• Hillary
    1.9k


    I don't know everything. What gave you that idea? I know the fundamentals. Which is but a small part but the necessary part to understand the origin and evolution of the cosmos.
  • noAxioms
    1.3k
    Just some comments.
    The speed of light is the universal speed limit for everything that exists in the universe, we can say "Whatever exists in the universe has a speed limit of the speed of light". Is this then true for the universe itself? The universe is about 13.8 billion years old, if the speed limit for the universe was the speed of light, the size of the universe would be at most 27.6 light-years across. the observable universe is however 93 billion light-years across.Magnus
    One issue here is that universe expands faster than speed of light.
    How is FTL possible?
    SpaceDweller
    The rate of expansion is not a speed. It has different units (m/sec/mpc) than speed (m/sec)

    Speed of light is only c in a vacuum in Minkowskian spacetime relative to an inertial frame.
    The rate of recession of some distant galaxy isn't specified relative to an inertial frame, but rather relative to the cosmological (or comoving) frame, which is a different sort of coordinate system. Under (approximate) inertial coordinates, that galaxy is not receding faster than c.
    Neptune moves faster than c relative to the frame of Paris, but Paris is stationary only in a rotating reference frame.

    Wayfarer quoted Ethan Siegel along the same lines:
    The restriction that "nothing can move faster than light" only applies to the motion of objects through space. The rate at which space itself expands — this speed-per-unit-distance — has no physical bounds on its upper limit.
    I mostly agree with Ethan here, but not quite right. I can put a mirror on the moon and time the light going round trip and it will exceed c by a little bit despite it very much being the rate 'through space' as he puts it. The reason for this is the non-Minkowskian spacetime (a change in gravitational potential) between here and there.

    Another illustration: Put up a circular wall of radius 1 million km with you at the center. Use a laser pointer to shine a red dot at it, to the excitement of your relativistic cat. You can flick your wrist and send the dot moving at arbitrarily high speeds around the screen. The dot moves at far faster than c in any direction at your choosing.

    Not saying I disagree with your conclusion in the OP, but the speed of light thing isn't a valid counter to the KCA. For one, it would have to be meaningful for the universe to have a speed, and for that you need to give it a location at different times.

    You also need to define universe. What did the god supposedly create? Just the visible universe? Everything since the big bang? What about the stuff beyond the bang which arguably caused it? Our spacetime is just part of a larger structure, so it is very much arguably caused. Just not by the deity.

    think the idea is that there is an inductive conclusion which is the first premise: "X is true for every thing". Then , "the universe is a thing". Therefore X is true of the universe.Metaphysician Undercover
    I agree, premise 2 is a category error, and Michael points out that classifying the universe as a 'thing' is not how the KCA is worded.

    Bear in mind that Craig believes the past is finite.Relativist
    He says that? Then God didn't create time? How unomnipotent of him.

    About premise 1: Whatever begins to exist has a cause. This is apparently not so. For instance yttrium-90 begins to exist by the un-caused decay of strontium-90. That's kind of thin since the existence of the strontium is admittedly a potential waiting to happen, just not a direct cause.

    "Exist" is not well defined.Jackson
    I personally agree with this, but most people kind of take the standard realist meaning. The KCA does beg this definition, and thus is dependent on it. Any additional premise, even unstated, weakens the argument since it only works if the premise is true.
  • Relativist
    2.1k
    Bear in mind that Craig believes the past is finite.
    — Relativist
    He says that? Then God didn't create time? How unomnipotent of him.
    noAxioms
    Yes, Craig says the past is finite (his KCA depends on it), and God chose to create spacetime, and to become temporal himself.
  • Hillary
    1.9k
    Bear in mind that Craig believes the past is finite.
    — Relativist
    He says that? Then God didn't create time? How unomnipotent of him.
    noAxioms

    Why needs time to be created? Thermodynamic time is an emergent property. Before TD time, another kind of time existed, without cause and effect.
  • Relativist
    2.1k
    Why needs time to be created?Hillary
    Because (according to Craig) everything is created, except for God).
  • Hillary
    1.9k


    But (thermodynamic) time can naturally emerge from a state without time yet. So it doesn't need God to be created.
  • noAxioms
    1.3k
    Yes, Craig says the past is finite (his KCA depends on it), and God chose to create spacetime, and to become temporal himself.Relativist
    First of all, my mistake. I read your comment from last week to say "Craig believes the past is infinite", which would have contradicted what I've heard.

    OK, but if God created spacetime, that's a structure of which time is a part, not a structure in time. A created thing is only applicable to a thing contained by time, which spacetime by definition isn't.

