David Levy Posted February 20, 2016 Posted February 20, 2016 (edited) Like I stated cosmology hasn't solved that problem yet .. ordinarily energy is conserved. As we don't know the mechanism for the cosmological constant we can't determine how to maintain the conservation of energy with regards to the cosmological constant. Dear Mordred Now we know that new mass/energy is created constantly in the Universe. However, do you agree that this was the basic idea of Fred Hoyle , as It is stated: https://en.wikipedia.org/wiki/Steady_State_theory "..This requires that matter be continually created in order to keep the universe's density from decreasing." Edited February 20, 2016 by David Levy 1
Mordred Posted February 20, 2016 Posted February 20, 2016 (edited) Yes I'm familiar with Hoyles steady state theory. Even he realized it didn't work. Particularly with observed evidence in measurement of expansion. His model didn't expand the size of the observable universe is steady. This didn't match observation, neither did temperature measurement. That statement I posted specifically means we don't understand the mechanism that keeps the cosmological constant. That's not the same thing as energy/matter being created from nothing. It just means we haven't figured out the cosmological constant... You also chose not to include the next part where I mentioned the Higgs field as a possibility. This is still under study but you can read the related paper here. Higg's inflation possible dark energy http://arxiv.org/abs/1402.3738 http://arxiv.org/abs/0710.3755 http://arxiv.org/abs/1006.2801 Edited February 20, 2016 by Mordred
David Levy Posted February 20, 2016 Author Posted February 20, 2016 (edited) Yes I'm familiar with Hoyles steady state theory. Even he realized it didn't work. Particularly with observed evidence in measurement of expansion. His model didn't expand the size of the observable universe is steady. This didn't match observation, neither did temperature measurement. Well, I didn't ask about the whole steady state theory. I have asked just about one issue - new mass creation. So, in order to distinguish between the different theories: Is it correct that based on the early concept of the BBT, new mass creation was not feasible? If so, do you agree that Fred Hoyle was completely correct with his idea about new mass creation, while based on the early BBT it was not even an option? Edited February 20, 2016 by David Levy
Mordred Posted February 20, 2016 Posted February 20, 2016 Not really, I've been studying the cosmological problem for years now. Enough to have strong faith in the Higgs field possibility which is shown to be accurate will still maintain the conservation of energy. The research limitation has more to do with funding and the CERN experiments. We already know our particle physics model may not be complete. We find new particles on a regular basis. One example is diquark particles. https://en.m.wikipedia.org/wiki/Diquark We predicted these before discovering them. Another series of predicted particles is the supersymmetric particles. The problem is the energy levels needed to create them. We predicted monopoles, same problem. Just because we don't understand something yet doesn't mean that it's created out of nothing. It just means we haven't figured it out Yet. The Universe from nothing model by Lawrence R Krauss or the zero energy universe both left out one vital detail. It takes energy to create virtual particles.
David Levy Posted February 20, 2016 Author Posted February 20, 2016 (edited) It seems that I didn't understand it correctly. So please let me know if the following is correct/incorrect: 1. The current cosmological constant is the same at any size of the universe. 2. Therefore, the energy density of the universe should be the same - today, 13 Billion years ago and in the next 100 billion years. 3. Based on this constant we can find that the total mass energy of the early universe is significantly lower than our time universe. 4. In the same token we can claim that in the future the total mass energy of the universe (let's say 10 billion years from now) should be significantly higher than our current total mass/energy. 5. Hence, new mass/energy must be created over time. Edited February 20, 2016 by David Levy 1
Mordred Posted February 20, 2016 Posted February 20, 2016 Not quite correct. Part one is correct, Part 2 not so much.. Recall the energy-density of matter and radiation changes at different rates but the cosmological constant stays constant. Matter and radiation interchange is easy to understand. A lot of the relations we can lab test on Earth. The problem is the Cosmological constant per m^3 is so extremely close to zero we require immense volume just to measure it. It's so close to zero we can't even determine if it's coming from the current mass or radiation density. This is why we can't tell with certainty if it obeys the conservation of energy. There was one post where I also stated that the universe energy equated to roughly 10^90 protons (equivalent). That's still true today as it was as early as we can measure the total energy/density. The part I was trying to get you to understand was matter, radiation and the Cosmological constant energy?density changes at different rates as the universe expands. Matter has a lower kinetic energy than radiation does. So when you took values today and compared them at a smaller volume, The ratio change would be different than if you used the formula I provided
Phi for All Posted February 20, 2016 Posted February 20, 2016 It seems that I didn't understand it correctly. +1 for that. Perspective like this is very conducive to breaking up the jams that often block our understanding.
