Large Hardon Collider

[Kuya]

Think of the distance between two objects (space) as a function of mass(gravity), velocity (relative to c), and time.

Viewing distance and space that way, you dont see it as this 3D graph of points and vectors, but actually a ever changing (based on relative perspective) mesh. The "bending" of space is actually how we describe how matter interacts with this relativistic mesh.

i.e. To a photon, space is a single point (a photon emitted at one end of the galaxy that travels for 1000000000billion years and hits a rock on the other side of the universe views that time as instantaneous, and thus the atom that absorbed that wave was literally right next to the atom that emitted it (in the eyes of the photon).

Let me put you guys to task on making me understand this.

What i understood from you was this: That the shape of space is relative to mass, velocity, and time. This makes sense because shape is also a characteristics that is used to define something. However, what is space made of? Like if you have two points on a piece of paper, the medium between the two points is a piece of paper; you can describe its shape and you can say what it is made of and where it came from. I don't seem to comprehend what this medium is made of.

I suppose one can answer that by saying that the medium is made of particles, but that answer would lead to me believe that space is particles and mass bends this, like we travel through and move the air (and the things it is composed of), but air also travels and exists in this medium called space, thus further confusing me. Maybe what space is and what matter is are two mutual concepts necessary to define eachother.

Anyway, i understood your post as telling me what the shape of space is. Is this right?

edit:
http://www.askamathematician.com/?p=270

Having read this a few more times, i only understood that heavy objects increase the distance between two points that are near a heavy object. How do you apply this to what space is, and how do you intepret it when objects fall towards heavy objects?

I probably already sort of knew this, since i've always heard that gravity bends space, so light has to bend around that point in order to get to its "destination".

[Eliseos]

A simplistic analogy on how matter bends space would be a bowling ball on a mattress. The ball would be some heavy object (like a planet), and the mattress would be space. The indentation would be gravity. What space is actually made out of is one of the things in physics being investigated, so we don't really have an answer of "space is made out of ____".

[Kuya]

God damnit, why are the most fundamental things so hard to answer. Now i will wonder about this forever.

[Neosutra]

Let me put you guys to task on making me understand this.

What i understood from you was this: That the shape of space is relative to mass, velocity, and time. This makes sense because shape is also a characteristics that is used to define something. However, what is space made of? Like if you have two points on a piece of paper, the medium between the two points is a piece of paper; you can describe its shape and you can say what it is made of and where it came from. I don't seem to comprehend what this medium is made of.

I suppose one can answer that by saying that the medium is made of particles, but that answer would lead to me believe that space is particles and mass bends this, like we travel through and move the air (and the things it is composed of), but air also travels and exists in this medium called space, thus further confusing me. Maybe what space is and what matter is are two mutual concepts necessary to define eachother.

Anyway, i understood your post as telling me what the shape of space is. Is this right?

edit:
http://www.askamathematician.com/?p=270

Having read this a few more times, i only understood that heavy objects increase the distance between two points that are near a heavy object. How do you apply this to what space is, and how do you intepret it when objects fall towards heavy objects?

I probably already sort of knew this, since i've always heard that gravity bends space, so light has to bend around that point in order to get to its "destination".

That's just it. Space is nothing. It doesnt exist (distance is just a measurement of a time/velocity ratio relative to mass/c).

There actually isnt a distance between objects, as the natural state of the universe is 'c' space (light speed). Space is the "perceived" distance you get between two objects that is generated via how mass reacts in our universe (i.e. non 'c' moving objects).

Why high energetic "natural state" (c speed) energy starts settling into formation of mass (and thus changing the dynamics of our mesh) is the real question.

[Kuya]

That's just it. Space is nothing. It doesnt exist (distance is just a measurement of a time/velocity ratio relative to mass/c).

There actually isnt a distance between objects, as the natural state of the universe is 'c' space (light speed). Space is the "perceived" distance you get between two objects that is generated via how mass reacts in our universe (i.e. non 'c' moving objects).

Why high energetic "natural state" (c speed) energy starts settling into formation of mass (and thus changing the dynamics of our mesh) is the real question.

But if space is "nothing" why does it "bend" (assuming space is what is bending, but as you said, if it doesn't exist, then space is not what is bending) in such a way that "light goes around the distortion that heavy objects create" (i put it between quotation marks because i'm not sure of that statement) and objects fall towards other larger objects because of the "bending" of space?

What i am understanding from you is that: space is more of a relationship between objects than an object itself, and that space exists as perception and not reality. Did i understand you correctly?

[BerenTebogo]

But if space is "nothing" why does it "bend" (assuming space is what is bending, but as you said, if it doesn't exist, then space is not what is bending) in such a way that "light goes around the distortion that heavy objects create" (i put it between quotation marks because i'm not sure of that statement) and objects fall towards other larger objects because of the "bending" of space?

