Here is a tweaked and more colorful version of the prior arguments favoring Big Bang Theory. [Comments welcome, of course.]
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Big Bang Bullets II
- Thread starter Helio
- Start date
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Catastrophe
"Science begets knowledge, opinion ignorance.
Helio, I don't think we finished the discussion on the origin of the BB, viz, backward extension of an expansion graph to a singularity?
Even so, I don't believe one could tell the difference between a singularity BB event, and a cyclic Universe where the singularity is replaced by a nexus. At t = 0, within a whisker, physics breaks down. Without the singularity, physics need not break down. I can't see how any of this is at variance with your bullets, but please correct me if I am in error.
Of course, none of this can be proved either way, but I would like to see as much consideration given to the/a cyclic Universe model as there is to the BB model.
Cat
Even so, I don't believe one could tell the difference between a singularity BB event, and a cyclic Universe where the singularity is replaced by a nexus. At t = 0, within a whisker, physics breaks down. Without the singularity, physics need not break down. I can't see how any of this is at variance with your bullets, but please correct me if I am in error.
Of course, none of this can be proved either way, but I would like to see as much consideration given to the/a cyclic Universe model as there is to the BB model.
Cat
There is no singularity established within the formal theory itself. The BBT, being scientific, only goes to where the physics equations run true. Just before and at t=0, the physics falls completely apart. Lemaitre envisioned his model to get down to something like the size of an atom, which he called the Primeval atom. He could have claimed a singularity since the very first solution to GR, outside of Einstein, came from Schwarzschild work with black holes, etc. But Lemaitre wisely avoided doing so.
But the BBT doesn't need to establish a beginning with t=0 any more than, say, Newton needed to explain gravity. Newton's gravity work was wonderful physics describing something he admitted he didn't know what it was.
Yes, a tiny glob for a recently crunched universe might be identical to what we claim for the tiny glob just after t=0. But, if so, the crunched version would need to be extremely isotropic and homogenous within that glob and I don't know if Humpty Dumpty would look identical if we throw his parts back into one spot his original size, if you see my point. It's just over my head but it is a key question to ask. Entropy would be next on my list, but even if this limits the number of cycles, then only more than one is needed.
Catastrophe
"Science begets knowledge, opinion ignorance.
"the crunched version would need to be extremely isotropic and homogenous within that glob and I don't know if Humpty Dumpty would look identical if we throw his parts back into one spot his original size,"
I don't understand. In BBT, do you envisage the singularity, or the first 'object' before inflation begins as isotropic and homogenous? And, if so, why? I don't understand what that object might be like? Since we cannot go back and examine it, are we talking philosophy and not science anyway? In which case, I cannot see any of this being counter to nexus over singularity.
I have not seen (from anywhere) an explanation of entropy at t = 0 (or wherever anyone would like to start). Is entropy at minimum in a singularity at infinite density/pressure/temperature? Surely entropy must increase after the BB? If maximum there, how can it increase with expansion? Beats me.
Cat
I don't understand. In BBT, do you envisage the singularity, or the first 'object' before inflation begins as isotropic and homogenous? And, if so, why? I don't understand what that object might be like? Since we cannot go back and examine it, are we talking philosophy and not science anyway? In which case, I cannot see any of this being counter to nexus over singularity.
I have not seen (from anywhere) an explanation of entropy at t = 0 (or wherever anyone would like to start). Is entropy at minimum in a singularity at infinite density/pressure/temperature? Surely entropy must increase after the BB? If maximum there, how can it increase with expansion? Beats me.
Cat
Catastrophe
"Science begets knowledge, opinion ignorance.
Searching is a little thin (on e.g., singularity entropy) but this
[1103.3898] Entropy of singularities in self-gravitating radiation (arxiv.org)
yields
"We find that the principle of maximum entropy provides a consistent thermodynamic description of the system, only if the entropy includes a contribution from the spacetime singularities that appear in the solutions of Einstein's equations. The form of the singularity entropy is stringently constrained from consistency requirements, so that the existence of a simple expression satisfying these constraints is highly non-trivial, and suggests of a fundamental origin."
Does this suggest "unknown"? I don't understand it.
And here is a beaut:
[1010.5513] The Generalized Second Law implies a Quantum Singularity Theorem (arxiv.org)
“The generalized second law can be used to prove a singularity theorem, by generalizing the notion of a trapped surface to quantum situations. Like Penrose's original singularity theorem, it implies that spacetime is null geodesically incomplete inside black holes, and to the past of spatially infinite Friedmann--Robertson--Walker cosmologies.”
