
What Is Space? - prostoalex
http://nautil.us/issue/49/the-absurd/what-is-space
======
mathgenius
If you are really serious about this question then you would also consider
what mathematicians have to say about "space". Unfortunately, this is pretty
much the whole of mathematics, but I think special attention should be given
to the duality between _geometry_ and _algebra_. This stuff goes back to
Descarte. For example, you can consider the points equidistant from a specific
point, which gives a circle. Or you can consider the algebraic expression
X^2+Y^2=1. Both of these viewpoints are in a sense, two sides of the same
coin. What is that coin? Deep answers can be found when you start doing funky
things like change your definition of numbers, to say, a finite field. Even
just having two numbers 0 and 1 is quite interesting to consider. What is the
corresponding geometry? Or, more confusing still, let's drop the requirement
that xy = yx (commutativity). Now what are the non-commutative geometries on
the other side of the coin?

Considering the wide variety of these apparently fanciful ideas that have made
their way into theoretical physics fills me with wonder. I wonder if the
authors of the article mention any of this stuff in their book.

~~~
westoncb
Controversial, I know—but I wonder how deep that connection actually is...

'the points equidistant from a specific point' and 'X^2+Y^2=1' are both
_descriptions_ that we know how to parse and and evaluate into the same thing.

Don't get me wrong, I do think it's a super interesting property of the
systems of description we formulate that it's possible to talk about the same
things with different abstractions (which happens a lot in math:
[https://en.wikipedia.org/wiki/Duality_(mathematics)](https://en.wikipedia.org/wiki/Duality_\(mathematics\))),
even with very high degrees of precision—but I have a hard time seeing how
this could be a property of space rather than of human conceptual
structure/language.

~~~
posterboy
The last bit can be said about anything. It might be relevant if the notion is
intrinsically motivated by an instinctive search for closed forms. "Space"
being emptiness would be isomorphic (dual) to many experiences of limits. In
contrast, mystifying the unknown might inspire curiosity at best, reserving
free space in the back of the mind, or philosophic arguments at infinitum at
worst.

The article is somewhere in the middle with its talk around gravitational
waves and einsteinian curvature of space, without directly mentioning them.

------
ravenstine
I'm simultaneously glad that someone's writing articles about these things and
dismayed that too many people will read this and believe they understand
astrophysics without having philosophized about it on their own. Analogies
like "space goo" are useful but can be a double-edged sword(seems the author
recognizes this) that can mislead the public in much the same way that the
holographic universe theory leads the public to think we might be in a
simulation run by space bastards, which doesn't really explain anything about
the very nature of existence.

~~~
lmm
Lack of philosophizing is less of an issue than ignorance of the physics, even
- especially - among philosophers. There ought to be a rule against
speculating on the nature of reality in the context of quantum physics if you
haven't completed the exercises in Nielsen and Chuang.

~~~
zdkl
There ought to be a rule against people making rules not founded in maths.

------
Razengan
Some related questions that I don't know where, or how, to ask:

\- Is there a “quantum” of space? Where/how is location stored?

\- If electromagnetic repulsion is what makes matter “take space”, and if
virtually all macroscopic phenomena are governed by electromagnetism and
gravity, then could this reality be said to be “gravelectromagnetic”, and
might there be other “dimensions” governed by other forces, like “cones”
extending in differing “directions” from the subatomic scale? [0]

\- Could gravity be the result of space trying to deflate/return to the pre-
Big Bang singularity, kind of like pulling magnets apart? i.e. is gravity the
“opposite” of, or a reaction to, “space?”

