Posted: Apr 15, 2011 10:50 am
Craig writes:
Ad (ii) Doesn't that mean, that - according to Craig's explanation - the universe did not begin to exist if there was no first time at which the universe existed?
Such as in cosmological models, that lack a first point of time?
Paul Davies writes in What Happened Before the Big Bang?:
Ad (iii) Has Craig shown, that there is no state of affairs, in which the universe timelessly exists? Doesn't the above article suggest, that there might have been such a timeless state of the universe? In that case, the universe did not begin to exist, according to Craig's explanation of 'beginnning to exist'. Maybe a physicist could clear that up?
Ad (iv) Has Craig shown, that an A-theory of time is correct? Craig writes, that "[t]he kalam cosmological argument presupposes from start to finish an A-theory of time." On a B-theory of time however "[t]he universe began to exist only in the sense that the tenselessly existing block universe has a front edge. It has a beginning only in the sense that a yardstick has a beginning. There is in the actual world no state of affairs of God existing alone without the space-time universe. God never really brings the universe into being; as a whole it co-exists timelessly with Him." Only a minority of philosophers seems to support an A-theory of time. I wonder what that means for the support of the premise, that the universe began to exist.
The kalam cosmological argument uses the phrase 'begins to exist.' For those who wonder what that means I sometimes use the expression 'comes into being' as a synonym. We can explicate this last notion as follows: for any entity e and time t,
e comes into being at t if and only if (i) e exists at t, (ii) t is the first time at which e exists, (iii) there is no state of affairs in the actual world in which e exists timelessly, and (iv) e’s existing at t is a tensed fact.
Ad (ii) Doesn't that mean, that - according to Craig's explanation - the universe did not begin to exist if there was no first time at which the universe existed?
Such as in cosmological models, that lack a first point of time?
Paul Davies writes in What Happened Before the Big Bang?:
Inevitably, scientists will not be content to leave it at that. We would like to flesh out the details of this profound concept. There is even a subject devoted to it, called quantum cosmology. Two famous quantum cosmologists, James Hartle and Stephen Hawking, came up with a clever idea that goes back to Einstein. Einstein not only found that space and time are part of the physical universe; he also found that they are linked in a very intimate way. In fact, space on its own and time on its own are no longer properly valid concepts. Instead, we must deal with a unified "space-time" continuum. Space has three dimensions, and time has one, so space-time is a four-dimensional continuum.
In spite of the space-time linkage, however, space is space and time is time under almost all circumstances. Whatever space-time distortions gravitation may produce, they never turn space into time or time into space. An exception arises, though, when quantum effects are taken into account. That all-important intrinsic uncertainty that afflicts quantum systems can be applied to space-time, too. In this case, the uncertainty can, under special circumstances, affect the identities of space and time. For a very, very brief duration, it is possible for time and space to merge in identity, for time to become, so to speak, spacelike-just another dimension of space.
The spatialization of time is not something abrupt; it is a continuous process. Viewed in reverse as the temporalization of (one dimension of) space, it implies that time can emerge out of space in a continuous process. (By continuous, I mean that the timelike quality of a dimension, as opposed to its spacelike quality, is not an all-or-nothing affair; there are shades in between. This vague statement can be made quite precise mathematically.)
The essence of the Hartle-Hawking idea is that the big bang was not the abrupt switching on of time at some singular first moment, but the emergence of time from space in an ultrarapid but nevertheless continuous manner. On a human time scale, the big bang was very much a sudden, explosive origin of space, time, and matter. But look very, very closely at that first tiny fraction of a second and you find that there was no precise and sudden beginning at all. So here we have a theory of the origin of the universe that seems to say two contradictory things: First, time did not always exist; and second, there was no first moment of time. Such are the oddities of quantum physics.
Ad (iii) Has Craig shown, that there is no state of affairs, in which the universe timelessly exists? Doesn't the above article suggest, that there might have been such a timeless state of the universe? In that case, the universe did not begin to exist, according to Craig's explanation of 'beginnning to exist'. Maybe a physicist could clear that up?
Ad (iv) Has Craig shown, that an A-theory of time is correct? Craig writes, that "[t]he kalam cosmological argument presupposes from start to finish an A-theory of time." On a B-theory of time however "[t]he universe began to exist only in the sense that the tenselessly existing block universe has a front edge. It has a beginning only in the sense that a yardstick has a beginning. There is in the actual world no state of affairs of God existing alone without the space-time universe. God never really brings the universe into being; as a whole it co-exists timelessly with Him." Only a minority of philosophers seems to support an A-theory of time. I wonder what that means for the support of the premise, that the universe began to exist.