Cat
[1103.3898] Entropy of singularities in self-gravitating radiation (arxiv.org)
yields
"We find that the principle of maximum entropy provides a consistent thermodynamic description of the system, only if the entropy includes a contribution from the spacetime singularities that appear in the solutions of Einstein's equations. The form of the singularity entropy is stringently constrained from consistency requirements, so that the existence of a simple expression satisfying these constraints is highly non-trivial, and suggests of a fundamental origin."
Does this suggest "unknown"? I don't understand it.
And here is a beaut:
[1010.5513] The Generalized Second Law implies a Quantum Singularity Theorem (arxiv.org)
“The generalized second law can be used to prove a singularity theorem, by generalizing the notion of a trapped surface to quantum situations. Like Penrose's original singularity theorem, it implies that spacetime is null geodesically incomplete inside black holes, and to the past of spatially infinite Friedmann--Robertson--Walker cosmologies.”
Cat
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Catastrophe
"Science begets knowledge, opinion ignorance.
At last!
Quote
Is this apparent logical ambiguity one of the reasons that physics "breaks down" at the singularity?
You cannot defined an entropy because physics breaks down. There is simply no way to establish something like phase-spaces with a singularity and current physical models.
Reference: https://www.physicsforums.com/threads/entropy-and-the-singularity.851834/
Quote
Cat
Quote
Is this apparent logical ambiguity one of the reasons that physics "breaks down" at the singularity?
You cannot defined an entropy because physics breaks down. There is simply no way to establish something like phase-spaces with a singularity and current physical models.
Reference: https://www.physicsforums.com/threads/entropy-and-the-singularity.851834/
Quote
Cat
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Helio enjoys presenting the Big Bang bullet summary list I note that the CMBR originating at some 3000 K and redshift to near 2.73 K as observed from Earth today due to 4D space expansion (not 3D space), underwent a variety of calculations to arrive at the 2.73 K found in the mid-1960s. In the late 1940s, George Gamow and Ralph Alpher calculated a background glow of some 51 K in the original model but the background glow would not be smooth. When you use the cosmology calculators, the 3000 K temperature applies to the CMBR with redshift = 1100 today and comoving radial distance today some 45 or 46 billion light years from Earth. 4D space expansion changes must be factored into the cooling rate for the CMBR to arrive at the nearly 3K temperature seen today from Earth. There is limited redshift plot to CMB temperature (TCMB) change documented in astronomy, not out to 45 or 46 billion light years distance as seen from Earth. The plots for TCMB are limited and involve lower redshift values but still show a slight warming to the CMB vs. near 3K we see on Earth.
Here is an example. Shadow of cosmic water cloud reveals the temperature of the young universe, https://phys.org/news/2022-02-shadow-cosmic-cloud-reveals-temperature.html, Feb-2022. My note. This new report for HFLS3 suggest most studies fall z = 0 to 1.0 range with a smaller number 1.8 to 3.3, now this report z=6.34 when plotting CMB temperature cooling to redshift values. The CMB temperature value for z=6.34 was found to be 16.4 - 30.2 K TCMB. This is warmer than the 3K we see on Earth but is a long way from extending out 45 or 46 billion light years and arriving at 3000 K or so and z~1100.
I note that the CMBR originating at some 3000 K and redshift to near 2.73 K as observed from Earth today due to 4D space expansion (not 3D space), underwent a variety of calculations to arrive at the 2.73 K found in the mid-1960s. In the late 1940s, George Gamow and Ralph Alpher calculated a background glow of some 51 K in the original model but the background glow would not be smooth. When you use the cosmology calculators, the 3000 K temperature applies to the CMBR with redshift = 1100 today and comoving radial distance today some 45 or 46 billion light years from Earth. 4D space expansion changes must be factored into the cooling rate for the CMBR to arrive at the nearly 3K temperature seen today from Earth. There is limited redshift plot to CMB temperature (TCMB) change documented in astronomy, not out to 45 or 46 billion light years distance as seen from Earth. The plots for TCMB are limited and involve lower redshift values but still show a slight warming to the CMB vs. near 3K we see on Earth.Here is an example. Shadow of cosmic water cloud reveals the temperature of the young universe, https://phys.org/news/2022-02-shadow-cosmic-cloud-reveals-temperature.html, Feb-2022. My note. This new report for HFLS3 suggest most studies fall z = 0 to 1.0 range with a smaller number 1.8 to 3.3, now this report z=6.34 when plotting CMB temperature cooling to redshift values. The CMB temperature value for z=6.34 was found to be 16.4 - 30.2 K TCMB. This is warmer than the 3K we see on Earth but is a long way from extending out 45 or 46 billion light years and arriving at 3000 K or so and z~1100.
