Freethought & Rationalism Archive

Plump-DJ · 01-30-2002, 08:16 AM

Here's a neat little way you can show the impossibility of a temporally infinite universe. (or a universe of infinite past events)

Firstly, this view maintains that an infinite number of events have preceded the present event, the event we are experiencing right now. It says that an infinite series of events that stretch out into the past has been traversed or crossed to bring us to the current event we are now experiencing.

The above position is vulnerable when it claims that an infinite number of events have been completely traversed. In other words, all members of the set we can call `the past events' have been crossed, and there are no events that can be called `past events' that have not been crossed. The position also maintains that there is no beginning to the series, thus the claim that the series is infinite.

To show the problem let's try a little theoretical experiment. Let's say we can reverse the logical order of events. So, we would begin going backward, crossing all events in the logical order except reversed.

The infinite universe models say that all past events have been traversed coming forward. So, we should be able to traverse all events going backwards. After all, there are no more events going backward, than are coming forward; there are the exact same number of events. But, if we can traverse all past events going backwards, we will have come to a point when there are no more events to cross. Thus, all events would be traversed. If all events have been traversed going backwards, and no events remain to be traversed, then we will have come to an end. If we come to an end, then the series is finite. You see, an end going backward would be a beginning coming forward, and if it had a beginning it must be finite. If it is finite it is not infinite.

What if we never get to an end going backwards? It would mean that all past events could not be traversed; and if all past events cannot be
traversed going backwards, then they could not be traversed coming forwards. The same number of events are involved. If the series of events
could not be traversed coming forward, then we would never be able to get to the current event we are experiencing right now. Yet, we are at the present event. Therefore, there are not an infinite number of events.

So in otherwords : If all past events could be traversed, then the past is not infinite. If the past is infinite then all past events could not be traversed to get us to the present event. Since the latter is patently false (we are at the current event) we can only conclude that an infinte regress of finite events is impossible.

[ January 30, 2002: Message edited by: Orbital ]</p>

Adrian Selby · 01-30-2002, 08:28 AM

"we will have come to a point when there are no more events to cross"

Would it make sense to counter with the possibility that it would take an infinite amount of time to traverse an infinite regress of events?

I know very little about mathematical models of infinity, but on my philosophers view of it, could I validly argue that 'all events' does no more than merely refer to an infinite series, rather than 'bound' that infinite series?

Adrian

Theophage · 01-30-2002, 08:40 AM

Reply and possible refutation to Orbital:

If you consider time to be infinitely divisable, then in the time since you started looking at my post, an infinite series of time has already gone by. So perhaps it isn't quite as impossible as it would seem...

Ism Schism. · 01-30-2002, 08:41 AM

There may be a slight differance between infinite and permanant. I currently know next to nothing about physics but this seems to be a question only physics can answer. Given that nothingness can not exist -- the universe is permanant (in a sense *infinite* if time is the measurement).

If the eventual "burn out" from the expanding Universe theory happens, what happens to all of that energy -- is it just so dispersed that it becomes a non-factor? If I am not mistaken energy and/or mass can not be created or destroyed -- it remains constant in a closed system.

If you ask me, based on the very little bit I know -- the Universe is permanant, if not infinite. It may not always be suitable for life, but these times of inhospitality may or may not be temporary. It all depends on exactly what is going on out there, if humans survive long enough I think we have a good chance of being reasonably sure of what is going to happen.

Francois Tremblay · 01-30-2002, 08:43 AM

It's nice to know there are other definitions, but that doesn't answer my more important questions, i.e. what functional difference does it make, and how does that make any actuality infinite. If I understood correctly, Clutch seemed to be of that position.

Clutch · 01-30-2002, 09:17 AM

Orbital, you are right that, working backwards, there is no finite time in which we could complete the series (on a bunch of assumptions). This would be a problem if the infinite-past model claimed that this had been done "frontwards" -- that the series had been traversed in a finite time. But it doesn't. It says only that before each event there was a previous one. So working backwards you'd find that, after each event, there's a next one. No problem.

Clutch · 01-30-2002, 09:23 AM

Cardinalman, thanks. Yep, I had that backwards.

Franc, my first post was simply a reply to the thread-starter. Indeed, many things that I write are not intended as replies to you -- typically, the ones that make no mention of you.

Yours hadn't appeared when I started composing. This explains why mine might seem a bit non-sequitur-ish, as a refutation of your claim.

Theophage · 01-30-2002, 10:26 AM

Quoted material by Ism Schism. will be in bold:

There may be a slight differance between infinite and permanant. I currently know next to nothing about physics but this seems to be a question only physics can answer. Given that nothingness can not exist -- the universe is permanant (in a sense *infinite* if time is the measurement).

The way I like to say it is that the universe has always existed and always will exist. Here, the word "always" is used as meaning "at every possible place and time". This means that the age of the universe is not necessarily infinite (I think it is quite finite), just that it has been around ever since it has been possible for it to be around. (Since you cannot have time before time begins, etc.)

If the eventual "burn out" from the expanding Universe theory happens, what happens to all of that energy -- is it just so dispersed that it becomes a non-factor? If I am not mistaken energy and/or mass can not be created or destroyed -- it remains constant in a closed system.

