“How do you find meaning in a universe that’s doomed?” – Astrophysicist Dr. Katie Mack @AstroKatie – Sentientism Episode 144

Find our Sentientist Conversation here on the Sentientism YouTube and here on the Sentientism Podcast.

Katie is a theoretical cosmologist who holds the Hawking Chair in Cosmology and Science Communication at Perimeter Institute. Her academic research investigates dark matter, vacuum decay and the epoch of reionisation. Katie is also a popular science communicator who participates in social media and regularly writes for Scientific American, Slate, Sky & Telescope, Time and Cosmos. She is the author of the book “The End of Everything (Astrophysically Speaking)

In Sentientist Conversations we talk about the two most important questions: “what’s real?” & “what matters?”

Sentientism is “evidence, reason & compassion for all sentient beings.” The audio is on our Podcast here on Apple & here on all the other platforms.

We discuss:

00:00 Welcome

01:58 Katie’s Intro

– #cosmology  & #astrophysics

– “The study of the universe from beginning to end from the smallest to the largest scales”

– #darkmatter, the beginning of the universe & the end of the universe

– Research & public engagement

03:33 What’s Real?

– Growing up going to church & youth group & #bible study

– United Church of Christ… liberal & open-minded #socialjustice #lgbtq rights

– Useful guidelines for life but “I never really understood how faith works… believing things without evidence”

– Exploring different religious traditions e.g. #judaism “attending church on Sunday mornings and synagogue on Friday nights”

– “I always wanted to believe something… there’s a fundamental urge most humans have to connect with the divine… #spirituality of some kind… the problem was I didn’t believe in anything”

– Connecting with religious songs, prayer, rituals about forgiveness & bettering yourself…

– Being told “just believe”… “I don’t know how to do that!”

– “I believe things if I see evidence for them… if I have some reason”

– A scientifically curious kid

– “The way I relate to the world… is through evidence”

– “I don’t fundamentally grasp the concept of choosing your perceptions… choosing your beliefs. I don’t think I can do that”

– Ontological & epistemological naturalism

– “I haven’t had a spiritual experience… I assume I would write it off as something explainable through psychology and physics… but I can’t say for certain”

– Enrolling in a #theology seminary school after graduating in physics: “wanting to understand religion… why people believe in things… I dropped out after 6 months”

– “I’ve done everything… went to every service… went to seminary… I did all the things and still god has not appeared to me in any way… I was a little bit jealous… that certainty, that feeling of peace… you are loved by the most powerful being in the cosmos… that sounds really cool… sign me up”

– “I could follow all the rules… I couldn’t believe”

– “If the idea is that you’re only saved by belief & not through actions then there’s no hope for me at all”

– No hassle at the seminary “everyone was assumed to be on their own spiritual journey… I just didn’t have one”

– Talking to Menonites, Fransiscan brothers, Unitarians… “nobody cared that I didn’t believe… I just felt out of place”

– Hearing others say “I find astrophysics so spiritual”… “I really don’t!”

– “Most of my colleagues have no idea that I studied religion”

– “I totally miss the community stuff… occasionally I think I should start going back to synagogue… the ritual, the mindset, the scholarliness…”

– “The idea that everybody gets together once a week to think about how to be better people”

– Secular people in religious communities “Practising but not believing… religious but not spiritual… now I guess agnostic… (I don’t know)”

– “I was very fortunate to be in religious communities… they were very progressive and focused on #socialjustice”

– Having no issues being #bisexual / #queer in those religious communities “I always understood that I would be accepted”

– Mystical traps in gaps & uncertainty: origins and ends of the universe, life, consciousness, free will. #Godofthegaps

– The weirdness of physics “weirdness is in the eye of the beholder”

– “What we’re trying to do in physics is create a mathematical model of the universe that best matches what we observe… a model that is useful… describe & predict”

– “Quantum mechanics seems really weird in a lot of ways but mathematically it’s extremely clear and simple… the evolution of these wave functions… it matches perfectly”

– The dissonance between our sub-atomic model & our macro models “we think of it as weird”

– “As long as we have a model you don’t even have a gap to put god into”

– Aspects of subatomic theory that we don’t yet understand

– Attending seminary lecture trying to connect god to quantum physics “it’s god who decides… how the wave function will collapse”… “You can do that but I don’t think it’s useful”

– Determinism & probability

– Quantum mechanics interpretations e.g. Many worlds / wave function collapse

– “Because I think of physics as being about creating models that are useful… there’s nothing useful about saying that a supernatural power is making a decision… you can’t use that”

– “It’s outside of what physics is about… I have no need of that hypothesis”

– “It’s not up to me to tell people how to think about the world but what is up to me is to try to make better models of the workings of the universe through physics and mathematics”

35:50 What Matters?

– Nihilism

– “I don’t think I ever saw it as being a question of what god wants me to do” Rejecting divine command theory

– “Commandments or rules in religion were based on not being bad”

– “The most important commandment is to love god… I don’t know what that means but I can not kill people… not lie… not steal… be an honourable person”

– Honour “as core to how I think about the world”

– “I always felt very keenly the suffering of others and not wanting to be part of that… not wanting to harm animals… or people”

– Hating violence in movies and “I can’t watch nature shows”

– The end of the universe: “There will be a point in the future when nothing that we’ve ever done will have mattered”

– Death and the attractive idea of “carry on”… “but if the universe is going to fully end – at some point that argument no longer applies… there will be a point where it will not have mattered if I kill someone tomorrow or not… it doesn’t matter”

– “Those black holes evaporating at the end of the universe are not going to care if I led a good life… if I hurt people… if there is suffering… it doesn’t matter to physics”

– “How do you find meaning in a universe that’s doomed?”