[0]: [http://i.imgur.com/6meZmc2.png](http://i.imgur.com/6meZmc2.png)

~~~
sillysaurus3
_Could gravity be the result of space trying to deflate /return to the pre-Big
Bang singularity, kind of like pulling magnets apart? i.e. is gravity the
“opposite” of, or a reaction to, “space?”_

I may be off the mark with what you believe, but just in case:

It's a common misconception that the big bang originated at a specific point.
The big bang seems to have happened everywhere simultaneously, so it wouldn't
be true to say that gravity is pulling everything back toward a point of
origin.

Here's an excellent video on misconceptions about the universe:
[https://www.youtube.com/watch?v=XBr4GkRnY04](https://www.youtube.com/watch?v=XBr4GkRnY04)

(Ironically, the video was created because the creator was a scientist, yet
they fell into the trap of believing something incorrect to the point of being
publicly mistaken about it. The universe is extremely counterintuitive!)

~~~
jsmthrowaway
Holy shit, the Big Bang happened everywhere simultaneously because the Big
Bang brought quantum fields into existence. Wow. I get it now.

As a non-physicist, wording it like that made a lot that I didn't understand
suddenly click.

~~~
andyjohnson0
> the Big Bang happened everywhere simultaneously

Until the big bang happened there wasn't any "where" for anything to happen in

------
terryf
"But if you use a rigid ruler, all of its atoms would hold on to one another
tightly (with electromagnetic forces), and the ruler would stay the same
length, allowing you to notice that more space was created."

This is the part that I don't really understand - how does the electromagnetic
force "know" the true distance?

Basically, there is an equation that determines the strength of the field that
depends on the _distance_ from the centre of the particle, or rather the
"particle" creates a ripple in the field. The ripple still has a length
though.

So, the question then becomes - somehow the fact that the field has a bigger
differential between two spots in space, keeps from more "space" appearing
between those two spots.

Yet where the field is zero (or whatever the lowest energy value is) more
space can be created within the field. So, it seems that there is a "space
field" and a number of other fields, that interact with each other and can
influence the properties of each other.

This kind of makes sense, essentially if the "space field" can have values
attached to it, that in effect would determine "distance" from our
perspective, then the interactions with other fields can influence the change
in distances.

IANAP, so if you are, would this be a correct line of thinking?

~~~
yk
The electromagnetic force does not know the true distance, here the ruler is
more of a theoretical construct.

Perhaps it helps, if you think about it as moving the underlying coordinates
vs moving the particle. (There is no difference between the two pictures in
the theory only the relation between coordinates and atoms appear. Sort of, at
least.) So, if you apply a force to an atom, that means that the second
derivative of its position changes. On the other hand, if we imagine for a
moment that the atom is stationary and the coordinates change, then the second
derivative of its position will change and it will therefore feel a force,
gravity.

------
205guy
Usually, I enjoy articles that explain difficult concepts in math and physics,
and I like to think about these concepts. But this article just rubs me the
wrong way. It throws out some scientific jargon in the first paragraph that
could be accurate, but instead they belittle it. Then they try to describe how
some people would describe "space" but then argue as if everybody thought that
way. I don't and felt talked down to. Worse, they argue as if "space" could
have a simple, singular meaning, when obviously it can be defined on many
levels, or at least looked at from many levels.

Then I got to the part that says: This is the part where your brain goes,
“Whaaaaat ... ?” No, my brain is not so easily confused that it expresses
itself in slack-jawed mono-syllables. I get it that the article is trying to
simplify some explanation, but I think it's trying too hard and failing. It
makes too many assumptions about what the reader thinks and then bases its
arguments on these wrong assumptions.

I much preferred the discussion and links here on HN.

Fwiw, I see space as the coordinate system of our universe but with no origin
because it's all inertial frames of reference. It is usually thought of as a
fixed 3-d Cartesian system plus time, but as I went through life and learned
about relativity and Big Bang theory and universe expansion, I understand it
as a much more dynamic and complex system.

~~~
205guy
I'm trying to read through the article now, and disappointed in every
paragraph. Even the illustration that are trying to be cute are blatantly
inaccurate. For example the one labeled "Space Expansion" shows a grid on the
floor. In the case of expansion, the number of grid lines would be the same
not more, and the point is that we definitely wouldn't feel the expansion.

And then the explanation of rigid rulers and soft taffy rulers seems wrong.
Both would expand because the underlying nature of matter expands along with
the universe. In other words, all atoms and their distances are affected
equally because the forces that determine those distances also change. It has
nothing to do with soft or rigid property of an object, which is at the macro
level of our perception of matter.

I really expected better of Nautilus, I thought they had a more rigorous
standard.