MigL Posted February 20, 2016 Posted February 20, 2016 You do realize that energy density is NOT a conserved quantity ? Energy IS. You do realize that density is a quantity per unit volume ? If energy is conserved, but volume increases, then energy density MUST decrease.
David Levy Posted February 20, 2016 Author Posted February 20, 2016 (edited) You do realize that energy density is NOT a conserved quantity ? Energy IS. So, Energy is conserved! Please let me know if I understand it correctly: 1. All the Total Energy of the Universe had been created at the first moment of the B.B. 2. This Total Energy is the source for the whole Mass/dark Mass/Energy/Dark Energy/Radiation/Particles... in the Universe. 3. There is no new Energy creation in the Universe after the B.B. 4. However, that Total Energy may change forms. It takes energy to create virtual particles. For example - At some point in the past, some of the Energy could be represented by radiation or particles. Those radiation and particles could be converted later on to Atoms and real Mass. 5. Therefore, the Total Energy (which had been created at the B.B.) can creat new mass, however, there is no new mass creation without that total energy (or out of noting). 6. Higgs field is fully correlated with that conservation of energy ...Higgs field possibility which is shown to be accurate will still maintain the conservation of energy. Is it correct - so far? However - I'm not sure about the impact of the following statement: You do realize that density is a quantity per unit volume ? If energy is conserved, but volume increases, then energy density MUST decrease. Hence: If energy is conserved, but volume decrease (as we go back on time). then energy density must increase. Therefore, in the past the energy density was higher than today. So, how that is correlated with the idea about the cosmological constant? Edited February 20, 2016 by David Levy
Strange Posted February 20, 2016 Posted February 20, 2016 So, Energy is conserved! That is not generally true in general relativity (and therefore the big bang model). http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html 1. All the Total Energy of the Universe had been created at the first moment of the B.B. There is no support for that. 3. There is no new Energy creation in the Universe after the B.B. Dark energy appears to increase with the expanding universe.
Mordred Posted February 20, 2016 Posted February 20, 2016 As Strange showed there is some debate whether energy is conserved or not. It's rather an open question. It gets rather confusing, particularly for the laymen. In GR it's considered that energy isn't a conserved quantity. This implies neither does the FLRW metric. However it's not quite that simple, if you read Cosmology textbooks that deal primarily with the particle aspects its considered conserved. On Cosmology textbooks that covers more heavily on the GR aspects its not. Sean Carroll's article has a half decent explanation. http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/ though he adds yet another dimension lol
David Levy Posted February 20, 2016 Author Posted February 20, 2016 Wow. After each answer its clear to me that if I thought that I understand someting - then it is incorrect. So what is correct? That is not generally true in general relativity (and therefore the big bang model). http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html There is no support for that. Dark energy appears to increase with the expanding universe. If I understand you correctly, Energy may not be conserved and dark energy appears to increase. Therefore, can we assume that there is a constant new energy creation after the B.B? Can we also assume that there is a possibility for new mass creation? 1
Strange Posted February 20, 2016 Posted February 20, 2016 Can we also assume that there is a possibility for new mass creation? Not without some evidence, no.