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I think this should be added here concerning bullets and Helio did a very good job (my thinking).
A new report on the search for magnetic monopoles. The IceCube Collaboration sets the most restrictive constraints on relic magnetic monopoles from the early universe, https://phys.org/news/2022-03-icecube-collaboration-restrictive-constraints-relic.html “Recent technological advances have enabled the development of increasingly advanced telescope and astrophysical instruments. This includes the IceCube telescope, which was originally built to detect and examine high-energy neutrinos in the universe. High-energy neutrino telescopes, such as the IceCube telescope, are not only sensitive to neutrinos; they can also be used to detect other exotic particles, including magnetic monopoles. Magnetic monopoles are hypothetical elementary particles comprised of an isolated magnet with a single magnetic pole."
The reference paper is Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.051101, 02-Feb-2022. My note. From the paper, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.051101#fulltext, "Magnetic monopoles could have formed in the early Universe as the temperature of the primordial plasma dropped below the energy scale of the GUT symmetry breaking [6,7]. The expected production rate of monopoles depends on the unknown nature of this phase transition (first or second order), but it can lead to a production comparable to the amount of baryons, predicting a relic density today above current observational limits. This has been dubbed the “monopole problem” [8]. It is through inflation that the primordial density of magnetic monopoles can be brought to a level consistent with observations."
My observation. Alan Guth developed inflation and a solution to the magnetic monopole problem. A 1984 NASA ADS Abstract report by Alan Guth on magnetic monopoles and inflation. The inflationary universe, https://ui.adsabs.harvard.edu/abs/1984SciAm.250e.116G/abstract, May 1984.
"The theory of the inflationary universe is discussed. The problems facing the standard big-bang model are described, including the horizon problem, the smoothness problem, and the flatness problem. The combination of grand unified theories and the standard picture explains the asymmetry of matter and antimatter in the universe, but raises the problem of monopoles and domain walls. How the inflationary picture solves or avoids these problems is shown. The original inflationary theory is contrasted with the new inflationary theory, and the theoretical roles of supercooling, Higgs fields, symmetry-breaking, the false vacuum, the energy-density function, and the slow-rollover transition are discussed. The possibility that the actual creation of the universe is describable by physical laws is considered."
There is more behind the explanation for the origin of the CMBR we see today near 3K used to support the Big Bang then commonly disclosed.
A new report on the search for magnetic monopoles. The IceCube Collaboration sets the most restrictive constraints on relic magnetic monopoles from the early universe, https://phys.org/news/2022-03-icecube-collaboration-restrictive-constraints-relic.html “Recent technological advances have enabled the development of increasingly advanced telescope and astrophysical instruments. This includes the IceCube telescope, which was originally built to detect and examine high-energy neutrinos in the universe. High-energy neutrino telescopes, such as the IceCube telescope, are not only sensitive to neutrinos; they can also be used to detect other exotic particles, including magnetic monopoles. Magnetic monopoles are hypothetical elementary particles comprised of an isolated magnet with a single magnetic pole."
The reference paper is Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.051101, 02-Feb-2022. My note. From the paper, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.051101#fulltext, "Magnetic monopoles could have formed in the early Universe as the temperature of the primordial plasma dropped below the energy scale of the GUT symmetry breaking [6,7]. The expected production rate of monopoles depends on the unknown nature of this phase transition (first or second order), but it can lead to a production comparable to the amount of baryons, predicting a relic density today above current observational limits. This has been dubbed the “monopole problem” [8]. It is through inflation that the primordial density of magnetic monopoles can be brought to a level consistent with observations."
My observation. Alan Guth developed inflation and a solution to the magnetic monopole problem. A 1984 NASA ADS Abstract report by Alan Guth on magnetic monopoles and inflation. The inflationary universe, https://ui.adsabs.harvard.edu/abs/1984SciAm.250e.116G/abstract, May 1984.
"The theory of the inflationary universe is discussed. The problems facing the standard big-bang model are described, including the horizon problem, the smoothness problem, and the flatness problem. The combination of grand unified theories and the standard picture explains the asymmetry of matter and antimatter in the universe, but raises the problem of monopoles and domain walls. How the inflationary picture solves or avoids these problems is shown. The original inflationary theory is contrasted with the new inflationary theory, and the theoretical roles of supercooling, Higgs fields, symmetry-breaking, the false vacuum, the energy-density function, and the slow-rollover transition are discussed. The possibility that the actual creation of the universe is describable by physical laws is considered."
There is more behind the explanation for the origin of the CMBR we see today near 3K used to support the Big Bang then commonly disclosed.
Yes.