What i am understanding from you is that: space is more of a relationship between objects than an object itself, and that space exists as perception and not reality. Did i understand you correctly?

To paraphrase Lawrence Krauss:

"In quantum mechanics, nothing is always something."

Space exists. There is no perception about it, really. Whether as matter or energy waiting to be converted into matter (or vice versa) it is "something" at all times, even if we do not fully understand the constituent parts.

The whole dark matter / dark energy (and people with more info on these subjects can correct anything I may mess up here) hypothesis are representative of the unknown "stuff" of space. The fact that the expected measurements necessary for a certain "structure" to the universe (open, closed, or flat) match experimental values so far indicates that we have a fairly good idea that a) the "stuff" exists and b) the ratio of the "stuff" out there.

Basically, while we don't understand, specifically, the exact nature of the "stuff" of space - we can measure it and base predictions off of it that end up being extraordinarily accurate - therefore we can reasonably assume that (until better evidence comes along) the universe is not some abstract philosophical construct, but rather a medium through which matter and energy interact via the fundamental forces.

Back to the first thing I said, and the others can explain this way better than I can, but matter and energy freely and spontaneously convert back and forth between each other. The "nothingness" of space is actually a massive body because of this principle. The total overall mass of the "stuff" is slightly positive (which balances out the slightly negative total energy of gravity [fact check here maybe?]) because of a infinitesimally small tendency to exist as mass longer than energy. (again, fact check by the quantum experts here).

Dunno if that clarified anything? Or if it just made you more confused

tl;dr of the "stuff" existing is that if we can make experimentally testable predictions based on the expected presence of something, and the predictions are accurate and true, that something exists.

[Max™]

Spoiler: show

http://img506.imageshack.us/img506/5...acetimelu3.jpg

http://onlinephys.com/spacetime.GIF

Note that Neo's statement that space doesn't exist except as a perception is not shared by everyone, and is more in the realm of philosophy. As I recall, space is generally taken to be a fundamental quantity which can not simply be defined in terms of something else.


Sath is referring to the vacuum pairs, I think, a result of the energy represented by the VEV (vacuum expectation value) of certain quantum fields not vanishing in their ground state, such as the standard model explanation of the Higgs. If it didn't have a non-zero ground state, the other particles would not interact with it in a manner which gives them mass.

He's also mixing in something related to inflationary theories, that a tendency during inflation periods found in most known models is to balance the energy/gravity content close to zero, explaining the "happy coincidence" that the Universe is mostly flat on cosmological scales.

[BerenTebogo]

Also, I'm pretty sure the whole discovery of the red shift disproved all notion of the universe being "nothing".

If the empty space was truly an empty void, gravity would be able to act upon the ever expanding universe - eventually slingshotting it back in a "big crunch".

Since we know that this is now false, that objects are accelerating away from each other at speeds that more than negate the diminishing effects of gravity (eventually galaxies will accelerate away from each other faster than the speed of light due to the effect of the dark energy's repulsive force overtaking the ever-decreasing effect of gravity as the galaxies accelerate further and further away from each other), some force must exist in the "medium" of space that is acting as a repulsive force.

I think it is described as taking the constant that Einstein added to this:
http://upload.wikimedia.org/math/3/f...e687cf74c3.png
(the cosmological constant, represented as basically +guvA to the left) to rationalize a static and unchanging universe, and subtracting it from the left and adding it to the right side.

This, effectively, transforms an incorrect view of a hypothesized binding force into a repulsive force that explains the true state of our universe.

That's a shitty explanation, but yeah. Undergrad.

Feel free to correct if I stumbled over something.

[Max™]

No, that's spot on, how much of that equation do you "get"?

[BerenTebogo]

No, that's spot on, how much of that equation do you "get"?

Only really the theory behind it, the how and why it works. As far as the math goes I only really get the gravitational constant and the speed of light, lol. Haven't even been as far as a philosoraptor when it comes to this math.

[Max™]

http://scienceworld.wolfram.com/phys...Equations.html

The gravitational effects produced by a given mass are described in general relativity by 16 coupled hyperbolic-elliptic nonlinear partial differential equations, called the Einstein field equations. As result of the symmetry of http://scienceworld.wolfram.com/physics/eimg94.gif and http://scienceworld.wolfram.com/physics/eimg95.gif, the actual number of equations reduces to 10, although there are an additional four differential identities (the Bianchi identities http://scienceworld.wolfram.com/imag...srefs/math.gif) satisfied by http://scienceworld.wolfram.com/physics/eimg94.gif, one for each coordinate. The Einstein field equations are given by
http://scienceworld.wolfram.com/physics/eimg96.gif

where http://scienceworld.wolfram.com/physics/eimg95.gif is the stress-energy tensor, and

