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What Is The Ruliad? | Stephen Wolfram | Robinson's Podcast Clips | YouTubeToText
YouTube Transcript: What Is The Ruliad? | Stephen Wolfram
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Core Theme
The "Ruad" is a conceptual framework representing the entangled limit of all possible computations, suggesting that our perceived universe, governed by the laws of 20th-century physics, is a specific, computationally bounded observation of this ultimate computational space.
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[Music]
I have not heard this word ruad before
so I'm guessing that many of my
listeners haven't either so before we
continue just what is a a roule
ad right so there's not a rou ad there's
only one rou ad okay it's um so it's a
term I invented it what is it a couple
of years ago now it's um okay let's see
we probably have to descend to really
understand it we have to descend a
couple of levels in a rabbit hole okay
but but let me let me say what the what
the sort of nominal definition is uh the
nominal definition is it is the
entangled limit of all possible
computations what do I mean by that so
let's say you have a touring machine
simple idealized model of computation
you start the T you have this touring
machine you start it in all possible
States you look at the touring machine
just does what it does it has rules it
just keep keeps running does what it
does so you start in all possible States
and what you can then do is you say for
this touring machine let's say they're
two different states of the touring
machine at the beginning maybe they
merge sometime later uh that's you know
so that that can happen and you kind of
mapping out what are the processes that
go on that go from state to state okay
so now you don't just think about one
touring machine you think about all
possible touring machine rules and in
that situation you start off from one
state and you can apply one Ching
machine rule it goes over here you apply
another Ching machine rule it goes over
here now maybe subsequently the states
those two different states will you
apply some turing machine rule they'll
merge so you get this whole structure of
branching merging uh states of let's say
touring machines then you continue that
for all time just keep it running
forever that the and it then turns out
it doesn't matter that you're talking
about touring machine
it's just a change of coordinate system
it's like rotating coordinates and
you're still talking about the same
piece of space so to speak but you're
describing it with different different X
and Y and Z values and so on so you
could change from turning machines to
Cellular autometer to other all kinds of
different models of computation this
limit will always be the same thing so
this this limit is sort of interesting
because it is it is it encapsulates all
that is computationally possible and it
is it is unique there's you know you can
describe it in different ways but
there's just one ruad there's only the
only way that it isn't unique is to say
well it only uses touring machines so a
touring machine has certain limitations
like for example if I say and it's
related to computational reducibility if
I say here's this touring machine is it
ever going to reach some halt State you
say well I ran it for a million steps it
didn't reach a halt State it's not going
to Halt but you you to it is not in
general possible to prove with a finite
proof that the system will eventually
halt or not and this is a feature of
computational irreducibility
computational ir I mean just to just to
give the logical flow of this the the
most fundamental principle here is the
principle of computational equivalence
the idea that systems are are equivalent
in their computational sophistication so
then the question is if you have a
system and it's running and it's running
according to certain rules and you are
saying I'm going to jump ahead I'm going
to predict what the system does without
having to follow all those steps well
how are you going to do that well
eventually you have to be somehow
computationally smarter than the system
itself you have to be able to say well
it's spent a billion steps but I've got
this really clever computational
technique that lets me answer that in
three steps okay but the principle of
computational equivalence tells you you
can't do that it tells you you as a
brain as a mathematician as whatever
else you are simply computationally equivalent
equivalent
to the system you're studying and so
that's why you get this phenomenon of
computational irreducibility so that's
kind of the that that's that's that
piece of it now when you're looking at
so but one thing you could say is okay
well computational irreducibility is
something where you can't jump ahead
because you're just computationally
equivalent to the system but I could
just say I just imagine that I have what
usually gets called an oracle imagine I
just have this box that answers
questions which Tak an infinite time for
a turing machine to answer and You' say
I'm going to attach this box to my
computer well with that box you can go
beyond mere computation you can go to
hypercomputation so there are there are
an infinite hierarchy of hyper RADS
which involve more than just ordinary
computation but the one sort of
contingent fact I think about the
universe is we live in the ruad and not
in the hyper ruad and there is a a
necessary Event Horizon kind of a causal
disconnection between the ruad there's
the same kind of causal disconnection
between the ruad and the hyper ruad as
there is between what we see in the
physical universe and the interior of a
black hole it's it has the same kind of
causal you can't have an effect going
from one to the other type thing so the
the it is not self-evident it's not
something we can prove in some sense
that we we can find empirical evidence
that we're in the ruad not in the hyper
ruad but it's the same it has the same
kind of status in kind of uh thinking
about what's necessary and what's not as
to say you know we are at this place in
the physical Universe there's not a
thing where you can say I'm going to
prove a theorem that the Earth is at
this place in the universe that doesn't
really make any sense it's just we
happen to be at this place in the
universe and given that we have certain
Impressions about how the universe works
well we happen to be in the ruad and not
in something else but there is only one
unque unique ruad and so then you ask
the question well so for example there