~~~
pavel_lishin
> _all atoms and their distances are affected equally because the forces that
> determine those distances also change._

Is that true? If the expansion of space didn't affect anything, wouldn't we
not see any of the redshift?

------
Noxchi
How fast are you really going?

One of the things I've thought about is relatively.

Consider a toddler strapped to his car seat in a luxurious BMW cocoon while
his father speeds down the autobahn at 200km/h. He calmy drinks from his sippy
cup.

You're in a passenger jet above him going 700km/hr. You're going 500km/hr
faster than him.

But how fast are you _really_ going?

Consider that the Earth is spinning around the sun at a rate of 1 billion
kilometers per year or about 100,000 km/hr.

You're on Earth, so is your jet's true speed 100,700 km/hr?

Relative to the sun, yes, but everything that orbits our sun is considered our
solar system which itself is orbiting our galaxy at a rate of 800,000 km/hr.

So if we add the 800k, 100k, and 700 km/hr your plane is moving, is it not
fair to say you are traveling at almost a billion kilometers per hour?

I'm sure you can infer the galaxy itself is hurling through space at an
ungodly speed.

I ask two questions:

1\. When does this stop? What is the most supreme center in the universe?

2\. Just as the child could roll down his window, and have instant access to
the outside, is there a way we can do the same?

~~~
platz
there are no absolute reference frames. only relative ones! however, at least
there is a fixed relationship between reference frames they all must obey with
regards to the speed of light.

~~~
tombh
Just thinking out loud here. If the speed of light is absolute (it's not
relative right? it doesn't change in any reference frame?), then could the
speed of light be considered the base axis, or to continue the metaphor in the
parent comment, that the speed of light is the 'outside the car'? Also,
doesn't time 'stop' when you are at C, so that the whole idea of space (speed
* time) sort of collapses?

~~~
lmm
> If the speed of light is absolute (it's not relative right? it doesn't
> change in any reference frame?), then could the speed of light be considered
> the base axis, or to continue the metaphor in the parent comment, that the
> speed of light is the 'outside the car'?

The speed of light is the same in any (inertial) reference frame. But you
can't use it as a reference to compare other speeds against, because there are
more degrees of freedom than you might think: a speed is calculated from both
a distance and a time. So you and I could be looking at an asteroid and you
say it's stationary and I say it's going half the speed of light, and we'd
both be right, even though we both agreed what the speed of light was. Special
relativity works like this.

> Also, doesn't time 'stop' when you are at C, so that the whole idea of space
> (speed * time) sort of collapses?

If you naively plug zeroes and infinities into the equations you won't get
good answers, but if you're careful and work with limits then everything works
right. What specifically were you asking about when going at C?

------
graycat
One of the ones that gets me and may be central to _space_ is the central idea
in the Young's double slit experiment, the Michelson-Morley interferometer,
the Fabry-Perot interferometer, etc. Indeed, the night I was studying for my
final in optics and radiography, I thought of this stuff and never really
studied for the exam!

So, just shine a light through a beam splitter. So, ballpark half of the light
continues on essentially straight and the other half is deflected 90 degrees.

Such a beam splitter is in the M-M experiment. For the double slit, it divides
the beam. For a Fabry-Perot, it ends up making many such splits.

Okay, as we heard from Feynman, we could send just one photon through any of
those devices and still get the same interference effects. Feynman also
explained that we'd get the same result sending one electron at a time instead
of a photon.

So, here, to heck with recombining the beams and getting it to interfere with
itself.

Instead, consider just the beam splitter. So, the photon (or electron,
neutron, whatever) is a wave function, and after the beam splitter that wave
function is in two parts traveling apart, in the case of the photon, if we add
a mirror to have the two halves going in opposite directions, at the speed of
light.

But such splits of the wave function happen at every window pane, no doubt in
every water droplet, etc., that is happen all the time.

And such a wave function doesn't split just once but commonly many times. So,
the one, poor photon as one simple wave function is soon in dozens of pieces
all moving away from each other usually never to come together again. After a
billion years, the pieces are still moving away from each other.

Then, presto, bingo, one part of that wave function enters our telescope and
hits our detector. Then all the dozens of pieces of that wave function,
scattered across a billion light years, have to disappear, instantly, since
with two telescopes we can never get two detections from the one photon.

Well, that's tough to believe.

So, maybe the universe is filled with tiny pieces of wave functions condemned
to go on forever. Maybe that's the dark matter?