– No rapture or judgement day

– “As humans living in a temporary world… we have to find structures of meaning that apply in the now… that don’t rely on the future at all… that are not outcome based.”

– “I’m not waiting for some judgement… it’s more about ‘am I harming now’… am I making things better or worse… in the moment.”

– JW: “All value is in every moment of sentient experience”

47:12 Who Matters?

– Going vegetarian at 7 yrs old “started to understand where meat comes from and how that works” & being vegan now

– At a restaurant eating a hot dog and seeing a kids menu with a picture of a pig on it “Oh that’s a pig – that’s a hot dog!”

– “I don’t want to hurt that animal and so I shouldn’t be eating this food… I didn’t want to be part of that any more… because I didn’t want to hurt animals”

– “I’ve always been someone who loved animals and wanted to care for animals”

– “The emotional aspect was very automatic and honestly very inconvenient… experiencing the pain of suffering creatures”

– Being teased by middle-school kids for getting upset about them harming & killing snails

– “It’s not about cognitive ability – it’s about does that animal suffer?… I don’t want to cause suffering… it’s not a complicated philosophical argument”

– “By perceiving that suffering I suffered”

– “My family assumed that it was a phase” & health concerns “they tried to trick me into eating chicken” but later supportive

– Awkwardness with friends “I had to remove myself from certain things” & arguments & teasing “I kind of got used to that”

– “I was never somebody who was very susceptible to peer pressure”

– “A lot of the social awkwardness comes from the fact that people do inherently understand it [veganism] to be a social justice cause”

– “The reason people don’t like vegans… because they do see it as a judgement on their own ethical viewpoints”

– “It doesn’t matter to anybody else what I eat unless they take it as a personal attack”

– “It’s the same reason people will sometimes give me trouble about wearing a mask in a public indoor place… because they feel judged that they’re not doing that… I’m reminding them”

– “When I was a kid… I would tell them sentimental reasons… I really didn’t want to get into that conversation… you could use friends that way”

– What are consciousness and sentience? “There’s a grand tradition of theoretical physicists getting really into consciousness… I don’t want to do that… I’ll leave the definition of consciousness to the neuroscientists”

– “I don’t think that consciousness is some important element of the cosmos… it’s something that happens in the brains of organic creatures”

– Spectrums of consciousness & sentience “when I’m half asleep in the morning I’m less conscious”… sleep and anaesthetic

– “There’s nothing very, very specific about the way the human brain works that’s vastly different from the way other animals’ brains work”

Adrian Tchaikovsky on Sentientist Conversations, spider & octopus & bird consciousnesses “evidence that jumping spiders can dream”

– Graduated evolution & development of cognition and sentience “maybe a baby experiences the world more like a dog or a mouse”

– “We are fundamentally creatures of matter and circuitry… there’s no special spiritual spark that we have that other animals don’t… it’s very strange to put us in a totally different ethical category”

– “The only thing that really matters is can you feel… can you suffer… and they all do”

– Fish feel pain too

– Quantification gets tricky “Is one human worth ten cows”… trolley problems & difficult judgements

– Ethical challenges of any consumption e.g. exploitative supply chains

– Panpsychism

01:10:55 How Can We Make a Better Future?

– “My expertise is in the total destruction of the future not making it better” 😊

– “As human societies evolve we generally expand our idea of who has moral weight… I hope we continue to do that… people who are unlike us…”

– “Trends towards isolationism and fascism… are moves backward”

– “As the worst impacts of climate change become more and more felt – one way humanity can respond to that is to become more isolationist and more aggressive to those trying to escape”

– “I hope we are able to find a path towards justice, climate justice, social justice, decolonialism, being more open & welcoming & more helpful”

– Climate reparations

– “Congruence of climate, decolonisation and animal welfare… part of the same cause”

– “It’s going to be a difficult century… there are ways to solve those problems in humane and positive ways”

– The role of science & science communication

– “The problem of climate change is not that much a science communication problem as a political problem these days”

– Political affiliations & values driving people’s responses

– “The science information is out there… but when it comes up against people’s identities and their values…”

– Prioritising connecting better with people on a values level

– “Just giving information is just never going to be enough”

– “There are groups… who have a very strong vested interest in maintaining certain status quos… ideas that are contrary to progress… they have a lot of money”

– “Not many people have very strong views about dark matter and the big bang… doesn’t tend to threaten people’s personal identities and livelihoods”

– Explaining the process of science (there isn’t a “Big Green Energy” conspiracy!)

– “We love finding mistakes… we prefer it to be other people’s mistakes 😊 – we love finding new answers”

– “All of science progresses through falsifying”

– Make it clear what scientists are like “we really do just want to find the answer… we’re not just trying to push an agenda… we are human beings… curiosity”

– Address legitimate concerns about how science be used to cause harm

– The Epilogue of “The End of Everything (Astrophysically Speaking)”

– On Twitter and Mastodon @astrokatie & TikTok and Instagram

… & much more!

Sentientism is “Evidence, reason & compassion for all sentient beings.” More at

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Thanks to Graham for the post-production and to Tarabella and Denise for helping to fund this episode via our Sentientism Patreon.

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