I would expect any tiny variation in energy distribution initially would be greatly expanded and easily observable in our universe. I don't mean perfect isotropy because quantum levels are never purely isotropic. Indeed, one of the first problems with BBT came when quantum physics recognized this fact and could not explain the great isotropy (relatively speaking) of what we observe, especially in the CMBR.
That's one of two reasons why Inflation Theory got added into the theory. A faster than light expansion has a smoothing effect, thus offsetting the anisotropy. I wish I understood it better but that's my understanding, in general.
Spock may have said it best when he described the first instant as having "Pure energy", as if there's such a thing as impure energy.
The temperatures near the first Planck time unit was in the many billions of trillions of degrees, IIRC. But, again, I am not going beyond physics and assuming a singularity, which is speculation and not part of a theory that requires tests.There is a point where physics works reasonably and reliably well, but a tiny bit farther, the physics' equations produce results that shoot to infinity. So that also is the line between science and philosophy, though perhaps "metaphysics" might be the apt term.
I hope this is not for me since you know I have no interest in even suggesting a singularity as a starting point. But you may be bringing-up an interesting question because Hawking demonstrated that the area of the EH around the singularity (BH) gives the entropy of the BH. So, if that is a physical reality, imagine the huge size of the EH radius, yet no space to have it. A paradox?
Entropy comes from processes, so they began at the beginning but I understand the entropy at the beginning was amazingly small, or negative if that helps. Max. entropy would just be very low level heat. The entropy of your refrigerator, for instance, dumps heat into the universe in order to provide a little less negative entropy for cooling. Entropy isn't just high temperature (as seen near t=0) but heat exchange along an isotherm. I've never gotten my head around entropy but I recall using it a lot to pass thermodynamics.
Helio in post #9 said about the smoothness of the CMBR we see today from Earth. "That's one of two reasons why Inflation Theory got added into the theory. A faster than light expansion has a smoothing effect, thus offsetting the anisotropy. I wish I understood it better but that's my understanding, in general."
Some questions could be asked. What is the vacuum energy density of the universe before the postulated inflation epoch? Do we see in astronomy today space with this vacuum energy density today? My answer is no unless someone argues about black holes at their center perhaps (but I do not see the vacuum energy density at the bottom of a black hole).
How fast was 4D space expanding during inflation epoch to solve the horizon problem that would be seen in the CMBR today (again Alan Guth mentions)? My answer is Alan Guth shows at least 10^20 c or faster. Do we see in astronomy today 4D space expanding 10^20 c or faster? My answer is no. Some of this post touches upon post #8 and where are the magnetic monopoles that we could see today. What I like to call exotic physics, need rigorous examination and evidence shown like the laws of motion.
Some questions could be asked. What is the vacuum energy density of the universe before the postulated inflation epoch? Do we see in astronomy today space with this vacuum energy density today? My answer is no unless someone argues about black holes at their center perhaps (but I do not see the vacuum energy density at the bottom of a black hole).
How fast was 4D space expanding during inflation epoch to solve the horizon problem that would be seen in the CMBR today (again Alan Guth mentions)? My answer is Alan Guth shows at least 10^20 c or faster. Do we see in astronomy today 4D space expanding 10^20 c or faster? My answer is no. Some of this post touches upon post #8 and where are the magnetic monopoles that we could see today. What I like to call exotic physics, need rigorous examination and evidence shown like the laws of motion.
I doubt many cosmologist would favor this CMBR temperature interpretation. Clouds can be misleading. The coldest known place in the universe isn't empty space but places like the Boomerang Nebulae at ~ 1K.
I also don't understand what they mean by a shadow cast upon the CMBR. That's just bizarre. What do they mean? The CMBR comes through the cloud, but that puts us in the shadow not the CMBR. Or, perhaps they are suggesting the cloud was heated at the higher temperatures of the flash that is now the CMBR, and it is being added to the CMBR. I'm unclear what they are saying.
Yes. A lot of questions are indeed being asked. The idea of the entire universe of what we can see and what we think is there squeezed into something like the size of an atom will not be something Newton could have handled in his day had he speculated about it. The very earliest history of BBT, and worse before it, involves only extreme quantum theory and extreme GR. The trick is to combine the two but they don't even like each other.
Alan's work is like the Wright Bros. aeroplane -- a wonder then but not that practical today. Any temperature had to be based on assumptions, especially how much expansion has taken place since Recombination. Had he nailed it and done more publicizing it, perhaps, then he may have gotten more credit. It's my understanding he had to fight to get people to recognize his early efforts.
