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Do We Need a Theory of Everything?
- qlk1123 6y agoI am surprised that nobody in this thread has mentioned this: https://writings.stephenwolfram.com/2020/04/finally-we-may-have-a-path-to-the-fundamental-theory-of-physics-and-its-beautiful/ https://writings.stephenwolfram.com/2020/04/finally-we-may-h... Edit in response to downvote: This is an effort to model the whole universe using graph theory. I found it amazing not because how possible it might be the true answer, but because it provides an insight that clicks: a computational world, where any limited space can store only a limited amount of information. At least it is a beautiful mental model. "Do we need a ToE" is indeed an important question. But if some theory has been proposed and it "looks like" a good candidate of Theory of Everything, then many of us can just skip such questions.
- darawk 6y agoTFA is about this exact thing, and is dismissing it. I think that's probably why you're getting downvoted.
- wintorez 6y agoI think the main questions we try to answer with a theory of everything is about gravity. How does gravity work at quantum level? Is it possible to convert other fundamental forces into gravity?
- BoiledCabbage 6y agoYes, and OP is explicitly saying that is incorrectly conflating two separate things. The questions you list would be answered by a theory of quantum gravity. That theory can be consistent and answer all of our questions. A theory of everything is superfluous.
- Kednicma 6y agoYes, we do need a "theory of everything," or at a minimum we need a model of quantum gravity. Consider the color of gold, as a famous example; gold has its unique and curious color because of a combination of relativistic and quantum effects at the subatomic level [0]. Edit: Wow, fast downvotes! Sorry, I'll add another paragraph: The reason why we cannot use quantum mechanics (QM) or general relativity (GR) alone to explain the color of gold is because we know that the color comes from photons being emitted by electrons, as in QM, but the electron orbitals are distorted as if the electrons were moving at a serious fraction of the speed of light, as in GR. I think that this flatly contradicts her when she says: > So far, this is a purely theoretical problem because with the experiments that we can currently do, we do not need to use quantum gravity. In all presently possible experiments, we either measure quantum effects, but then the particle masses are so small that we cannot measure their gravitational pull. Or we can observe the gravitational pull of some objects, but then they do not have quantum behavior. So, at the moment we do not need quantum gravity to actually describe any observation. The color of gold, the liquidity of mercury, and even the ability of lead-acid batteries to turn over car starters are all everyday observations which need both QM and GR to explain. But, as she correctly notes, we can't put QM and GR together yet! So we do need some sort of quantum gravity. [0] https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
- Strilanc 6y agoDownvotes might be because the article distinguishes between a theory of quantum gravity and a theory of everything: > Physicists would much rather have all these forces unified to one, which means that they would all come from the same mathematical structure. [...] At the energies that we have tested it so far, the symmetry would have to be broken, which gives rise to the standard model. This unification of the forces of the standard model is called a “grand unification” or a “grand unified theory,” GUT for short. > What physicists mean by a theory of everything is then a theory from which all the four fundamental interactions derive. This means it is both a grand unified theory and a theory of quantum gravity.
- Kednicma 6y ago
- ketanmaheshwari 6y agoA bit tangential to the article but I just had this thought: Human knowledge has gaps because humans do not live long enough to effectively pass enough knowledge from generation to generation. Each generation generates knowledge and records it in one form or the other AND also passes it with direct verbal and non-verbal communication. However, since the overlap between two generation's cognitive prime age is narrow, not every thought, intuition, idea is passed along well enough. This creates a continuous rot in knowledge among generations and hence the humanity causing perpetual gaps in knowledge. This is the main reason why humanity at large does not have perfect knowledge of things such as universal forces, exact nature of universe, ability to predict random events and so on.
- imustbeevil 6y agoAnother thing is that the way we store information in our brains is different than the way we store information on paper or in computers. It's not possible to communicate ideas directly between brains so we're always going to be losing information in that transfer.
- ehsanu1 6y agoBut there's also that saying about how science progresses one funeral at a time. I think incremental progress might be more likely to occur with long lived humans, but breakthroughs may come only with new blood. Though, if a very long lived human were to become an expert in many different fields, that could also be conducive to innovation.
- irjustin 6y agoYou're saying that if we simply lived long enough we'd be able to predict random events? I have strong objections to this theory/thought. You'll have to describe to me how this mechanism works in greater detail because even within my personal lifetime, I do not have perfect anything for anything and I have no clue on how living longer helps that particular problem.
