Existential physics: answering life's biggest questions - with Sabine Hossenfelder

[@TimBitts649]

Sabine is a gem. The kind of teacher we all wish we had.

[@BonsaiBurner]

For an intellectual, Sabine always comes off as intellectually honest and having a "real" conversation. This is refreshing and appreciated in an ever polarized world.

[@georgesheffield1580]

Because she is

[@EllyCatfox]

because she's a woman

[@BonsaiBurner]

@@EllyCatfox authentic people come in all forms and are to be cherished, no need to exclude half the humans from the pool of people with the qualities because of sexism.

[@davidpantoja676]

Just love that I can watch content like this at my leisure.

[@gefginn3699]

Sabine has a great gift for delivery of tough topics. A great teacher.

[@lrvogt1257]

I really appreciate how Ms Hossenfelder insists on what we don't know or can't know... yet. Her KZbin videos are excellent

[@schmetterling4477]

Except that many of the things that she insists on to be unknown are quite trivial. She simply relies on you not having read the literature on those topics.

[@GeorgesDupont-do8pe]

@@schmetterling4477 Do we really actually know ANYTHING? We just have hypotheses that seem to work to one degree or another. Unless you're talking about religion of course.

[@schmetterling4477]

@@GeorgesDupont-do8pe Yes, WE know a lot of things. Even I know a lot of things. That YOU don't know anything is simply the consequence of YOU not paying attention in school. ;-)

[@needheartranken]

Everytime I get crazy contemplating about what reality is really, I look at Sabine's videos and gets calmed. Thank you, Sabine. My existential crisis saviour! We DON'T KNOW, and I think that's enough. Living as a human in the blip of time is an amazing ride!

[@northernhemisphere4906]

Good point.

[@_lumos4029]

@@JohnPretty1 existence is also a word

[@larrytheloose]

She is out there dealing and handling these ideas and has enough space in soul to talk to us about us! f'en love her to, she communicates levels that many speakers skip.

[@captainoates7236]

Sabine. I am in awe of you trying to cover most of what I have learned over several years of watching your videos in one go to an audience. Your communication skills no no bound.

[@bobbabai]

I think the no-no bound is the edge of current understanding

[@lawman3966]

I'm pretty sure that a no-no bound is what holds a person in place while the person's spouse (or duly selected professional) dispenses physical punishment.

[@jamesyoungerdds7901]

The New York Post reported that scientists had found a boundary to Dr. Hossenfelder's science communication skills and her ability to convey complex topics in an approachable way. But when she studied the literature and consulted with colleagues in the field, it became apparent they had not in fact done that. It was merely a manipulation of the data. And upon further examination, the results were not repeatable.

[@dionysianapollomarx]

That's a double negative, Sir. Not exactly a positive statement without the correct spelling of "know." But, I agree with your intended praise.

[@hugegamer5988]

@@dionysianapollomarx you’re failing to not apply logic there buddy.

[@wacomtexas]

Thank you Sabine for a great talk, and for reminding us that what we don't understand is as important as what we think we understand..

[@iv0447]

As a former physics student I find Sabine's videos refreshing. I can recall when I first learned about a concept and why I still find it interesting, basic curiosity about the world. What I find most amazing is that the physical laws haven't changed as much as we have. I am an entirely different person today than the kid who liked reading about new particles and worm-holes at the library after school. Then I dreamed of discovering something that would change the world, now I am not sure technology is really the right means to do it. Science can tell us what we can do and how to do it, but not if or why. It is important to understand where we live and what we are made from, what is time...etc. But a more important question for me now is, what is consciousness, its function and how does it fit with what is being observed? I would like to see more on this....many "big" scientists have contemplated these questions, even without a theory or proof. Yes, That guy again : ) Sabine, you have a crush on Einstain!

[@rajendranegi7330]

Isn’t the object and the observation within the observer (consciousness) itself?

[@paultraynorbsc627]

👩‍❤️‍👨

[@Kveldred]

I don't think there's really a good way to change the world that *doesn't* involve technology.

[@AlexanderWerner]

Sabine talking at the RI. Like Christmas and Birthday at the same day! Superb!

[@crowlsyong]

You and Matt O'Dowd are keepin it real for us all. Thank you.

[@michaelhunter2136]

I like simple stand-up presentations like this rather than videos with sound effects and flashy video editing. This was a special treat for me.

[@Hithere-ek4qt]

Yes, I agree Wholeheartedly.

[@deborahferguson1163]

I agree too. More relatable and enjoyable! (Though I have liked the other presentations)

[@Mando4Dan]

Much thanks to Sabine. Big concepts translated to an easy to understand, honest presentation about what our collective observations teach us. (And clarity about what they don't).

[@ramkumarr1725]

Good reading.

[@plasmaburndeath]

OMG I am so excited that Sabine got to be in person lecture 😀 I discovered her work and her KZbin Channel a few weeks ago and now she is popping up everywhere heh.

[@FLScrabbler]

Pleased I discovered her and her channel about two years ago... 😇

[@eljcd]

At last! I wanted to see Sabine in the hall for years, thank you!

[@davidkent2804]

Why is intellectual honesty so rare? Thank you, Sabine

[@michaelfried3123]

because some science disciplines have been hijacked by philosophy and pseudo-science.

[@davidkent2804]

@Edward Armstrong No proof - personal observation about the media and the way it seems to affect people

[@rayoflight62]

Congratulations Dr. Hossenfelder for the great intervention!