Peebles, et. al, estimated in the 60's that the CMBR might be about 10K. They were building a microwave telescope to discover it when they got the famous phone call from Bell Labs hoping they had a better explanation for noise over their proposed, and failed, pigeon poop idea.
Helio, your post #11 I concur, *unclear what they are saying*. I had to eat that report and kept track of others published over the years before the TCMB compared to redshift plots started to make sense. Example.
A precise and accurate determination of the cosmic microwave background temperature at z = 0.89, https://ui.adsabs.harvard.edu/abs/2013A&A...551A.109M/abstract, March 2013. "...Results: We determine TCMB = 5.08 ± 0.10 K at 68% confidence level. Our measurement is consistent with the value TCMB = 5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of TCMB at z > 0 to date."
You can read the detailed paper too if desired, https://arxiv.org/pdf/1212.5456.pdf
Some locations in space, objects are found that reflect the CMBR temperature for a redshift other than 0 (where we are at on the plot). We see a CMBR near 3K at Earth but other locations where z > 0 will be slightly warmer. What we do not see is z = 1100 and TCMB 3000 K. There is a limited number of redshift plots for TCMB changes documented and these are lower number redshifts, not objects with z like 50, 100, 500, etc. As the redshifts get larger and larger, the CMBR temperature should get warmer and warmer and follow the BB model cooling curve for expanding 4D space, otherwise Houston, we have a problem
A precise and accurate determination of the cosmic microwave background temperature at z = 0.89, https://ui.adsabs.harvard.edu/abs/2013A&A...551A.109M/abstract, March 2013. "...Results: We determine TCMB = 5.08 ± 0.10 K at 68% confidence level. Our measurement is consistent with the value TCMB = 5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of TCMB at z > 0 to date."
You can read the detailed paper too if desired, https://arxiv.org/pdf/1212.5456.pdf
Some locations in space, objects are found that reflect the CMBR temperature for a redshift other than 0 (where we are at on the plot). We see a CMBR near 3K at Earth but other locations where z > 0 will be slightly warmer. What we do not see is z = 1100 and TCMB 3000 K. There is a limited number of redshift plots for TCMB changes documented and these are lower number redshifts, not objects with z like 50, 100, 500, etc. As the redshifts get larger and larger, the CMBR temperature should get warmer and warmer and follow the BB model cooling curve for expanding 4D space, otherwise Houston, we have a problem
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Do you see this as contradictory to mainstream cosmologies' estimates of today's CMBR? [It may be a while before I have time to read some of your links.]
The original 3000K temperature is what we would have seen 13.8 billion years ago because everything in the universe was in this sea of light. With expansion, the light that was farther away from us but headed in our direction eventually reached us, but this was, of course, a continuous stream of light. This light that has finally reached has redshifted (z = 1100) and is now in the microwave band. Thus, with greater redshift, the temperature of what we observe will continue to be less and less.What we do not see is z = 1100 and TCMB 3000 K. There is a limited number of redshift plots for TCMB changes documented and these are lower number redshifts, not objects with z like 50, 100, 500, etc. As the redshifts get larger and larger, the CMBR temperature should get warmer and warmer and follow the BB model cooling curve for expanding 4D space, otherwise Houston, we have a problem
Helio, in your post #14 you ask, "Do you see this as contradictory to mainstream cosmologies' estimates of today's CMBR? [It may be a while before I have time to read some of your links.]"
That is possible but not definite as far as I can tell from the reports. Remember that for a given redshift or z value like 1.0, the object will be at a given distance from Earth (look back time and comoving radial distance) and formed at a specific period in the expanding universe model. You can see this using the cosmology calculators, their age at redshift relative to BB and origin of CMBR), thus those objects should show a warmer CMB temperature compared to what we see here on Earth.
Helio to clarify a bit more here, you said "Thus, with greater redshift, the temperature of what we observe will continue to be less and less." My answer is no, the larger redshift objects formed earlier in the BB model expanding universe and thus should show a warmer CMB temperature than we see here on Earth today.
That is possible but not definite as far as I can tell from the reports. Remember that for a given redshift or z value like 1.0, the object will be at a given distance from Earth (look back time and comoving radial distance) and formed at a specific period in the expanding universe model. You can see this using the cosmology calculators, their age at redshift relative to BB and origin of CMBR), thus those objects should show a warmer CMB temperature compared to what we see here on Earth.
Helio to clarify a bit more here, you said "Thus, with greater redshift, the temperature of what we observe will continue to be less and less." My answer is no, the larger redshift objects formed earlier in the BB model expanding universe and thus should show a warmer CMB temperature than we see here on Earth today.
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Catastrophe
"Science begets knowledge, opinion ignorance.
