Data Analysis in Cosmology
1:09:52
Жыл бұрын
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@antondahr6792
@antondahr6792 7 күн бұрын
50 years before Hubble discovered redshift we knew that light was a wave and as soon as we know that we should assume that it has a loss parameter. All known waves experience friction and it goes against basic physical principles that any wave could propagate without it. We should have been looking for this propagation loss. When cosmological redshift was discovered the ONLY CORRECT SCIENTIFIC CONCLUSION was that light loses energy as it propagates. All expanding universe hypotheses are willful ignorance. Furthermore, the idea that everything known to exist was concentrated to one point is preposterous. There is no mechanism for that to happen so the idea implies that everything suddenly appeared, or was created, at this point. What?! Are we nuts?!
@KannurBusLovers
@KannurBusLovers 9 күн бұрын
Hey, I have a question . In the long run limit of universe with a tends to infinity and if H is decreasing, does the various entropy(kaniadakis,tsallis,barrow) corrected friedmann equations become equal to standard friedmann equation?
@cosmickap
@cosmickap 9 күн бұрын
I don't know about that.
@KannurBusLovers
@KannurBusLovers 12 күн бұрын
Hi, I have a doubt. In the late time limit of our universe , when scale factor tends to infinity, for decreasing energy density, Which term among the following will dominate. H^2,H^4,H^-4. Pls provide an answer😊
@leokap
@leokap 12 күн бұрын
Linear term should dominate. That is so far the trend that has been observed. However, as we have no way of observing the future, we can't determine for sure whether H would indeed be decreasing, increasing, or becoming constant.
@KannurBusLovers
@KannurBusLovers 12 күн бұрын
@leokap ok. Suppose from gsl, omega >=-1 , means energy density decrease. So suppose if H is decreasing and I have a friedmann equation says (H^2+k/a^2)-(H^2+k/a^2)^-1 =8 pi G/3 rho. In the late time limit, as a tends to infinity, considering H to be decrease , Here we neglect the second term right and the consider first one as dominant? And approximate the first one to r.h.s? If opposite is the case, negative power of H could lead to diverging scenario right if H is considered to be decreasing in late time limit.
@pranavkhd1338
@pranavkhd1338 13 күн бұрын
Well, I don't know whether asking a question related to gravity is relevant for this video.. Suppose we are assuming equally distributed configuration space, which is related to ergodic hypothesis or generally the asymptotic equipartition property, Can these be justified while applying to gravitational context? That is this ergodicity or equipartition property?
@indranilbanik3424
@indranilbanik3424 15 күн бұрын
There is a slight typo in my slide with the table of distances to the void centre for the best fits to the bulk flow curve in the different void underdensity profiles. 4 Mpc should be replaced by 40 Mpc. So it seems we should be about 50 Mpc from the void centre for the models to work.
@KannurBusLovers
@KannurBusLovers 21 күн бұрын
How did u write P total as x 2 - y 2. U divided k3/3H2 on 39.00. Then what happened to them on the numerator
@cosmickap
@cosmickap 21 күн бұрын
the denominator becomes 1 and numerator will become x^2-y^2
@KannurBusLovers
@KannurBusLovers 25 күн бұрын
Hello, I am unable to create that environment. Runs into error. can u please assist me
@cosmickap
@cosmickap 25 күн бұрын
Kindly see my latest video where I explained supernova data. There you won't need to create any environment and you can directly start with the Ubuntu terminal using VS code. In the ubuntu terminal you will not find any error, while some syntax error can be found in windows terminal.
@KannurBusLovers
@KannurBusLovers 25 күн бұрын
​@@cosmickap ok. Then after installing mcmc, and vc code, skip the remainjng portion of the first video? Before there any other content that may get affected directly switching to ubuntu?
@KannurBusLovers
@KannurBusLovers 25 күн бұрын
​@@cosmickapthe problem I encounter is that I choose venv and microsoft global version of python 3.9.13. Then requirements_full.txt selected and it runs but after sometimes runs into error.
@cosmickap
@cosmickap 25 күн бұрын
If you are using windows, most probably you will encounter error.
@KannurBusLovers
@KannurBusLovers 25 күн бұрын
@@cosmickap ok I will try.
@Phil000002
@Phil000002 29 күн бұрын
I really enjoyed the talk by Mr. Sulzenauer :)
@SubhajitSaha1729
@SubhajitSaha1729 Ай бұрын
Very helpful video! Great initiative! It would be nice if a similar step by step guide is provided for Ubuntu.
@cosmickap
@cosmickap 29 күн бұрын
You can download vscode in ubuntu.. and run your code in the terminal. You can see my recent videos on how to compile in the ubuntu terminal.
