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A talk that I gave at the Strings 2020 conference: https://www.youtube.com/watch?v=u73rsTpnPrY Since the Strings-conference audience is very broad, it was intended for people who are not directly thinking about the same questions, and provides a quick summary of some of our recent work. So the video may be useful.

We had a long panel discussion on Black Hole information later, which capped off the conference. But, I should mention that we also discussed similar issues at the BH microstructure conference last month with some of the same panelists. (Bena, de Boer, Maldacena, Mathur and me.) The emphasis was slightly different because the question there was “Do typical states have horizons?” but I think that discussion was also interesting. It is available here: https://youtu.be/31f_2G5DLaw?t=11367

About a month ago, the government conducted a press-conference reporting the results of various “studies”, each claiming that the lockdown had saved thousands of lives. A few days later, some independent scientists also decided to chime in with their own predictions that broadly supported this idea. Even though a few weeks have passed, I think these claims remain relevant, as another round of lockdowns is contemplated in various parts of the country.

So I decided to examine these claims in a little more detail and found that they were very misleading. In fact if the compartmental models used in these studies teach us anything, it is that lockdowns of the kind witnessed in India — which are imposed early in the epidemic but fail to quash it — may delay fatalities but do not avert them. So, within these models, the efficacy of a lockdown cannot be gauged by simply comparing figures for fatalities at the end of the lockdown with the projected figure for fatalities at the same date without the lockdown.

These models do not account for several important real-world effects: the lockdown has caused a humanitarian crisis, it has restricted access to essential healthcare for other conditions and, to a limited extent, it has also been used to ramp up testing and tracing. Moreover, the lockdown has engendered economic insecurity, and in the longer-run, this makes it harder for people to maintain physical-distancing norms. All these effects are more important than the transient direct effect of the lockdown on fatalities. But given the paucity of currently available data, none of them can be quantified. So epidemiological models are simply not in a position to accurately quantify the impact of the lockdown on fatalities.

If this is the case, what motivates these “studies”? Perhaps the independent groups inadvertently fell into a trap set by the government. But, as for the government-backed studies themselves, the answer seems to be clear. There is widespread concern that the lockdown has failed. So, rather than address these concerns, it is “useful to point to “advanced scientific studies” that “show” that the lockdown has saved thousands of lives. Since people tend to get intimidated by differential equations, this helps to shut down critics.”

I discussed some of this in an explainer for the Scroll today:

https://scroll.in/article/965814/what-do-mathematical-models-tell-us-about-the-impact-of-lockdown-on-covid-19-fatalities-in-india

I also discuss what these “studies” do in practice, how they get these numbers, why it doesn’t make sense, and some broader concerns about models.

This is a summary of a more technical note (written for internal discussions in the Indian Scientists Response to COVID-19 group) that is available publicly here: https://zenodo.org/record/3901516

Both the technical note and the explainer make very simple points. I only felt compelled to write them in light of the claims above, which have received wide publicity.

The government would like to claim that the lockdown has “saved lives”. But in this article for the Wire, I tried to explain why it makes no sense to gauge the efficacy of the lockdown by blindly comparing the current number of cases to the number obtained by extrapolating the early rates of growth. The final toll of the pandemic is almost entirely controlled by its rate of spread after the lockdown ends, not its rate of spread during the lockdown. So the correct question is whether the lockdown has put the country in a position where it can keep this rate of spread low after the lockdown ends. The data suggests otherwise. A simple calculation comparing the number of recorded deaths to recorded cases suggests that a large number of active cases remain undetected, and so contact-tracing cannot succeed. Most seriously, the long-term rate of spread is controlled by whether people can sustain physical-distancing measures and other precautions. But, because the welfare of people was relegated to an afterthought, the lockdown has made it harder for people to implement precautionary measures, which might otherwise have been manageable. https://thewire.in/government/indias-lockdown-has-failed-heres-what-we-can-learn-from-it

Abolition 2000, which is a global network of nuclear disarmament groups asked 9 disarmament-campaigners across the world to record short videos in advance of its AGM that takes place on the weekend. The question we were asked to address was a broad one about how we saw the world changing by the time of the NPT Review Conference next year and how we felt this would affect our work. So rather than addressing topical issues, which we do often, I took the opportunity to talk about some of the broader issues that frame our work and spoke about “The Pandemic, Hegemony and Disarmament.” Here is the video. https://www.youtube.com/watch?v=jGOnPFLJz5A and here is a link to the other videos: https://www.youtube.com/playlist?list=PLNLSpPdpFraDiSCjFejKiVk7WNgIQRImq

An op-ed I wrote for the Hindu on the importance of accountability during a crisis. https://www.thehindu.com/opinion/op-ed/lacking-in-transparency/article31447809.ece