Can I please have your answers/suggestions on one question, which afaik, has been touched on, but not answered/explained to my satisfaction.
What is the entropy of the Universe at or slightly after t = 0?
Or does the concept of entropy at t = 0 break with the rest of physics?
What is the entropy when physics becomes operative?
I can see arguments for being minimum or maximum.
Also, is a cyclic Universe (if it exists - hence metaphysical model like the BB) , a closed system? Hence (also metaphysical) would entropy decrease during a contracting phase between one nexus and the next? Assuming contraction follows expansion.
Cat
https://courses.lumenlearning.com/p...loss of,increases in an irreversible process.
What is the entropy of the Universe at or slightly after t = 0?
Or does the concept of entropy at t = 0 break with the rest of physics?
What is the entropy when physics becomes operative?
I can see arguments for being minimum or maximum.
Also, is a cyclic Universe (if it exists - hence metaphysical model like the BB) , a closed system? Hence (also metaphysical) would entropy decrease during a contracting phase between one nexus and the next? Assuming contraction follows expansion.
Cat
https://courses.lumenlearning.com/p...loss of,increases in an irreversible process.
Can I please have your answers/suggestions on one question, which afaik, has been touched on, but not answered/explained to my satisfaction.
What is the entropy of the Universe at or slightly after t = 0?
Or does the concept of entropy at t = 0 break with the rest of physics?
What is the entropy when physics becomes operative?
I can see arguments for being minimum or maximum.
Also, is a cyclic Universe (if it exists - hence metaphysical model like the BB) , a closed system? Hence (also metaphysical) would entropy decrease during a contracting phase between one nexus and the next? Assuming contraction follows expansion.
Cat
https://courses.lumenlearning.com/p... loss of,increases in an irreversible process.
Cat interesting questions. I do not know the answers but I noticed from the link you provide (courses.lumenlearning) it says, “But in terms of the universe, and the very long-term, very large-scale picture, the entropy of the universe is increasing, and so the availability of energy to do work is constantly decreasing. Eventually, when all stars have died, all forms of potential energy have been utilized, and all temperatures have equalized (depending on the mass of the universe, either at a very high temperature following a universal contraction, or a very low one, just before all activity ceases) there will be no possibility of doing work. Either way, the universe is destined for thermodynamic equilibrium—maximum entropy. This is often called the heat death of the universe, and will mean the end of all activity. However, whether the universe contracts and heats up, or continues to expand and cools down, the end is not near. Calculations of black holes suggest that entropy can easily continue for at least 10^100 years.”
Cat, do you accept that view of entropy and the expanding universe? If this is true, no cyclic universe will appear. Just a single creation event or *beginning* and eventually, heat death with no work remaining to accomplish will terminate the universe and activity. Many folks today have philosophical issues with a distinct *beginning* and recent origin in time (i.e. not eternal or infinite in age) that ends in the 2nd Law winning out and terminating all
Catastrophe
"Science begets knowledge, opinion ignorance.
Rod, "Cat, do you accept that view of entropy and the expanding universe?" My emphasis.
Note the underlined expanding.
There is so much unknown to us, in our tiny corner of space(and)time I believe it is utterly beyond belief to suggest that we know (with the full force and ignorance of unscientific assumption) that our wonderful infinite knowledge applies beyond even the observable universe. We don't even know what happens in a black hole, and there are plenty of those much nearer. Not long ago, every book and paper you read stated that not even light could escape from a black hole. Now Hawking radiation can.
Not long ago (200 years approx) some know-it-all said "give me the position and motion of every particle in the Universe, and I will tell you the whole of the future" (in effect, maybe not verbatim). Guess what? Heisenberg came along saying (in effect) "you can't have it both ways.
I am not saying that like principles might not apply in like circumstances. More like, under normal conditions Newton is good enough. under more extreme conditions we need Einstein. What I am saying is that some unforeseen circumstance might arise (ring any bells?) which might change what we think are normal circumstances. At the very least, some rogue planet or moon might hit us, let alone an asteroid (or comet) the size of Chicxulub. Are we even sure we are going to be around the week next Tuesday?
If (whatever is the fashionable belief), if, some skybluepink energy becomes the next ad hoc assumption (polite name for fudge factor), and the Universe does go into contraction, who can state unequivocally that entropy will not decrease? If the entropy in the BB was at a minimum, then surely a contracting Universe would lead to a BH nexus and a new BB.
This is all metaphysics, and neither you nor I can prove any of it either way. I am not going to be the next Laplace. Are you?