http://scienceworld.wolfram.com/physics/eimg97.gif


is the Einstein tensor, http://scienceworld.wolfram.com/imag...srefs/math.gif with http://scienceworld.wolfram.com/physics/eimg98.gif the Ricci curvature tensor http://scienceworld.wolfram.com/imag...srefs/math.gif, http://scienceworld.wolfram.com/physics/eimg99.gif the metric tensor, and R the scalar curvature. http://scienceworld.wolfram.com/imag...srefs/math.gif The nonlinearity of the Einstein field equations stems from the fact that masses affect the very geometry of the space in which they dwell. And this is the fundamental insight of (1): mass curves the geometry of spacetime, and the geometry of spacetime in turn tells masses how to move.

Nice starting entry into it, the stress-energy tensor basically represents the mass in question, with the metric tensor, such as the Ricci and whatnot, basically being functions telling you how to compute distance between two points in space.


Further depth here on Baez's page: http://math.ucr.edu/home/baez/einstein/

Baez rocks.

[Neosutra]

To paraphrase Lawrence Krauss:

"In quantum mechanics, nothing is always something."

Space exists. There is no perception about it, really. Whether as matter or energy waiting to be converted into matter (or vice versa) it is "something" at all times, even if we do not fully understand the constituent parts.

The whole dark matter / dark energy (and people with more info on these subjects can correct anything I may mess up here) hypothesis are representative of the unknown "stuff" of space. The fact that the expected measurements necessary for a certain "structure" to the universe (open, closed, or flat) match experimental values so far indicates that we have a fairly good idea that a) the "stuff" exists and b) the ratio of the "stuff" out there.

Basically, while we don't understand, specifically, the exact nature of the "stuff" of space - we can measure it and base predictions off of it that end up being extraordinarily accurate - therefore we can reasonably assume that (until better evidence comes along) the universe is not some abstract philosophical construct, but rather a medium through which matter and energy interact via the fundamental forces.

Back to the first thing I said, and the others can explain this way better than I can, but matter and energy freely and spontaneously convert back and forth between each other. The "nothingness" of space is actually a massive body because of this principle. The total overall mass of the "stuff" is slightly positive (which balances out the slightly negative total energy of gravity [fact check here maybe?]) because of a infinitesimally small tendency to exist as mass longer than energy. (again, fact check by the quantum experts here).

Dunno if that clarified anything? Or if it just made you more confused

tl;dr of the "stuff" existing is that if we can make experimentally testable predictions based on the expected presence of something, and the predictions are accurate and true, that something exists.

I was talking about the empty "space" between two objects (which is literally "nothing"), not "the entirety of space in general". And I wasn't referring to it as "some aspect of psychological perception", but as relativistic dynamics >.>. You're over simplifying the problem.

[Kaylia]

I probably asked this before, but forgot: What is it about mass that bends space exactly? I suppose i keep asking this because it's hard to comprehend, because first you have mass which i believe isn't well understood and then you have a statement like "bends space" which i'm not sure if i'm supposed to be taking literally or not, since it implies that space is a "thing" that can be bent and not just "empty space". Even using language to describe it seems inadequate.

Kuya is like that 4 years old kid who constantly ask his parent awkward question that can't be answered. I'm not sure I even want to try to answer this one, hell, I'm not sure I understand any of this myself (actually, I'm sure I don't).



[edit]
I know it was covered in details already, but in General Relativity, space is "nothing", or rather, it's a concept needed to describe trajectory. It's no different from your every days concept of space, except this time, it's a little more malleable. That doesn't mean there is no fundamental concept behind space, but if there is, we don't know them yet. Time, distance, and space are basically on the same level, we observe them, but why the universe behave this way is not known.

Also, when we are talking about "bending the space", it's in relation to the Newtonian/eucledian space. We have to bend normal space to build model that allow us explain our observation. QM might eventually explain why mass modify space, but we have a long way to go still.

[Max™]

Where do spacebabies come from?

[Kuya]

Alright, i guess i'll just have to wait and see what experiments show. If not, go into the field and do the experiments myself.

[Azull]

Where do spacebabies come from?

From Monoliths .. duh.

[Mizango]

From Monoliths .. duh.

Good answer lol.

[Tristam]

hay guys, this super serious scientist has something to say about the speed of light, or something.

http://blogs.answersingenesis.org/bl...rs-in-genesis/

Sadly his "technical" paper isn't out yet, but I would love to hear you guys obliterate it when it does. Physicists get to play with creationists now! (side note: postdoc rage at "half a year or more", I think most physics grad students would commit murder to get a paper out in less than a year of work).

[BerenTebogo]

Read that earlier, shit's hilarious.

[Cleverness]

The guy from that site must be all sorts of crazy, biblical and space research should never be in the same sentence.