[@stevefrayne]

I love your strict adherence to the scientific method. It is best shown in the 16 seconds from 20:51 to 21:07 where you focus on what we KNOW (presume true) and go out of your way to minimize your own speculation. So many physicists irresponsibly speculate on these matters well beyond the frontier of science but not you. That is why you are gaining popularity among serious supporters of the scientific method. Thank you for keeping us from fanciful daydreaming and calling that science. Gratefully yours, SF

[@schmetterling4477]

Sabine's papers seem to be almost entirely speculative. I am not aware that she has worked much on some serious data driven physics.

[@arasharfa]

Sabine is so extremely clear in describing complexities, i love her lecturing style.

[@hugegamer5988]

Probably because she attempts to disbelieve her own two hands at least once a day to make sure her understanding isn’t built on unfounded principles. Because of it she sniffs out the caveats and exceptions and frames them with a consistent and descriptive world view. I’m just afraid as an excellent German scientist steeped in dry dead pan humor she isn’t breaking enough stereotypes.

[@mrblackmamba117]

@@hugegamer5988 I had to read this more than once but it made me laugh when i understood what you said hahaha PS: That's the definition of a true scientist studying concepts humanity isn't able to grasp, yet.

[@davidhowell2269]

Thank you so much for such an interesting and thought stimulating talk. Thank you also for making the trip to the RI, I hope they are looking after you!

[@spiralsun1]

Yes, Rhode Island is beautiful this time of year 😂

[@carlosalbertoteixeira375]

How great to see you here, dear Sabine! Grüß dich from Niterói, Rio de Janeiro, Brasil!

[@koenth2359]

4:20 Off by a factor 3600. But never mind, fastfast.

[@zetacrucis681]

just a slip of the tongue

[@MrHelkeys]

Sabine in RI. Definitely on my must-watch list.

[@MichaelHarrisIreland]

A breath of fresh air blowing through the houses of science. ....from Ireland.

[@schmetterling4477]

Sabine? Sabine is the most boring physicist in the world. ;-)

[@Thomas-gk42]

​@@schmetterling4477 and you are the most boring Sucker. Not need to work? Hope I don't feed you with tax pay ❤

[@spirosmatthaios2297]

Sabine is always impressive and inspiring! Allways to the point and "down to earth" despite being an astrophysicist!

[@vauchomarx6733]

Technically her main field is not astrophysics anymore, but phenomenology and foundations of quantum mechanics. But I agree with the sentiment, Sabine is brilliant!

[@cosminvisan520]

@@vauchomarx6733 No. She is just a mumbo-jumbo materialist.

[@klammer75]

@@cosminvisan520 I do not think those words mean what you think they mean🤔😉🤓

[@cosminvisan520]

@@klammer75 They clearly do. Consciousness is all there is.

[@rubiks6]

@@cosminvisan520 - Ummm ... okeydoke. (rolling eyes) That's a bit contrary to the empirical evidence, wouldn't you say?

[@shuchko]

Thank you for inviting Sabine, she is my favorite science communicator

[@CrowMagnum]

The "for all we currently know" bit is something that needs to be said more. So many scientists state current theories as truth instead of the best theory we have. Please keep saying it and don't bury it in a footnote.

[@DarkSkay]

Absolutely agree. Of course, it would be impractical to relativize every single detail that may or may not be seen differently in the future, in coming centuries of research and philosophy. A special case are arguments built on non-falsifiable assumptions that should ideally always be declared, unless evident from context or part of common sense. Finding a good balance here is even more important when venturing into what could be called "mataphysics" (*), where philosophy, metamathematics, belief systems and other perspectives can build on experimental and theoretical results gained in physics.

[@liralenx3513]

I agree, too. I've been a fan of Dr. Hossenfelder for several years now, for precisely that reason. That was because physics had reached the point where empirical science was in the process of being discarded as unnecessary. She was the first physicist I read who objected to that, probably at great cost to her professionally.

[@didack1419]

@@DarkSkay Can you give examples of "special cases"? "Metaphysics" is too much of a fuzzy word for any of this, I know that you know that by your own clarification, but regardless.

[@DarkSkay]

@@didack1419 Perhaps following are decent examples of non-falsifiable assumptions: 1) "information cannot be created or destroyed" 2) "in our universe 'true randomness' resp. 'divine dice' do not exist" 3) "the cause of inertia will always remain hidden" 4) "the flow of time in the universe is synchronized by clocks, which are driven by another clock, which in turn is driven by yet another clock...etc." 5) "observing or not observing has no influence on events"

[@steveflorida8699]

@@DarkSkay "finding a good balance" might very well venture into "metaphysics". Case in point --- the origin of Life (living organisms). Scientists know WHEN Life appeared in the evolutionary timeline, but do Not Know HOW Life was introduced into lifeless molecules. Having said that, Life is Not Inherent in mechanistic atoms and lifeless molecules. Also, physics cannot quantify the Values of... love, beauty, goodness and truth. The human condition, experiences and nature is more complex, than mere scientific analysis.

[@rudolfquetting2070]

The Multiverse and the Flying-Spaghetti-Monster have one thing in common: Both principally can’t be refuted by observation. Hence, there must be a consistent theory, which can do without. And Sabine just follows Ockham’s Razor, whe she says, good science can easily do without multiverses.