David Levy Posted February 20, 2016 Author Posted February 20, 2016 Not without some evidence, no. So, there is no new mass creation. But - there is new energy creation. Is it correct? 1
Mordred Posted February 20, 2016 Posted February 20, 2016 (edited) it depends on how you define the system your describing. I think Sean Carroll has an appropriate expression. "There’s nothing incorrect about that way of thinking about it; it’s a choice that one can make or not, as long as you’re clear on what your definitions are" you can choose either choice conserved or not. depending on how your modelling the system. If your modelling just the thermodynamic aspects you'll conclude more often than not that it is conserved, but if your modelling the system via an evolving spacetime, with GR its not. this is one of those cases where there isn't a wrong answer, the answer will depend on the system state your modelling. as far as the cosmological constant vs the Higgs field here is a non technical article. https://www.newscientist.com/article/dn24043-dark-energy-could-be-the-offspring-of-the-higgs-boson/ Edited February 20, 2016 by Mordred
David Levy Posted February 20, 2016 Author Posted February 20, 2016 (edited) Thanks for the support. At least - now I know that I don't know. However, after reading the articles, I hope to have better understanding. . Edited February 20, 2016 by David Levy
MigL Posted February 20, 2016 Posted February 20, 2016 I ( unlike some of the others ) have the understanding that mass/energy IS conserved. GR says nothing about mass/energy conservation, one way or the other. It seems to be another example where the model is inapplicable. If the virtual particle/cosmological constant/dark energy model is realized ( currently gives way too large, non-sensical results ), then its based on 'borrowed' energy ( most likely gravitational potential ), and there is no mass/energy creation That would violate one of the most fundamental symmetries of our universe. ( IIRC E. Noether was working on the problem GR has with energy conservation when she came up with her theorem )
imatfaal Posted February 20, 2016 Posted February 20, 2016 I ( unlike some of the others ) have the understanding that mass/energy IS conserved. GR says nothing about mass/energy conservation, one way or the other. It seems to be another example where the model is inapplicable. If the virtual particle/cosmological constant/dark energy model is realized ( currently gives way too large, non-sensical results ), then its based on 'borrowed' energy ( most likely gravitational potential ), and there is no mass/energy creation That would violate one of the most fundamental symmetries of our universe. ( IIRC E. Noether was working on the problem GR has with energy conservation when she came up with her theorem ) It is quite ok to think of Energy (and mass energy) as not being conserved in GR - although there are other ways in which one can avoid this (the energy of the gravitational field ). GR does explicitly talk about Energy Momentum relationships in saying [latex]\nabla_{\mu} \cdot T^{\mu \nu} = 0[/latex]
MigL Posted February 21, 2016 Posted February 21, 2016 The problem seems to be that," while energy conservation is a good local concept, and can be defined more generally in the special case of an isolated system in asymptotically flat space, there is not a general global energy conservation law in GR theory." Principles of Physical Cosmology, P.J.E. Peebles '
David Levy Posted February 22, 2016 Author Posted February 22, 2016 (edited) The problem seems to be that," while energy conservation is a good local concept, and can be defined more generally in the special case of an isolated system in asymptotically flat space, there is not a general global energy conservation law in GR theory." Principles of Physical Cosmology, P.J.E. Peebles' Yes, I fully agree – there is an issue with the Energy conservation. In our discussion about the expansion: http://www.scienceforums.net/topic/92918-universe-expansion/page-5 It was stated that the cosmology constant is constant at any size of the Universe: Ok David think of it this way the Cosmological constant is constant. It's energy density per metre cubed stays the same. No matter when you measure it. So if you take the energy density of the cosmological constant multiply that by the volume of the observable universe TODAY. Then do the same for the cosmological constant for the volume at the CMB. Which is higher in total energy/mass? Now do you understand