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I think Hawking's belief is that the laws of physics mean that the universe was inevitable, as in it was always going to create itself from nothing due to those rules. Perhaps I'm wrong though? I don't think it was that there is no cause exactly, just that the universe / physics itself is the cause in Hawking's opinion.
ChaoticOrder
reply to post by Blue Shift
with the universe both expanding and curving in on itself
As far as we can tell, the Universe does not curve in on its self:
EnPassant
In this case t = 0 refers to the beginning of time at the big bang.
EnPassant
I'm reading Jim Holt's book Why does the World Exist? and I have come across this Hawkingesque idea about the beginning of time, early on in the book, and I'd like to explain why I think this idea is philosophically naive.
Hawking's idea is that the question "What came before the universe?" is null and void, because at the beginning of the Big Bang there is a beginning to time and there was no time before that.
Well and good. But the argument goes on to say that this fact means that the universe does not need a cause because there was no time before t = 0, for a cause to exist. This, to my mind, is a thundering fallacy and shows how naive Hawking is when it comes to philosophy.
First a few notes on time.
It has been said that change is the definition of time. While change is evidence of time it is not a sufficient definition of time. Rather, time is that order according to which change comes about. It is the WAY change happens.
EnPassant
Einstein's general relativity describes how change happens in physical terms and as such it can be seen to be a mathematical description of how change happens. This is the correct definition of time, from which we get the concept of spacetime. Spacetime is a mathematical order - it is not change - and as such it is a more rigorous definition of time. Time is the order of things. This order, abstractly, does not require the flow of time. It is a timeless order according to which change happens.
EnPassant
Now when it comes to cause and effect, it is a mistake to imagine that cause and effect are necessarily separated by the flow of time. All that is required is that there is an ordered, necessary relationship between cause and effect. The flow of time is not required. Here are some examples of necessary relationships (cause and effect) that are not dependent on change or the flow of time.
Imagine you are drawing a triangle. You have two sides drawn and are in the process of drawing the third side. The triangle does not exist until you have completed drawing the third side. Only when you have completed the third side does the triangle exist. But the moment the triangle exists the area of the triangle also exists - as do many other properties. There is a necessary relationship between the triangle and its area. The triangle is the cause and the area is the effect but both triangle (cause) and area (effect) come into existence at the same instant. No temporal separation between cause and effect as they come into existence simultaneously.
EnPassant
In mathematical logic 1 + 1 = 2. There is a necessary relationship between the 1s and the 2. In this relationship time, as defined above, as the order underlying relationships, exists, but the flow of time is not necessary. Indeed, in the mind, time exists as an order, whence necessary mathematical and logical relationships exist in a time order that does not require the flow of time or temporal precedence. All that is required is a set of necessary relationships. In this respect logic is to the mind what time is to the physical universe: it is the order inherent in relationships. Logic = time. Indeed, any mathematical system is the equivalent of time in the way that general relativity is time in physical terms.
EnPassant
In other words, one thing can precede another without the need for simple time (the flow of time). There can be a logical precedence or necessity that does not require the flow of time. This is why the definition of time needs to be rigorously defined, as above.
Given these facts we can see how Hawking is being naive when he imagines that there must be a flow of time for the universe to be necessarily dependent on a preceding event. Such an event would not require the flow of time to exist. All that would be needed would be a logical or necessary relationship between the universe an its cause.
Another way to see how the flow of time is not necessary for logical relationships is to imagine you are opening a door. To open the door you must put the key in the lock, turn it, and push to door open. You could do this very slowly so that it takes five minutes to open the door, or you could do it quickly, in two seconds. The flow of time, here, is not, in principle, a factor. All that is required is the necessary relationships between events; the key must be turned if the door is to open. This logical dependency is purely geometric and arises out of the order of spacetime, not the flow of time. Indeed, it may turn out that the flow of time is a purely human, subjective, experience. What all this means is that the universe does not need a cause that precedes it in temporal terms but does precede it in logical or necessary terms so there is no need for an earlier cause to exist before t = 0.
edit on 16-12-2013 by EnPassant because: (no reason given)
You are talking about the subjective experience of time. All that is necessary are the laws of nature to tell us that there is an order in spacetime. This order allows science to be possible. It is the regularity and predictibility of events that tells us there is an order in things. This order is time. The subjective experience of the flow of time is a pedestrian experience of the order according to which events are related. It is the order itself that is important, not subjective experience of it.
Consider a train pulling carriages. One carriage pulls the other without the need for the passage of time for the cause and effect to obtain.
Longitudinal Train Dynamics
By including the Ft/db in each equation, thus on every vehicle, the equations can be applied to any locomotive placement or system of distributed power. For unpowered vehicles Ft/db is set to zero. For nonlinear modelling of the system, the stiffness and damping constants are replaced with functions. It is usual to express stiffness as a function of displacement and incorporate coupler slack and piece-wise-linear approximations of draft gear response. Damping is usually expressed as a function of velocity. More complex functions, incorporating a second independent variable, (i.e., displacement and velocity for a stiffness function), can also be used. The generalised nonlinear equations are therefore:
For the lead vehicle: [equation]
For the ith vehicle: [equation]
For the nth or last vehicle: [equation]
Sou rce
Cause and effect are one type of necessary order. Mathematical statements are another. In time two raindrops can become one raindrop but in mathematical order there is no need for the passage of time. Time is simply the order of things. In mathematics time is the logical relationship between the elements of a statement.
The flow of time is not a factor in the definition of the logical relationships.
