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joigus

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Posts posted by joigus

  1. On 3/31/2024 at 6:12 AM, icarus2 said:

    But what about photons, which are not relativistic particles? Which expression is correct for photons that have no rest mass?

    What do you mean non-relativistic photons? Photons are always relativistic. Am I missing something? Everybody else seems to understand what you mean, but I don't.

    Because they're always relativistic, the equation of state (pressure as a function of density) is what it is in the matter term of the Friedmann equation.

  2. The alleged title,

    14 hours ago, NormaVega said:

    A microbial survey of a subterranean ant nest using culture-dependent and culture-independent and methods.

    Doesn't even make syntactical sense.

    It's perhaps significant that this OP seems to be in answer to one of the main objections to previous bogus thread on "fluorine-based biology".

    In particular the part that says,

    16 hours ago, exchemist said:

    You also need to pay some attention to what solvent a life chemistry will use. Water would be fairly useless with fluorocarbons, I suspect. Are you envisaging HF or something as the solvent? 

     

     

  3. 43 minutes ago, swansont said:

    Don’t fluorocarbons still require a fair amount of carbon?

    It seems like they do. Close to 50% as much carbon as fluorine for fluoroalkanes. More if double bonds C=C or higher occurs (or other radicals).

    Linear chains 2n+2 F's per n C's

    cyclic chains 2n F's per n C's

    2-cyclic chains 2n-2 F's per n C's

    That assuming nothing else is goin on but C-F bonding, which sounds pretty boring.

    Carbon is still the structural scaffolding in FC's. And F is monovalent, which leaves little room for anything interesting going on IMO.

  4. 18 hours ago, jnana said:
    if we take Newton’s law of gravitation
     
    F = G(m1m2)/R2.
     
    Thus when we move object A it effects the other two objects B and C
    But when objects B and C move that effects object A


    So
     
    we can say that A in effect caused its own motion
     thus we can say the antecedent cause of A is infact just the antecedent A itself
     
    in other words the cause of the cause is the cause
     
    just nonsense meaninglessness

    This definition of the principle of causality as applied to classical mechanics is indeed a meaningless nonsense one, as you don't include time in it, or the paradigm of the differential equation, which is the way in which causality is implemented in physics. Fortunately neither Newton, nor Laplace, etc said anything of the kind.

    It is, rather, state of A, B, C at time t1 causes state of A, B, C at time t2, which causes state of A, B, C at time t3, and so on.

  5. 20 minutes ago, martillo said:

    Thanks. More clear now. You are talking about the vibrations approach.

    Molecules can vibrate, rotate, twist, and scissor, etc. In fact, there are DOF that are not obviously rotational/vibrational, etc. but some complicated so-called normal modes like,

    Quote

    The normal modes of vibration are: asymmetric, symmetric, wagging, twisting, scissoring, and rocking for polyatomic molecules. Figure 1: Six types of Vibrational Modes.

    https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Number_of_Vibrational_Modes_in_a_Molecule

    Symmetrical_stretching.gifAsymmetrical_stretching.gifWagging.gifTwisting.gifScissoring.gifModo_rotacao.gif

    Recently, a key to why CO2 (kinda mysterious, as it's just a boring non-polar linear molecule) is such an important agent in global warming has been found to have a root in resonances of such non-obvious normal modes due to Fermi resonances:

    https://arxiv.org/pdf/2401.15177.pdf

  6. 11 minutes ago, martillo said:

    For any material system, solid, liquid or gas an average temperature is maintained by the atoms/molecules which stay interchanging photons with the environment. Remember that after all the there's a lot of space between them.

    The surface to be considered is just a representative little "differential" area inside the system through which a "differential" quantity of photons are passing in two directions.

    I'm sorry but I cannot follow you in this. I don't understand the vocabulary properly and may be I'm not capable to put the subject in your terms.

    Sorry. Here's a lowdown of the vocabulary I've used. Tell me, please, where the problem is:

    Degree of freedom

    Temperature

    Specific heat

    internal (rotational/vibrational) vs external (CoM)

    cutoff (making some energy --or wavelength-- domain irrelevant; see next)

    freezing (as in freezing degrees of freedom by making them very unlikely to store energy under thermal-equilibrium conditions).

