since 2004 in my home page http://www.santavuori.com and maybe some day I will get some merit of this.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)