#115 – David Wallace on the many-worlds theory of quantum mechanics and its implications

#115 – David Wallace on the many-worlds theory of quantum mechanics and its implications

Quantum mechanics — our best theory of atoms, molecules, and the subatomic particles that make them up — underpins most of modern physics. But there are varying interpretations of what it means, all of them controversial in their own way.

Famously, quantum theory predicts that with the right setup, a cat can be made to be alive and dead at the same time. On the face of it, that sounds either meaningless or ridiculous.

According to today’s guest, David Wallace — professor at the University of Pittsburgh and one of the world's leading philosophers of physics — there are three broad ways experts react to this apparent dilemma:

1. The theory must be wrong, and we need to change our philosophy to fix it.
2. The theory must be wrong, and we need to change our physics to fix it.
3. The theory is OK, and cats really can in some way be alive and dead simultaneously.

(David and Rob do their best to introduce quantum mechanics in the first 35 minutes of the episode, but it isn't the easiest thing to explain via audio alone. So if you need a refresher before jumping in, we recommend checking out our links to learn more, summary and full transcript.)

In 1955, physicist Hugh Everett bit the bullet on Option 3 and proposed Wallace's preferred solution to the puzzle: each time it's faced with a ‘quantum choice,’ the universe 'splits' into different worlds. Anything that has a probability greater than zero (from the perspective of quantum theory) happens in some branch — though more probable things happen in far more branches.

While not a consensus position, the ‘many-worlds’ approach is one of the top three most popular ways to make sense of what's going on, according to surveys of relevant experts.

Setting aside whether it's correct for a moment, one thing that's not often spelled out is what this approach would concretely imply if it were right.

Is there a world where Rob (the show's host) can roll a die a million times, and it comes up 6 every time?

As David explains in this episode: absolutely, that’s completely possible — and if Rob rolled a die a million times, there would be a world like that.

Is there a world where Rob becomes president of the US?

David thinks probably not. The things stopping Rob from becoming US president don’t seem down to random chance at the quantum level.

Is there a world where Rob deliberately murdered someone this morning?

Only if he’s already predisposed to murder — becoming a different person in that way probably isn’t a matter of random fluctuations in our brains.

Is there a world where a horse-version of Rob hosts the 80,000 Horses Podcast?

Well, due to the chance involved in evolution, it’s plausible that there are worlds where humans didn’t evolve, and intelligent horses have in some sense taken their place. And somewhere, fantastically distantly across the vast multiverse, there might even be a horse named Rob Wiblin who hosts a podcast, and who sounds remarkably like Rob. Though even then — it wouldn’t actually be Rob in the way we normally think of personal identity.

Rob and David also cover:

• If the many-worlds interpretation is right, should that change how we live our lives?
• Are our actions getting more (or less) important as the universe splits into finer and finer threads?
• Could we conceivably influence other branches of the multiverse?
• Alternatives to the many-worlds interpretation
• The practical value of physics today
• And much more

Chapters:

  • Rob’s intro (00:00:00)
  • The interview begins (00:02:15)
  • Introduction to quantum mechanics (00:08:10)
  • Why does quantum mechanics need an interpretation? (00:19:42)
  • Quantum mechanics in basic language (00:30:37)
  • Quantum field theory (00:33:13)
  • Different theories of quantum mechanics (00:38:49)
  • Many-worlds theory (00:43:14)
  • What stuff actually happens (00:52:09)
  • Can we count the worlds? (00:59:55)
  • Why anyone believes any of these (01:05:01)
  • Changing the physics (01:10:41)
  • Changing the philosophy (01:14:21)
  • Instrumentalism vs. realism (01:21:42)
  • Objections to many-worlds (01:35:26)
  • Why a consensus hasn’t emerged (01:50:59)
  • Practical implications of the many-worlds theory (01:57:11)
  • Are our actions getting more or less important? (02:04:21)
  • Does utility increase? (02:12:02)
  • Could we influence other branches? (02:17:01)
  • Should you do unpleasant things first? (02:19:52)
  • Progress in physics over the last 50 years (02:30:55)
  • Practical value of physics today (02:35:24)
  • Physics careers (02:43:56)
  • Subjective probabilities (02:48:39)
  • The philosophy of time (02:50:14)
  • David’s experience at Oxford (02:59:51)

Producer: Keiran Harris
Audio mastering: Ben Cordell
Transcriptions: Sofia Davis-Fogel and Katy Moore

Episoder(300)