~~~
lmm
> And such a wave function doesn't split just once but commonly many times.
> So, the one, poor photon as one simple wave function is soon in dozens of
> pieces all moving away from each other usually never to come together again.
> After a billion years, the pieces are still moving away from each other.

> Then, presto, bingo, one part of that wave function enters our telescope and
> hits our detector. Then all the dozens of pieces of that wave function,
> scattered across a billion light years, have to disappear, instantly, since
> with two telescopes we can never get two detections from the one photon.

> Well, that's tough to believe.

There are a dozen different possibilities for what the photon has done - a
dozen different universes, if you like. As long as the photon never interacts
with anything else, this bundle of a dozen universes can act much the same as
a single universe. Certainly if you're just looking at a telescope, all dozen
versions of that telescope are behaving the same, so they behave like a single
unified instance.

When the photon hits the telescope in one universe, the perspective shifts:
the telescope is now "inside" the 12-way split, either the photon went one way
and the telescope recorded it or the photon went another way and the telescope
didn't. And when we look into the telescope, we again shift from looking at
the superposition from outside to being part of the superposition on the
inside.

Our language isn't great for talking about this, because it's not a binary
is/isn't thing - entanglement is a continuous phenomenon. If you imagine just
two photons each in one of two states, then it's easy enough to imagine:
photon A is in a superposition of states 0 and 1, photon B is in an
independent superposition of states 0 and 1 - each photon has two possible
"local universes", but because they're distant and noncommunicating, to each
one the other looks like it's in a superposition. And it's easy enough to
imagine: photon A is in a superposition of states 0 and 1, photon B is in a
superposition of states 0 and 1, but they're entangled such that we know the
sum is 1 - here there are two possible "global universes", and we see a
superposition between them, but ecah particle knows the other is in the same
universe - if A is an 0 then it knows B is a 1 and vice versa. The part that's
hardest to imagine is that it's also possible to be somewhere in between these
two states: A and B can be partially entangled such that e.g. there's a 75%
chance that the sum is 1.

> So, maybe the universe is filled with tiny pieces of wave functions
> condemned to go on forever. Maybe that's the dark matter?

No. The evolution of quantum systems is unitary and conserves energy.

~~~
kefka
> There are a dozen different possibilities for what the photon has done - a
> dozen different universes, if you like. As long as the photon never
> interacts with anything else, this bundle of a dozen universes can act much
> the same as a single universe. Certainly if you're just looking at a
> telescope, all dozen versions of that telescope are behaving the same, so
> they behave like a single unified instance.

Well that's interesting you bring it up this way.

If what you said is possibly true, then light could be a carrier of things
like multi-dimensional spin, or possibly where dark matter really comes from
(inter-dimensional interference).

I know Greg Egan has discussed the possibility of infinite orthogonal
dimensions that energy can leak into. And by energy conservation, the result
would be things like dimensional rotation and other effects we cannot yet
perceive.

One theory is that the EM-Drive uses a rudimentary version of this effect.
We're all still awaiting the results.

~~~
lmm
> If what you said is possibly true, then light could be a carrier of things
> like multi-dimensional spin, or possibly where dark matter really comes from
> (inter-dimensional interference).

That's a total non-sequitur. What on earth are you talking about?

