How good is the evidence for Dark Energy? 

Amazing minds, what a great pleasure to listen to even though I don't know many things you are talking about. This is the great advantage of Internet, being schooled by the greatest. How else we will have such a chance?

Brilliant! Subir did an excellent job in explaining the problem he sees with Dark Energy.

I learned a few things ... 100 megaparsecs is small scale! They only analysed a million galaxies. They need to analyze 100 times that. On the shoulders of giants, indeed!

Sabine ! You must do another interview with Subir to update this very superb interview. It is fantastic to see you in a serious interview mode adding gold nuggets to the discussion. This is far and away your best interview i have seen so far (aug 2023)

Absolutely brilliant presentation by the Professor Sarkar, and good decision by Sabine to let him speak uninterrupted. He had a lot to say and he is amazingly articulate about a difficult subject. 5 Sigma all the way. Thanks Sabine for getting and sharing that interview!

Dr Sarkhar has a tremendously scientific mind. I’d love to see more interviews with him.

An excellent explaination of the how easily it is to jump to conclusions without adequate data, and modification of the data used for a particular study. Very good work Dr. Hossenfelder, , and thank you very much!! I strongly suggest cosmologists to watch this..

I love how scrupulous he is about giving credit to other peoples' work.

this channel deserves waaaaay more subscriptions !

This is how all scientific interviews should be: Expert to expert. They capture all the important points without oversimplifying it. The conversation and bouncing of thoughts happened so smoothly and precisely, unlike most pop-sci interviews. Definitely hope that such interviews happen more frequently.

Fascinating interview. It's a little scary that this natural skepticism is not more prevalent in the cosmo community.

It would seem that data analysis and statistics has been sorely lacking in the astrophysical community. Thank you for this wonderful insight Dr. Hossenfelder and Professor Sarkar!

The old adage of "garbage in equals garbage out" applies to LCDM. Of course, it goes without saying that in order to confirm published conclusions, the dataset used must also be made available. True science is not an exercise in 'black box cosmology'. Kudos for a very interesting interview Sabine!

I am still impressed by the breadth of prof. Sarkar's knowledge. Thank you, Sabine, for your interest in the pursuit of thought-provoking scientific ideas and debates.

Dr. Hossenfelder: "..... And you mean by 'high'? Answer: " More than one." One of the most thought-provoking interviewers I've ever seen..

Rarely have I had to pay closer attention to a video to even begin to understand. It was well worth the effort. Thanks.

I can't say I understood everything ...as I'm not a physicist or an astronomer but I got the gist of it pretty well. This is a great example of scientific thinking in action.

I was amazed back in the '90's how fast Dark Energy became scientific dogma. The total overthrow of the existing paradigm was swift and total. Now in the last 6 years the whole concept is under attack from various sources including the scrutiny of the original data talked about here and also new observations that throw serious doubt on the concept. They're calling it a crisis in cosmology. The only crisis would be to continue in error.

Great interview! Thank you!

Beyond the amazing Dark Energy discussion, I feel like there is a lot to learn from Dr Sarkhar at a fundamental level about how to reason about the world, what an extraordinarily clear-thinking scientist.

I enjoyed learning so much from the careful explanation from Professor Sarkar.

Thank you for updating us with the guy who did the study!! Amazing work. Wish this kind of stuff actually made it on tv. Thankfully you provide us with this content regardless.

Thank you very much for taking the time to explain all this, Mr. Sarkar. Also thank you Sabine and team for making this possible !

Thanks for this amazing interview Sabine. I was delighted to find I could just about follow it all. Prof. Sarkar was really good at explaining his points. Would love to see more like this. When I studied astrophysics I got the idea that a lot of analyses were very imprecise. Order of magnitude estimates were common. One lecturer said even pi was commonly approximated as 1. In recent years we're supposed to have entered the era of "precision cosmology". Looks like not everyone has the same idea about what "precise" means. When I learned about the integrated Sachs-Wolfe effect nobody ever told me it hadn't been measured precisely enough to even know if it exists!

One of the things I've found out over decades of research (though not in physics) is that the deeper you delve into the way that the available datasets were actually constructed, the more sceptical you become about basing conclusions on them.

A transcript of this wonderful interview should be a part of any astronomy or physics class.