[@lepidoptera9337]

Yes, but she is lying to you about the multiverse ever having entered science to begin with. It hasn't. You won't find any serious cosmology textbook that discusses the topic within a multiverse setting. The LambdCDM model is very explicit about the structure of the universe. There is no ambiguity there at all.

[@rudolfquetting2070]

@@lepidoptera9337What about Everett, Wheeler, Graham, Hawking, Weinberg, Deutsch, Zeh, ….. ? From this perspective, I think it is somehow hasty to accuse Sabine Hossenfelder of lying. Of course, as far as applied physics is concerned, you are perfectly right. The many worlds assumption is a hypothesis only, that isn’t and can’t ever be based on observations. And therefore, the theory is not suitable for scientific textbooks. But it’s discussed in many peer reviewed papers. (I guess, some people forget, that math can model myth as well as it can model reality. And sometimes it can do that in one single model only, as quantum theory shows.)

[@ThePepzo]

Great talk Sabine! Thanks Ri!👍👍👏👏🙏🙏

[@cinemaipswich4636]

Sabine is one of the best and most respected science educators I know. No BS from her, for she is a straight shooter armed with facts and current knowledge.

[@schmetterling4477]

And how would you know? It's obvious that you don't know anything about physics. ;-)

[@jamesyoungerdds7901]

Thank you for such an amazing presentation. You have such a huge fan base of people who care about your unbiased take on physics and reality. If you've ever watched John Carmack talk about video games and technology - he just cares about pursuing what's true and real, and I get the same vibe. Really grateful for your dedication! 🙏

[@HystrixLignum]

Sabine seems to be a little nervous and slowed down the Speed of light a little bit... but she's briliant as ever.

[@SubroutineLtd]

A slip of the tongue but yes, as you also say, quite brilliant. In the debates I've seen, she is able to hold her ground against anyone and stays remarkably unfazed, nomatter who they are.

[@bytefu]

That's just the nature of a live talk, in contrast to a recorded video, where you can record the lines multiple times and pick the best takes.

[@eswn1816]

3,600 times slower!?!? (I noticed too... 🥺)

[@barnicle77]

Yes, and she sped it up too (or she stands very close to people). At 5:24 she said it would take a fraction of a nano second for light to reach her from someone else. People! Light travels at 1 foot per nano second ... sorry to those of you that only use metric.

[@jamesyoungerdds7901]

Ha, I noticed that too, but it kinda adds to her charm. I was watching the video thinking, I can relate - I'm very nervous speaking in front of audiences, so I'm sure I'd make at least that same slip. Love it.

[@leematthews6812]

Yes, it was a Friday night, and there was a tube strike, but even so, it was disappointing to see so many empty seats. I hope Sabine makes a return trip sometime, I would certainly be interested in attending another of her lectures.

[@stephenhicks826]

Sabine is the best Physics / Science explainer on the internet. This was a wonderful talk.

[@schmetterling4477]

Also full of technical errors. ;-)

[@aleksandrpeshkov6172]

@@schmetterling4477 Enters Optional Chronology : " I challenge You to provide the notion of... Particle..."

[@schmetterling4477]

@@aleksandrpeshkov6172 Enters that you didn't pay attention in school. ;-)

[@aleksandrpeshkov6172]

@@schmetterling4477 Enters MeterLingam : " I am relative to... Myself..."

[@schmetterling4477]

@@aleksandrpeshkov6172 Enters total idiocy. ;-)

[@TahsinPratik]

I think she wanted to say, 300,000 km per second. Not hour.

[@1959Berre]

I'm pretty sure she knows she made that silly mistake. It can happen to the best.

[@doncourtreporter]

Light travels 300,000 km per second and she knows that. She misspoke at 4:23. That never happens with her. Sabine is a treasure.

[@zbigniewprzedpelski7221]

Nobel prize 2022 in physics on enanglement which travels faster tjen light

[@doncourtreporter]

@@marope Hahaha. Sadly, you are likely correct. Peace.

[@doncourtreporter]

@@zbigniewprzedpelski7221 Non-sequitur. I am correct.

[@boring7823]

Hopefully this now means she will remember that a nice measure of lightspeed is 30cm/ns.

[@beattoedtli1040]

Naaa, c=1

[@StaringCompetition]

Subbed to both RI channel and Sabine, did a bit of double take there. Wonderful.

[@robertromero8692]

I like the way Sabine is willing to answer "we don't know" to some of these questions. It would seem that there are limits to our knowledge.

[@kensurrency2564]

we are pattern-recognizing creatures. if one thing is constant throughout human history, “i don’t know” is a consistent theme. so, does that imply that there will always be some mystery for us to seek an answer? are knowledge and understanding an infinite process? i think that’s quite probable.

[@nealkonneker6084]

I really appreciate your willingness to say "we don't know". Thank you. Real scientists like you may someday restore the credibility of "science" squandered by those who misuse it.

[@sfinxwojerz]

science and academia are to different things.

[@mrtransmogrify]

You know an academic and an explorer and a knowledge seeker when they talk semi-confidently and they know LOTS of things, yet they don't know... 👍🏽 we need more ppl like Dr Hossenfelder... There probably are bt they get pushed to the background by those confident-talkers.

[@Syntax753]

This is outstanding! What a wonderful presentation

[@TurboJon]

Sabine is an excellent presenter and clear, logical thinker. Very much enjoy her talks and books. Looking forward to reading this new one. Thanks.

