What is the fabric of space made of

  1. What is space itself made of? i.e. if you take both your hands and put them in front of you--parallel to your shoulders, what is the empty space between your hands made of.

    Is this space just a void? Did this area of space between your hands exist before the big bang. And if it didn't, didn't this space need to be created?
     
  2. jcsd
  3. HallsofIvy

    HallsofIvy 40,795
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    The "fabric of space" is not made 0f anything- it is just space itself. No, space did not exist before the big bang, yes, it was created, along with everything else.
     
  4. Faraday, Maxwell and Thomson believed that the space fabric consists of something, force or energy, under pressure which had a type of fluidic response to deformation. De Broglie, Dirac, Bohm, Casimir and Puthoff among others have all drawn some particular aspect of that primitive conception into more refined but also more abstract terms.

    Would it be fair to say that Einstein reduced that away? In doing so did he remove the pieces of the model that are actually useful to understanding why it works the way it works?
     
    Last edited: Dec 31, 2008
  5. Fredrik

    Fredrik 10,527
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    The theory that predicts the big bang (general relativity) doesn't say that space was created by the big bang. No theory does, at least no theory that's fully developed and experimentally distinguishable from general relativity. But I think a lot of people expect something like that to be a part of the "correct" quantum theory of gravity.
     
  6. No one knows exactly what constitutes space...nor time, for example.

    as posted above

    just doesn't seem complete to me ... after all, quantum theory correctly predicts the random emergence of particles and antiparticles from "nothing" (space) which to me suggests it is "something" ...and we know quantum fluctucations, and dark energy, reside there in the form of the cosmological constant....

    One way to imagine space is as Penrose Spin networks...which can be drawn out from string theory....theoretical, of course, but a geodesic type construct with volumes and areas integers of Planck length represented via edges and nodes of the geodesic....(just think of a dome shaped roof with flexible edges and nodes....) ....Or maybe space are multidemensional strings....membranes in other words....

    Another clue for me is that space and time are inextricably linked in relativity...and both are "flexible", that is undergo length contraction and time dilation at relativistic speeds..again hard for me to agree are "nothing" when they vary with speed. What further solidifies the idea that space IS something is that spacetime curves, its the geometric foundation for gravitational (force) via general relativity...gravitational potential molds spacetime...it curves light..odd were it " nothing"...

    Newton talked of absolute space, Einstein improved that via concepts of absolute spacetime...in his theory of special relativity....
     
  7. Physics = Mathematics (at least for TOE)
    You dont ask 'what numbers are made of'?
    The same here. Space is just a mathematical object.
     
  8. tiny-tim

    tiny-tim 26,041
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    Welcome to PF!

    Hi planck! Welcome to PF! :smile:

    You may as well ask, what is time made of?

    Time isn't made of anything, but we can still measure it. :tongue2:

    Why shouldn't space be exactly the same? :wink:
     
  9. Exactly, I agree... this is the problem in physics today. Einstein, I believe has set physics back 100 years not because what he developed is wrong but because it has gotten everyone else lost. It is impossible that a thing called space-time is affected by matter if space-time is actually nothing - nothing cannot be affected by something. Einstein was saying that we did not need to have a medium in order to describe what is happening - it is just a mathematical model which works. We can argue all day about what it is but this is a way to visualize and mathematically represent what is happening.
     
  10. It depends on what you call a spacetime.
    Spacetime in our universe can be affected by matter - but it is a brane and it is made of energy

    In my first reply I meant an 'absolute' space(time?) of the Bulk (landscape)
     
  11. Spacetime is just the geometry of physics.
     
  12. Relativity is not that complicated, lots of people understand it and are not "lost". I would challenge you to come up with any evidence supporting your claim that physics has been set back 100 years by Einstein.
     
    Last edited: Dec 31, 2008
  13. Agreed. It may very well be energy. But it isn't "nothing" - as in an absolute vacuum or some abstract notion of space and time - it must be comprised of something or be represented by something.