  7. On 3/15/2024 at 5:08 PM, sethoflagos said:

    And yet when we measure temperature gradients between systems at different temperatures, in non-extreme conditions they are generally linear in agreement with the dominant mechanism for transfer of heat being by momentum exchange.

    If the dominant mechanism were EMR as you suggest, then the measured gradients would be highly non-linear (cubic in delta T I think).

    I understand your POV but I think it's a misleading one. Particle collisions in gases that support rotational and vibrational modes only follow conservation of linear momentum on average. In the general case, some momentum is transferred via the other modes.

    Absolutely. Sorry I missed this very good argument for so long. It's only because of what you say that different molecules have different specific heats as a function of temperature. The internal degrees of freedom are totally relevant. This is exactly the reason why different molecular components have different specific heats. What other reason could there be for different gases to display different specific heats if only the CoM DOF were relevant?

    Quite a different matter is how quantum mechanics introduces a cutoff for short-length degrees of freedom (independently of how poly-atomic a gas is), and how this played a crucial role in the dawning of quantum mechanics itself. (Birth of the old quantum theory as a mechanism to freeze the short-wavelength DOF.)

  8. 1 hour ago, KJW said:

    I'm not the one who started the discussion on assigning temperature to a single particle. Oddly enough, @martillo rejected my suggestion in favour of something that is not going to work.

     

    Agreed.  @martillo's suggestion is not going to work. Your suggestion is, if I understand correctly, a valiant attempt --let's put it that way-- to try and make sense of their hopeless intention to define temperature as an attribute of one molecule or atom.

    I think you're right to say that the ergodic theorem is essential to define thermodynamic equilibrium. If most typical physical systems we deal with were not ergodic, I don't think statistical ensembles would work at all within the context of variables such as the partition function, temperature, Helmholtz's free energy, entropy, and such. It would be a disaster. The least I can say is those variables would be as good as useless.

    So why bother trying to make sense of something that just doesn't? Just to spite me? Temperature is an ensemble-related parameter. There is no operational definition that would allow us to measure the temperature of a molecule either. There is no theoretical framework that allows us to define it in such a way except by way of the ensemble.

    Temperature is an ensemble property. Even more so than entropy is. At least the microscopic entropy of a molecule can be defined as the volume of phase space for that molecule, which is always the same. Not so for temperature.

     

  9. I'm sorry I was disrespectful to the geometry[?!].

    I think you're trying to talk about the Arahonov-Bohm effect. Now I'm positive that's how you connected the words "Bohm" and "holonomy".

    It's about this:

    https://en.wikipedia.org/wiki/Aharonov–Bohm_effect

    Aharonov-Bohm holonomy has nothing to do with realism, locality, or any of that, even though the word "Bohm" appears there too. It's the De Broglie-Bohm theory that does.

    Kinda like the Maxwell-Boltzmann distribution has very little to do with Maxwell's equations, except for Maxwell.

    Do these comments help a little bit?

  10. On 3/19/2024 at 8:42 AM, Eise said:

    Yes, but only after Germany was defeated. Heisenberg was in charge. The infamous meeting between Heisenberg and Bohr in 1941, gave the latter the impression that the Nazis were making serious work of the atomic bomb, and brought this impression to the US.

    Hey, nice account.

    BTW, I recommend you Copenhagen, by Michael Frayn. It's about that (in)famous meeting, and offers a possible development that I can only conceive as happening with a many-world view. ;)

  11. 1 hour ago, Genady said:

    I also am very far from being an expert, rather just a witness. In the case I've witnessed, specific environmental factor has made obvious a very serious form of schizophrenia, but then its signs could be traced back for years of misdiagnosis.

    From what I know (and I know one case personally) it wasn't obvious during pre-pubescent stage and there were environmental factors that triggered it post-puberty. So what you say checks with my personal experience. That's why gene-based diagnosis is sure to become essential in the future.

  12. On 3/17/2024 at 5:44 AM, KJW said:

    It occurred to me how one might do that. One could define the temperature of a single particle in thermal equilibrium with its surrounding environment in terms of the kinetic energy distribution over time of the particle. Applying the ergodic principle transforms this to an ensemble distribution for which the notion of temperature naturally applies.

     

    Only when a system is in thermal equilibrium, and provided it is ergodic, the time average of the kinetic energy coincides with the ensemble average at any one time. So you need the ensemble plus the fact that the system be in thermal equilibrium plus ergodicity. Very very special conditions indeed. And when it works, you've used the whole ensemble to define it... So it's not a property of the particle. It's a property of the ensemble!