[@George_slough]

I love Sabine's videos and dry sense of humour!

[@JohnChampagne]

Re Sabine, what's not to love?

[@cesarjom]

This is a great lecture from Sabine Hossenfelder who always has a critical and insightful perspective to offer. It really frustrates me to see society's intense interest, and in some cases obsession, with pseudoscience and false claims (mis)using science when the real physical theories for the universe is so fascinating and far more interesting to explore and gain confirmation through advancing technology (able to perform the necessary measure)!

[@laioren]

Dr. Hoss is a BOSS! Love her, love her work.

[@Turbohh]

Honest, frank, humble and fascinating. Thank you.

[@TheSonicfrog]

A brilliant talk at a historic venue, well done! FINALLY the answer to life's biggest questions ... we ... just ... don't ... know ....

[@bernardputersznit64]

Wonderful! - So many diverse ideas al brought together in one talk - Thank you Sabine, you are the best 🙂

[@mercurius8725]

Bring back content like this, this is great

[@j.477]

for me it's not depressing at all when she keeps on destroying my scifi-dream-bubbles, even though very often I have to first go through a seconds long phase of disappointment, when Sabine is saying FTL travel isn't very realistic without negative energy or sth like that... but whenever I listened to Sabine, she takes out all the nonfacts and what's left are facts that I can trust. This gives me a real good sensation of clarity and a sense that things have been put in the right order again...she relentlessly separates the wheat from the chaff ... I really appreciate that. thanks!

[@nagendrabala9756]

Sabine is a great explainer of physics 🥰😎😎

[@goduniverse1024]

She’s the best in the world 🌎

[@gastonlagaffe9156]

And, I think, a reliable one.

[@cosminvisan520]

@@goduniverse1024 Fanboy.

[@carlospenalver8721]

There’s several signs that serves as a telltale of “if” or “if not” someone may just be a genius , and that’s when they say “ I” or “we” don’t know. She’s definitely extraordinary. Someone who thinks they’re genius never if rarely admits to something they’re not sure about trivial or complex so, yeah she’s not full of bullcrap.

[@ChaineYTXF]

she's probably a good teacher

[@mpperfidy]

Sabine is always interesting and educational. This is the first lecture I've seen from her, being a longtime follower of her YT channel. She's possibly even more impressive as a lecturer.

[@schmetterling4477]

Not really. She is much better at tearing down than at teaching. How can I tell? I have read some of her papers. They are not very good. She lacks a clear grasp on the topics she likes to write about as far as I can tell.

[@markcampbell7577]

Now depends on the velocity and the relationship between the objects. The object or subject that is moving at any speed has a different time interval. The coast to coast airlines experience an increase in interval of about 30 minutes. The elapsed time difference between the stationary time and moving time is 30 minutes. As real as a normal travel experience.

[@farhadfaisal9410]

Sabine Hossenfelder's forte is in ''debunking headlines''. So it is not quite surprising that this time, in an attempt to avoid being ''depressing'', she spoke of ''what is possible'' and came up in the end with a quick review of certain ideas of recent physics of whose validity she could conclude, perhaps not unhappily, ''we don't know''.

[@apricus3155]

Let the woman be famous. This is her big moment and you are not helping

[@Mikey-mike]

We can thank our lucky stars for Sabine. Good one, Sabine.

[@seanphurley]

Very sober physicist, she was the nex step in my armature physics education, very excited frthe future

[@WyomingGuy876]

Sabine, I love your lectures! Don't stop 😁

[@pshehan1]

Sabine, if you are reading this I am in furious agreement with what you have said. I am a now retired research scientist (nuclear magnetic resonance) but also studied philosophy at the undergraduate level and completed a part time graduate diploma in history and philosophy of science while working at my day job. So I have been thinking and reading about these matters for quite some time. I have not gotten around to buying your books yet but will now remedy that oversight.

[@schmetterling4477]

What's your day job? Parking attendant? ;-)

[@pshehan1]

@@schmetterling4477 Now retired. My day job at the time was biomedical research.

[@schmetterling4477]

@@pshehan1 So it's parking attendant. ;-)

[@Thomas-gk42]

​@@pshehan1her books are great, and don't feed this troll (the german butterfly?)

[@mindyourself7063]

I'm in agreement that the "popular" trending topics of modern physics simply push the mathematics beyond their assumptions and constraints. Strikingly reminiscent of the creation stories conjured as our ancestors projected to model existence. I'm encouraged that Sabine is humbly speaking to this issue with perhaps more decorum than I can muster given the disservice that mis-information many in this field capitalize on.

[@user-yv8bw3zf6n]

May I ask what kind of scientific background you have?

[@daarom3472]

I think we have to distinguish the hard work of the thousands of unknowns grinding out measurable results and carefully stacking mathematical explanations from the 10-20 popular physicists talking about multiverses and the like (Kaku, Green, Dyson etc.). These people do not represent the entire physicist community yet are always assumed to be by Sabine/Erik Weinstein. Not saying Physics is perfect, but we have to accept that its harder and harder to provide empirical evidence for our theories and most of the low-hanging fruit has been plucked. It's extremely unlikely we'll ever see guys like Newton, Maxwell or Einstein again as any progress will require an insane amount of specialization and collaboration.

[@mindyourself7063]

@@daarom3472 Agreed. The distinction is important and I'm heartened to see I'm not alone in tiring of the attention seeking subset seeking celebrity with such conviction. I share in your short list here as a good start for case in point.