are many many questions you can ask so
the the you know the important thing is
we are sampling the ruad at one place in
the ruad which means that among other
things we have given the way our minds
work given the way our senses work and
so on we have a particular view of how
the universe is working if we were to
move ourselves to a different place in
Ral space sort of a different place in
the ruad we would have a different point
of view about how the universe works
it's still the same underlying ruad but
we're sampling it in a different way
just like in physical space we can move
from here to there and we'll have a
different point of view about what's
happening in the universe so in this in
this case what we uh the way I see it
actually um and this is sort of a a
philosophical plong that is not 100%
worked out but the way I think of it is
you know different minds are are
different points in the ruad they're
different points in Ral space so you
know you can be physically in a
different place and you have a different
point of view about things you can be in
a different place in Ral space which
means you have a different view of you
have a you attribute different rules to
the way the universe works and it's just
like you know in in in my mind versus in
your mind we might uh we might think
we're talking about the same thing but
the actual internal operation of our
minds is quite different and so one one
of things that's really kind of fun that
is a place where sort of you see a
contact between physics and and all of
this stuff is in physics one of the
remarkable things in physics is that
pure motion is possible that is you can
take an object and you can move it
somewhere and it's still the same thing
it's not obvious that will be true you
know and if you if you happen to move it
very close to a space-time Singularity
it won't be true but in most of space
you move something from here to there
and it's still the same thing that that
is there is a sense in which the
identity of the object is not changed by
the way in metam mathematical space that
that same kind of uh sort of uh
preservation of of identity under motion
I think is the reason that there are
these big dualities between different
areas of mathematics you can think of
different areas of mathematics as
existing in different places in MA meta
mathematical space and this kind of idea
that sort of you can you can move from
one to the other is kind of like the
algebra to Geometry translation things
like this but back to back to physical
space so we have this idea of of motion
in physical space the possibility of
pure motion the question is what are
things that are subject to Pure motion
so for example particles like electrons
electrons preserve their identity while
moving through space uh in the in the
course of time and this is so in a sense
we can think of an electron as being
some sort of well in our models of the
the universe everything is just made of
space spaces I I should say this this is
a I'm I'm kind of I'm sort of bizarrely
ascending some rabbit hole I started
from the roule ad which is kind of the
bottom of the rabbit hole but um uh the
I mean sort of a fundamental piece of
our just just to outline this because
it's relevant to the intuition of these
other things in our kind of current
theory of fundamental physics um I say
our there thing that well I'd been
working on it from the 1990s but really
got developed in um about 3 years ago now
now
and um it's now become I would say
decent number of physicists and
mathematicians are working on it and
it's sort of becoming a bigger bigger
snowball it's very very very beautiful
I'm it just it just came out more
beautifully than I could ever possibly
have imagine no I can tell the way that
you talk about it it's like a
child yeah yeah right well it's kind of
like I you know I had no idea that for
example the three fundamental theories
of 20th century physics general tivity
theory of SpaceTime Quant mechanics and
statistical mechanics the thing that
leads to the second world of
thermodynamics all three of those
theories can be derived from the same
principle they are in a sense the same
Theory and I had no idea that would come
out that way and it's really to me it's
a just an amazing thing and really all
three of those theories we can talk
about it are the results of the
interplay between the way we are as
observers interacting with this
underlying ruad object MH but just to
just to start off from kind of The
Theory of physics the
you know the starting point
is one important point is space is
discreet in our model so you know people
have imagined ever since uclid and so on
space is just this thing where you put
stuff at different positions in space
and you can put things anywhere you want
in space well back you know in in
ancient times and so on people wondered
is matter continuous so discreet and you
know for a long time that was unclear
and it became clear at the end of the 19
Century that matter was actually made of
discrete molecules and then you know
another big surprise electromagnet the
electromagnetic field light and so on is
also made of discrete particles at that
time at the beginning of the 20th
century it was like well presumably
space is also discret but there were
technical reasons why people didn't
manage to make that work I mean Einstein
famously at least famously to me um you
know had this statement back from 1916
said in the end space will turn out to
be discreet but we don't have the
mathematical tools to understand how
this will work yet so 100 years later we
do and turns out that it is so the
starting point is realizing space is
discrete it isn't the case you can just
put things anywhere you want just like
you know you have water you can't say
there's a piece of water everywhere
there's only sort of water where there's
a molecule type thing so space is
discrete this the everything that is in
the universe is a feature of
space and we have this kind of a good
way to think about the structure of
space is it's like a hypergraph you have
these these atoms of space just these
points disembodied points and all that
you can say about them is how they're
related to other points so building up
this kind of graph this network of
connections between the atoms of space
they don't they're not placed anywhere
particular all they know is they have
these relationships between them that
are defined by these relations
associated with this graph and that's
that's the structure of space and
everything in space so for example just