------
Jaruzel
"Space is big. Really big. You just won't believe how vastly, hugely, mind-
bogglingly big it is. I mean, you may think it's a long way down the road to
the chemist, but that's just peanuts to space." \- Douglas Adams

~~~
knouth
"At some point in the future, we’re going to look back and say how did we do
it without space?" \- Donald Trump

------
mjfl
To all I recommend Tim Maudlin's Philosophy of Space and Time:

[https://www.amazon.com/Philosophy-Physics-Princeton-
Foundati...](https://www.amazon.com/Philosophy-Physics-Princeton-Foundations-
Contemporary/dp/0691165718/ref=sr_1_1?ie=UTF8&qid=1499137957&sr=8-1&keywords=tim+maudlin)

It might not answer the question, but really helped me understand the nature
of space time.

------
ChuckMcM
This continues to be one of my favorite questions.

In high school we were creating a vacuum in a bell jar to do the 'drop a
feather and drop a weight' experiment and my physics teacher asked it. "So if
we didn't have our apparatus in there, and we sucked it dry, what would be in
there?"

It makes a great interview question because it helps identify people who have
a hard time holding an unknown concept in their head and working with it.

I asked that of one of the folks I interviewed for Google when I was there and
we spiraled off into a discussion of branes and multi-dimensional manifolds
and quantum wave equations[1].

[1] Fun interview and they got the job :-)

~~~
kobeya
I went into entrepreneurship because I hate these kinds of interviews. You
think a good way to tell whether I'd be good at writing code is my opinion on
philosophy outside my domain of expertise?

~~~
anonymoose111
google interviews try to gauge how smart you are, not how well you can program

~~~
kobeya
I fail to see how someone who is not a domain expert on the nature of space-
time asking someone else who is not a domain expert can result in a reliable
determination of how smart either person is.

To be clear, I don't think the correct answer of "I don't know, but I'll do a
review of the literature and see what the scientific consensus is" is what the
interviewer was hoping for, which is my contention.

~~~
TheSpiceIsLife
You can have it both ways. I'd probably say something like "That's not my
field of expertise, though if you'd like me to speculate I'd be glad to."

~~~
kobeya
The point is I don't see how speculation about things you know nothing about
is supposed to be an accurate gauge of a persons inate intelligence.

~~~
shardo
What if I put it this way.

Do you think speculation on things that are an inferential step[1](or a couple
of steps) away from things you currently know could be a gauge of a person's
innate intelligence?

Intelligence is required to make inferences. Assuming a common starting
ground, a person who could make the most logical inferences from it to explain
a result would suggest that he's smarter. I do not claim to say a person who
makes 10 good points is less smart than someone who makes 11 good points. But
he surely you can agree that a person who is able to make 0 inferences is
likelier to be less intelligent than someone who makes a hundred.

[1] Where my idea of inferential step is taken from -
[http://lesswrong.com/lw/kg/expecting_short_inferential_dista...](http://lesswrong.com/lw/kg/expecting_short_inferential_distances/)

~~~
kobeya
> Do you think speculation on things that are an inferential step[1](or a
> couple of steps) away from things you currently know could be a gauge of a
> person's innate intelligence?

No, I do not. It introduces a large capacity for things to go wrong, and it is
very difficult for the interviewer to separate themselves from process.
Speculative development is a road marked by dozens or hundreds of failed
efforts before you hit on success. Either the interviewee happens to hit upon
one of the few "correct" answers in the time available -- password guessing --
or some tolerance of wrong answers is to be accepted. But it is quite
difficult to differentiate bad speculation from fruitless speculation, in a
way that usefully differentiates candidates based on capability.