    But go talk to engineering and physics students at any level and I will bet you that they do not connect the idea of sapce-time with anything of "tangibility" (not that it must be something that we hold in our hands).

    e.g. - I had a discussion with one of my physics TAs and he has taken relativity or at least an introductory course and electrodynamics, etc. In this case we were talking about the EM field, I asked him: "A field in what?(referring to the EM field)" His answer: "a field in space". Asking for more clarification I think he said something like the fabric of space-time. But essentially a circular answer and would not dare say that space-time was actually comprised of something (not energy, not ether, non alia).

    But our problem, as the quote in my previous post states, is that we have churned out generations of physicists who have blocked out the very direction of thinking which will get us the answer. TV shows draw up that table-cloth image of space-time fabric and show how a piece of mass "warps" it. So everyone goes around thinking that there is an abstract 2D sheet of spandex that curls and twists in hyper-dimensional knots to create "space-time" which creates gravity and maybe other things.
     
  14. I agree with you that OUR spacetime is made of something (it is a brane)

    But I insist that the fundamental (bulk) spacetime is not made of 'something'. You say

    and this is wrong because it creates an unlimited sequence of elephants/turtles staying on top of each. You claim that spacetime is made of something 'X', and that 'X' - what is made it of?

    Look at mathematic systems. Peano arithmetics, for example. What is more fundamental - number 1 or + ?
     
  15. That's because when they use the word "space", they are not referring to the contents of the space, whatever they may be. They are just referring to the three dimensions (4 with space-time). The fact that the word space is not being used to refer to its contents doesn't imply that there are no contents.

    Al
     
  16. turbo

    turbo 7,366
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    That was very early on. By 1920 (Leiden Address) he said that an etheric space was needed for the propagation of EM, and the emergence of gravitational and inertial effects. He reiterated this again more forcefully in his 1924 essay "On the Ether". That essay is chapter 1 of "The Philosophy of Vacuum" - recommended reading.

    Pricey, so a good excuse to visit a library.
    http://www.amazon.com/Philosophy-Vacuum-Simon-Saunders/dp/0198244495
     
  17. You are at odds with a phantom.

    Einstein's Ether

    http://physicsworld.com/cws/article/print/2384

    and

    "It would have been more correct if I had limited myself, in my earlier publications, to emphasizing only the nonexistence of an ether velocity, instead of arguing the total nonexistence of the ether, for I can see that with the word ether we say nothing else than that space has to be viewed as a carrier of physical qualities." A. Einstein
     
  18. Well, I agree with you all then. All I am saying is that a vast majority of physicists don't recognize an ether-like medium at all - they just think "space-time". I agree that Einstein did not intend to do away with a medium but that his work has accomplished that accidentally.

    Looks like an interesting text - philosophy of the vacuum.
     
  19. turbo

    turbo 7,366
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    It's "The Philosophy of Vacuum", edited by Saunders and Brown. Simon Saunders translated Einstein's essay from the German. Chapter 2 is an essay by Penrose. It's a great book - I'll have to buy a copy someday.
     
    Last edited: Dec 31, 2008
  20. I'd like to think that the make-up of space has something to with the virtual particles that are popping in and out of existence in accordance with [itex]\Delta E\Delta t \ge \hbar/2 [/itex] and that curvature might have something to do with a concentration of virtual particles around an object of mass.
     
  21. First of all, thanks to everyone for welcoming me to the forum and for contributing to my thread. You guys really know your physics so I'm going to enjoy reading your posts.

    I'm not a physics major at all. I only took a high school physics class. But I've seen a ton of documentaries and read a bunch of michio kaku and brian green books.

    Doesn't general relativity tell us that energy/matter warps space. So shouldn't that space be comprised of something.

    But more importantly, why does the cubic volume of space between my hands that I mentioned in my initial post, have the ability to contain no density/mass. But in that same cubic volume, it has the ability to host a black hole.

    Atoms and other particles of mass are allowed to freely move through that cubic volume of space, as einstein wrote:

    "space has to be viewed as a carrier of physical qualities."

    yet you can also fit a supermassive amount of particles in it also. Why is that possible?
     
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