Thank you for sharing this interview it is indeed quite a disturbing to hear how poorly the response of the cosmological community has been regarding something as large as statistical inconsistencies and biases. Especially given the extent at which this effects other areas of astrophysics and quests for a grand unified theory as well. Humans are not wired through evolution to understand statistics well and unfortunately an independent statistics course is not a required course even at the graduate level. It is all too easy to fall into innate human biases. In particular this situation sounds like it largely has been able to propagate unnoticed in part due to the current system biased towards interesting results that lends to most null hypothesis results going unpublished. I definitely feel this should be a far more important issue not only for what it means for a given field but for the academic community as a whole. The current system of academic publishing needs to have its focus shifted to methodology relative to initial assumptions and proper use of statistical tools. There seems to be an uncomfortably strong resemblance to what was described here and how atmospheric gravity waves were handled up through the early 2000's where the meteorological community relied on artificial forcings to parameterize their models to match observations rather than basing parameterizations off physical equations of state. As a result they completely failed to account for energy conservation by treating wave amplitudes constant for varying density. Accounting for that the effects of atmospheric gravity waves can't be neglected in the thermosphere where the mean contribution on the temperature is comparable to Joule heating with direct effects on the ionosphere as well particularly the F region.

Finally, we have some wisdom addressing cosmology in a way that actually makes sense. Let them have more of a voice. Sabine is the best physics communicator out there, and Sarkar is a true gem to articulate what many suspect but would never dare to say in the open. I have been questioning things that were obviously inconsistent ever since Penzias and Wilson "proved" the current cosmological model of the time by proclaiming perfectly uniform noise (no dipole, no galactic plain or point sources), which supposedly mapped to the edge of space, though it was acquired within the Earth's ionosphere. Nobel prize after Nobel prize, I remain baffled at the willingness to hand out awards to vacillating sociological concordance and not to mathematical consistence. While the measurements from modern sensors are much more advanced, we (everyone) must demand access to the un-doctored data and discount model-driven preconceptions.

I remember reading an article on this, so it's great to have an interview. Many thanks! Edit: @Sabine Hossenfelder now change the video from unlisted to listed!

Fantastic post , making the current state of affairs accessible for everyone .

Thank you so much for taking the time to make content like this! I've got a M.Sc degree and I'm very interested in these topics, but I still sometimes lack the knowledge required to follow all the details in the conversation. But I'm very pleased that my knowledge is challenged and I have the opportunity to learn something.

Very clear, understandable, insightful presentation by Dr. Sarkar. Thanks for doing this Sabine, and well done!

Okay now we need another video that actually explains what he is going on about. This is so condensed it only makes sense for those already in the know

Sabine! That was an amazing interview! Thank you so much for that.

Wow!! Great interview. I did not understand the most of it, but I love how professor Sarkar emphasizes on measurement and draws from so many different fields of knowledge

Great conversation, thanks S.

The best video I've listened to in a long time. But I would like if Sabine would explain it and give the implications in her own way, so the huge number of interested amateurs among the masses can understand.

Thank you for this and your other amazing content.I think observation ,interrogation and confirmation should be fundamental in science.

I am so glad you have continued your discussion on the groundbreaking paper on Anisotropy in Cosmic Acceleration! And to interview one of the authors no less! Thank you very much Sabine for this video!

Dear Sabine, Thank you for conducting this amazing interview, and for sharing it with everyone. It is a great relief for me to discover that there are at least two other *actual scientists* still left in the world: you and Professor Sarkar. With all of the bad science going on in the past century, I was beginning to believe that the breed had become entirely extinct. You have given me hope for the future of science. I am grateful.

Best discussion I've heard yet on this subject. Thank you for posting.

Such a pleasure to watch this, thank you very much!!!

The "publishing factor". I like how he points out that cosmologists tend to avoid, ignore, & omit conflicting evidence just to get favorable(publishable)results, despite appalling sigma values.

When he said that the others guy’s book is hard going for him… I can’t even imagine what it’s like.

This was a fascinating interview; I enjoyed it very much.

Great interview, thanks Sabine !

Pretty impressed with this guy. He seems very unbiased and extremely knowledgeable. He doesn't seem to be on a crusade or to be making things personal, he's just making observations and asking questions that seem too uncomfortable for the cosmological community to substantively address. Which make them less credible and makes it easier to believe they may have made some important mistakes.

Aside from the scientific value of this conversion, I am in awe of the peace in which it is conducted. Thank you.

I find all this fascinatingly interesting...thank you Sabine, and guests for broadening my knowledge on all your many topics.. .

something so pragmatic about this man's way , a real no-nonsense approach.