------
jhallenworld
There have been some recent experiments and proposals looking for discreteness
of space:

[http://backreaction.blogspot.com/2015/12/what-fermilabs-
holo...](http://backreaction.blogspot.com/2015/12/what-fermilabs-holometer-
experiment.html)

[https://www.space.com/29629-quantum-foam-bubbly-universe-
sea...](https://www.space.com/29629-quantum-foam-bubbly-universe-search.html)

------
graycat
Do we know enough yet to have some good guesses about

(1) the purpose of the universe,

[https://news.ycombinator.com/item?id=14570170](https://news.ycombinator.com/item?id=14570170)

(2) the end of the universe, (A) big expansion and cool down to nothing, (B)
no more expansion and cool down to nothing, (C) contraction back to another
big bang, (D) something else very different?

~~~
cyphar
> (1) the purpose of the universe,

This question is far more philisophical than anything. Personally I subscribe
to Camus' Absurdism[1] -- that our yearning for meaning and purpose is ironic
given how uncaring and lacking in meaning our universe is.

> (2) the end of the universe

There are several theories[2], but from my understanding we need to better
understand "dark matter" and "dark energy" (scare quotes because those names
are really silly, since we know effectively nothing about either).

In particular, it appears that we live in a flat universe but the evolution of
the universe becomes more complicated with the cosmological constant terms in
the evolution equations (believed to correspond to dark energy). Effectively,
the cosmological constant can be seen as an energy density that remains
constant throughout the universe which means that the amount of dark energy
increases as the universe expands. I believe we discussed the current theories
in my second-year cosmology course, but I can't recall the conclusion (it
wasn't taught very well).

[1]:
[https://en.wikipedia.org/wiki/Absurdism](https://en.wikipedia.org/wiki/Absurdism)
[2]:
[https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe](https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe)

~~~
graycat
For my first question, I was wondering if by now we had enough information to
make a guess that is not just philosophical.

~~~
cyphar
But I don't understand how the question "what is the purpose of X" can be
anything but philosophical. Science is primarily concerned with creating
models of reality and testing the predictive power of those models. The
"purpose" of something is not really a meaningful concept in that context.

... unless by "purpose" you mean cause? As in, what caused our universe to
exist? That is also not really a meaningful question, because time began with
our universe so it's not clear what the concept of "before our universe"
actually would refer to. Physically, I believe the currently popular theory is
that the progenitor for our universe was an anti-matter explosion caused by
the spontaneous creation of a matter+anti-matter pair (which happens all the
time in a perfect vacuum due to Heisenberg's uncertainty relation -- \Delta E
\Delta t \ge \hbar/2). There are several unsolved problems with this theory,
the biggest one being how does it explain that there is a clear imbalance
between the amount of matter and anti-matter in our universe.

~~~
graycat
> But I don't understand how the question "what is the purpose of X" can be
> anything but philosophical.

Again, my guess is that this depends on how much we know. Or, there about has
to be a purpose. And eventually as we learn more there should be some clues
about what that purpose is. So I'm wondering if we know that much yet?

A first little clue is the speed of light speed limit that so far seems to say
that we are quite isolated from the rest of the universe. So, somehow having
us isolated was _deliberate_. Then, what might be the purpose of having us so
isolated?

Then there's the 3 K background radiation. That's one heck of a clue. What
might be the reason for giving us such data? To answer, what can we do with
it? If we note what we can do with the 3 K data and that seems really special,
e.g., we wouldn't be able to do that without the 3 K data, then what is so
special we can do with the 3 K data might be a clue for the purpose of letting
us have that data.

There's the Heisenberg uncertainty principle. So, it keeps us from being as in
an 1890 view of physics, _mechanistic_. We are stopped at that level by some
_dice rolling_. So, why? When we see how that stops us, we might get a clue of
a purpose.

All of that is very thin stuff, but maybe we are on the way to discovering
enough to start to conclude what the purpose is.

One point is our existence and our abilities: First cut, how the heck to look
at the basic physics and guess the chemistry, then, especially the biology,
and, astounding, how the biology developed into us. That's some amazing laws
of physics that let that happen, maybe ensured that it would happen. So, what
the heck is the purpose of us being here, our existing? That is, we're the
most special and amazing thing we know of in the universe. So, if there is a
purpose, then it looks like we are a key part of it. So, just what the heck
might be what we are to do with our abilities to understand the universe?
Then, do we get a hint of the purpose from what we can do? That is, is the
purpose the special stuff we can, or will be able, to do? For that if we look
ahead, just how much might we be able to do? Build Dyson spheres? Okay, then
what would that enable?

