The fabric of space-time

Discussion in 'Physics & Math' started by Saint, Feb 12, 2020.

  1. Saint Valued Senior Member

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    What causes space and time to combine and become a fabric?
    How time and space react to each other?
    Does space exist first or time first?
    Or they must exist together at the same time?
     
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  3. paddoboy Valued Senior Member

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    It's simply a multi dimensional framework that we have modeled, and in which we locate events and describe the relationships between them in terms of spatial coordinates and time. Intervals of space and time considered separately are not the same for all observers. In GR, gravitation is described in terms of curvature/warpage of spacetime. The concept of spacetime follows from the observation that the speed of light is invariant.
    The more warped/curved spacetime is, the slower time will appear to pass.
    Space and time, as we know them [hencforth known as spacetime] evolved from t+10-43 seconds together.
    Yes.
     
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  5. paddoboy Valued Senior Member

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    It is simply the unified multi-dimensional framework within which we model and locate events and describe the relationships between them in terms of spatial coordinates and time.....Iit does not vary with the motion of the emitter or the observer. Intervals of space and time considered separately are not the same for all observers. In GR, gravitation is described in terms of curvature of spacetime.
    The more curved/warped spacetime is, the slower time will appear to go from the point of view of an observer in another FoR.
    Space and time as we know them, evolved at t+10-43 seconds and their dependence on one another, lead to spacetime.
    Yes.
     
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  7. QuarkHead Remedial Math Student Valued Senior Member

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    The expression ", fabric of spacetime" is a metaphor, probably used because, in physics, any space (or here) spacetime, must be equipped with a metric (mathematicians are not so picky)
     
    Last edited: Feb 12, 2020
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  8. paddoboy Valued Senior Member

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    No argument.
    Other then that is what GR tells us and describes?
    Gravity is geometry, geometry of spacetime in the presence of mass/energy.
    Or to quote John Wheeler [I think] "Mass tells spacetime how to curve, and spacetime tells mass how to move."
     
  9. James R Just this guy, you know? Staff Member

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    Our particular choice of mathematical models.
    Study relativity and you will find out.
    Yes.
    Nobody knows. Science is descriptive, not prescriptive.
     
  10. paddoboy Valued Senior Member

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    And our descriptive model, the BB, tells us that space and time [as we know them] evolved/expanded from a hot dense state, at 10-43 seconds. As space evolved, so to did time: As time evolved, so to did space. Or putting that another way, within GR space and time are interchangeable within the multi dimensional framework we call spacetime.
     
  11. paddoboy Valued Senior Member

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    I'm interested in hearing the why and the how. Care to elaborate?
    I mean other then what I said earlier re gravity being geometry caused by mass/energy according to GR, I'm not really sure we actually know why.
     
  12. arfa brane call me arf Valued Senior Member

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    A four-dimensional spacetime is a useful fiction. In "reality" we see one of the four as very different to the other three. Moreover, since space and time are different and have different units, that suggests that Minkowski space is not equipped with a Euclidean metric (where units are identical along any axis).

    It's why the metric is called a pseudometric for one. And it's why units of time are multiplied by c so the units are then comparable mathematically (since space and time are not in general things you can say are physically comparable).

    Notice, Saint's question "which existed first, time or space?" isn't really meaningful. Physical existence implies time also exists, there's a big problem with trying to use ordinary language which has verbs in it, to talk about what time is. All such talk will be self-referencing, hence at best tautological. If something exists because of time, it has existed, it will exist etc; then time exists because of itself.
     
    Last edited: Feb 15, 2020
  13. Q-reeus Valued Senior Member

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    4,089
    Wrong. Newtonian physics can be formulated within a non-relativistic, elliptical geometry spacetime framework:
    https://en.wikipedia.org/wiki/Non-relativistic_spacetime
    philsci-archive.pitt.edu/13227/1/cst2.pdf
    Invariance of c merely stipulates a particular kind of spacetime geometry - a relativistic one with hyperbolic geometry. Minkowkian in the absence of gravity.
    Well at least in a later post that was corrected - 'slower time' is a purely relational thing.
    https://en.wikipedia.org/wiki/Planck_energy
    That's some 15 or so orders of magnitude greater than what particle physics has explored and fairly well understood. Stop promoting pop-sci claims as though fact. You keep repeating that mantra in many threads and posts here. Try tempering it with the caveat it is actually speculation and far from being established fact.
     
