Mordred

That's why I'm adding links for reference. Thermal conductivity is governed by very different relations that it is in thermal radiation. I am describing thermal conduction specifically for the case of solids. None of the equations for thermal radiation such as Plancks radiation law, Bose-Einstein statistics, Stefan Boltzmann, etc apply as thermal conduction is distinct from radiation. For solids the thermal conductivity of a material follows the Fourier Law of Heat conduction which for a 3d solid is \[\vec{\hat{q}}=-k(\frac{\partial T }{\partial x}\vec{i}+\frac{\partial T}{\partial y}\vec{j}+\frac{\partial T}{\partial z}\vec{k})\] most times you will see it as \[\vec{q}=-k\vec{\nabla} T\] such as this wiki link https://en.wikipedia.org/wiki/Thermal_conduction q is the heat capacity while k is a constant of proportionality for a materials conductivity. One can use the above law to mathematically describe the scenario Swansont just gave. (Though that's typically one of the earliest lessons articles will give on Fouriers Law.) Lattice networks are typically the homogenous and isotropic scenario using the Fourier law in that link. Quantum mechanically though the Fourier is represented by the quantum mechanical master equation for heat transfer lol just so you know I'm not blowing fluff on the name lol here is an example article on arxiv https://arxiv.org/abs/0711.4599 very few ppl will understand the mathematics of this article

Swansont beat me to it. Once again there is a difference in thermal conduction of a material and thermal radiation. In solids you also have to factor in the conductivity of the material which will also involve density of states. little side not there is a reason why photons aren't used in a crystal lattice. The reason has to do with momentum invariance within the lattice. There is only 1 vector in a lattice where the momentum is invariant and this doesn't represent the overall momentum of the entire lattice network. Instead they use a quasi-momentum and phonons as a quasi particle for the distinction. example details here https://www.ucl.ac.uk/~ucapahh/teaching/3C25/Lecture12p.pdf phonons are used to represent lattice waves, while its common to use magnons for magnetic waves and keeping photons for EM waves. All three directly apply to thermodynamics of a solid or more accurately its conductivity

In the case of radiative heat transfer using photons is common as a mediator. However heat transfer is not the same thing as an objects temperature. In order to understand how photons can be used in thermal radiation one has to also understand the interaction with the molecules and atoms of a substance/state. So one also has to understand how this alters its temperature

Try not to confuse how thermal energy is transferred until you understand why thermal energy is described via its mean average kinetic energy. There is a difference between the two both however are required. I do have to ask why you would think the current understanding of temperature is incorrect in regards to frequencies/vibrations etc ? Particularly when we can definitively show our understanding via previous experiments and observations ? One example I can think of, offhand that clearly demonstrates our understanding is using lasers to supercool atoms and molecules to form a Bose-Einstein condensate. Using lasers to cool something is not something one would expect but in essence the lasers are used to reduce the internal motion of particles within the condensate. Its not just any laser in that example its specific laser frequencies that vary depending on the condensate. Just another thing to keep in mind there is also a distinction between conductive heat transfer and radiative heat transfer in regards to Stefan-Boltzmann...

I already have if you looked at the two equations I posted. However I ask you the following if you cause vibrations an object to increase via any mechanism including sound do you agree that the average temperature of resonating nearby objects will increase ? or that you can heat up metal by hitting it with a hammer? Any time you increase an objects vibration you also increase the molecular and atomic vibrations. So ignoring molecular and atomic vibrations makes absolutely no sense whatsoever.

There is also the Cosmic neutrino background however that's irrelevant. What is relevant is that there a temperature even with particles that does not interact with photons. As far as considering why your ignoring the kinetic energy terms of molecular vibrations your simply incorrect to do so. As such your model will fail Seems to me that you have chosen to completely ignore the fundamental definition of temperature or at the very least a good portion of the kinetic energy terms involved.

just to add to this with another example. How would a cosmic neutrino background which has no photon interactions have a blackbody temperature of 1.95 K ? I concur with Swansont on the rest of the quote

So let me get this correct Joigus provided you with links directly related to the vibration of molecules and you feel that atoms and molecules have no vibrational modes is that correct ? Do you for some unusual reason feel that the details provided by Joigus didn't apply ? what happens to your vibrational and rotational temperature ? \[\theta_{vib}=\frac{h\tilde{v}c}{K_{B}}\] and \[\theta_{R}=\frac{hc\bar{B}}{K_{B}}\] You know I honestly cannot think of a single static particle. Every particle has harmonic oscillations including those of atoms and molecules. It would certainly make absolute zero viable as under QM absolute zero temperature is impossible.

