/sci/ - Science & Math

I print a journal called Space. It is about space but we capitalise it since it's the name of the publication.

>>3038956

Excuse my typos, I am in an altered state of mind and was too eager to send my message.

If you have a specific question about space in any physical theory I might give you an answer. Otherwise

>It seems like no-one even thinks about this.
http://en.wikipedia.org/wiki/Philosophy_of_space_and_time

>>3038966

It might be more aesthetically pleasing if you didn't. I think.

>>3038975

I don't have specific questions, but I am looking for an answer based in hard physics, not philosophy. What is this 3 dimensional "space" all around us and why is does it exist? What holds it together?

>>3038990

Additionally, you can consider my question being "what is a vacuum". Not what is the definition of a vacuum, but what the fuck _is it_. As to my understanding there is no way to measure a vacuum except by it's boundaries (i.e. the energy/mass surrounding it). Why is that, how is that possible? What the fuck is a vacuum?

Think of everything thing as this. What is the difference between the space in outer space and the space down here on Earth. Both have gravity (outer space has micro gravity not a lack of gravity) and particles (space has particles just not to the same degree per meter cubed). When it comes down to it, space can be the word to describe all coordinates in our plane of reality. The only difference is the amount and kind of particles there (granted the location and ammount of particles are used to determine the force of gravity)

>>3038969
>I am in an altered state of mind

Tell us something we don't know.

>>3039012

But you're talking about particles. That is matter and energy existing exists in space. But what is it where they exist? And I'm not talking about nomenclature either, but the answer rooted in physics. What is space? As far as I know, we have no definition for it. The only way we can define a vacuum (and consequently, space) is by the _absence_ of matter and energy. But that's not good enough, it doesn't answer the question: what is it?

>>3038990
In general relativity it is a set of points

http://en.wikipedia.org/wiki/Set_theory

which are there, even without an observer, and which admit a metric and therefore a topological structure

topology: "which point is close to another?"
http://en.wikipedia.org/wiki/Topology

metric: "how far away are two points"
http://en.wikipedia.org/wiki/Riemannian_geometry

the concept of topology makes sense even without a metric, but we have one, yay.
in general relativity, in empty space (additional fields), if you consider a single point, then there is no structure (since the metric is always locally flat)
if you consider some neightborhood, then in empty space there is the metric structure, which you might consider a (tensor-)field.

so the only thing in space are points and some field, which basically tells you how far away things are and how curved the space is.

http://en.wikipedia.org/wiki/Metric_tensor_%28general_relativity%29

you can compute the metric using the einstein equations

http://en.wikipedia.org/wiki/Metric_tensor_%28general_relativity%29

which depend (on the global topology and) if there is some matter around (matter influences the metric in empty space even from a distance (but not instantaneously (gravitational waves)))

From what I know a vacuum is a space absent of matter. For what ever reason nature abhors vacuums, hence the force created by them.


*This may be wrong, but when an item moves it has a push and a pull, two equal forces. The push is the directional as well as kinetic energy and the pull the previous space filling back up (pull may be wrong). When you remove the pull, the force builds up....hence a vacuum

>>3039047

But you're talking about concepts and math. About our definition of space. Not the PHYSICAL reality of space. _What_ is it, physics wise? Space is not coordinate systems or points, those are just human abstractions used to understand how all this shit around us functions in space. It doesn't answer the ultimate question.

Can't space be defined because in a sense it is what encompasses us? In order to understand space we would need to step outside of it? But of course that is not possible.

>>3039037
You are a fucking retarded.

Sober up and we'll talk.

>>3039052

But again, that's not answering the question. Yes, a vacuum is absent of everything. But what is that what is absent of everything. The 3 dimensional volume absent of everything. What is it? We have no definition for it. The only way we define it is by what it is lacking.

>>3039076

I believe this is what Einstein felt like. I'm sure I'm on the verge of a scientific breakthrough here.

>>3038956
You fucking derp, SPACE didn't expand. There is nothing to expand. It's the lack of matter, so it's infinite. You mean THE UNIVERSE, as in, the collective name for all matter.

>>3039012
<div class="math">BACK\; TO\; HIGHSCHOOL</div>

I wanted to post something like >>3039047
but you beat me to it. So instead, QM point of view:

vacuum is most definitely not just an absent of matter. There is a solution for vacuum that predicts random fluctuations which make particles pop out from nothing from time to time temporarily and this shit really happens.

>>3039072
the same logic can be applied to any physical object (what is an electron?).
You can think of it as an physical representation of mathematical concept (in this case, a manifold) just as you do with every single fucking thing in physics.