why your method leads to error? Why cosmological constant stays constant is one of the biggest mysteries in Cosmology. So don't ask me to solve that problem lol. Here lets go over these relations again I assume your familiar with the scale factor a... https://en.m.wikipedia.org/wiki/Scale_factor_(cosmology) [latex]\rho_{radiation}\propto R^{-4}[/latex] [latex]\rho_{matter}\propto R^{-3}[/latex] [latex]\rho_{\Lambda}=constant[/latex] [latex]a=\frac{R}{R_o}=\frac{1}{(1+z)}[/latex] [latex]\rho=\frac{\rho_{r,o}}{a^4}+\frac{\rho_{m,o}}{a^3}+\rho_\Lambda[/latex] So, the Cosmological constant is constant and the energy density per metre cubed stays the same. However, the volume of the current universe is significantly higher than the volume of the early universe. Therefore, I have assumed that the total energy of our current universe must be significantly higher than the early universe. Never the less, I was informed that this assumption is incorrect. So, if the volume of the Universe increase (while It's energy density per meter cubed stays the same"), than how could it be that it's total energy does not increase? Hence, with regards to the Energy, we should choose one of the following options: 1. If the energy density per meter cubed stays the same. Than as the volume of the Universe increase - the total energy should also increase. 2. If the energy density per meter cubed isn't the same. Than there is a possibility that as the volume of the Universe increase - the total energy could stays the same. How can we win them both? It's a real enigma for me. Edited February 22, 2016 by David Levy
MigL Posted February 23, 2016 Posted February 23, 2016 From the previously mentioned textbook by P.J.E. Peebles ( fairly intense math/GR )... pg. 139 in the chapter THE THERMAL CBR : Blackbody Radiation in an Expanding Universe, he deals with the 'paradox' of the NET radiation density DECREASING as the universe expands. The resolution he draws from the math is the quote I provided in my previous post. an excellent book. If you can find it, give it a read.
David Levy Posted February 23, 2016 Author Posted February 23, 2016 (edited) From the previously mentioned textbook by P.J.E. Peebles ( fairly intense math/GR )... pg. 139 in the chapter THE THERMAL CBR : Blackbody Radiation in an Expanding Universe, he deals with the 'paradox' of the NET radiation density DECREASING as the universe expands. The resolution he draws from the math is the quote I provided in my previous post. an excellent book. If you can find it, give it a read. Thanks for the advice. However, as currently I don't have this text book, let me ask the following: Why do we need to deal with the 'paradox' of the NET radiation density DECREASING as the universe expands? If we assume that the Total Energy of the Universe is the same at any size, than it is quite clear that the net density radiation should decrease as the universe expands. However, if we assume that the net radiation density is fix at any size of the universe, than it is clear that the Total Energy should increase as the universe expands So simple. The paradox is in our mind! Only one of the above statements might be correct. We can't win them both – that is the source for the paradox. We must take a decision. Left or right - and deal with the outcome of any decision. Edited February 23, 2016 by David Levy
David Levy Posted February 24, 2016 Author Posted February 24, 2016 (edited) Any feedback? I assume that it's a difficult issue to deal with. Somehow we must keep two constants at the same time and at the same Universe as follow: 1. The cosmologic constant must be constant 2. The Total Energy of the Universe must be constant This is the base for that paradox. Would you kindly advice if (at least) I understand it correctly? Edited February 24, 2016 by David Levy
Mordred Posted February 24, 2016 Posted February 24, 2016 It's not an easy topic to cover on a forum due to the number of calculations involved. This arxiv may help. "Does the Universe obey the conservation of energy law" http://www.google.ca/url?sa=t&source=web&cd=3&rct=j&q=energy%20conservation%20in%20the%20universe&ved=0ahUKEwj7rruO3Y_LAhVP92MKHacUAzwQFgggMAI&url=http%3A%2F%2Farxiv.org%2Fpdf%2F0810.1629&usg=AFQjCNFEE3r8ue80KsHouYnJnhcePF7lqA
David Levy Posted February 24, 2016 Author Posted February 24, 2016 Thanks for the prompt reply. I will read it carefully. However, please advice if I have understood correctly the paradox.
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