Cat
Appendix:
"Laplace's demon was a notable published articulation of causal determinism on a scientific basis by Pierre-Simon Laplace in 1814.[1] According to determinism, if someone (the demon) knows the precise location and momentum of every atom in the universe, their past and future values for any given time are entailed; they can be calculated from the laws of classical mechanics.[2]" Wiki.
Note the underlined expanding.
There is so much unknown to us, in our tiny corner of space(and)time I believe it is utterly beyond belief to suggest that we know (with the full force and ignorance of unscientific assumption) that our wonderful infinite knowledge applies beyond even the observable universe. We don't even know what happens in a black hole, and there are plenty of those much nearer. Not long ago, every book and paper you read stated that not even light could escape from a black hole. Now Hawking radiation can.
Not long ago (200 years approx) some know-it-all said "give me the position and motion of every particle in the Universe, and I will tell you the whole of the future" (in effect, maybe not verbatim). Guess what? Heisenberg came along saying (in effect) "you can't have it both ways.
I am not saying that like principles might not apply in like circumstances. More like, under normal conditions Newton is good enough. under more extreme conditions we need Einstein. What I am saying is that some unforeseen circumstance might arise (ring any bells?) which might change what we think are normal circumstances. At the very least, some rogue planet or moon might hit us, let alone an asteroid (or comet) the size of Chicxulub. Are we even sure we are going to be around the week next Tuesday?
If (whatever is the fashionable belief), if, some skybluepink energy becomes the next ad hoc assumption (polite name for fudge factor), and the Universe does go into contraction, who can state unequivocally that entropy will not decrease? If the entropy in the BB was at a minimum, then surely a contracting Universe would lead to a BH nexus and a new BB.
This is all metaphysics, and neither you nor I can prove any of it either way. I am not going to be the next Laplace. Are you?
Cat
Appendix:
"Laplace's demon was a notable published articulation of causal determinism on a scientific basis by Pierre-Simon Laplace in 1814.[1] According to determinism, if someone (the demon) knows the precise location and momentum of every atom in the universe, their past and future values for any given time are entailed; they can be calculated from the laws of classical mechanics.[2]" Wiki.
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Cat in post #19 said, "This is all metaphysics..."
Well said Cat. I enjoy science that adheres to the scientific method. Example, observing the Galilean moons moving around Jupiter with my telescopes that are accurately predicted today, amateurs using their telescopes and measuring an asteroid parallax showing its distance from Earth. The debate between geocentric astronomy and heliocentric astronomy was not *metaphysics*. It required real demonstration using nature to support the arguments and the arguments were observable in the present day, not postulated events that took place billions of years ago. The immovable Earth with Sun moving around the Earth or Earth that moves around the Sun is an example. I do not need to postulate various events billions of years ago to determine the truth here and see that the Earth is moving around the Sun - today. Same for the round Earth argument vs. flat Earth that is still accepted by various folks today.
Well said Cat. I enjoy science that adheres to the scientific method. Example, observing the Galilean moons moving around Jupiter with my telescopes that are accurately predicted today, amateurs using their telescopes and measuring an asteroid parallax showing its distance from Earth. The debate between geocentric astronomy and heliocentric astronomy was not *metaphysics*. It required real demonstration using nature to support the arguments and the arguments were observable in the present day, not postulated events that took place billions of years ago. The immovable Earth with Sun moving around the Earth or Earth that moves around the Sun is an example. I do not need to postulate various events billions of years ago to determine the truth here and see that the Earth is moving around the Sun - today. Same for the round Earth argument vs. flat Earth that is still accepted by various folks today.
Catastrophe
"Science begets knowledge, opinion ignorance.
Rod, I heartily support and endorse the real science taking place today, especially by those amateurs making real contributions by assisting professionals by their sheer force of numbers. I totally deplore pseudo science which attempts to bastardise the truth by distorting the import of accurate observation to support its weird fantasies.
Having said that, I tried to point out that knowledge does move on, and our discovery of the truth is bettered by more and more observation of facts and by careful and reasoned consideration of the new facts discovered.
Do not mistake my pointing out that progress does take place as an excuse for believing nonsensical fictions. Flat Earth and other palpably ridiculous ideas can be, and are being, disproved by observation and sound logic.
Nevertheless, let us not deny that ideas, hypotheses and theories sometimes denote progress. As scientists, we know the difference between the advancement of science and the distortions of neurotic belief in proven fictions. Sadly, there are some cases where new theories are not accepted even when scientifically proven. These proven theories, few in number in comparison with rubbish speculation, do eventually find their rightful place in the hall of science, although ultimately to be improved by the ever continuing advancement of science. I hope you are in no doubt about where I stand in this exegesis.
