
Do We Need a Theory of Everything? - COGlory
http://backreaction.blogspot.com/2020/07/do-we-need-theory-of-everything.html
======
knzhou
I'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.

~~~
immmmmm
I 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
... and string theory was the most badly funded field i ever worked in...

~~~
cygx
Imagine what we could have achived with all that money allocated to buy paper
and pencils for string theorists!

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irjustin
This 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
I 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
I'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=PLsPUh22kYmNCHVpiXDJyA...](https://www.youtube.com/playlist?list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR)
[1]
[https://www.youtube.com/watch?v=iTTa9YcTe1k&list=PLsPUh22kYm...](https://www.youtube.com/watch?v=iTTa9YcTe1k&list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR&index=8&t=534s)
[2]
[https://www.youtube.com/watch?v=IhpGdumLRqs&list=PLsPUh22kYm...](https://www.youtube.com/watch?v=IhpGdumLRqs&list=PLsPUh22kYmNCHVpiXDJyAcRJ8gluQtOJR&index=9&t=53s)

------
axilmar
I 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).

~~~
BoiledCabbage
I 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.

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l33tman
The 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).

------
aahhahahaaa
We're not exactly a species that's content with what we need.

~~~
bjt
The 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.

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jessenichols
David 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
I thought Penrose also has such a theory.

~~~
jessenichols
I 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.

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mxcrossb
> 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
Einstein 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
Lagrangian 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.

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Kednicma
Yes, 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)

~~~
garmaine
I’m a physicist and I downvoted. Relativistic quantum field theory (which
explains gold’s color) and quantum gravity are two entirely different things.
We already have a relativistic quantum theories which combine quantum
mechanics with Einstein’s special relativity, and explains everything we know
about chemistry. Quantum gravity would combine the standard model with general
relativity, which is only really needed for non-human scale things like black
holes and the origin of the universe.

Special relativity and general relativity are two very different things. Don’t
conflate them.

~~~
Kednicma
Thanks. There's a recent video [0] out by Sean Carroll that delves more into
the difference between SR and GR.

[0]
[https://www.youtube.com/watch?v=353lEB63iyg](https://www.youtube.com/watch?v=353lEB63iyg)

------
wintorez
I 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
Yes, 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.

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mellosouls
Original blog article:

[http://backreaction.blogspot.com/2020/07/do-we-need-
theory-o...](http://backreaction.blogspot.com/2020/07/do-we-need-theory-of-
everything.html)

~~~
dang
Changed 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!

------
openfuture
We already have one, Maxwell's equations are just one equation in Geometric
Algebra..

~~~
simiones
Don'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?

------
auntienomen
At 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
I would really only attribute "sunlight" to the second of those.

~~~
garmaine
Without gravitational pressure, the sun would fly apart cool down very
quickly, causing and fusion would stop. No source of heat, no light.

~~~
auntienomen
Exactly.

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frogpelt
I have a theory of everything (or at least things involving humans).

Theory: When humans fix one problem they are likely creating another problem.

~~~
rimliu
I really wish misanthropy were met with the same response as racism, misogyny,
etc.

~~~
frogpelt
I 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.

------
ketanmaheshwari
A 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.

~~~
anu7df
Not sure I buy the "narrow overlap of generations" as the main reason for
imperfect knowledge. Yes humans don't live long enough. But generations and
population ages vary smoothly in a cohort. May be centuries ago, when the
effective number of people you interact with is small and finite due to slow
transport of information, people and goods. But I would argue since the advent
of books, organized schools and universities this is less of a problem. Now
with the internet this is really a non issue. One has all the lectures that
one could possibly want to listen and all the books and papers to spend every
waking moment consuming. So I guess fundamentally we are only limited by our
finite lifespan, and may be working memory that has a good decay rate.

~~~
xvilka
> Now with the internet this is really a non issue.

A good chunk of valuable information disappears all the time from Internet.
Many thoughts expressed in personal blogs usually go away within a few years.
See, for example, demise of Geocities and Yahoo Groups. While only a small
part of this disappeared information is valuable, some of it incredibly useful
and important.

~~~
imtringued
You're completely ignoring the argument. The purpose of the internet is not
recording information for all eternity. It's to transmit information from
person to person. If you want to preserve information then write a book and
publish it. It will be archived in organizations that specialize in archival.
They allow the internet as a communication method but in theory nothing
prevents you from just driving to the location and reading the book on site
without the internet.

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qlk1123
I am surprised that nobody in this thread has mentioned this:
[https://writings.stephenwolfram.com/2020/04/finally-we-
may-h...](https://writings.stephenwolfram.com/2020/04/finally-we-may-have-a-
path-to-the-fundamental-theory-of-physics-and-its-beautiful/)

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
TFA is about this exact thing, and is dismissing it. I think that's probably
why you're getting downvoted.

