Fair enough (for the record - most people aren't likely to look outside the current thread regarding potential posts/links et al). It looks like you are referring to this: https://arxiv.org/abs/1202.2362 Yes? If I'm reading that right - it would seem to suggest he is referring to planets already within the stellar cluster: An interesting proposition, but not exactly one that applies to the "pass through" capture that was being discussed. Likewise, it doesn't really apply to the discussion going on here, and you still haven't produced anything that suggests expansion of the universe with a set quantity of energy wouldn't cause a temperature decrease.
Still disputing?? That's two body. I suggest either you acknowledge or drop it now. And again you are misquoting me on this thread. I never said that the expansion would not cause the reduction in temperature, I was talking about the proof, the science behind reduction in temperature on expansion. That is the expansion is adiabatic, the entropy remains constant, the entropy is VT^3 and hence on increase of V (the expansion) the T would reduce. Exchemist etc are linking to CMBR etc, which is not the correct explanation for the reduction in temperature. That's the observation and evidence not the explanation.
Still pointing out that you are, apparently, utterly oblivious to the differences in the proposed scenarios (as well as the fact that it is entirely off topic to this discussion) I am misquoting exactly nothing. You challenged the idea that expansion would cause a reduction in temperature - examples and evidence were provided to you. You, once again, challenged it whilst providing zero refutation of the evidence provided. Thus, I am challenging you to provide an alternate, or to accept that expansion should, by our current understanding of physics, result in cooling. You don't get to have this both ways... either quit being pointlessly confrontational, or make a point. To wit: What, exactly, are you trying to say Exchemist is claiming? His explanation fits with both known physics and what has been observed. Meanwhile, you have offered no alternative, yet continue to claim he is wrong. It's time for you to pony up with an alternative, or admit you are simply being needlessly obtuse.
You not only dispute Prof Perets who is an authority on the subject but you are dishonestly misquoting me. Why are you so dishonest, where the fuck did I say that on expansion temperature does not reduce?
*sigh* Perhaps, one day, you will learn that playing the fool doesn't suit you... Timojin asked: Origin replied: You responded: Exchemist countered: You again: My response: Your response: You then started to further obfuscate, seemingly arguing against the very premise that the universe is cooling due to expansion of a system with a set amount of energy. Every time you have been asked to clarify your position (such as are you saying the universe is not, in fact, a closed system) you have declined to do so, instead simply reiterating the "you are wrong" bollocks: When called out on it, you ran away: You have been taking a contrarian stance against this premise the entire thread; now you have the gall to say I'm being dishonest by calling you out on it? Reality to The God - you have railed against the very idea this entire time! Now, I am giving you one final chance to prove you are not simply trolling this thread - either make a point and back it with relevant data, or accept that the initial answer to the question was, in fact, correct. Quit with this vexatious posting game you have going on - you are fooling precisely nobody.
Kittamaru, playing the fool does not suit you; you are playing not me. I will explain you both the points which you are vociferously attempting to bulldoze and unfortunately couple of your friends, by giving your posts undeserving likes, are making you look further unequipped to handle physics of this level. This time you do not twist the matter and respond pointwise, no bullshit, no obfuscation, just science, rather I would suggest seek or invite someone who understands physics. May be you can request Rpenner if he is still around. My pointwise response is in next post.
1. In the earlier thread, my emphasis was on the initial conditions (Velocity vector and position) for orbital capture. 2. You guys vehemently denied 2 body capture scenario even though I suggested that it is the matter of initial conditions. 3. I cited a paper of Prof Perets et al which explicitly mention 2 body scenario, you ignored or missed in that thread, the thread was locked by James R, when somehow that issue came up here you tried to brush it down. Now coming to this thread, you either dishonestly or due to lack of understanding attributed to me that I am having a contrarion view on reduction of temperature due to expansion of universe. No, the temperature reduces on expansion, that was my stand, the argument was more on the explanation that how temperature reduces on expansion. For that I very rightly with formulae reference posted that expansion of universe is adiabatic and VT^3 remains constant thus reduction in temperature on expansion. That's the accepted physics. Your friends were talking about CMBR and Black Body radiation, I stated that whatever they are talking about is the observational evidence not the explanation. Now I want to ask you some question, try them and you will see what you are dragging... 1. Can you assign temperature to a photon or red shifted photon ? 2. How do you get z = 1100 for CMBR? Actually CMBR spectrum excellently matches with a black body spectrum at 2.5 Degree Kelvin, this tallies with a temperature of around 4000 Deg K of recombination era and with the age of that era at 360000 this gives a red shift of around 1100 for CMBR. This is what your friends are saying. What is this? Observational evidence that the temperature of universe has become 2.5K from 4000 K on expansion. But this is not the explanation for reduction in temperature.