    I'm just wondering what Craig actually says. Kalam certainly didn't word things that way since the concept of spacetime was unknown then. I've seen Craig do his debates, and he seems to deliberately use fallacious naive reasoning (incredulity against a straw man) rather than stronger arguments. I suspect he doesn't believe his shtick at all but knows very well from where his paycheck comes. So he plays to his audience in preference to playing to his debate opponent, and he excels at that. The audience hired him and wants rationalization, not rational reasoning.

    Bottom line is that to propose the creation of a spacetime structure, one has to posit a 2nd kind of time that is entirely separate from the time that is part of the structure.

    To 'become temporal' is pretty self contradictory. God wasn't temporal (there was no time), and 1) later on there was time (a self contradiction), and 2) God 'became temporal', which also implies a time before which God wasn't temporal, and that God seemed to choose this limitation, to be contained.
    Maybe that's just all the inability of language to speak of concepts outside our normal sphere of existence. I'm not trying to disprove a god here, but the argument certainly seems fallacious on several levels.

    Why needs time to be created? Thermodynamic time is an emergent property. Before TD time, another kind of time existed, without cause and effect.Hillary
    I pretty much agree with this. The time that we know (part of spacetime) is only applicable within, and creation is only defined under the physics of it.

    Because (according to Craig) everything is created, except for God).Relativist
    Isn't it easier to say that everything is created except the universe? But no, that again commits the fallacy of categorizing the universe as a 'thing'. Saying it is created is not even wrong.
  • Hillary
    1.9k
    OK, but if God created spacetime, that's a structure of which time is a part, not a structure in timenoAxioms

    Thermodynamic time is no part of the initial vacuum yet. TD time emerges from the TD timeless state.
    As you agree with, I see only now!
  • Agent Smith
    9.5k
    The rate of expansion is not a speed. It has different units (m/sec/mpc) than speed (m/sec) — noAxioms

    :fire:

    Another illustration: Put up a circular wall of radius 1 million km with you at the center. Use a laser pointer to shine a red dot at it, to the excitement of your relativistic cat. You can flick your wrist and send the dot moving at arbitrarily high speeds around the screen. The dot moves at far faster than c in any direction at your choosing. — noAxioms

    So the red dot "moving at (an) arbitrarily high speed(s)" (faster-than-light) is nonphysical! Hasta be, oui?

    @Wayfarer
  • Hillary
    1.9k
    So the dot "moving at (an) arbitrarily high speed(s)" (faster-than-light) is nonphysical! Hasta be, oui?Agent Smith

    Ouioui! Good point!
  • Hillary
    1.9k
    Isn't it easier to say that everything is created except the universe? But no, that again commits the fallacy of categorizing the universe as a 'thing'. Saying it is created is not even wrong.noAxioms

    That's easier but it's not what's actually the case. In the heavenly eternal kingdom, time exists in a purely divine non-material form, like the gods and the heaven they live in. They could have created the 5d spacetime (time fluctuating) structure with inherent fluctuating, non thermodynamic time, from which the universal 3d space and TD time emerge.
  • Relativist
    2.1k
    if God created spacetime, that's a structure of which time is a part, not a structure in timenoAxioms
    Well, Craig also says that by creating time, became a temporal being. One of his slogans is, "God exists timelessly sans the universe, and temorally with it". So he does not consider time to merely be a dimension of spacetime, and he absolutely rejects block-time.

    to propose the creation of a spacetime structure, one has to posit a 2nd kind of time that is entirely separate from the time that is part of the structure.
    Not necessarily. Craig is a presentist: only the present exists and it is universal (includes God). In terms of special relativity, God has a privileged point of view.

    IMO, Craig's views are coherent, albeit that they depend on some questionable metaphysical assumptions.
  • Relativist
    2.1k
    But (thermodynamic) time can naturally emerge from a state without time yet. So it doesn't need God to be created.Hillary
    I pretty much agree, except for the phrasing "without time yet"- this sounds like there's a point prior to time. My view is that there is an initial point OF time (t0). IMO, there could be multiple thermodynamic arrows of time emerging from initial conditions, each causally independent of each other, but retrospectively converging at t0. This is a hypothesis of Sean Carroll. (I don't know if it's true, but it seems as reasonable as anything).
  • noAxioms
    1.3k
    The dot moves at far faster than c in any direction at your choosing.noAxioms
    So the red dot "moving at (an) arbitrarily high speed(s)" (faster-than-light) is nonphysical! Hasta be, oui?Agent Smith
    Depends on your definition of 'physical' I suppose. It is very arguably not an object, but if it has a name, it also arguably is an object.
    The dot cannot be used to transfer information faster than light.

    A moiré pattern also can move at well over light speed without the need to stand a million km from it.

    It would be interesting to work out exactly what the cat would see as the faster-than-light red dot approached it and then passed it by. Just like you can't hear a supersonic jet coming, you also cannot see the dot coming as it outruns the light it emits.

