David Mumford

Blog and Archive for Reprints, Notes, Talks

Professor Emeritus
Brown and Harvard Universities
David_Mumford@brown.edu

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I started this blog in 2014 after I retired as a place to put ideas of many sorts online. At the same time, because I had papers in multiple specialities, I decided to make an online archive too, an idea I heard first from Martin Groetschel when digitization had just begun to be used widely. I set up this personal website at Brown University to do both. This archive is still live, accessible wby clicking the other items in the "navbar" at the top of the page.

In 2021 I approached the American Mathematical Society to see if they were interested in collecting expanded versions of some of my posts as a book. I worked at that time with their editor Eriko Hironaka. Although there was some disagreement, I shortened controversial parts and Numbers and the World: Essays on Math and Beyond was published in 2023. But I continued to play around with ideas and continued the blog. Below are my posts excluding those that appeared in my book. (pdfs of the old posts are HERE.) I have also posted here the final draft of the book as I submitted it to the AMS HERE, including my submission for the cover that date from my and my student's work in the late 1990's. Needless to say, the book is also available at the pirate Russian website genesis.

CAUTION: Some posts have mathematical formulas in them that require "mathjax" to display properly. If you access the blog via https, they may not display. Please use http.

Black hats and white hats again — defining evil

January 20, 2025

After I wrote "Black Hats and While Hats" and posted it on my website, I understand that it led to a perception of anti-semitism for some people. This makes me very sad. The problem is that nearly all people take sides and find one side, either Hamas's attack or Israeli bombing of Gaza, evil and unforgivable, the other side acting with justified self preservation. I tried to say neither side is wholly good nor wholly evil. I have always treated my teachers, colleagues, students and friends exactly the same, whether they were Jewish, Christian, Muslim, Hindu or Secular. I simply tried in that post to assemble the facts, as I knew or read them, and pose the huge moral dilemma over who has a claim to the small stretch of land "between the river and the sea", called Palestine.

With the exception of Buddhism, every religion seems to tell us mere humans that God wants us to do "good" actions, and avoid "bad" actions, especially "evil" ones. The foundation Judeo-Christian story is Eves temptation by Satan as snake to eat an apple from the Tree of Knowledge that God had forbidden. We bear the heavy burden of original sin. In all sects of the "religions of the book" (this includes Islam) there is no doubt that God has opinions about human actions and keeps track of what everyone does. So it is up to us humans to decipher God's wishes and use their God-given free will to act accordingly.

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Letter to my Grandchildren-2

August 30, 2024

Dear Henry, Linus, Maya, Leela, Kaspar, Anarkali, Neerja and Arjuna.

Four years ago I wrote you what I thought were reasonable speculations and warnings about what I expect to happen in your future lives. I felt that major changes are going to happen in the 21st century and that I had a little insight, looking at the future from a scientific viewpoint. And I wanted to share this with you as it might be useful. It's a blog post with URL https://www.dam.brown.edu/people/mumford/blog/2020/Letter.html. In particular, I described the power of both artificial intelligence and of genetic engineering to transform your lives. Of course, the first has come true in spades in just a few years. I expanded this letter in the last chapter of my book "Numbers and the World, Essays on Math and Beyond" giving more details and references to buttress my arguments. But a number of new things have shocked me since then and made me now a good deal more pessimistic about the trajectory of 21st century culture. It may be worthwhile for everyone to know that some terrible cataclysm could happen. In this case, I hope I'm wrong. I am also well aware that pessimism is a well known trap that snares people who live a long time (I'm now 87). But humor me and read this blog post describing my chain of thought.

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Consciousness, Robots, and DNA

January 3, 2024

This is a paper to appear in the Proceedings of the International Congress for Basic Science, based on my talk in Beijing on July 17, 2023. The talk explores the complex interplay between consciousness, robotics, and DNA using the insights of artificial intelligence, neuroscience and physics. Specifically, I discuss the evolution of language models and the quest for human-level AI, the scientific dimensions of consciousness, the elusive nature of "now" in consciousness, and the enigma of so-called cat-states in quantum theory. Finally, we examine the role of DNA replication as a possible generator of cat-states and its implications for understanding consciousness, free will, and the nature of reality. I hope to encourage further exploration at the intersection of these fields, highlighting the profound questions they raise about the nature of consciousness in both biological and artificial systems.

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Black hats and white hats

December 12, 2023

In classic Hollywood westerns, you could always tell the villains from the good guys by the color of their hats. There was no doubt who was the struggling family trying to forge a living in the wild west and who was the villain trying to cheat him and her of the fruits of their labor, by murdering and pillaging. It is only human to seek clear cut moral judgements, to have unshakable convictions of what are allowable acts and what are hideous transgressions. But, in reality, this is simply not the way the world usually works. The history of Israel and of the Palestinians demonstrates the absurdity of summary judgements and the need for sympathy for both sides who are caught in an ever worsening spiral of hatred and killing. Unfortunately, almost everyone feels compelled to take sides. But from my perspective, there is a remarkable symmetry between the passions and fears of these two antagonists that compels sympathy for both. Both sides have feel that their continued existence in the "holy land" is threatened; their religions sanction war and they cannot see the humanity of the other side; they are locked in a spiral of hate. The terrorism of Hamas and the actions of Netanyahu's government have slammed the door shut on any 2 state solution. How did this ghastly situation happen?

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Ruminations on cosmology and time

March 1, 2021

Like many people, I have been riveted for decades by the breathless bulletins from cosmologists describing the latest twist to their model of space and time at the largest possible scale. But recently, I have been looking more closely at these theories and, frankly, do not find them 100% convincing. Maybe it's all true but maybe in 50 years, it will all change. My biggest source of skepticism is its treatment of time: it feels as if in several ways it is trying to undo the vista that special and general relativity opened up for potential models of space-time, that the "standard model" reverts to a very Newtonian perspective on which an extremely simple relativistic model has been foisted. Let me explain.

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The Dismal Science and the future of work

July 20, 2015

Economics is an area that is built on mathematical models that simplify highly complex phenomena. People often forget that, as a result, economic models omit human and historical factors that are fundamentally non-mathematical and outside its scope. Thus the impossibility of building mathematical models of human psychology undermines that basic building block of economics, the "rational economic agent". But I also want to argue that advances in technology are transforming society in ways not dealt with in economic models, by altering the need for most human work, another foundation stone of economics. My thesis in this post is that, in addition to dealing with the Malthusian constraints caused by population growth, the next 50 years will see the growth of a nearly completely automated society that requires only minimal work from the large majority of its citizens. Such a development destroys the basic axioms on which economics is built, not to mention the basic structure of human lives. How in heaven's name will we adjust to such a "gift"?

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