Hawking cannot make an appeal to a need for an earlier time than t = 0 to make a cause of the universe possible.
...if the universe is expanding, there may be physical reasons why there had to be a beginning. One could still imagine that God created the universe at the instant of the big bang, or even afterwards in just such a way as to make it look as if there was a big bang, but it would be meaningless to suppose that it was created before the big bang. An expanding universe does not preclude a creator, but it does place limits on when he might have carried out his job!
— Hawking, A Brief History of Time
Another example of cause and effect that do not need the flow of time is the EPR experiment. It seems to operate outside normal time.
You are mistaken. There is no absolute order to events in spacetime.
Granted, but that does not imply that the universe must have a cause, or that anything exists outside spacetime. What you would have to show is that time is not a factor in causal relationships — and that is an absurd proposition.
Astyanax
reply to post by EnPassant
I am afraid your attempt at clarification is little better than gibberish.
You invoke a source from which matter and spacetime emerge. No such source is known to exist. It is not even agreed that one should exist. Certainly no-one is in a position to make any definite assertions about such a thing, as you are attempting to do.
String theory and the mysteries hinted at by the discovery of the amplituhedron are entirely conjectural. They provide no support for your argument. Surely you do not imagine that Stephen Hawking was unacquainted with string theory when he wrote his book?
An acquaintance with physical cosmology based on half-understood articles in the popular press is insufficient grounding for anyone who wishes to contradict the world's most famous living physicist on the subject. You have no idea how many howlers you have already perpetrated, but I shall spare your blushes. I merely suggest you give this thread up for lost, collect your thoughts and start another one, this time on a topic of which you have some genuine knowledge.
Time does not exist in a subatomic world, but we exist in a macro universe and can only frame our observations using spacetime, even when this leads to causality violations, which it can do.
I am not criticizing Hawking in scientific terms but in philosophical terms.
Astyanax
reply to post by EnPassant
I am not criticizing Hawking in scientific terms but in philosophical terms.
Then you should have started your thread in the Philosophy forum, not in this one.
Anyway, your claim is false. There is nothing philosophical about your criticism of Hawking's work; it is magical and superstitious, not philosophical. You are attempting to refute his ideas based on a personal view of reality that you have introduced without either logical argument or empirical proof.
Some of us here have actually studied physics. And philosophy. As it happens, I am also something of a connoisseur of mumbo-jumbo, and I can recognise it when I see it.
ImaFungi
reply to post by EnPassant
Ive come to the conclusion (still cautious of it) that time is (nothing more then) the transfer/transformation of energy. What think you of that? And yes the sequence of events is also part of the concept time. And I followed your OP, and think I catch your drift. It makes me think, with regards to your points on confusing sequencing, what caused what and what does that cause etc. Its like if you had a large room and an open ceiling and dropped 1000 basketballs in and then tried to determine what ball caused what ball to move where and when. I also am envoked to wonder if the concept of time would exist, if say, all that existed as the universe, all that existed forever was just the idea of that game pong, 2 paddles and a ball, and they had no friction, and hypothetically for some reason the ball was put in motion, and it literally bounced back and forth forever, with no observers, with yes change, yes relative sequence of events, but still, the same constant unwavering event, with no true detection of difference, would their be such thing as time? Related to the Hawking skepticism, if that scenario I just described was a symbolic universe, hawking is claiming that the ball 'just started moving', actually that the ball just appeared out of no where, and that before it appeared, nothing existed, nothing moved, nothing changed, no time.
edit on 19-12-2013 by ImaFungi because: (no reason given)
EnPassant
These are interesting thoughts. I had a similar idea about a universe consisting of nothing but a rotating sphere. If there are no reference points outside the sphere is it logical to say this sphere is rotating? (assuming the sphere is made of some kind of perfectly homogenous stuff with no marks on it.)
You could argue that the sphere has momentum but Mach's Principle says that it would only have momentum if a surrounding universe existed.
As for time - the source of matter is a field of energy in the universe. Consequently, the source of classical spacetime (which is geometry) is in this field of energy. But this field of energy is 'outside' the classical geometry, the macroscopic geometry. This means that everything that happens in the material geometry is determined elsewhere, outside the material universe. The cause of things is deep in the fields of energy in the universe.
But matter and mass are merely geometry, they don't exist in the naive way our physical senses tell us. They are concepts. The hydrogen atom is a concept. The substance of this concept is energy. But what is energy? Ultimately it is substance because all cannot be geometry, abstraction.
In this way the cause of time in the classical universe - which is really only a mirage of geometry - is in quantum reality. So, the way time proceeds is determined elsewhere, in fields of energy beyond classical spacetime. This means that the WAY cause and effect play out in classical geometry is prescribed elsewhere.
EnPassant
reply to post by HanoiLullaby
Time does not exist in a subatomic world, but we exist in a macro universe and can only frame our observations using spacetime, even when this leads to causality violations, which it can do.
Classical time does not (see my last two posts.) But time is not simply 'stuff happening' or 'change'. Time is the WAY change happens. It is spacetime. General Relativity describes material spacetime. But if there is a universe of energy then the mathematical description of the way change happens in that universe is a description of time. But it is not classical time. All matter can, in principle, evaporate back into pure energy. If this happened classical time would vanish. But quantum time would still exist. You would still have a field of energy, undergoing change in space and that is all that is required for time to exist. Time is merely a description of events and relationships. The geometry or nature of time depends on the nature of the reality it is describing, energy or matter.