[@mehdibaghbadran3182]

There’s a speed which is more than speed’s of lights, 1-speed of dark 2-the speed of imagination which we called quantum mechanics, and 3-holographic worlds

[@danieljohnmorris]

Very happy Sabine has joined your roster!

[@thorn7bush]

I'm not sure I agree with what Sabine says about all moments existing in the same way. If two points in spacetime are timelike separated, then there is no way that any observer can see them as simultaneous, and we can say unambiguously that one happened before the other (if we want to). I guess that what she means is that spacelike separation is not transitive.

[@lepidoptera9337]

Indeed, it is the existence of spacelike separation that is behind a lot of the "mystery" behind e.g. uncertainty and the determinism question.

[@manalzd764]

Sabine is amazing as always. So excited to listen to this!

[@cosminvisan520]

Preaching her materialistic dogma ?

[@smlanka4u]

Yes, she is amazing. Science is simple than we think. The universe is locally simple, and it depends on relationships between emptinesses. Moments of time at each location could make the relative time and distance. And the conversation of energy law could make Big Bounces and other cyclic processes. Scientific explanations must predict both the past and the future. Therefore, it requires reliable scientific calculations to confirm scientific explanations. If some observations infer that the universe was a tiny singularity with infinite density, then that prediction should be able to predict the previous state of the tiny singularity in order to call it a good scientific prediction.

[@cosminvisan520]

@@smlanka4u Nobel prize for you!

[@williamhatfield8935]

A fascinating talk and exposition of the sorry state of modern Physics with its plethora of false assumptions. Instead of asking how did the Universe begin the question should be is there any reason to believe that the Universe had a beginning. We should not be asking if information is lost as it enters a Black Hole but why the myth of the Black Hole has continued for sixty years. Einstein inevitably pops up with his set of insoluble equations which can only be solved by making a series of assumptions depending on what result you would like to have. His equations contain as a main element G which is assumed to measure gravitational attraction when it can be easily shown to be a repulsive force by carrying out Cavendish’s classical big G at the surface and deep underground. The deeper you go the lesser the value of G so obtained. CMB measures the radiation of black objects in the Universe, of which there are many and easily seen and nothing to do with some creationist cult. And so on.

[@cosminvisan520]

@@williamhatfield8935 Universe doesnt exist. "Universe" is just an idea in consciousness.

[@Blackopsmechanic338]

I love these series. Can learn so much.

[@simonrigac8201]

This is what I've been waiting for! Finally a refresher for the already a bit boring RI.

[@MartinClausen]

You don't need quantum phenomena to get information loss problems. They come up in classical physics too. If you roll a ball up a hill with the exact speed the lets it settle on the peak, there is no way of reversing that in a way that lets you predict when it will start rolling down if you view it from the future.

[@archstanton1628]

The speed of light seems to slow down hugely for Sabine 😁

[@claudiozanella256]

3600 times.

[@mikhailfranco]

Penrose would say the gravitational field collapses the wavefunction. So black hole information loss is just the same issue as 'normal' measurements.

[@schmetterling4477]

Penrose has lost his mind a long time ago.

[@irfanbanning5393]

Every discussion of simultaneity I've seen makes it dependent upon the observer, but I think it ought to depend on causality. Using the train thought experiment, if the train is an inertial frame, and the lights are controlled by equal-length circuits to a common trigger, then the flashing is simultaneous, no matter how the light is seen by observers.

[@davidsalvia6294]

You are almost right. There is a mistake in the video. The flashing lights needed to be outside the train, then the flashes would arrive at the same time for the outside observer and at different times for the woman on the train.

[@daylesuess552]

Your missing the point. Simultaneously to who? Time behaves differently for every observer. If there are no observers what and who determines or decides time. If there are no particles and no waves there can be no measurement of time. What would you be measuring and what would be an interval of time? E.g. No turning of the earth for a day, no vibrations of an atom to mark a second. Time would have no meaning.

[@davidsalvia6294]

@@daylesuess552 I'm not missing the point. Sabine is misquoting an Einstein's gedanken experiment.

[@realfreedomofspeechoriginal]

@Irfan I don't think the past still exists at all. We are only seeing the light, not the actual physical event. People seem to be equating seeing an event with actually experiencing an event.

[@APaleDot]

You don't need an equal length circuit. You can set each light on a timer such that they flash at the same time from the point of view of the person on the ground. The person on the train will see them flashing out of sync with each other.

[@walkabout16]

Hail to Sabine Hossenfelder, with intellect profound, In the realm of physics, where answers are found. With quantum mechanics, she delves deep, Exploring the mysteries that our universe keeps. From black holes to string theory, she takes flight, Guiding us through the cosmos, shining bright. In particle physics, her wisdom unfurls, As she tackles life's questions, with unfaltering curls. Existential physics, a journey sublime, As Sabine Hossenfelder leads us through time. With curiosity as her compass, and knowledge her guide, She illuminates the shadows, where mysteries reside. So let us applaud her, with hearts full and wide, For daring to journey where few dare to stride. In the quest for understanding, she blazes a trail, And in her wisdom, we find solace and hail.