    So no --I insist--, there is no temperature as a property of a singled-out particle of an ensemble in general. And when there is such a thing, it's only by stretching the concept so that what really is a property of the ensemble is decreed to be a property of any and every one of the members of the ensemble.

    I don't see how this definition does anything, really. And believe me, I would like nothing more than to be illuminated about anything physics.

  13. 1 hour ago, exchemist said:

    But you still stigmatise them as ill. So ill but stable?

    I didn't mean religious people --see my comments to Luc Turpin below.

    Apparently schizotypals were discovered as a consequence of behaviour scientists wondering: How come an illness as detrimental as schizophrenia is so significantly present in the gene pool? --In the ballpark of 1%. Wouldn't there be a milder but related version of the illness that could be proven as advantageous under certain circumstances? The parallel was sickle-cell anemia, which can kill you, but a milder version of which can protect you from malaria. So they found a high correlation of peculiar characters in relatives of people suffering from schizophrenia.

    I wouldn't dare to use the term "ill" for any of these people. AFAIK triggering of even serious form of schizophrenia only happens after environmental factors have made their appearance.

    But I'm very far from being an expert here and I'd gladly accept corrections by anyone who knows more about this.

    14 minutes ago, Luc Turpin said:

     

    On 3/16/2024 at 7:00 PM, joigus said:

    Religious types could, after all, be not much more than socially-accepted schizotipicals, that have somehow met the medium, and the way, to make their illness socially palatable.

    But not this one.

    Sorry, by "religious types" I didn't mean the followers of a religion. Rather, I meant the prophets, the visionaries, the people who hear voices, the people who see angels. You know, the founders of religions.

    The following of a religion is a completely different matter. Some people join because they feel comforted, others because they want to fit in, others because they are folklore-motivated, etc. Who knows. At least, I don't.

  14. 5 hours ago, JosephStang said:

    Geometry is not math. 

     

    It is a branch of math.

    https://www.britannica.com/science/geometry

    Quote

    Geometry, the branch of mathematics concerned with the shape of individual objects, spatial relationships among various objects, and the properties of surrounding space. It is one of the oldest branches of mathematics,

    The branch is part of the tree, although the tree is not the branch.

  15. 23 minutes ago, Luc Turpin said:

    My religious friends appear more mentally stable than most in society.

    Schizotipical behaviour is not to do with mental stability. It's to do with delusional perception of experience (sensory or otherwise). Have you skimmed through the wikipedia article or references thereby? My emphasis in boldface in a sample from mentioned article:

    Quote
    1. Crespi B, Dinsdale N, Read S, Hurd P (2019-03-08). "Spirituality, dimensional autism, and schizotypal traits: The search for meaning". PLOS ONE. 14 (3): e0213456. Bibcode:2019PLoSO..1413456C. doi:10.1371/journal.pone.0213456. PMC 6407781. PMID 30849096.
    2. ^ Carvalho LF, Sagradim DE, Pianowski G, Gonçalves AP (2020-10-19). "Relationship between religiosity domains and traits from borderline and schizotypal personality disorders in a Brazilian community sample". Trends in Psychiatry and Psychotherapy. 42 (3): 239–246. doi:10.1590/2237-6089-2019-0085. PMC 7879071. PMID 33084801. S2CID 224828232.
    3. ^ Breslin MJ, Lewis CA (2015-03-04). "Schizotypy and Religiosity: The Magic of Prayer". Archive for the Psychology of Religion. 37 (1): 84–97. doi:10.1163/15736121-12341300. ISSN 0084-6724. S2CID 144734469.
    4. ^ Byrom GN (2009). "Differential Relationships between Experiential and Interpretive Dimensions of Mysticism and Schizotypal Magical Ideation in a University Sample". Archive for the Psychology of Religion. 31 (2): 127–150. doi:10.1163/157361209X424420. ISSN 0084-6724. S2CID 143580864.

    Etc.

  16. 2 hours ago, JosephStang said:

    Why would I have to specify position variables while describing a 3D geometry?

    The very moment you posit that your theory is local.

    7 hours ago, JosephStang said:

    It overcomes Bell’s inequalities with Bohmian style locality by mediating FTL

    (emphasis mine)

    A theory is or is not local depending on a postulated interaction, or else by way of an ad hoc postulate or axiom. Yours is neither. It is neither non-local, nor is it local. It's only named "local" by you.

