What is space made of?

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poita

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This is a physics question i guess.<br /> If everything is removed from an area of space, including light and all invisible emitted and none moving things so that it is a truly pure vacuum devoid of anything then does the space actually exist?<br /> In othe words, i space defined only by being the gap inbetween things or a potential area for things to exist or does space have properties of it's own (other than a place for things to be)?
 
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jurgens

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It will exist because virtual particles that are created and destroyed will exist within "space"
 
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poita

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That doesn't answer my question as to whether or not space exists independantly or only relative to something that is occupying it, virtual, imagined or real.
 
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centsworth_II

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<font color="yellow">"...space... a potential area for things to exist..." -- Poita</font><br /><br />I would say that the potential you mention IS a property -- the prime property of space. But more than a potential area for things to exist in, space is a potential area for things to be created in. The creative force for virtual, and potentially real, particles does not come from outside of space but from within it. This creative potential is THE essential property of space. <div class="Discussion_UserSignature"> </div>
 
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fangsheath

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Your question is in fact a very profound one, and one that physics (not to mention philosophy) is still grappling with. Although "removing everything that occupies a given space" sounds simple, it is anything but. Remember that what occupies space are energy fields, gravitational, electromagnetic, and so on. How would you go about "blocking" gravitational fields? And it gets worse. Space, like time, is something that we measure only with reference to objects or processes. What is a meter? It is the length of an actual object. There seems to be no way to get around this, believe me people have tried. We know that neither space nor time are constant, but change depending on our frame of reference. If we did manage to remove all matter and energy in a given space, how would we then go about measuring how much space there was there?<br /><br />I am not trying to be obtuse. Niels Bohr tried to tell us that science is not concerned with how things actually are, whatever that means. It is concerned with what we can perceive, what we can measure. This is a hard pill for many to swallow, myself included. But if anyone can demonstrate that space, time, or anything else is "out there," independent of our measurement of objects and/or processes, I would like to hear it. Our present model divides the universe into two "things," matter/energy and space/time. But this is nothing more than a convenience, a model to help us think about our universe. My personal view is that both are expressions of something more fundamental.
 
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poita

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I'm not scientifically trained at all so i'm prone to be lax when it comes to dealing with the hypothetical.<br /> Science can sometimes make predictions even when there is no cocievable way to mesure and even generatins later when science is ready the experiments can varyfy or refute the theory.<br /> Then when we consider what lies beyong our univers, the space that will be filled by it whe it has expanded to many times its current size. what do we call this. Is it called space also?<br /> We can guess that there is probably nothing occupying the area where our universe will be whe it has expanded in a trillion years time. Does this area actully exisit then. Is this 'space', if i can call it that, an actual thing or is it more like the children that i dont have but one day may get married and have, or not? We can say that those children don't exist but the potential for them to is there. <br /> I'm afraid i may be too untrained to get your explanatins but i enjoyed reading them so far.
 
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aetherius

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<font color="yellow"> We can guess that there is probably nothing occupying the area where our universe will be whe it has expanded in a trillion years time. Does this area actully exisit then. </font><br /><br />I think most would say that it does not exist. It is the same for pre Big Bang.<br /><br />This topic is related to issues in the "Big Bang" thread in the "Ask the Astronomer" forum.<br /><br />What is the basic building block of reality. Vibrating filaments of energy called "strings"?<br /><br />Whatever the most fundamental piece of reality is, then I think that space itself must consist of this "thing", and it has to be some form of energy that allows the transmission of the known forces. (By the way, can we identify the most fundamental unit of a force?)<br /><br />Before the Big Bang there was "nothing". After the Big Bang there was space. So space must be "something". By "something" I mean something physical.
 
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fangsheath

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Let me reverse your question. If and when the universe collapses, what do we call the space that exists now but will cease to exist? We call it space. Clearly, the implication is that more "locations" exist now than then. But this is a tricky concept. Intuitively, we see that there must be, potentially, an infinite number of "locations" in a given space. So how can there be more or less than infinity? Answer: Infinity is not a number. There are an infinite number of whole numbers. There are an infinite number of real numbers. Yet the number of real numbers must be greater than the number of whole numbers. This little paradox gives us a clue about how to think about the expansion/contraction of the universe. Is there an "outside"? Perhaps. But that doesn't mean that what's "inside" is finite. You can have, in principle, an infinite space that expands to become another infinite, larger space.<br /><br />If your brain feels like a pretzel now, you aren't alone.
 