[@protocol6]

The problem I have with block time is that if you ask "does the past exist," implicit in that question, thanks to the tense, is "still" or "now." Asking if 1 minute ago exists now is the same as asking if 18 million kilometers along your path behind you is where you are. Unless your path through space-time is cyclic, the question has already answered itself in the negative. The past exists at its time, not at a different time. You can argue over whose numbers you assign and in what coordinate system all you like and it won't change that.

[@jeffkaylin892]

If "now" exists then I'll agree that the "past" exists. However, to make a VERY subtle distinction, I believe "now" is existing, not exists. Something about present perfect or present progressive verb meaning. I don't believe the present leaves a wake behind it. I'm called a Human Being, not a Human Is.

[@maximumentropy1863]

Is "now" equal, exact, a precise finite moment in "time" everywhere, in all that exist (including void or empty vacuum", in the all encompassing term Universe of infinitum, not observations from the speed of reflection (by some detections: eyes, made devices or other "natural" way) or the speed of the expanding Universe from infinite different points in the Universe?

[@DrDeuteron]

Does now exist at the andromeda galaxy? 2.5M light years away. Approaching at 0.1% c. Lorentz transform says right now in andromeda their right now says it’s 4522 AD on earth. In a similar galaxy receding it’s 478BC. Who is right?

[@protocol6]

@@DrDeuteron The light you see arriving from Andromeda is old, yes. That's got nothing to do with what's going on in Andromeda now. Your inability to see it is a separate issue.

[@protocol6]

@@maximumentropy1863 The manifold that I would call "now" isn't entirely free from local deviations in curvature so you'll always have to argue over whose numbers to use. Those defects are mostly due to gravity's effects on the rate at which clocks tick. Distance from the origin also affects the rate at which clocks tick so gravity's effect on time is just as much to do with that region of the manifold being closer to the origin. In that sense, you could say more than one time exists simultaneously but it's a small amount and spatially separated so it's trivial compared to the idea of block time. The moon, for instance, is a bit older than the likely collision event that created it on Earth. When we go there, we travel into the future more than normal. When we come back we travel into the future less than normal so Earth catches up with us since the Earth is, in one sense, in the moon's past and it's not just the mutual issue with light delay. That's a very different notion than block time, however, that's just a lumpy surface. I see no evidence that the surface isn't simply connected and infinitely thin, though thinking of it in terms of the minimum proper interval between two events at any given point is useful, particularly as that 4 volume is invariant so you can use that to work out the rate clocks tick at any given distance from the origin.

[@RghHgr]

Certainly, Sabine is one of the Top 100 brightest brains on KZbin!

[@schmetterling4477]

She is certainly a very brightly shining troll...

[@hartwigkoppi901]

Hello! I have a question to the multiverse theory: If all universes are expanding (maybe infinitely) like ours, is there no risk that they are colliding? And what gravitational impact must they have to each others?

[@MentalFabritecht]

It would depend on what space they lie in. They could be embedded in a much higher dimensional space where they would not necessarily intersect each other... it gets pretty wild 😅

[@elisabethloxley6124]

I have seen Sabine in a discussion with Michio Kahu and Roger Penrose. She and Roger concluded that the ‘multiverse’ is not science, but conjecture.

[@ogoshikimura5621]

Couldn't be more German then this: effective, precise, straight forward, no romantic add-ons. Love it.

[@nwogamesalert]

Ordnung muss sein.

[@freddyjosereginomontalvo4667]

Sabien good and excellent video. I love your channel.

[@alternative1999]

Thank you Sabine. I feel you have read my mind and produced the very questions I have had for years. You are obviously a brilliant Physicist, but you are also an engaging, gifted and talented Lecturer. I am someone who:- Desires to Observe Real Knowledge. It makes me proud to aspire to this. Not everyone understands my contemplating and searching for guidance and answers. I even wonder if our perception of Time as 'Past, Present and Future' is entirely subjective. Often reacting to the past then realising it's the future is either forgotten as a mistake, felt as 'deja vu' or lumped into parapsychology being called Premonition. I have observed many very young children, under 5yrs mostly, easily 'remember' the future but lose or dismiss this as wrong as they learn how to understand time in the normal human way.

[@jasperpike242]

Dont be a dork

[@woodchuck9]

Sabine in the house! Amazing 😊

[@tcarr349]

Sabines presence at this great hall is Spectacular.

[@SimonBrisbane]

Sabine is almost the exact same age as me. Talking about relativity , this leaves me feeling like I’ve wasted my life!

[@99guspuppet8]

You have wasted your life…… Sabine has wasted her life…… Let’s all go to Sugar rock Candy Mountain

[@danielvarga_p]

Panpsychism - you collide particles in the speed close to C, what would you expect they are doing inside your body? Do they travel the speed of C in your body? There is some elegant way to think about it, I am working on it.

[@Nocontextturkishboi]

she’s the queen/icon of popular science! I admire her holistic thinking and storytelling skills!! Even though many scientific problems and perpexling paradoxes that always blow people’s minds were mentioned, i didn’t lose my focus or have existential crisis moment 😂 she was really careful and sensitive while choosing the words!!! Also her mental & emotional stability is so consistent even in the subject that everyone can go crazy and feel excitement ( such as multiverse)

[@D0li0]

At 28:25, core wisdom.

[@johneonas6628]

Congrats Sabine.

[@tresajessygeorge210]

THANK YOU...!!!