Try to wrap your study on the difference between an invariant vs a variant measurement. The former all observers agree on literally all observers. That's is what's used to calculate the expansion and age of the universe etc. The commoving observer is used to establish that needed invariance

The term for the observer your looking for is the commoving observer. This is an observer at the same influences of the global spacetime conditions. In essence the flat global metric. The flat spacetime of the LCDM parameters has no significant curvature term for any time dilation effects. Subsequently the age of the universe is determined from the commoving observer. The formulas applies the Hubble parameter in its formula. There is absolutely no point in using the observations of an observer in a traveling spacecraft, particularly using redshift. One simply has to realize how useless thar would become by recalling that as the spacecraft approaches a destination you blueshift while at the same time getting redshift from the crafts origin point. Makes using observers on a spacecraft essential useless. Particularly once you start applying transverse Doppler for every angle not parallel to the travel direction. In essence an observer in a spacecraft would get different redshift values at every single angle of measurement. Kind of pointless to use that to calculate expansion or age.

No problem, hope your getting better. Hospitals are never fun. I would suggest instead of thinking of alternative universes. Simply apply the quantum vacuum positive and negative frequency modes for particle production. QFT already has all the applicable formulas for that scenario. Modelling a 2 component scalar, boson of even a fermionic field under QFT has plenty of textbook support at the introductory level. In QFT field and momentum are your primary operators. Though having familiarity with Fourier transforms and the Langrangian/Hamilton greatly helps to understand and apply QFT.

Correct any finite portion will not extend to infinity. However we do not know if the entirety of universe beyond our Observational portion is infinite or finite. Our Observable universe portion will always remain finite. Had findings of our universe term been precisely flat at unity then we likely would have had an open infinite universe. However their is a slight curvature term that raises the possibility of a closed universe.

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Your logic is not the same as my logic or Bob's logic. Logic means nothing. It's simply an aid. There is no preferred frame this is well established and if you understand the mathematics of GR with its application of invariant quantities you would understand the truth of that statement. Let's use the following math statement on the Lorentz transforms \[\mu \cdot \nu= \nu \cdot \mu)\] This statement describes the symmetric relations of the Lorentz transform.

Thats a poor excuse, one cam still stick to the math and model any form universe conditions by applying the correct math alterations provided one correctly performs the correct math operations. I can easily adapt the FLRW metric to a form that does not require a homogeneous and isotropic dstribution as per the Cosmological principle or even adapt the metric for a rotating universe. That's because I know the needed math steps. You don't learn those by simply studying pop media literature. Regardless if you study the arxiv and professional papers instead of paying attention to pop media you will learn that pop media literature makes mountains out of mole hills. Pop media will always lead a reader astray. The cosmological Principle is quite secure by observational evidence a good example is the uniformity of the CMB. The scale however one must apply is per 100 Mpc.

Ds is the separation distance interval is designated by (ct) though that's usually shortened to simply t. The interval allows time to have the same dimensionality of length via the interval

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You will never learn physics if you pay attention to interpretations which the block universe is. We don't use the block universe interpretation in actual physics. It's just an interpretation. Stick with the math involved would show

I should add the positive frequency modes are well described via any Good Dirac equations article. In case your familiar with them.