Having only a limited appetite for tedious argumentativeness, I'll just answer your (1). No, a single photon has no temperature. If you had read the Wiki article on the CMBR, you would not be asking this question. Someone who was genuinely interested in the subject (as opposed to just stirring up argument vexatiously) would have read it by now. Be that as it may, I will answer the point, for the benefit of other readers at least. The frequency distribution of the CMBR is that of a black body, i.e. a perfect emitter of thermally induced radiation. From its shape and position on the frequency spectrum, we can work out the temperature a black body would need to have in order to emit precisely that distribution. That is what is meant by the temperature of the CMBR. It refers to the temperature of the black body emitter, not to any supposed "temperature" of an individual photon. Obviously. The red shift of this spectral distribution corresponds to a temperature drop. It is explained by the expansion of space stretching the wavelengths. This is of course exactly the mechanism of the cosmological red shift: a stretching of the metric itself as the universe expands. If one unwinds this expansion one gets back to the temperature of the final plasma (the "surface of last scattering"). This is all in the Wiki article.
Good, so from photon you cannot figure out temperature. In any case whatever you are saying does not explain why the temperature should reduce on expansion. See, do we talk of temperature reduction when we get red shifted star light, that too follows the same metric expansion scenario? So Exchemist, CMBR or black body spectrum mapping gives us s value of 2.5K, which is the evidence of reduction of temperature along with four other figures (380000, 4000, 1100, 13.4 byears. It is not the explanation for reductikn in temperature.
This is where the second question, which you did not attempt, is crucial. How do you get z = 1100 for CMBR? For a general distant star light you get z value by comparing the same with absorption/emission spectra for known elementd but for CMBR how ? If you explore these questions they will take you in right direction.
Could have fooled the rest of us... And once more, you are back to the insults... 10 points from Gryffindor. Postcount ++ I guess...
For crying out loud just RTF wiki article. Or did you read it and just not understand it? It would certainly seem that the right direction is the direction opposite of which ever way you are going. Here is a synopsis of what the wiki article says. At about 380,000 years ago the universe became transparent. That was when atoms began to form (recombination event). The temperature at which this happens is about 3000k. So the starting point is a BB radiation corresponding to 3000k. The CMBR currently has a BB radiation corresponding to 2.7k. The change in the wavelength from 3000k to 2.7k corresponds to z=1100. Simple. Since you did not write this down you will consider it to be incorrect. But hey, what ever....
That paper is quite explicitly, clearly and repeatedly about very long period orbits (>100AU) around bodies in stellar clusters. i.e. there are - not just three, but multiple bodies - involved. It's kind of the whole point of the paper. But back on this topic. That topic has, after all, been resolved.
I'm going to disregard this tripe, since it is utterly and absolutely irrelevant to the thread at hand. About fucking time you came out and said what you meant. I would say Thank God, but I wouldn't want to confuse you. And yet, you also continued to argue from a standpoint indicating you did NOT believe expansion resulted in a drop in temperature. Surely you can understand how that can be viewed as "vexatious" or otherwise trolling? *looks behind himself* I wasn't aware I was "dragging" anything. This is two questions. To the first: no, a single photon has no temperature itself. Photons can, and do, contribute to a change in temperature of other masses due to them carrying energy. To the second - I will allow Dr. Leila Belkora to answer for me: http://www.fnal.gov/pub/science/inquiring/questions/red_shift1.html O...kay? What's your point? The explanation is as was provided - the universe has a set amount of energy, and the volume of the universe continues to expand. Thus, the energy is spread across a greater area, resulting in a lower concentration... As to the "why 1100"... I think Dave's explanation is about as simple of one as it can get... Again, what, exactly, is your claim here? Your continued desire to be obstinate and vexatious is growing tiresome.
[Waits patiently for the obfuscation from the god...]Please Register or Log in to view the hidden image!
Some people are more interested in destruction rather than construction. It's the difference between 'Your birdhouse is junk' and ' Actually, here is how you build a fine birdhouse'. Few know how to build birdhouses; but anyone can tear them down. This is why it is impossible to get these types to actually advance their own solutions; they don't have any solutions, just criticisms.
Sure it talks about multi body. But it does specifically and explicitly talk about two ffp or white dwarfs scenario without stellar host. As far as distance is concerned, as I said initial velocity vector and position matter. If you accept Prof Perets on 2 body, then yes it is after all resolved.
No I am not criticizing anyone here, you all are doing exactly that. Even this boy sweatpea is talking about my bed time with absolutely no other relevant contribution. Btw Kittamaru in #74 attributes something to you. Can you mention the post where you explained this z~1100.? For your information it's nothing but simply (Temp of recombination era)/2.7. because there is no way to assess the redshifts for cmb as no emission or absorption spectra can be referred. (Like we do for star lights)
That seems to be a GR question. As I understand it, this has nothing to do with the actual physical properties of a photon. One could also ask if a temperature can be assigned to a blue shifted photon. If it is the same photon viewed from different perspectives, would the actual temperature of the photon itself change? Are we not talking about the actual physical energetic (heat) properties of EM particles? http://www.davidterr.com/science-articles/electromagnetic_spectrum.html I am making no claims, I am not qualified. But I'm sure someone here can make an argument about the various temperatures (amount and type of energy) contained in the above list of EM particles.