like in a fluid you know you might have
a Vortex when you run your finger
through the fluid you'll see a little
Eddie that Eddie is made of the exact
same molecules as make anything else in
the fluid and so similarly a particle
like an electron we think of as being
something a little bit like an Eddie but
now in this in this um graph that
represents the structure of space rather
than in this bunch of molecules bouncing
around so an important point in this
kind of picture is what is time
and in this in this model the the graph
is continuously getting Rewritten There
are rules that say if you see a piece of
graph that looks like this it's going to
change into one that looks like that and
so there's this Progressive computation
of new graph from old graph and that
computational process is the progress of
time and computational irreducibility is
the reason that there's sort of
something definite happening in the
progress of time and it's so we kind of
have this idea space is a very different
kind of thing than time and you know
relativity still works out it works out
very beautifully it's an emergent
feature of of how the system works it
wasn't something space and time start
very different but they still have this
relationship the relativity implies and
so on but then so then the the next
thing to realize is we got this system
it's evolving through time and then the
next thing you realiz is well there are
all these different rewrites that could
happen on this graph there are actually
many different rewrites that could happen
happen
to a given graph there are many
different rewrites that could happen
next and that means that time is not a
single thread time is this
multi-threaded thing that has both
branching and merging and so then it
turns out the quantum mechanics is the
feature is is a consequence of this fact
that you get these many threads of time
and one of the one of the strange
features is one one of the critical
things about this model is that that we
are embedded within the model so we have
to think what is an entity embedded as
part of this model think about what's
going on so for example an important
feature is there are many branches there
many threads of time but our minds are
spread across many threads of time so in
other words it becomes this question of
what how does a branching mind perceive
a branching universe and that turns out
to be what gives one kind of the
essentially what gives one quantum
mechanics there are details there that
still to be worked out but at a at a
qualitative level that's the story is is
that it is and and then it becomes very
critical that we have this idea that we
have a single thread of existence
because that's what causes us to be
forced to knit together all these
different threads of time so anyway the
the final part of the rabbit hole
descending down to the rabbit hole is
that so we have you know all these
possible rewrites are happening they
Define different threads of time and so
on but then you might ask yourself you
know what a confusing situation we've
got all these things happening we got
this Rule and we can hold in our hands
the rule for the universe and we say
look you know it's rule number 156 or
something and that's a very bizarre
possibility that we could just say our
whole universe we got rule number 156
and Another Universe might have got
another Rule and it's then very
mysterious why we got a rule that's kind
of a low-numbered rule not a rule so
complicated that we can never make a
prediction about what happens in the
universe because we're always you know
sampling a different part of the rule
and so on so I was very confused about
this for a while but then I realized
actually the right way to think about it
is the universe is running all possible
rules and that's what the ruad is is
this a universe that is you know where
you could slice it to look at just the
space part you can slice it to look at
the quantum mechanics part but in the
end it's running all possible rules and
the the sort of the the big fact is that
knowing that to an observer like us
there are certain necessary features of
the perceptions that we have about the
universe so the universe is is
ultimately just this ruad that's doing
all these crazy things but as a
computationally bounded believing your
persistent in time Observer there are
certain necessary features of what you
perceive about that universe and those
necessary features turn out to be
exactly the big theories of 20th century
physics which I think is really really
interesting because it's kind of like
it's on us so to speak but it's not
completely on us it's any obser
who has these General attributes that
are like us will conclude these
particular things about physics and so
you know that's that's a a sense in
which both the universe is inevitable
and the universe is dependent on the way
we particularly are but I was going to
say uh you know in this kind of picture
so a particle in this in this kind of
picture is this kind of uh lump of kind
of structure in this graph that can move
without change through time so now the
question is in Ral space and this is
where it kind of philosophy meets
science in some strange way in um in Ral
space you've got two minds that are at
different places in Ral space and you
can always translate between them just
like you can translate between two
different computers two different
touring machines there is a way of
translating between them but if you ask
what can you propagate what what thing
can be produced by one mind and kind of
move un changed through Ral space and
land at the other mind I think that the
you know again not not fully worked out
but I think concepts are the packaging
of thought that get to be transportable
like particles through in this case Ral
space rather than physical space so in
other words you take what's in your mind
and there are all these neuron firings
that are happening and so on and then
you say a word you you know elicit some
kind of concept and that's a thing
that's packaged enough that it can you
know arrive at my mind and be unpacked
and it's kind of the same thing in some
sense it's kind of the analog of motion
this this idea that there can be a a a
kind of a a lump of stuff that is
translated from one mind to another I
think that's kind of the the uh uh you
know that that's that's something one
can think about as um as kind of you
know that's sort of the analog of
particles it's a very bizarre idea that
the analog of an electron in physical
[Music] concept
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