Great interview! Didn't understand everything, but still found this discussion fascinating. Thank you Sabine.

Thank you for the important video that promotes objectivity in science. I wish Professor Subir Sarkar that the scientific community will take his courageous research more seriously.

Thank you, Sabine. This was wonderful.

Love your videos Sabine! Keep it up! You're also low key hilarious. ❤️

Fascinating interview. Thank you both.

Refreshingly this took me beyond the ‘boring, trite, already-know’ information I get from many other science videos. Thanks for a real glimpse at challenges and work involved, with great depth but still keeping it understandable. Great!

Well done Sabine. Informative as per usual.

Watching this a year later, but wow! Dr Sarkar explains things so perfectly without going into long and confusing analogies

The conversation is enriching. He totally tells the procedure so it becomes easy to follow in the sense I can understand the team's methods and therefore the argument.

At 23:56 Subir says ". . .this is not what is written in the sky . . ." He is an honest-to-God scientific thinker. Students should run to Oxford today to study under Professor Subir Sarkar.

Excellent interview. Thanks Sabine!

Thank you so much for your videos. I think it's important to listen to these types of discussions, and it is always so hard to find in public spaces. So again, thank you very much

Very interesting! Thanks Dr. Sabine and Prof. Sarkar.

Hi Sabine, thank you for your great videos and this interview! I have also read your book and it justifiably changed my perspective of theoretical physics a lot, thank you for that too. You should go on making the videos as they are highly clear, unique, and entertaining. Regarding the interview, I wondered that neither of you have not mentioned the article "Planck evidence for a closed Universe and a possible crisis for cosmology" (Nature Astronomy, Nov 2019) that suggests that the Universe might be closed with 99% certainty based on Planck 2018 data, which also overthrows a bit our view on the flatness. I was also surprised that you did not make comment on it anywhere on the channel or your blog (or I have not found it, albeit thoroughly searching). I would like to hear your perspective, as the original article contains pretty much data and is worth reviewing, especially in the light of evanescence of Dark Energy evidence.

I have watched a few of these videos now (working backwards from the most recent video) and I have to say her humor, especially her delivery, is awesome. She never ceases to make me laugh.

Summarised we can say: Evidence for dark energy is not so good. Sabine: what do you mean with "not so good"? Me: Less than one.

Wonderful discussion! Had to search up a bunch of unfamiliar terms and ended up really enjoying this talk!

This is wonderful! The rethink for which I've been waiting. And I wonder how long it will be before something similar is done about the dark matter problem.

Wow. This was very interesting. The implications are astounding.

Highly critical and important statement almost at the very end, 44:10 . Thanks for the video.

Publishing is easy... Rigor is hard. Thank you both.

One of sabines very best videos. Cannot wait until you do an update . Must be done !!!!

Awesome interview, very interesting points raised!

This was really good. I hope you make more videos with Sarkar. You two choice analysts.

Excellent discussion, outstanding guest. Love the hair, Sabine....Einsteinian. I applaud all of the mathematicians and scientists who dutifully go back and verify data sets. How horrible are the models, for example, for climate models, built on selective or incomplete data? (Unrelated). Thank you for sharing this more detailed discussion on the evidence, and how we must be careful in our interpretation. I trust you both are educating younger minds to be scientific, more skeptical. As always, fantastic stuff, Dr. Hossenfelder.

As a meta-critique, Sabine's videos take an unmistakable disposition being both educational and refreshingly free of dogma.

Thank you so much Dr. Hossenfelder, this is an amazing insight for the layman. Your hair is all right BTW.

This channel is as good as being at Uni again and pestering my lecturers for answers in their free time!

Good one, good talk. This is such an exciting part of theoretical physics because it stumps everyone, and offers new turf for discovery. When the SUSY Wimp and Axion experiments failed, theoretical physics was sent back to the drawing board. Obviously there exists a principle which hasnt been imagined or discovered yet.

Sabine and Professor Sakar, thank you! Excellent discussion. I would like to express my sincere gratitude for being so willing to take the risk of not hiding the possible flaws of the current state of science. I applaud you for your work!

Thank you both for a talk full of interesting content without random blabla. Sabine is one more time a great communicator.