#3 - Dario Amodei on OpenAI and how AI will change the world for good and ill

#3 - Dario Amodei on OpenAI and how AI will change the world for good and ill

Just two years ago OpenAI didn’t exist. It’s now among the most elite groups of machine learning researchers. They’re trying to make an AI that’s smarter than humans and have $1b at their disposal. Even stranger for a Silicon Valley start-up, it’s not a business, but rather a non-profit founded by Elon Musk and Sam Altman among others, to ensure the benefits of AI are distributed broadly to all of society.  I did a long interview with one of its first machine learning researchers, Dr Dario Amodei, to learn about: * OpenAI’s latest plans and research progress. * His paper *Concrete Problems in AI Safety*, which outlines five specific ways machine learning algorithms can act in dangerous ways their designers don’t intend - something OpenAI has to work to avoid. * How listeners can best go about pursuing a career in machine learning and AI development themselves. Full transcript, apply for personalised coaching to work on AI safety, see what questions are asked when, and read extra resources to learn more. 1m33s - What OpenAI is doing, Dario’s research and why AI is important  13m - Why OpenAI scaled back its Universe project  15m50s - Why AI could be dangerous  24m20s - Would smarter than human AI solve most of the world’s problems?  29m - Paper on five concrete problems in AI safety  43m48s - Has OpenAI made progress?  49m30s - What this back flipping noodle can teach you about AI safety  55m30s - How someone can pursue a career in AI safety and get a job at OpenAI  1h02m30s - Where and what should people study?  1h4m15s - What other paradigms for AI are there?  1h7m55s - How do you go from studying to getting a job? What places are there to work?  1h13m30s - If there's a 17-year-old listening here what should they start reading first?  1h19m - Is this a good way to develop your broader career options? Is it a safe move?  1h21m10s - What if you’re older and haven’t studied machine learning? How do you break in?  1h24m - What about doing this work in academia?  1h26m50s - Is the work frustrating because solutions may not exist?  1h31m35s - How do we prevent a dangerous arms race?  1h36m30s - Final remarks on how to get into doing useful work in machine learning

21 Jul 20171h 38min

#2 - David Spiegelhalter on risk, stats and improving understanding of science

#2 - David Spiegelhalter on risk, stats and improving understanding of science

Recorded in 2015 by Robert Wiblin with colleague Jess Whittlestone at the Centre for Effective Altruism, and recovered from the dusty 80,000 Hours archives. David Spiegelhalter is a statistician at the University of Cambridge and something of an academic celebrity in the UK. Part of his role is to improve the public understanding of risk - especially everyday risks we face like getting cancer or dying in a car crash. As a result he’s regularly in the media explaining numbers in the news, trying to assist both ordinary people and politicians focus on the important risks we face, and avoid being distracted by flashy risks that don’t actually have much impact. Summary, full transcript and extra links to learn more. To help make sense of the uncertainties we face in life he has had to invent concepts like the microlife, or a 30-minute change in life expectancy. (https://en.wikipedia.org/wiki/Microlife) We wanted to learn whether he thought a lifetime of work communicating science had actually had much impact on the world, and what advice he might have for people planning their careers today.

21 Jun 201733min

#1 - Miles Brundage on the world's desperate need for AI strategists and policy experts

#1 - Miles Brundage on the world's desperate need for AI strategists and policy experts

Robert Wiblin, Director of Research at 80,000 Hours speaks with Miles Brundage, research fellow at the University of Oxford's Future of Humanity Institute. Miles studies the social implications surrounding the development of new technologies and has a particular interest in artificial general intelligence, that is, an AI system that could do most or all of the tasks humans could do. This interview complements our profile of the importance of positively shaping artificial intelligence and our guide to careers in AI policy and strategy Full transcript, apply for personalised coaching to work on AI strategy, see what questions are asked when, and read extra resources to learn more.

5 Jun 201755min

#0 – Introducing the 80,000 Hours Podcast

#0 – Introducing the 80,000 Hours Podcast

80,000 Hours is a non-profit that provides research and other support to help people switch into careers that effectively tackle the world's most pressing problems. This podcast is just one of many things we offer, the others of which you can find at 80000hours.org. Since 2017 this show has been putting out interviews about the world's most pressing problems and how to solve them — which some people enjoy because they love to learn about important things, and others are using to figure out what they want to do with their careers or with their charitable giving. If you haven't yet spent a lot of time with 80,000 Hours or our general style of thinking, called effective altruism, it's probably really helpful to first go through the episodes that set the scene, explain our overall perspective on things, and generally offer all the background information you need to get the most out of the episodes we're making now. That's why we've made a new feed with ten carefully selected episodes from the show's archives, called 'Effective Altruism: An Introduction'. You can find it by searching for 'Effective Altruism' in your podcasting app or at 80000hours.org/intro. Or, if you’d rather listen on this feed, here are the ten episodes we recommend you listen to first: • #21 – Holden Karnofsky on the world's most intellectual foundation and how philanthropy can have maximum impact by taking big risks • #6 – Toby Ord on why the long-term future of humanity matters more than anything else and what we should do about it • #17 – Will MacAskill on why our descendants might view us as moral monsters • #39 – Spencer Greenberg on the scientific approach to updating your beliefs when you get new evidence • #44 – Paul Christiano on developing real solutions to the 'AI alignment problem' • #60 – What Professor Tetlock learned from 40 years studying how to predict the future • #46 – Hilary Greaves on moral cluelessness, population ethics and tackling global issues in academia • #71 – Benjamin Todd on the key ideas of 80,000 Hours • #50 – Dave Denkenberger on how we might feed all 8 billion people through a nuclear winter • 80,000 Hours Team chat #3 – Koehler and Todd on the core idea of effective altruism and how to argue for it

1 Mai 20173min

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