I tried to point out above, as you well know, that there are some interesting things about the Universe which are not, and maybe never will be, amenable to science. We will most probably never be able to travel back in time to observe the big bang to study it scientifically.
It is this latter situation where we find ourselves in the realm of metaphysics. We can only consider suggestions, which is totally different from unwarranted belief in patent fictions. At the moment BBT is the best we have and has many supporting arguments. The closer we get to t = 0, the less science applies and the more metaphysics takes over. Infinities and division by infinity have no place in reality. At t = 0 we are leaving science and confronting metaphysics.
As an example, let us consider the idea of a cyclic Universe. This is in the realm of metaphysics. It is no more amenable to science than the idea of a singularity at t = 0 in BBT. Neither can be observed and proven or discarded. I am not promoting a Cyclic Universe, although I find the idea interesting. I accept BBT until it gets within a whisker of t = 0. In other words, I accept science as long as science applies. Closer to t = 0, I am interested in the idea that the idea of a singularity is replaced by the idea of a nexus, connecting with another 'phase' of the Universe. I do not believe in the singularity suggestion or the nexus suggestion.
Both are within the realm of metaphysics.
Cat
Having said that, I tried to point out that knowledge does move on, and our discovery of the truth is bettered by more and more observation of facts and by careful and reasoned consideration of the new facts discovered.
Do not mistake my pointing out that progress does take place as an excuse for believing nonsensical fictions. Flat Earth and other palpably ridiculous ideas can be, and are being, disproved by observation and sound logic.
Nevertheless, let us not deny that ideas, hypotheses and theories sometimes denote progress. As scientists, we know the difference between the advancement of science and the distortions of neurotic belief in proven fictions. Sadly, there are some cases where new theories are not accepted even when scientifically proven. These proven theories, few in number in comparison with rubbish speculation, do eventually find their rightful place in the hall of science, although ultimately to be improved by the ever continuing advancement of science. I hope you are in no doubt about where I stand in this exegesis.
I tried to point out above, as you well know, that there are some interesting things about the Universe which are not, and maybe never will be, amenable to science. We will most probably never be able to travel back in time to observe the big bang to study it scientifically.
It is this latter situation where we find ourselves in the realm of metaphysics. We can only consider suggestions, which is totally different from unwarranted belief in patent fictions. At the moment BBT is the best we have and has many supporting arguments. The closer we get to t = 0, the less science applies and the more metaphysics takes over. Infinities and division by infinity have no place in reality. At t = 0 we are leaving science and confronting metaphysics.
As an example, let us consider the idea of a cyclic Universe. This is in the realm of metaphysics. It is no more amenable to science than the idea of a singularity at t = 0 in BBT. Neither can be observed and proven or discarded. I am not promoting a Cyclic Universe, although I find the idea interesting. I accept BBT until it gets within a whisker of t = 0. In other words, I accept science as long as science applies. Closer to t = 0, I am interested in the idea that the idea of a singularity is replaced by the idea of a nexus, connecting with another 'phase' of the Universe. I do not believe in the singularity suggestion or the nexus suggestion.
Both are within the realm of metaphysics.
Cat
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Cat, thanks for sharing post #21. As science extrapolates back to t=0, the vacuum energy density of space we see today changes dramatically and another vacuum energy density must be used, otherwise BBT falls apart. This postulate must be accepted as true like round Earth today, or all falls apart. There is a difference though. Today I can see the round Earth (Apollo images, Israel Moon mission images, etc.) but not the original, postulated vacuum energy density in the universe used in BBT.
Catastrophe
"Science begets knowledge, opinion ignorance.
Rod,
"another vacuum energy density must be used, otherwise BBT falls apart"
I do not see 'falling apart' as a single valid reason.
In my view, it means science falls apart, so we know nothing until we have a valid candidate.
Does not science say "BBT falls apart until we have a scientific accepted candidate - not let's use a fudge factor?
Perhaps I am misunderstanding you?
Cat
"another vacuum energy density must be used, otherwise BBT falls apart"
I do not see 'falling apart' as a single valid reason.
In my view, it means science falls apart, so we know nothing until we have a valid candidate.
Does not science say "BBT falls apart until we have a scientific accepted candidate - not let's use a fudge factor?
Perhaps I am misunderstanding you?
Cat
Cat you said in post #23, "In my view, it means science falls apart"
I would say the doctrine of uniformity falls apart (science in the here and now does not) and the explanation for the origin of the CMBR falls apart too.
I would say the doctrine of uniformity falls apart (science in the here and now does not) and the explanation for the origin of the CMBR falls apart too.
Catastrophe
"Science begets knowledge, opinion ignorance.
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