[@tom-kz9pb]

Sabine seems like a fellow traveller with the same condition that many of her viewers probably share, something that you could call "ontological wonder sickness". As I would describe it, "ontological wonder sickess" is when you have a burning passion and curiosity, and really, really want to know the answers to unanswerable questions, like "What is time?" "How did the universe get here?" "What is the ultimate, deep reality that causes the laws of physics to be what they are?". We cannot answer the questions, but cannot stop the itch to keep asking them, so we helplessly chase our own tails, ridiculously like a kitten, in a whirlwind fury, Maybe there are highly advanced aliens watching us, and finding it hilarious, yet it still seems somehow like the most noble endeavor of life.

[@atarahashirazi1941]

You should put this on a t-shirt. I would buy that. It's quite accurate.

[@ThePurza]

Good point. Accepting that we just don't know many many things seems too hard for some, hence all the crazy theories out there

[@martinzarzarmusic5338]

Sabine doesn’t define consciousness but dismisses the idea that elementary particles may have some rudimentary consciousness. One can glean a certain predilection from her discourse toward defining consciousness as degrees of freedom… however, if we live in a super deterministic universe (as she has in other lecture suggested), then consciousness would have no degrees of freedom, just like the particles in question. I sense she has not thought of the implications of her argument very deeply. In general a very interesting talk. (One small correction: the speed of light is approximately 300,000 km/s, not km/hour, as she stated in the beginning).

[@schmetterling4477]

There are no particles. Quanta are energy values that are exchanged irreversibly between quantum fields. We taught you what energy is in high school. It's the ability of a system to perform work on another system. How do you get from that to consciousness without a heavy dose of magic mushrooms, exactly? :-)

[@martinzarzarmusic5338]

@@schmetterling4477 Obviously you do. Because here we are, conscious. the first step to recovery is admitting we have a problem. Then we can find solutions. I think it is wise to see things as not divided and then part of problem goes away. You are correct, to speak of particles is haphazard. And yet she does because it is part of the theory. Particles and waves are different expressions of the same who knows what.

[@schmetterling4477]

@@martinzarzarmusic5338 The human brain is not based on quantum effects. It's based on classical pulse density coding. And no, it's not called "particle theory". It's called "quantum theory" for a reason. ;-)

[@martinzarzarmusic5338]

@@schmetterling4477 I didn’t say it was called particle theory. I am simply commenting on what sabine said. Those are her terms. I’m well aware of the nomenclature. 😂 theories about consciousness are still in the early stages. To pretend we have a clear answer one way or another is hubris. There is not even an agreed on and satisfactory definition of consciousness so we are quite in the dark. Perhaps you know more, but I remain unconvinced either way, especially from a reductionist point of view. It doesn’t seem to work. Works great for other things, but seems to fail miserably when it comes to consciousness. However we still need a definition… What’s your definition?

[@douggale5962]

I have seen first hand that anything that can happen, will happen. In software, I have seen bugs that are incredibly unlikely occur, occurring. You have to completely seal off the possibility and make its probability zero, or it will eventually happen, no matter how unlikely it is.

[@herwighuener3256]

Quite true. Serious working to defend agains such things requires time, and managers do not like time being spent. But see the bright side (of life?!) of it: There is a branch of the multiverse, where a software-error in *every* ICBM in the world renders the thing non-functional, so there is a happy mankind downstream of history in at least some universes!

[@botboy0]

@@herwighuener3256 assuming the multiverse does exist ^^

[@herwighuener3256]

@@botboy0 As soon as you get used to it, you cannot help "believing" it. So, SH ist quite right in comparing multiverses with some sort of religions. However, physicists do not burn non-believers on the stake. That must mean something. I have to forward a more precise statement: whenever I personally speak of multiverses, I think about the Everetian kind and the Max Tegmark kind. All others: maybe, or maybe not. I am not fanatic about it. Not in this universe.

[@RockAristote]

Sabine is the simply the best!

[@kayakMike1000]

You think THOSE headlines are bad? I saw one predicting the end of the world sometime next week and another that says science has proven reality isn't real.

[@benmcreynolds8581]

I love that at least One Acclaimed Scientist is speaking up with a good perspective on the current state of physics. Because, for too long, it got popular for outlandish theories taking up all the air in the room anytime science talks came up. Certain things will always be untestable, that doesn't mean pondering about a theory is outlandish BUT some Theorists have made it far too popular to talk about certain things as if they are FACT, when I prefer Sabines approach: where she is deeply profoundly curious. Yet she is not afraid to admit when we aren't able to make good enough measurements, to admit that we don't know, but it doesn't mean she isn't driven to find new directions and perspectives. That's why I appreciate Sabine a ton.

[@schmetterling4477]

Why are you telling us that you don't know what the word "theory" means? ;-)

[@Pontiffeye]

This channel always has the real intelligent and quality content I desire 😅👍

[@cosminvisan520]

Neah. It just has materialistic mumbo-jumbo.

[@scott1285]

Watching Sabine talk about chucking turkeys into a black hole in thanksgiving

[@a.randomjack6661]

@@cosminvisan520 You reLLY should stick i you lala realm 🦄👻👼 This universe makes you too whiny

[@cosminvisan520]

@@a.randomjack6661 Universe doesnt exist. "Universe" is just an idea in consciousness.

[@singlechannelstuff8666]

I can't remember whether it was Dostoyevsky or Tolstoy who wrote, 'a man's opinion is of value only to himself '. Sabine says much the same thing, when she said 'I don't want to give you my opinions '. As allways she sticks to evidence not opinion, even hers. What is, almost, more valuable she's prepared to say 'we don't know'. She has grown in my estimation over the last few years. I'm glad to see her at The Royal Institution.