>>3039089
sorry bro, space DID expand.

Trying to illustrate my point here:

We know our universe is expanding. In a sense, more "space" is being generated. What is this space that is being generated?

>OP THINKS HE'S MAKING SENSE THANKS TO DRUGS


>WANTS SCIENTIFIC INTERPRETATION OF SPACE
>DOESN'T WANT SCIENTIFIC EXPLANATION OF HOW HIS BRAIN IS NOT FUNCTIONING

>>3039072
I think I stole your link.
Well yeah, if you talking physics then you get mathematical definitions, the rest is much philosophy - but actually, I don't see why you have a problem with the philosophical considerations anyway

>>3038990
In general relativity it is a set of points

http://en.wikipedia.org/wiki/Set_theory

which are there, even without an observer, and which admit a metric and therefore a topological structure

topology: "which points are in the neighborhood ofsome specific point?"
http://en.wikipedia.org/wiki/Topology

metric: "how far away are two points?"
http://en.wikipedia.org/wiki/Riemannian_geometry

the concept of topology makes sense even without a metric. But we have one (yay) and it also encodes the topology.

In empty space of general relativity (no additional fields), if you consider a single point in space, then there is no structure (since the metric is always locally flat).
But if you consider some neighborhood, then in empty space there is the metric structure, which you might consider a (tensor-)field. It's some information, which "exists", even in vacuum. It's basically the information which way a totally free particle would go if it would cross this area.
So the only thing in space are points and some metric-field, which basically tells you how far away things are and how curved the space is.

http://en.wikipedia.org/wiki/Metric_tensor_%28general_relativity%29

you can compute the metric using the einstein equations

http://en.wikipedia.org/wiki/Metric_tensor_%28general_relativity%29

which depend (on the global topology and) if there is some matter around (matter influences the metric in empty space even from a distance (but not instantaneously (gravitational waves)))

so much for GR...

Gravity bends space. Space's bending determines gravity. All gravity is just gravitons, a type of string. Even so called vacuums are filled with gravitons. Space is basically just gravitons, which detirmine spaces structure. The real question is then, if space itself is merely particles, with no space in between them because they are space, then how do these gravitons have a position in space if they are space. String theory has some pretty weird implications for space-time.

>>3039101

But again, this is about understanding the _form_ of space and _how_ it behaves. It doesn't answer the question of _what_ is space.

>>3039096
>We know our universe is expanding. In a sense, more "space" is being generated.

In the sense of my post above
>>3039101
the statement "space is expanding" is a property of the metric.
In this case:
http://en.wikipedia.org/wiki/Friedmann-Lema%C3%AEtre-Robertson-Walker_metric

there should be a factor a(t) somewhere, and if time t goes by then a(t) gets bigger which means that the metric says (in the sense of my post above) that different points (points of the manifold in the set theoretic sense) are more and more far away.

Einstein predicted the expansion of the universe because he solved the equations for the metric he made up (posted above) and they told him it's a likely metric for our universe. And then it was observed. Well, good for Einstein.

>>3039114

Now we're getting somewhere, even though I disagree that space is "made of" gravitons. But even in that case, if there were gaps between the gravitons, then what would those gaps be? Now, if indeed space was made of gravitons and there were no gaps, it would still boggle my mind as to _where_ the fuck the gravitons exists in? Shit, my mind feels like a fractal.

>>3039121

I didn't understand much of that link, and it most certainly failed to educate me in regards to my question.

>>3039133
>>3039122
well, two points:
1) you're asking "what is space", accept no mathematical definition but still say you want an answer in physical terms and not in philosophical terms.
Well, you won't get far, physics just makes up models and the existence of the correspondence between reality and some mathematical theory is not a given fact.
2) You state here
>Now we're getting somewhere
because you seem to like the idea that gravitons explain space in terms which are more matter-like, something you could grab, but gravitons are literally just the quantized version of the metric
http://en.wikipedia.org/wiki/Graviton

furthermore, string theory is much more backgroud dependend than GR.

You might consider just dropping the notion of the existence of space. maybe you feel better then.

Lastly, you might consider some ideas like quantum gravity in the sense of loop quantum gravity. There, in the end, the aim is to describe only correspondences between configurations of fields/states in a way that time isn't as prominent as in other theories. just another parameter so to speak.

http://en.wikipedia.org/wiki/Wheeler_dewitt_equation
(although this link is again very technical)

From The Elegant Universe;
1/2
Heisenberg's uncertainty principle asserts that a similar frantic shifting back and forth of energy and momentum is occurring
perpetually in the universe on microscopic distance and time intervals. Even in an empty region of space—inside an empty box, for
example—the uncertainty principle says that the energy and momentum are uncertain: They fluctuate between extremes that get
larger as the size of the box and the time scale over which it is examined get smaller and smaller. It's as if the region of space inside
the box is a compulsive "borrower" of energy and momentum, constantly extracting "loans" from the universe and subsequently
"paying" them back.