@trungtamienmayquocquang7233
@trungtamienmayquocquang7233 Ай бұрын
yes lerner
@indranilbanik3424
@indranilbanik3424 Ай бұрын
There is a recent paper by Wagenveld et al. showing the cosmic radio dipole anomaly has disappeared. It looks like the Universe is homogeneous and isotropic on large scales. Please see arxiv:2408.16619.
@emanuelsferios5783
@emanuelsferios5783 Ай бұрын
In the first presentation, I don't understand what Sebastian Von Hausegger means when he says that the Lambda CDM model "explains the current data sets." Is he referring to data sets that assume universal expansion? Eric Lerner's comments on his presentation made sense to me, but Hausegger's responses did not. Thank you.
@johnsorrelw849
@johnsorrelw849 Ай бұрын
I presume you're referring to the exchange at 55:04. I just heard Von Hausegger address specifically Lerner's statement that the fractal structure of mass concentrations disproves the homogeneiry hypothesis. Von Hausegger agreed about the fractal structure but not that it invalidated homgeneity at large scale, showing the graph of clumpiness that flattens out by 1 gigaparsec. His larger point was that Lambda CDM expllains a huge number of data sets, as summarized in his presentation, and that alternative theories have a lot of work cut out for them to explain the whole array of astrophysical phenomena to such a degree of detail.
@emanuelsferios5783
@emanuelsferios5783 29 күн бұрын
@@johnsorrelw849 But it does invalidate homogeneity, because we see these fractal patterns repeating on larger and larger *scales*. It's not just a web-like pattern on a single scale. Galaxies are strung out on plasma filaments with vast spaces between the filaments. Galaxy clusters are strung out on cluster-sized filaments with even larger spaces between those. And then we see galactic walls showing the edges of what are likely gigantic filament structures that span billions of light years across. Not only could these structures not have formed in 14 billions years, but they must be larger than the visible universe (consider the Hercules-Corona Borealis Great Wall, for example). But for this conversation, the point is that we see matter in fractal-like structures that *scale*. The scaling aspect shows clumpiness in ever greater and greater concentrations, clearly disproving homogeneity.
@emanuelsferios5783
@emanuelsferios5783 28 күн бұрын
@@johnsorrelw849 Did you see a reply I made here? It seems to be missing now.
@johnsorrelw849
@johnsorrelw849 24 күн бұрын
​@@emanuelsferios5783 No, I did not see it. I might add to the previous comment that I wonder if Von H's claim that the homogeneiry remains at the largest scales holds up in light of the huge structure (the Great Circle? I forget what they are calling it) that's like a billion light years across.
@emanuelsferios5783
@emanuelsferios5783 23 күн бұрын
@@johnsorrelw849 I made a comment which seems to have disappeared. Basically I said that the fractal structure we see (and that Lerner describes) is, by definition, non-homogeneous. This is precisely because it *scales*. The helical filaments on the smaller scales (that hold the galaxies) are separated by vast spaces. But then the clusters are also on much larger filaments with even vaster spaces between them, up to the galactic walls, that suggest the edges of even larger filaments with even larger empty space. Is this patterned? Yes. Is it homogeneous? Absolutely not. The homogeneity needed for general relativity to work (a gravity-only system) requires relatively even distribution of matter, not a scaling fractal system. (Let's see if this comment appears.)
@cosmickap
@cosmickap Ай бұрын
The first session is now concluded. Thank you everyone for attending the discussion and making it successful. The next part of the conference will be live on Oct 18, 2024.
@melkynsnneyderquintanaroja3748
@melkynsnneyderquintanaroja3748 Ай бұрын
Great work! I have a couple of questions, one one hand, I don't get why you use the chi squared statistic instead of classic natural logarithm of likelihood to run emcee, on the other hand i wold be very grateful if you can share a text or a paper whit the theory about differential equations instead of integrals. Thank you so much
@cosmickap
@cosmickap Ай бұрын
Thank you😊. The natural Logarithm of likelihood is proportional to the negative of 1/2 of chi squared; that's why I have calculated it. If you are looking for the differential equation for LambdaCDM model, you may find it in Chapter II of my thesis work: inspirehep.net/literature/2807106 and references therein. For the differential equation of D_L, you have to do a deep search for papers, since more often authors report the integral form. Further, you can check out my GitHub link pinned in the comment section, where you may find more references and a link to a recent video on BAO analysis. Let me know if you have any other queries.
@cosmickap
@cosmickap 2 ай бұрын
Do you like the video?
@melkynsnneyderquintanaroja3748
@melkynsnneyderquintanaroja3748 2 ай бұрын
Great work!! I have a question, what is the parameter on the second column of "OHD.txt", i thnk that it's the Hubble parameter, defined like H(z) = H_0 * E(z), but i'm not sure about that, because we usually don't find this value on SN Ia datasets (e.g. Pantheon+) thank you for your help
@cosmickap
@cosmickap 2 ай бұрын
Thanks. Yeah, in the 2nd column it is the values of Hubble parameter binned at different redshift. From there we are estimating H_0 a constant quantity which should be the same at all the redshift.