We don't see other planets flashing light signals at us from their Dyson
spheres. So, why not? Sure: There are other, better forms of long distance
communications, and every planet with a Dyson sphere knows this. So, soon we
should discover this better means of communications. So, where the heck to
look for those better means. Then when we find them, what would that enable us
to do in the universe that would be special? Communicate only? Or both
communicate and travel? Or, if long distance travel is possible, then why ever
bother to travel; just send robots and have them send back the communications
so we can view it. Then does that communications give us a clue about a
purpose; that is, suppose we could send robots and they would communicate
back; what might we discover that begins to suggest a purpose.

Or, generally, as a meta argument, if we find some things that look really,
really special that finally, with our development, we can do that seem to
impact, explain, discover, reveal the universe, then maybe our doing that is
the purpose of the universe.

I fully agree this is very thin stuff. Still I have to suspect that as we
learn more, maybe 1 million years from now, we will begin to guess at a
purpose.

Or, if there is no purpose, then this is one heck of a big show for nothing!

~~~
lmm
> Or, if there is no purpose, then this is one heck of a big show for nothing!

It isn't really. The universe all falls out of a very few, very simple rules
playing themselves out - and the more we study it the smaller and simpler that
set of basic rules is. Physically it's pretty big, sure, but the Kolgomorov
Complexity is actually pretty small, and that's the kind of measure you need
to use when considering how good a given explanation is.

~~~
graycat
I like Kolmogorov a lot (father of modern probability) and have heard of his
complexity but need to study that and see how it applies to physics.

~~~
cyphar
Kolmogorov complexity isn't directly related to physics (and I would argue it
also falls into philosophy in this case), but what GP was saying is that the
complexity of the universe far exceeds the complexity of the laws that govern
it. So really the laws of physics are very simple if you consider how
complicated the systems they produce are.

You can fit the laws that govern the entirety of particle physics on a single
page. Add another quarter-page for general relativity and you have all of the
laws required to run our universe (on paper).

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signa11
fwiw, a tangential comment, jorge-cham, is also the progenitor of phd comics.

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narrator
One thing about space that I didn't see mentioned in the article is that even
in a complete vacuum billions of miles away from anywhere there is still
inertia. If something spins around it will still experience centrifugal force,
so this is an absolute property of space and the universe that isn't caused by
interaction with another body.

~~~
cyphar
That's because rotation is a form of acceleration, and you can measure the
acceleration (or if you prefer, the gravity) of a non-intertial (accelerating)
reference frame. Galilean relativity only applies to inertial reference
frames.

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dredmorbius
John Baez, UC Riverside physics professor, on elements of various fundamental
units, limits, and constants:

[https://plus.google.com/+johncbaez999/posts/RBwcd1jTDxM](https://plus.google.com/+johncbaez999/posts/RBwcd1jTDxM)

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FeepingCreature
My reaction to the illustrations:
[http://i.imgur.com/wF3HSDM.png](http://i.imgur.com/wF3HSDM.png)

~~~
gramstrong
Well, this is ironic.

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piotroxp
Also, ive posted this here sevral times, check out and google electromagnetic
field patterns

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Piccollo
Space is what?

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basicplus2
Maybe space is the ether afterall

~~~
copperx
It could be infinity. We don’t really don’t know. But it could be. It has to
be something, but it could be infinity, right?

\- DJT

~~~
recursio
At the macro level, Space could expand outward infinitely, or maybe if you
travel further enough and you return to where you started. Or maybe there's
the multiverse thats teaming with infinite universes?

Most physicists will tell you that at the quantum level, the most fundamental
level is at the Planck scale, and the "nothingness" of space is still teaming
with particles popping in and out of existence. Some particles being
hypothetical and have yet to be discovered.

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piotroxp
They just forgot to mention the theory of everything,right

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burnbabyburn
"baby don't hurt me, don't hurt me, no more"