>>3038956

Dude. It's nothing.

>>3039197
2/2
But what participates in these exchanges in, for instance, a quiet empty region of space? Everything. Literally.
Energy (and momentum as well) is the ultimate convertible currency. E = mc
2
tells us that energy can be turned into matter and
vice versa. Thus if an energy fluctuation is big enough it can momentarily cause, for instance, an electron and its antimatter
companion the positron to erupt into existence, even if the region was initially empty! Since this energy must be quickly repaid,
these particles will annihilate one another after an instant, relinquishing the energy borrowed in their creation. And the same is true
for all of the other forms that energy and momentum can take—other particle eruptions and annihilations, wild electromagnetic-
field oscillations, weak and strong force-field fluctuations—quantum-mechanical uncertainty tells us the universe is a teeming,
chaotic, frenzied arena on microscopic scales. As Feynman once jested, "Created and annihilated, created and annihilated—what a
waste of time."
32
Since the borrowing and repaying on average cancel each other out, an empty region of space looks calm and
placid when examined with all but microscopic precision. The uncertainty principle, however, reveals that macroscopic averaging
obscures a wealth of microscopic activity.
33

>>3039174
+1000 internet for you sir

>>3039197
>>3039201
your point is?

>>3039201

But you misunderstood me. I'm not talking about what is IN space. I'm talking about WHAT is it. Why does it exist?

I wonder if I'm thinking so outside the box here that you people have difficulties understanding my question? Imagine yourself observing our universe from the universe. What is that volume in which everything in our universe exists?

>>3039221
>from the universe
from the outside

Space is nothing more and nothing less than the potential area in which matter can be.

What's your favorite thing about space? Mine is space.

>>3039230

It has to be more since it is not potential, it does exist. It is there regardless of whether there is anything in it or not.

>>3039221

DUDE - I'm at telling you - it's nothing.

Why it exists? That is a WHOLE other question which I have no idea about.

Space is just the volume where things are allowed to exist.

>>3039241

That's wrong.
Read my post again.

Space is nothing more and nothing less than the POTENTIAL area in which matter can occupy.

It doesn't matter whether matter is occupying it. The potential for matter to occupy it is always there, unless it's already occupied (in which it needs the potential matter to occupy it in order for the it to be occupied in the first place).

>>3039221
For the moment, I'll assume there is something which you consider to be existence. Let's say your nose and your navel.

okay, so the is something called OPs nose and something called OPs navel.

Now let's say space doesn't exist, but for every two things which exist (for example nose and navel) there is a function which gives you one real number, you call distance.

>>3039269
to be in existence*

>>3039269

Still does not answer the question of _what_ space is. You're simply describing it in relation to the objects existing in it. You're trying to explain what a my maple table is by telling me that my mouse and keyboard are 10 centimetres apart.

>>3039277
Space is space, just like an electron is an electron. What is an electron? It's an electron because nothing IS like an electron. It's not something you can relate to from your experience the way you'd like to.

>>3039277
no I'm trying to suggest that if you don't even like the idea of space being an abstract set of points then you should drop the notion of space. the problem with space and vacuum is that many words/things/notions of it are described as the absence of something but you struggle with that. You ask "what" because you think of things as things (we have a Wittgensteinian problem here).
So I'm suggesting you replace space with some mathematical attributions with are defined between things whos existence you don't struggle with - because that's a possibility.

Maybe that's a mean question, but can you imagine an answer which you would like?

Anyway, you won't find your answer in physics I'm afraid.
Maybe there is an answer, but I think nobody knows it.

>>3039221
>>3039224

Well, there you have the main problem.
In order to differentiate between space and the objects it does(n't) contain so you could regard it as a stand alone phenomenon or whatever you want to call it, you must be outside of the space itself.

However, this is by definition impossible for us to do, so we simply can't know and have no way to do so. Although I believe that philosophy and science should go hand in hand -as most of the greatest scientists used to-, this is not a question that can be answered by science - or (for the sake of it) at least yet- but can only be guessed by philosophy.

>>3039402

I refuse to accept this. To me, you're Planck explaining to Einstein how the theory of relatively cannot be generalized. You're contained within the barriers of your thought.