@leonardocolaco1904
@leonardocolaco1904 2 ай бұрын
Thank you so much for helping me understand how to extract the exact columns from PantheonPlus Dataset.
@cosmickap
@cosmickap 2 ай бұрын
You are welcome!
@cosmo_phile
@cosmo_phile 2 ай бұрын
Ftom t=0 to t=10^-⁴⁷ sec, there was an era called Plank Era, where the positrons, electrons, neutrons, photons, neutrinos came into the picture. You should make a video on 1st 3 minutes just after the big bang, which will cover all the basic informations of early universe
@leokap
@leokap 2 ай бұрын
I'll make one. 🎉
@zdvzxdvxdv-r8n
@zdvzxdvxdv-r8n 2 ай бұрын
Hello Sir, I am not able to understand how to get Pantheon_cov_all.cov from Pantheon+SH0ES_STAT+SYS.cov . And When I use Pantheon+SH0ES_STAT+SYS.cov instead of Pantheon_cov_all.cov , the shape gets squared. Please, guide thank you so much.
@cosmickap
@cosmickap 2 ай бұрын
@@zdvzxdvxdv-r8n use that complete file. I have renamed that one.
@zdvzxdvxdv-r8n
@zdvzxdvxdv-r8n 2 ай бұрын
@@cosmickap okay sir. Thank you.
@zdvzxdvxdv-r8n
@zdvzxdvxdv-r8n 2 ай бұрын
@@cosmickap sorry to interrupt. it gives error: cov_mat = cov_data.reshape(1701,1701) ValueError: cannot reshape array of size 2893402 into shape (1701,1701)
@cosmickap
@cosmickap 2 ай бұрын
@@zdvzxdvxdv-r8n open that file, remove the first digit =1701.
@zdvzxdvxdv-r8n
@zdvzxdvxdv-r8n 2 ай бұрын
@@cosmickap Okay Sir
@harishankarjoc
@harishankarjoc 2 ай бұрын
Sir how to use lambda symbols in pytearcat cat output
@cosmickap
@cosmickap 2 ай бұрын
@@harishankarjoc use english word.
@muhammadsadiqnasir8433
@muhammadsadiqnasir8433 2 ай бұрын
thank you so much for making this video.
@cosmickap
@cosmickap 2 ай бұрын
subscribe and share it ur friends
@adamkaczmarek4751
@adamkaczmarek4751 2 ай бұрын
Thank you for the video. I ve followed you on RG in order to get updates from your research projects
@cosmickap
@cosmickap 2 ай бұрын
@@adamkaczmarek4751 Thanks for following.
@himanshuchaudhary4197
@himanshuchaudhary4197 2 ай бұрын
I have never seen the way BAO has been explained here, the simplicity and Efficiency is amazing 🤩
@mudassiriqbal409
@mudassiriqbal409 2 ай бұрын
Great job sir, very useful information
@D_J40
@D_J40 2 ай бұрын
If I have various data sets and I wish to do a simultaneous fit. How should I do this? I am having technical difficulty in coding.
@leokap
@leokap 2 ай бұрын
everything u can find here. Just watch till the end.
@D_J40
@D_J40 2 ай бұрын
Yes. I was to comment back. Everything, you have mentioned.​@@leokap thanks a lot.
@D_J40
@D_J40 2 ай бұрын
Great. These videos are very much useful to me. Thanks. I was waiting for this.
@dhjagadale
@dhjagadale 3 ай бұрын
This was very helpful. I wanted to learn this so eagerly and I go this video. I want to fit a cosmological model with 3 datasets including pantheon+ data. How can I do this simultaneously with these data sets? Thank you for your time.
@cosmickap
@cosmickap 3 ай бұрын
add find chi square for each data sets simultaneously and add them in the end.
@dhjagadale
@dhjagadale 3 ай бұрын
Oh.. Okay. I will try doing this. Thank you so much.​@@cosmickap
@HassanAmirhashchi
@HassanAmirhashchi 3 ай бұрын
Hi Sir, thank you for sharing your knowledge: The shape of ". cov" is (2893402,), how we can get it as (1701,1701)?
@cosmickap
@cosmickap 3 ай бұрын
use the argument np.shape(1701,1701).
@himanshuchaudhary4197
@himanshuchaudhary4197 3 ай бұрын
Special appreciation goes to Dr. Leo Kap for their recent video on Pytreact. Students who want to learn how to find the Christoffel symbols, Riemann tensors, Ricci tensor, and Ricci scalar field equations should watch this amazing work.
@D_J40
@D_J40 3 ай бұрын
Nice!