[@schmetterling4477]

It's just too bad that science doesn't run on opinions. It runs on facts.

[@douggale5962]

For a normal person, yes, the speed of light is incredible. For computer architects, the speed of light is so slow it prevents you from doing things. For astronomers, the speed of light is too close to zero.

[@DeLiverpool]

Mmm, I disagree. The speed of light, c, is merely the maximum velocity attainable by any object within the knowable universe, i.e. the universe as describable in mathematical terms.

[@iamvfx]

You hit way way more software and hardware bottlenecks before you get to the bottleneck of the maximum speed of light.

[@TheMonkeydood]

@@iamvfx definitely agree

[@baarni]

The speed of light is not slow if you’re the one travelling at that speed… just remember that anything travelling at the speed of light doesn’t experience time or distance so you will arrive at your destination the instant you reached light speed.

[@system0fadowner251]

@John Shipp yes. Still impractical for traveling tho. Sure the astronauts will get to and back Andromeda instantly in their pov, but they'll return to a time 2.5 million years after leaving.

[@kevindoom]

Another bringing science down to earth video!!!! thank you Sabine

[@JmWro]

5. I think that particles, well atoms to be precise, do think and they are conscious. I'm not saying that there is proto-consciousness or hidden properties. I just think that we need proper definition of consciousness. You can not say that we don't know what consciousness is. We invented that term. So the definition should be: consciousness is the ability of the system to respond to the environment. So single electron is not consciousness. But hydrogen atom is. It can absorb light and the re-emit it in it's own frequency (hydrogen line). And all other systems are just more complex so they are more consciousness, more inteligent. There is no magic. It's just growing complexity. If you don't agree with that you should then tell when consciousness started? Were your parents conscious? Grandparents before them? Neanderthals before them? Dinosaurs before? Bacteria in oceans? RNA? Carbon dioxide molecule? Where you draw the line? Only logical approach is to draw the line before the first system that started this whole evolution. And that was a single hydrogen atom.

[@theunifiedtheorycom]

No, its actually more ‘hidden’ than this! Mind is always conscious. There is no such thing as unconsciousness. And the hidden aspect everyone is looking for is the ‘Fulcrum.’ Mainstream physics will have to understand the electric wave to this level of detail if they want to understand the unified theory. Lauren Dove, author of ‘‘The Design Equation - The Unified Theory and the Mathematics of Hidden Dimensions.’

[@stn5334]

First hominids What do we gain from this redefinition?

[@APaleDot]

But single electrons _can_ respond to their environment, after all a hydrogen atom can only absorb light _because_ the electron gets pushed to a higher energy state by a photon.

[@JmWro]

​@@APaleDot I would argue that in such case you just increase potential energy of the whole electron, so the electron itself is not internally modified. But I might be wrong. Then we can say that single electron is also conscious, sure, why not :).

[@CosmosNut]

Thank you for another remarkable presentation about the current state and enduring and current issues.

[@MattHare]

She finally performed where she should be a long time ago. Mock me but to me, she's the next Feynman. Witty, funny, no selling or taking BS. She's also musical, just like Feynman was (well, in a way, at least)

[@uku4171]

Feynman did groundbreaking research

[@Axiom23573]

Every time she mentions Einstein I find myself waiting for "...yes, this guy again..." 🙂

[@bartvenken7138]

What I always wonder about re the speed of light: imagine two fotons going opposite directions, is their relative speed (in reference to each other) still the speed of light? If so, how does this happen?

[@russellsharpe288]

Yes. According to Galilean (and Newtonian) physics if two particles are travelling at velocities u and v then their velocity of the second relative to the first is just v - u. But in Einsteinian relativity this relative velocity is instead (v - u) / (1 - uv/c²). (c is the speed of light of course) So eg if two particles were travelling each at half the speed of light but in opposite directions, their velocity relative to each other would be (0.5c - (-0.5c)) / (1 - (0.5c)(-0.5c)/c²) = (0.5c + 0.5c) / (1 + 0.25c²/c²) = c / 1.25 = 0.8c. In your case with two photons, each travelling at the speed of light, we get (c - (-c)) / (1 - (c)(-c)/c²) = 2c / (1+1) = c.

[@BulentBasaran]

@@russellsharpe288 Applying relative velocity concept to photons would very quickly lead to absurdities. E.g., imagine two photons going in the same direction (u = v = c = 1). Their relative speed would then be: (1 - 1) / (1 - 1/1) = 0/0. To stay clear from such inconsistencies, we better apply relative speed calculation only to inertial reference frames with v < c. Also keep in mind that to a photon, time never passes. So, speed is not even a meaningful concept from the perspective of a photon. Light is special :-)

[@schmetterling4477]

@@BulentBasaran The distance between two wave fronts of the same light wave stays constant in every coordinate system (it's just not the same because of Doppler shift), so the scenario is neither absurd nor particularly complicated.

[@RubensteinIan]

if two trains are moving 60 miles an hour in opposite directions, how fast are the trains going?

[@schmetterling4477]

@@RubensteinIan That depends on the observer, kid. You need to pay attention on school. ;-)

[@hybridepigenes]

I love your approach and educational perspective. You are infinitely inspiring.♥️♥️♥️♥️♥️