I'm start with this statement which is rather erroneous but rather than point out the mistakes I will instead describe the quantum vacuum in accordance with the mainstream. From that the errors will become more readily obvious. I will be including related formulas so may take it a bit (in case of cross posts lol). Lets start with the period prior to inflation the hot dense state. We all agree its a tiny region at an immense density and temperature. In our models we feel the energy density is roughly \[10^{19} K\]. So everything is in that thermal equilibrium state. All particles are in thermal equilibrium. At that temperature if you apply the Bose-Einstein statistics formula you will find you have roughly 10^90 photons. This is an equivalency its actually a quark/gluon plasma state other particles can exist but recall we cannot distinguish any particle species. Here is the Bose-Einstein statistic. Don't worry I don't expect anyone to be able to use these formulas. \[ n_i = \frac {g_i} {e^{(\varepsilon_i-\mu)/kT} - 1}\] In that formulas the effective degrees of freedom is 2 for photons. I gave you an article with the pertinent details earlier on. That's your low entropy state. Now lets look at the quantum vacuum including zero point energy. Were all familiar with the quantum harmonic oscillator. This was one of the earlier studies on universe from Nothing scenarios. Including Guth's original inflation which unfortunately had the effect of "Runaway Inflation". Now one of the problems you have in that quoted section is your likely not aware that when particles come into existence they have to obey numerous conservation rules. The relevant one is conservation of charge in this particular case this includes matter and its antimatter pair. For photons it is its own antiparticle the distinction lies in its circular polarization. anti-photons are Right hand polarized while photons are left hand. This rule also applies to other particles such as neutrinos. Hopefully you can see a problem with your negative and positive universe scenario. Particularly since anti matter is readily formed in numerous processes including stars. https://www.space.com/21889-solar-flares-antimatter-particles.html not to mention we collide matter particles and can can produce antimatter. Knowing that how would this correlate to you negative and positive energy universes ? Something to keep in mind, just like an electric circuit where you cannot measure voltage by placing your test leads on the same copper wire until you have a potential difference between the two lead points. One cannot determine how much energy a vacuum contains between any two coordinates with there is no difference in its potential energy. We can however look for indirect evidence Casimarr effect is one example. The main problem with the zero point energy quantum vacuum is that observations vs calculation show an error margin of 10^(120) aka the vacuum catastrophe. There are plausible solutions to this still underway. \[d{s^2}=-{c^2}d{t^2}+a({t^2})[d{r^2}+{S,k}{(r)^2}d\Omega^2]\] \[S\kappa(r)= \begin{cases} R sin(r/R &(k=+1)\\ r &(k=0)\\ R sin(r/R) &(k=-1) \end {cases}\] lets start with the FLRW metric we wont need curvature so we can keep it set at k=0 c=1 following formulas will be in normalized units. We need to describe two field of lets go with photon/antiphoton for simplicity. Under QFT we have two operators the creation/annihilation operators. They further correspond to their propagators as well but we don't need that detail. QFT uses them to model how particles are created subsequently destroyed. This link details how it applies to the quantum harmonic oscillator aka zero point energy https://en.wikipedia.org/wiki/Creation_and_annihilation_operators#Ladder_operators_for_the_quantum_harmonic_oscillator In essence the positive and negative modes of the harmonic oscillator propagates the operators. Where the operators correspond to particle I wont go into too much detail to see if you have any comments/questions up to this point. However this is the zero point energy field and how it can give rise to particle production in essence.

An explosion has different dynamics that are measurable. You can easily confirm the difference yourself. Take a ruler from a central point at various different angles measure off 1 cm then 3 cm then 6 cm etc. Now think of the ratio of change the result of radiating outward from the central point and measure the angles. You should notice angle changes as well as a preferred direction and location. Now place dots on a balloon measure the angles prior to inflating (inflate just enough to get a sphere. Then inflate the balloon further. The angles do not change and the ratio of change in distance is identical between any two points.

It's all good I wasn't expecting you to be an expert on cosmology applications. For any post I will try to keep as much to the FLRW metric as well as supply support material on those formulas. This evening after work I will post some relevant formulas that will apply.