- ketanmaheshwari 6y agoI will try to elaborate. Let's say I throw a rock in a parabolic curve in a plain field. Humans can predict exactly where it will fall. This is because humans know everything about gravity, mass, etc. However, we cannot predict when and where exactly will a random meteor fall. This is because we do not know exactly everything about the universe and the various forces of universe. My thought is that a lot of humans might have understood more about those forces in the past but were unable to effectively pass that information for the next generation to build upon. This could be simply because the cognitive prime of the two generation overlaps for a relatively short period of time. Now had the humans lived long enough to cross some threshold of effective communication and longer overlap of cognitive peak between generations, they could have better able to pass their intuition, experience, thoughts, ideas to the next generation. In other words, there would be less loss of information/knowledge which would be just enough to fill the critical gaps to know everything about the universe. Knowing everything about the universe would enable them to predict everything precisely just as in the example of a parabolic throw of a rock on earth's surface.
- auntienomen 6y agoAt the moment, we are using two mutually incompatible theories to explain sunlight. We need gravity to explain how the sun formed and we need QFT to understand how it produces radiation.
- thaumasiotes 6y agoI would really only attribute "sunlight" to the second of those.
- garmaine 6y agoWithout gravitational pressure, the sun would fly apart cool down very quickly, causing and fusion would stop. No source of heat, no light.
- auntienomen 6y agoExactly.
- mellosouls 6y agoOriginal blog article: http://backreaction.blogspot.com/2020/07/do-we-need-theory-of-everything.html http://backreaction.blogspot.com/2020/07/do-we-need-theory-o...
- dang 6y agoChanged to that from http://nautil.us/blog/do-we-need-a-theory-of-everything http://nautil.us/blog/do-we-need-a-theory-of-everything. Thanks!
- irjustin 6y agoThis whole space fascinates me, but I do not have the maths/time/intelligence to understand the nitty gritty. For anyone who really wants to dig deeper but still get 'noob' explanations, PBS Space Time on youtube[0] is my goto. Black holes was where I started and boy did I get sucked in. [0] https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g
- darepublic 6y agoI did enjoy watching the spacetime videos although I also could not understand most of it. But I feel like the content and topics jumped around a lot and they would present string theory more or less as fact. It was a grabbag of cool ideas but it would be more fruitful I think to build upon layers of knowledge
- irjustin 6y agoI'm right there with you - I've watched their videos for better part of 2 years. Each video I've seen most likely twice while some of them I need to watch 4-5 times to understand. At times, I'll think I understand it. Come back 6 months later having a bit more understanding of related topics only to realize I understood absolutely none of the original video and am just beginning to get it =/. Seemingly innocuous sentences carry insane amounts of information (i.e. Do anything to a blackhole and the surface area never decreases except in Hawking Radiation) The topics do appear jump around a lot, but there's method to the madness. Topics such as Blackhole/Thermodynamic entropy require foundations that appear unrelated at first. Sure, they have video lists[0] to help but I've rewatched this one so many times. > they would present string theory more or less as fact To be fair, they have a why ST is right[1] and wrong[2]. As you can tell, I'm a SpaceTime fanboy. [0] https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyA... [1] https://www.youtube.com/watch?v=iTTa9YcTe1k&list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR&index=8&t=534s https://www.youtube.com/watch?v=iTTa9YcTe1k&list=PLsPUh22kYm... [2] https://www.youtube.com/watch?v=IhpGdumLRqs&list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR&index=9&t=53s https://www.youtube.com/watch?v=IhpGdumLRqs&list=PLsPUh22kYm...
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- aahhahahaaa 6y agoWe're not exactly a species that's content with what we need.
- bjt 6y agoThe article's point is deeper. > There is no reason that nature should actually be described by a theory of everything. While we *do need a theory of quantum gravity to avoid logical inconsistency in the laws of nature, the forces in the standard model do not have to be unified, and they do not have to be unified with gravity. It would be pretty, yes, but it’s unnecessary. The standard model works just fine without unification. We don't need the theories to be unified for them to be consistent. Putting all our efforts into that unification could actually be leading us astray and postponing the day when we've figured out how they're consistent.
- frogpelt 6y agoI have a theory of everything (or at least things involving humans). Theory: When humans fix one problem they are likely creating another problem.
- rimliu 6y agoI really wish misanthropy were met with the same response as racism, misogyny, etc.
- frogpelt 6y agoI don't mean to imply that humans are terrible. I just mean that we think we have a lot of answers when we don't. I came up with my theory when I read about Norman Borlaug and how he developed GMO semi-dwarf wheat which is purported to have saved a billion lives from starvation. But people now blame GMO crops for all manner of problems like unhealthy gut, Autism Spectrum Disorders, gluten sensitivity, etc. In sum, we're just trying to do the best we can, and we can't see all the possible consequences of our actions.
- foobiekr 6y agoTwo of these are not like the other.