    Well, Craig also says that by creating time, became a temporal being.Relativist
    This is what I was talking about when I said that language cannot express this. Creation implies a temporal event: The thing exists, and it didn't earlier, but if there's no earlier, it isn't really a creation, or a 'becoming' for that matter. We haven't language (or any valid logic) to describe an act or thought being performed by a non-temporal entity. The assertion seems to bury any counterargument behind this haze of self-contradictory language.

    So he does not consider time to merely be a dimension of spacetime, and he absolutely rejects block-time.Relativist
    OK, you said otherwise earlier:
    Craig says the past is finite (his KCA depends on it), and God chose to create spacetimeRelativist
    so I assume that was said in error. God created or fired-up time, and then created a 3D universe (space, not spacetime) in that time. This goes pretty much along the lines of him playing to the naive audience who expect confirmation of their biases, and not to science. It is a rejection of Einstein, but I doubt he has openly suggested that Einstein (his postulates right down to the 1905 ones) was wrong, especially without an alternate theory to replace it except something pathetic like neoLET which only says all of Einstein's equations are to be used despite them being derived from premises that are false. Craig knows his science and knows that there are real flaws to be exploited by the naturalist view, but rather than attacking those flaws, he chooses to state his case using mostly arguments from incredulity and such. The paying audience eats that stuff up and they'd not understand the stronger argument.

    In terms of special relativity, God has a privileged point of view.
    SR does not forbid such a POV. Out of curiosity, does Craig ever mention which quantum interpretation jives best with the God view? I mean, it all sounds entirely classical, but it has been shown that our universe cannot be explained in classical terms.
    If locality is abandoned, then some effects are caused by events that have not yet happened, which doesn't work well with presentism. In fact, I'm hard pressed to find an interpretation that is compatible with presentism, but I haven't looked for articles on it.
  • Hillary
    1.9k
    It would be interesting to work out exactly what the cat would see as the faster-than-light red dot approached it and then passed it by. Just like you can't hear a supersonic jet coming, you also cannot see the dot coming as it outruns the light it emits.noAxioms

    The moving dot is just a marquee. You can let a number go seemingly faster than the speed of light. Without anything actually moving.

    God created or fired-up time, and then created a 3D universe (space, not spacetime)noAxioms

    To let both (apparently) 3d space and thermodynamic time (which Einstein compared with an ideal, non-existent clock, which he placed on an imaginary axis: it), there has to exist a substrate (apparently) 4d quantum vacuum first (by which I mean a bulk vacuum filled with, or made up of virtual particles). If the gods create such a TD timeless state (with special geometry, and the right particle properties) first, the universe as we know it (and a right-handed mirror version with antimatter) will automatically follow. And infinite big bangs after it.
  • Relativist
    2.1k
    This is what I was talking about when I said that language cannot express this. Creation implies a temporal event: The thing exists, and it didn't earlier, but if there's no earlier, it isn't really a creation, or a 'becoming' for that matter.noAxioms
    "God exists timelessly sans creation" refers to the counterfactual case, the non-actualized, metaphysically contingent possibility in which God did not choose to create the universe. So it doesn't entail a time before time. Craig relies on atemporal causation, which seems to entail God and the universe's initial conditions coexisting at t0. But Craig doesn't commit to this. He says that God could exist temporally prior to the universe (a time before spacetime), because he's omnipotent. So I don't think there's a logical problem.

    , you said otherwise earlier:
    Craig says the past is finite (his KCA depends on it), and God chose to create spacetime
    — Relativist
    so I assume that was said in error. God created or fired-up time, and then created a 3D universe (space, not spacetime) in that time.
    noAxioms

    No, not an error. Although spacetime is a package deal, omnipotence means he can behave temporally without the full package. So he's not going against general relativity, just saying God's not constrained by it. The assumption of omnipotence is quite a convenience when constructing a metaphysical account.

    mostly arguments from incredulitynoAxioms
    That is his Forte.
  • Agent Smith
    9.5k
    Depends on your definition of 'physical' I suppose. It is very arguably not an object, but if it has a name, it also arguably is an object.
    The dot cannot be used to transfer information faster than light.

    A moiré pattern also can move at well over light speed without the need to stand a million km from it.

    It would be interesting to work out exactly what the cat would see as the faster-than-light red dot approached it and then passed it by. Just like you can't hear a supersonic jet coming, you also cannot see the dot coming as it outruns the light it emits.
    noAxioms

    These are the limits of my understanding. Interesting nevertheless.

    I was just drawing a conclusion that seemed to be staring me in the face! "Something" (the red dot) has a measurable speed that's greater than c. Ergo, it can't be physical (all matter & energy follows the cosmic speed limit c).

    How would you characterize the nature of the red dot whose speed exceeds c? The red dot is like time to me - can be measured, but quid sit? No clear answer.

    Gracias for replying.
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