@mudassiriqbal409
@mudassiriqbal409 3 ай бұрын
Good work sir👍👍👍
@cosmickap
@cosmickap 3 ай бұрын
Thanks.. I guess this week I will put my video on BAO data.
@D_J40
@D_J40 3 ай бұрын
Will you pls check your distance modulus and absolute magnitude relations? That should be: meu = 5log(D) + 25 And since meu = m -M, M= m - meu Therefore, M = m - 5log(D) - 25 Thanks.
@leokap
@leokap 3 ай бұрын
The formula used here is absolutely fine. Here i am using the shoes calibrated data, the data corresponding to mu not m.
@Yurinho99
@Yurinho99 3 ай бұрын
Excelente video.
@cosmickap
@cosmickap 3 ай бұрын
Thanks.
@isthenew-wy2kd
@isthenew-wy2kd 4 ай бұрын
I'm interested in this topic. Can you recommend me a book so I can study it further?
@cosmickap
@cosmickap 4 ай бұрын
you can find some interesting review papers. just search k-essence and quintessence review.
@FermionAP
@FermionAP 5 ай бұрын
im your 200th subscriber
@cosmickap
@cosmickap 5 ай бұрын
Yeah . Thanks.
@FermionAP
@FermionAP 5 ай бұрын
@@cosmickap so im starting my 1st research internship in Cosmology which will focus on DATA SIMULATION AND PARAMETER FITTING. what i will need it will help me if yu can suggest/advice something
@cosmickap
@cosmickap 5 ай бұрын
@@FermionAP As you are entering in research I would advice, solidify your basic theoretical cosmology part, model building and analysis. As you are interested in numerical simulations, I think you must have already known python. Grasp its advanced concepts, go through the statistical analysis. Make sure to learn a little bit of C programming, Parallelization techniques, and Mathematica (for theoretical work).
@jamahmad-d5b
@jamahmad-d5b 5 ай бұрын
Great work sir. I am trying to learn and work on cosmomc package. May I contact you via email?
@cosmickap
@cosmickap 5 ай бұрын
yeah, sure
@jamahmad-d5b
@jamahmad-d5b 5 ай бұрын
@@cosmickap Sir! I am not getting your contact email/number.. Please.
@cosmickap
@cosmickap 5 ай бұрын
@@jamahmad-d5b [email protected]
@D_J40
@D_J40 6 ай бұрын
Hi.. Very nice work. Thanks for video. Which compilier are you using for compiling code here, this looks new to me.
@cosmickap
@cosmickap 6 ай бұрын
This is compiled in linux.
@DavidBrown-om8cv
@DavidBrown-om8cv 6 ай бұрын
"If there is dark matter, then there must be Chandrasekhar dynamical friction. ... Existence of dark matter halos falsified ..." Do MOND's empirical successes indicate that something is wrong with the equivalence principle? Do string vibration's carry paradoxical MOND inertia? Google "paradoxical mond inertia".
@sreerag03
@sreerag03 7 ай бұрын
Hey, you should look at the numba module. It's not as useful as cython or cpython, but it's way easier to implement on existing code.
@cosmickap
@cosmickap 7 ай бұрын
I have tested numba. not useful with scipy libraries.
@sreerag03
@sreerag03 7 ай бұрын
@@cosmickap yes, it cannot work with scipy. Can you give me any references to learn how to code in cython? I have a system of differential equations, but as you said in the video, it's very slow. I would like to 'cythonize' my code.
@cosmickap
@cosmickap 7 ай бұрын
you can find some reference books. A book by Kurt W Smith - Cython_A Guide for python.
@sreerag03
@sreerag03 7 ай бұрын
Thanks
@AKUMAR281
@AKUMAR281 7 ай бұрын
Sir can you share the optimised code
@cosmickap
@cosmickap 7 ай бұрын
It is a bit of a complicated program. But the code I have given gains enough speed with parallelization.
@mudassiriqbal409
@mudassiriqbal409 7 ай бұрын
Sir,supernova pantheon dataset txt file is not present in your gitHub pro, plz share
@cosmickap
@cosmickap 7 ай бұрын
I have mentioned how to find the data in the video.
@mudassiriqbal409
@mudassiriqbal409 7 ай бұрын
​@@cosmickapok sir
@cosmickap
@cosmickap 7 ай бұрын
Find the code in my Git Hub repo: github.com/sleonardokap/cosmological_data
@abolhassanmohammadi6342
@abolhassanmohammadi6342 6 ай бұрын
Thanks for the nice video, and good explanation. I checked the repository. the code is not there. the one that include cython.
@cosmickap
@cosmickap 6 ай бұрын
yeah... you can try to write yourself by watching the video.. I will add it in a few days.
@jozen604
@jozen604 5 ай бұрын
@@cosmickap Thanks for the nice one! Could you add the code with cython to the repository? That'll be a huge help!