- knzhou 6y agoI'm glad that Sabine correctly describes Wolfram, Weinstein, and Lisi's theories as what they really are. I'm disappointed that she trots out the tired old "zero sum game" rhetoric. I work on small-scale experiments, a field that Sabine portrays as starved of funding because of string theory. But that's not at all how funding actually works. Generally, all of our boats rise or fall together. String theory is so distant from my field that defunding it and expecting funding for me to rise is like defunding pharmacology and expecting an immediate revolution in palaeontology. Removing funding from one subfield doesn't move it to your favorite field, it just removes it from science in general.
- philwelch 6y agoWell, maybe. Or maybe concentrating funding in less promising fields and approaches leads to disappointing results, which in turn leads to lower funding in the long term.
- immmmmm 6y agoI really like her blog, it brings a lot of critical thinking in a field that often lack of. I however think she misses the point by constantly taking string theory as the sole example of bad science.. Disclaimer: I a former string theorist who has worked in many other scientific fields.
- immmmmm 6y ago... and string theory was the most badly funded field i ever worked in...
- cygx 6y agoImagine what we could have achived with all that money allocated to buy paper and pencils for string theorists!
- neutronicus 6y agoYeah, in grad school the theory grad students were the ones who had to TA a bunch to cover gaps in their funding. When you have a couple million tied up in lab equipment it's easy to divert some to grad students to keep it running but us theory folk were switching projects every couple years just to keep the lights on as it were
- mxcrossb 6y ago> Having said that, what do you think I think about Lisi’s and Weinstein’s and Wolfram’s attempts at a theory of everything? Well, scientific history teaches us that their method of guessing some pretty piece of math and hoping it’s useful for something is extremely unpromising Is this really true? Perhaps we can make this critique of string theory but what about other cases?
- QuesnayJr 6y agoEinstein had the physics idea for general relativity first, and adopted the mathematics of differential geometry to try to implement it. People had the idea for quantum mechanics first, and then discovered that there already existed mathematics for it. For quantum field theory, there was no existing mathematics for it, so they invented their own. For gauge theories (such as the Standard Model), I'm not quite sure the initial motivation. On the other hand, I think you could argue that Lagrangian and Hamiltonian mechanics were developed for aesthetic reasons, and these both proved influential for twentieth-century physics.
- DiogenesKynikos 6y agoLagrangian and Hamiltonian mechanics were useful early on, though. They make perturbative calculations much easier in classical mechanics. If you want to analyze the effect of one planet on the time evolution of another planet's orbital parameters, Hamiltonian mechanics is the formalism to work in.
- axilmar 6y agoI disagree that we don't need to unify gravity and the other 3 forces under one model. We need to unify them because there is obviously a missing link between the two theories (QM and GR), since spacetime is one and the same and there are properties defined in one theory that clearly affect the other one (but we don't know them yet).
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- BoiledCabbage 6y agoI believe you are being imprecise with your terms. Understanding how gravity applies on a quantum level is a theory of "quantum gravity". That is a very different concept than a "unified" theory. Your post uses appears to use the concepts interchangeably, although OP took care to show they are different.
- empath75 6y agoWhen scientists talk about unification, they're talking about the idea that all the forces are fundamentally the _same force_ at high enough energy (or early enough times after the big bang).. They've only thus far been successful at unifying the electromagnetic and weak forces.
- andrewla 6y agoAnother thing to note here is that the quantum theories are completely compatible with Special Relativity. That is, in non-curved spacetime Quantum Field Theory makes all the same predictions as special relativity does, plus all the quantum weirdness.
- openfuture 6y agoWe already have one, Maxwell's equations are just one equation in Geometric Algebra..
- simiones 6y agoDon't Maxwell's equations all apply to the electromagnetic interaction? Why would unifying Maxwell's equations help unify electromagnetic forces with the weak and strong nuclear forces?
- l33tman 6y agoThe author describes the unification process of the non-gravity forces under various symmetries and that there are desires to find a way to unify these under a GUT, and also describes there is a need to modernize gravity so it fits logically with the QFTs. But then the author seems to make a point of that a ToE has to be a GUT with gravity in it and that might not be how nature works? Which I agree with but I would not have used that semantics of ToE. I think most physicists at this point would settle for any logical merging of gravity with the QFTs that is consistent even if it postulates more free parameters and not less :) Anyway, just a nitpick on the terminology.. just seemed a bit click-baity (but I'm sure that was not the intention).
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- jessenichols 6y agoDavid Deutsch is the only person who has a theory of everything, not just for mechanics. He connects quantum theory (he wrote the first quantum algorithm), evolution (of genes and memes), and computation into the only true theory of everything. It's elegant, meaning the explanation of the theory is beautiful and highly structured. He presents it in The Fabric of Reality (1997) and has since been building it into constructor theory http://constructortheory.org/ http://constructortheory.org/
- rurban 6y agoI thought Penrose also has such a theory.
- jessenichols 6y agoI don't think he has attempted to fold epistemology into physics or has a deep understanding of evolutionary epistemology and how it connects with computation or mechanics.