Great interview. There are few people that can get such an interview out so we can hear these very insightful comments of a top astronomer to a broader audience first hand. Written articles are old technology anyway. With respect to the content: Although much of it will be beyond the knowledge level for most of us, the essence is clear. The 'inventors' of dark Energy for long shielded original data sets or in any case failed to mention they had intentionally manipulated them. The scary part however is that this is not a stand alone phenomenon. Over the past decades all major 'discoveries' that have been 'sanctioned' by a Nobel Prize, eventually all turned out to have been based on either NO actual data sets at all (LIGO ! ) or on manipulated data sets. This goes for 'Dark Energy', 'Dark Matter,' GW's LIGO, IPCC (which is witholding all original data behind the infamously manipulated 'hockystick' graphs even after two courts rulings). So it is not that 'science' is in crisis. It would appear this is something very intentional. Stated a bit bluntly, It appears that for decades we are facing a wide spread and very well organized effort by top gremia, prizes and journals to deliberately promote deceitful theories, wasting intellect and budgets. If the idea is that we are not supposed to grow beyond our fundamental understanding of nature of roughly 100 years, then why not say so? We could all go home and have a beer and it would save us and especially Sabine a lot of effort and stress trying to improve a scientific community 'bottom-up' which does not want to chance its its ways top-down anyway, leading us into perpetual non-sensical 'new buzz theories' thus ensuring perpetual budgets. But again, this is a great interview. Hopefully we will soon learn the nature of gravity (the emergent effect of the SPEED of and within mass) so we get the fundamentals behind dipole effects in order, also in the universal scale and skip the mathematical fudge ideas of 'dark energy and dark mass once and for all....keep them going!

great interview and guest.

Such a great interview thank you both.

Your interviews are excellent.

Very interesting conversation. Thank you for posting.

I tried some superficial digging into these various cosmological claims about a year ago... and also didnt like the smell of it. Methods sections that were extremely handwavy, and of course no downloadable reproducible code or data. If it does not seem like a particular paper was ever independently reproduced in any meaningful sense of the word... it most probably wasnt. Deep respect for Sarkar and his work, and the calm and clarity with which he challenges the dominant narrative.

awee i love this channel whatever you say, it's so cool, i love the discussion, and it's like a fresh of breath air, we always need to think, acknowledge, and idk think/discuss!!

Very very interesting interview! I didn't understand everything, but I think I managed to capture the essence of the argument. All these signs point to the fact that since the whole society is in a deep philosophical, ethical, economical, political and cultural decline, science is bound to be caught up in this. After all it's great knowing that there are still people out there, that dare question what is taken for granted, and what is deemed as an established way o thinking. Well done!

This shows that the astronomical community needs a wakeup call. This guy showed that the people writing the dark energy paper were like high school kids making foolish mistakes.

Very good explanation of how science can be captured by group think and assumption think. Dark matter and dark energy was always an indication of calculation errors, not the existence of a thing that can't be measured in itself. Science has a responsibility to be honest .... this discussion is honesty in science at its best..

Excellent content once again, thanks

How rich ! Took me more than 2 hours to go through the whole interview. brilliant. To me professor Sarkar has produced (largely) enough hard work to be considered and debated respectfully. Will see what the future holds.

Absolutely fascinating. I'd never really thought about the relative paucity of real-world evidence in cosmology vs particle physics, but when you mentioned it, it made a great deal of sense. A million galaxies sounds like a lot but that really isn't the case, statistically.

I'd like to see another interview with Sarkar about whether the recent Muon-G data is consistent with dark energy. For a lay consumer of pop-physics, the idea that the current data can be explained without dark energy is mind-blowing.

Excellent interview. To her credit Sabine is a terrific listener.

Great respect of both of you - I am so tired to hear everyone repeat the same mantra without making the effort to actually check. With this approach we would still refine the epicycles of the geocentric model. One more time thank you for your contribution. We need more critical thinkers like both of you.

Ah! I love the rounded accent of our Bangali Babu Subir Sarkar. Proud of him as a Bengali.

A tremendous scientific talk which does not need any CGI & Sound Effects in order to attract attention. To my view Sarkar's claims about the lack of sufficient and/or unbiased data should cause serious concerns regarding a considerable portion of our current cosmological inventory. Observational data are a most valuable asset - esp. in that science branch, where we're forced to collect them over decades, centuries and even more... Much longer periods than the average lifetime of interpretations and models. So both shall never be mixed up...

Have there been any developments in the issues discussed in this interview? I found it fascinating and have probably watched this video half a dozen times.