    And forgive me having overlooked this, but, what do you mean it overcomes Bell's inequalities? Quantum mechanics as is already overcomes Bell's inequalities, ie, it violates local realism. Bell's inequalities are a consequence of local realism.

    So again, what do you even mean?

  17. 4 hours ago, JosephStang said:

    Description: Each electron/proton is a ring.

    Protons are nothing like electrons. We do know as much.

    In what sense is this "holonomic"? "Holonomic" means integrable, exact, it goes back to itself after a loop. I don't see anything holonomic here.

    I can't fathom what's Bohmian about it, or local/non-local, as the case may be, as no mention of how position variables function in the "theory" can be spotted.

    Summarising, it very much sounds like word salad with no maths underpinning it. No calculation, no formal-mathematical justification.

    21 minutes ago, JosephStang said:

    Do you not understand the description?

    What description?

  18. On 11/12/2023 at 4:04 AM, Chris Sawatsky said:

    A sphere exploded but did not expand in every possible direction simultaneously?

    Picture an inflating balloon. Now suppress the space around and inside the balloon, as there is no such thing as "inside" or outside the balloon. There would be only whatever stuff makes up the balloon. Now make the balloon itself 3-dimensional, with time providing for the "history" aspect of it.

    Spaces don't have to be embedded in higher-dimensional spaces. IOW, the only existing directions are those tangential to the balloon's rubber if you will.

  19. How about StPD at the root of many, if not all, of these reports?

    https://en.wikipedia.org/wiki/Schizotypal_personality_disorder

    Quote

    classification describes the disorder specifically as a personality disorder characterized by thought disorder, paranoia, a characteristic form of social anxiety, derealization, transient psychosis, and unconventional beliefs.

    Religious types could, after all, be not much more than socially-accepted schizotipicals, that have somehow met the medium, and the way, to make their illness socially palatable.

  20. 4 hours ago, Markus Hanke said:

    That’s because mass never appears in the GR field equations - what is generally called the source term here is the energy-momentum tensor. One must also remember what these equations actually say - they state a local equivalence between a certain combination of components of the Riemann tensor (the Einstein tensor) and the energy-momentum tensor. Nowhere does it claim a ‘causative relationship’, but instead it says that these two are the same thing (up to a constant of course); neither one comes first and ‘causes’ the other.

    Indeed. I --and others, you among them-- have said it before elsewhere on the forums, actually. It's the energy-momentum that sources the gravitational field.

    I also agree with the absence, of necessity, of any causal connection between the Einstein tensor and the energy-momentum tensor.

  21. On 3/14/2024 at 8:55 AM, martillo said:

    the temperature of an atom is [...]

    There is no such thing.

    Thermodynamics defines temperature based on thermal equilibrium. Statistical mechanics relates it to average kinetic energy per degree of freedom. For statistical mechanics to make the connection between both concepts through the partition function and the Maxwell distribution, we need approximations on really big numbers of molecules.

  22. The group of symmetry of electromagnetism is U(1) (complex numbers of length 1), and electrical charges are at the centre of it.

    From the POV of symmetries, conservation laws, and irreducible representations of groups (particle multiplets) QFT of electromagnetism and its brethren --weak interaction, strong interaction-- is more user-friendly by orders of magnitude. Things kinda "fall into boxes."

    GR is not like that. Not by a long shot.

    The group of symmetry of GR is basically just any differentiable transformation of the coordinates. Once there, after one picks a set of coordinates that locally make a lot of sense (they solve the equations easy, yay!), they could go terribly wrong globally, so that one must introduce singular coordinate maps to fix the blunder.

    Because the symmetry group of GR is this unholy mess, group theory doesn't help much, if at all. The equations are non-linear, so: Are there any solutions that might help clarify divergences, and so on, that we might have missed entirely? Who knows.

    In my opinion, the very fact that the set of coordinates that, locally, happens to be the most reasonable one could (and sometimes does) totally obscure the meaning of the coordinates far away from the local choice, and thereby their predictive power out there, makes the status of any parameters that the theory suggests (mass in particular) much less helpful than charge is in EM.

    Mass to GR is nowhere near anything like charge is to Yang-Mills theory (our paradigm of an honest-to-goodness QFT field theory).

     

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