fair enough however there are sections of part 3 that indicate that you have a few misunderstandings in regards to universe geometry. Universe geometry doesn't describe the shape of our universe. In actuality it describes the the null geodesics due to spacetime curvature terms. Our observable universe is a sphere. However that is not its metric geometry. (Newtonian solution under GR for flat spacetime). Now this has ramifications on redshift as well as any visual observations. In point of detail spacetime curvature causes distortions. whereas flat spacetime doesn't. So we can confirm that our universe is indeed flat by studying the CMB for distortions. There is a statement in my signature. " If you wish to change the rules, you must first understand the rules." the meaning of this is that one must understand the models they wish to fix and why those models state what they do before they try to fix it. I'm positive as a physicist you can relate to that statement. Another key point is that a homogeneous and isotropic expansion can also be tested by not distance per se but just as important any changes in angles. For example let us assume expansion started at some central point radiating outward. In this scenario you would have measurable changes in angles between stellar objects as those objects move further away from the starting point. This would be an anisotropic and inhomogeneous expansion. Expansion rates would vary in locations and have a preferred direction with a preferred location. The preferred location being the starting point. You would also have varying mass density distribution. keep in mind much of this post is also to the benefit of other readers so they can also learn what is involved As many of the older forum members can tell you, I tend to try to provide as much added information as I can as well as resource links etc for those very reasons. That way everyone learns something and it has the side effect of attracting interest in a thread. I have another key policy. If a poster wishes to learn how to go about developing a model correctly and is willing to work at learning then I have no issue with doing my best to guide them in the needed formulas, lines off research or textbooks etc. Regardless if I believe their model is feasible or not. Provided that there is some measure of feasibility of course. Now I fully recognize at no point are you stating your hypothesis is correct but simply examining the feasibility. That is part and parcel of the scientific method (examine all possibilities). that being said it would be helpful to know your skills in the FLRW metric and GR. The FLRW metric itself is likely sufficient for toy model development but if you understand GR its a good step to understanding how the FLRW metric works. Thermodynamics is something you likely already know but may not be aware of how its applies in Cosmology. One further point in section 3 you describe a UCOM. I'm assuming this refers to a center of mass of the universe. If that was your intent then that would be in error. Newtons Shell theorem would apply for a uniform mass/energy distribution such as described by the Cosmological principle.

That doesn't meet observational evidence. We know that expansion is accelerating in so far as the radius of our observable universe. Might surprise you to know though that the Hubble parameter itself is decreasing over time. If the universe were in gravitational contraction this would overpower the cosmological constant which is not something that observational evidence supports. \[\rho_{crit} = \frac{3c^2H^2}{8\pi G}\] this here is the critical density formula. Historically it was use to describe the point where an expanding universe would commence in collapse. This formula was derived via the equations of state for matter. The discovery of Lambda however made this equation less useful in that regard however its still used to calculate the energy density of Lambda today as we are currently in the Lambda dominant era. Lambda aka cosmological constant aka dark energy is currently the dominant contributor to expansion. In point of detail the universe was starting to slow down in expansion towards the end of the matter dominant era however Lambda turned over and started accelerating expansion. This occurred when the universe was roughly 7 Billion years old. The calculator in my signature can show the inflection point but finding it is rather a painful exercise. The precise time however will vary depending on which cosmological parameter dataset is being used

As your new to the site Be aware your restricted to 5 posts on the first day. After that the number of posts/day is unlimited. I was gathering an article you will find useful in regards to early universe entropy as well as cosmology in general as its in a textbook style. Particle Physics of the Early Universe Uwe-Jens Wiese Institute for Theoretical Physics Bern University http://www.wiese.itp.unibe.ch/lectures/universe.pdf see section 4.2 with regards to how entropy is calculated in |Cosmology applications Inflationary models commonly use the inflaton which is a quasi-particle placeholder. However a lot of modern research is leaning towards Higgs inflation this includes Allen Guth as one of his recent papers ran a comparison between the inflaton and Higgs. I myself also support Higgs inflation however I never push personal feelings as to a preference. I'm not sure what you mean by mass contracting however the mass/energy density distribution is commonly understood via the equations of state (cosmology). https://en.wikipedia.org/wiki/Equation_of_state_(cosmology) with this we can further detail the evolution of said components as the universe expands. Those details are also in the link. I should further note the BB isn't a kinetic type explosion but a rapid spacetime expansion caused by those ideal gas laws as well as inflation. A kinetic explosion has different measurable properties. That are not homogeneous and isotropic and cannot give an homogeneous and isotropic expansion