A virtual seminar I gave at the Albert Einstein Institute at Potsdam a few days ago https://www.youtube.com/watch?v=RlZlj6_Y92s

A few comments on the topic of virtual seminars, which have become the norm over the past few weeks. Michal Heller invited me to give this seminar as a virtual seminar last year, well before COVID surfaced. The AEI group was ahead of the times and they were organizing virtual seminars as standard practice. I must admit that, at the time, I was slightly skeptical :-)

This is because, virtual seminars I’ve organized and attended in pre-lockdown days have usually involved a virtual speaker but a physical audience. This certainly doesn’t work as well as a physical speaker. For instance, it is not easy to ask a question from the audience. And there is information asymmetry. The speaker can’t see the audience too clearly but the audience-members can see each other. This matters a surprising amount because the physical audience has collective dynamics that the speaker can’t respond to. For instance, if one person looks skeptical or bored, others in the audience notice but the speaker can’t take note and modulate the talk.

But, things are completely different if everyone is in front of an individual screen. In many respects this works as well as a physical talk and, in some ways, even better: the slides are certainly clearer. And, of course, a significant advantage is that people from all over the globe can attend on an equal footing. This talk, for instance, had people from Japan, India, Europe, U.S, Argentina… There is even scope for informal discussion at the end of the talk if a few people remain behind. (And yet another advantage is that if the talk is boring, you can switch to doing other things without being rude and “leaving” the virtual room :-) )

I think there is something to be said, quite seriously, for sticking to this mode of organizing seminars and conferences even when COVID is gone.

This is an unusual post. I was reluctant to make it, but it seems to be necessary. A few days ago, the paper https://arxiv.org/pdf/2003.12055.pdf appeared, with various suggestions for controlling the epidemic in India: a lockdown of 49 days or a lockdown of 21 days followed by 28 days etc. This paper seems to have gone viral, even appearing in neighbourhood WhatsApp groups.

I would like to point out that the conclusions in this paper are absurd and, moreover, it requires no expertise in modelling to understand their absurdity.

The question one should ask is: how do the authors arrive at their various precise figures for the length of the lockdown? The assumption is hidden away on Page 6: “This brings the number of infective below 10 where explicit contact tracing followed by quarantine may be successful in preventing a resurgence.” You read that right! Their “lockdown” is aimed at ensuring that only 10 infectious cases remain in the entire country!

Why 10? Why not 50? Indeed, why can’t a country do contact tracing when 500 people remain infectious? Their choice is completely arbitrary and depending on whatever threshold one sets for contact tracing, one can use their model to get any prediction for the length of the lockdown: starting from 0 days to an arbitrary long time.

Second, it should be clear that any model that suggests a lockdown can reduce the absolute number of infections to 10 in the whole country shouldn’t be taken seriously. At small numbers, these models are grainy and shouldn’t be used.

This, by itself, should be enough for everyone to stop taking the paper seriously at least insofar as serious epidemiological predictions are concerned.

But, let me mention a few additional minor points about the model itself. First, they make a simple mathematical error. They fail to correctly account for delays in the effect of the lockdown. So, in their model, the number of infections starts decaying as soon as the lockdown starts, which is absurd, even for a mathematical model. (Diseases have incubation periods, and so any lockdown takes time to act.) In particular, their predictions have already been falsified by more-recent data. Second, they use official data on the number of infections until the start of the lockdown to fit their parameters, but this has enormous error bars given our poor testing rate. So of what value are their numbers?

I am very sorry to have to debunk a paper on social media. But some time back, I had some questions about this paper, and another colleague communicated them to the authors. The authors have not responded, and I know that they have also not responded to other scientists who have tried to contact them. While refusing to engage the Indian scientific community, they have nevertheless propagated their findings to the news media. And, in various news-articles on this paper, I don’t find the authors making any attempt to point out the caveats in their analysis.

I feel this violates elementary scientific ethics. So, given the exceptional situation at hand — where this “study” may have real-life consequences — I felt it was important to make this post. It is a public post, and feel free to share it.

If the authors feel that I am misrepresenting their paper, I would still be happy to engage with them.

Some of us have prepared a statement on the current lockdown and Covid-19 epidemic.

It states that the lockdown, by itself, is not a permanent cure and so urges the government to prepare a post-lockdown plan. It also urges an increase in testing, and urges the government to use its stock of foodgrains and urgent cash transfers to ensure the welfare of workers and stem the risks associated with a reverse migration.

The statement is here: https://docs.google.com/document/d/1ednE0lVYLM2ARUh_HJ6UwQNxHd4s0LBD3_FtApe-2Dc/edit

and it can be signed through this form: https://docs.google.com/forms/d/e/1FAIpQLSfpGMUO7P8DUfqdgp-hPSDIQpVa5seEXq4g2dfqaZ6L13fdTQ/viewform

Please share this post with others if you feel it might be helpful.