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aetherius

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<font color="yellow">If and when the universe collapses, what do we call the space that exists now but will cease to exist? We call it space. </font><br /><br />But if you believe that space has physical characteristics then wouldn't all the space that exists also collapse with the rest of the universe? If the universe, and <b>everything</b> in it, collapses to a singularity then you still don't know if space or something like it exists outside of the singularity.
 
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fangsheath

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Saying that space is physical doesn't constrain it very much I'm afraid. Let's say I'm flying by you at high speed. I measure the length of my spaceship. It's 100 feet. You measure it at the same time and find that it's 70 feet. Aren't we measuring the same space? What is the "actual" length? <br /><br />This isn't some optical illusion, either. Each of us is accurately recording the distance in our respective reference frame. If we can't rely on "physical" space to be constant in this situation, how can we demand that parts of it not wink out of existence when the universe is collapsing?<br />
 
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aetherius

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<font color="yellow"> If we can't rely on "physical" space to be constant in this situation, how can we demand that parts of it not wink out of existence when the universe is collapsing?</font><br /><br />I'm not sure I follow. I thought you were claiming that space remains if the universe collapses so your view requires that parts of it not wink out.<br /><br />My view is that before the big bang there was nothing and if the universe collapses then it will take <b> everything</b>, including space, with it. There will be no residual "space" after all matter and energy collapse. I view space as part of the matter and energy that collapse. It seems that to claim otherwise is consistent with the conlcusion that space existed before the big bang.
 
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fangsheath

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I didn't mean to suggest that space would remain if and when the universe collapses. In fact, I agree with you - the universe of matter/energy and space/time would cease to exist at the point of singularity. There would be no residual space. But it is not required to view space as part of matter/energy to reach this conclusion, merely that matter/energy and space/time are both elements of a universe that disappears at singularity.
 
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nexium

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The actual length of your space ship is 100 feet. The 70 feet is the perception of someone in a different frame of reference. Neil
 
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fangsheath

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But one perception is just as real and legitimate as another. If you say to yourself, "I know the ship is actually 100 feet long, not 70," and proceed to "correct" for this, firing a laser accordingly so as to hit the nose of my ship, you will miss. If you go with your observation of 70, you will be on the nose. You are accurately perceiving the nature of space in your reference frame, and none have a privileged status.
 
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poita

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Actually my brain hurts when i read the complex quantum explanations. I feel good about the idea that space is just an abscence of matter. That space is just 'potential'. But then again you can't bend potential by siting a planet next to it so space can't be merely that.<br /> Sometimes in my simple way of thinking I'm a bit suspicious of the way scientists take short cuts and just use any theory that fits until they can find one that fits better or some part of the shape that shows it didnt fit after all. <br /> The idea that gravity can't affect light so it must have affected the space the light passed through just seems convenient to me and a way of maintaining the theory that gravity can't affect light. (that's probably way too simplistic to the higher thinkers here).<br />
 
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chew_on_this

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<font color="yellow">...you can't bend potential by siting a planet next to it so space can't be merely that.</font><br /><br />Another assumption based on theory.
 
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i_think

Guest
"we know that the QFT involves the 'planck length' and presumably there is a planck level involved in space"<br /><br />I'm curious, let's just say for arguements sake that space is something in and of itself, and it's basic components are of planck length size. What shape would the basic components be, a sphere of planck length diameter?
 
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aetherius

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I think if space is "something" then it must be continuous. In other words there could be no empty space between the planck size "units" of space.
 
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nissasa

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I don't have any facts to back the following up...<br /><br />I think "space" has a more direct connection to EM. Find me one bit of space without any EM radiation. Instead of light traveling through space, it is a byproduct of space. When the space is for lack of a better term "agitated" it becomes active and produces electro-magnetic radiation. When space is dormant it is basically undetectable. Of course, how could we find it in it's dormant state without introducing it to some level of EM. <br /><br />I am aware that the idea of an ether is not popular anymore. But I still like the way it sounds. <img src="/images/icons/smile.gif" />
 
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paintwoik

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<blockquote><font class="small">In reply to:</font><hr /><p>Some have thought that space was an extension of matter.<p><hr /></p></p></blockquote> This is where I stand on the matter, hook, line, and sinker. This is to say that space and matter are one and the same.
 
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grooble

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Could space be collected in a special box, and examined with scientific instruments back on earth?<br /><br />I wonder what space looks like if you zoom in with a magnefying lense
 
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paintwoik

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<blockquote><font class="small">In reply to:</font><hr /><p>so, space/time exist. Simply by getting rid of light and matter, does not eliminate space/time.<p><hr /></p></p></blockquote><br /><br />This would be incorrect from my standpoint in that light and matter are spacetime. As light and matter goes...so goes the spacetime.
 
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