  14. paddoboy Valued Senior Member

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    Nup, sorry, I don't see it as wrong, and will stick with the realistic correct version I have stated. I'm speaking of spacetime under GR, that which you seem to have a problem with and have for quite a while now.

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    Methinks you need to spend more time correcting the real nonsense in these threads like river and MR propose, rather then silly vengeful nitpicking of mine and Dave's posts. Is that close to the mark q-reeus?

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    Our laws fail to apply at and below the quantum/Planck level. I'll stick to the usually accepted BB being the evolution of space and time as we know them[henceforth known as spacetime] from t+10-43 seconds as quite satisfactory. I also refer you to my previous answer.

    https://en.wikipedia.org/wiki/Planck_units#Cosmology
    In Big Bang cosmology, the Planck epoch or Planck era is the earliest stage of the Big Bang, before the time passed was equal to the Planck time, tP, or approximately 10−43 seconds.[17]

    Note carefully q-reeus, it's BB cosmology and GR that we are generally talking about...both of course being our overwhelmingly accepted and working theories of universal evolution and gravity.
     
    Last edited: Feb 16, 2020
  15. paddoboy Valued Senior Member

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    Time dilation is a fact q-reeus, despite how you see the need to define that fact.

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    GPS satellites, particle accelerators muons etc attest to that fact.

    https://en.wikipedia.org/wiki/Time_dilation
    "Time dilation is a difference in the elapsed time measured by two clocks, either due to them having a velocity relative to each other, or by there being a gravitational potential difference between their locations. After compensating for varying signal delays due to the changing distance between an observer and a moving clock (i.e. Doppler effect), the observer will measure the moving clock as ticking slower than a clock that is at rest in the observer's own reference frame. A clock that is close to a massive body (and which therefore is at lower gravitational potential) will record less elapsed time than a clock situated further from the said massive body (and which is at a higher gravitational potential).

    These predictions of the theory of relativity have been repeatedly confirmed by experiment, and they are of practical concern, for instance in the operation of satellite navigation systems such as GPS and Galileo.[1][2] Time dilation has also been the subject of science fiction works, as it technically provides the means for forward time travel"
    <<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>
     
  16. Q-reeus Valued Senior Member

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    No. Unsurprisingly you characteristically attack straw man caricatures of what I actually wrote. In all your reply posts. Too bad virtually no-one here really cares - just as long as it entertains.
     
  17. paddoboy Valued Senior Member

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    You think so? Factual actually, and is evident in general with a general consensus of your posts.
     
  18. Q-reeus Valued Senior Member

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    I doubt you actually believe your own BS. More the case of 'attack is the best means of defense'. No matter how silly and incoherent that attack is.
    It's now evident you have indeed been 'unofficially' banned at SFN, but your ego blocks admission of that, or why, here. Special pleading gets you remaining there in name only. Like at PhysicsForums.
    Sure I got banned from both, but for very different reasons - and NEVER would I beg for favors.
    Everyone knows James R wants you life banned from SF, yet somehow you continue to plague the place. Charmed life, in keeping with 'the devil looks after his own'.
     
    Last edited: Feb 16, 2020
  19. paddoboy Valued Senior Member

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    Tell me oh delusional wise one, how do you get unofficially banned?

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    You have it bad mate!

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  20. Q-reeus Valued Senior Member

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    That link again: https://www.scienceforums.net/profile/74220-beecee/content/
    Sept 15 2019, paddoboy aka beecee. Check the frequency of postings leading up to that full-stop date. I don't know how you rigged it, but 'unofficial ban' fits the evidence.
    Your deflecting does not. We have of course got way off topic. Trouble is, you simply keep lying and distorting when 'on-topic'.
     
  21. foghorn Registered Senior Member

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    Yeah, I always suspected paddoboy of having something to do with the fiddling about with your e-mail notification settings too.
    That was so classic paranoia on your part.
     
    Last edited: Feb 16, 2020
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  22. paddoboy Valued Senior Member

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    If he only knew how silly he makes himself look

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    ...add that to his notion on ID and UFOs of Alien origin, and voila!!!

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  23. foghorn Registered Senior Member

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    He just can't stop himself.
    By the way, when is JamesR going to start your life time ban here, you know, the ban everyone knows JR want's to give you?
     

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