That is correct, the energy in the universe doesn't disappear or get destroyed, it just spreads out and becomes useless. In physics terms, energy which is useless (or cannot be used to perform work) is called "entropy".

The reason the energy becomes useless is that to perform work there must be a transfer of energy from a higher to a lower state. Once the universe spreads out and dies of "heat death", everything will be at the lowest energy state, and thus nothing can go from higher to lower to do work.

Daniel "Theophage" Clark

[ January 30, 2002: Message edited by: Theophage ]</p>

Francois Tremblay · 01-30-2002, 11:04 AM

It's ok Clutch, I wasn't assuming that you were answering me. But I still asked you a question though

Draygomb · 01-30-2002, 11:13 AM

If there is a finite amount of energy then there is a finite amount of matter and space and a finite number of possible combinations of matter in space. Tf each combination is a unique moment in time and time must continue then eventually some combination must be repeated. This means that if energy is finite then time looops around and starts its self.

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

01-30-2002, 08:16 AM	#11
Plump-DJ Regular Member Join Date: Oct 2001 Location: Oztralia (Aussie Aussie Aussie) Posts: 153	Here's a neat little way you can show the impossibility of a temporally infinite universe. (or a universe of infinite past events) Firstly, this view maintains that an infinite number of events have preceded the present event, the event we are experiencing right now. It says that an infinite series of events that stretch out into the past has been traversed or crossed to bring us to the current event we are now experiencing. The above position is vulnerable when it claims that an infinite number of events have been completely traversed. In other words, all members of the set we can call `the past events' have been crossed, and there are no events that can be called `past events' that have not been crossed. The position also maintains that there is no beginning to the series, thus the claim that the series is infinite. To show the problem let's try a little theoretical experiment. Let's say we can reverse the logical order of events. So, we would begin going backward, crossing all events in the logical order except reversed. The infinite universe models say that all past events have been traversed coming forward. So, we should be able to traverse all events going backwards. After all, there are no more events going backward, than are coming forward; there are the exact same number of events. But, if we can traverse all past events going backwards, we will have come to a point when there are no more events to cross. Thus, all events would be traversed. If all events have been traversed going backwards, and no events remain to be traversed, then we will have come to an end. If we come to an end, then the series is finite. You see, an end going backward would be a beginning coming forward, and if it had a beginning it must be finite. If it is finite it is not infinite. What if we never get to an end going backwards? It would mean that all past events could not be traversed; and if all past events cannot be traversed going backwards, then they could not be traversed coming forwards. The same number of events are involved. If the series of events could not be traversed coming forward, then we would never be able to get to the current event we are experiencing right now. Yet, we are at the present event. Therefore, there are not an infinite number of events. So in otherwords : If all past events could be traversed, then the past is not infinite. If the past is infinite then all past events could not be traversed to get us to the present event. Since the latter is patently false (we are at the current event) we can only conclude that an infinte regress of finite events is impossible. [ January 30, 2002: Message edited by: Orbital ]</p>

01-30-2002, 08:28 AM	#12
Adrian Selby Senior Member Join Date: Jan 2002 Location: Farnham, UK Posts: 859	"we will have come to a point when there are no more events to cross" Would it make sense to counter with the possibility that it would take an infinite amount of time to traverse an infinite regress of events? I know very little about mathematical models of infinity, but on my philosophers view of it, could I validly argue that 'all events' does no more than merely refer to an infinite series, rather than 'bound' that infinite series? Adrian

01-30-2002, 08:40 AM	#13
Theophage Senior Member Join Date: Jun 2000 Location: Tucson, AZ USA Posts: 966	Reply and possible refutation to Orbital: If you consider time to be infinitely divisable, then in the time since you started looking at my post, an infinite series of time has already gone by. So perhaps it isn't quite as impossible as it would seem...

01-30-2002, 08:41 AM	#14
Ism Schism. Banned Join Date: Aug 2001 Location: Wilmington, Delaware Posts: 320	There may be a slight differance between infinite and permanant. I currently know next to nothing about physics but this seems to be a question only physics can answer. Given that nothingness can not exist -- the universe is permanant (in a sense infinite if time is the measurement). If the eventual "burn out" from the expanding Universe theory happens, what happens to all of that energy -- is it just so dispersed that it becomes a non-factor? If I am not mistaken energy and/or mass can not be created or destroyed -- it remains constant in a closed system. If you ask me, based on the very little bit I know -- the Universe is permanant, if not infinite. It may not always be suitable for life, but these times of inhospitality may or may not be temporary. It all depends on exactly what is going on out there, if humans survive long enough I think we have a good chance of being reasonably sure of what is going to happen.

01-30-2002, 08:43 AM	#15
Francois Tremblay Banned Join Date: Sep 2000 Location: Montreal, QC Canada Posts: 876	It's nice to know there are other definitions, but that doesn't answer my more important questions, i.e. what functional difference does it make, and how does that make any actuality infinite. If I understood correctly, Clutch seemed to be of that position.

01-30-2002, 09:17 AM	#16
Clutch Veteran Member Join Date: Oct 2001 Location: Canada Posts: 3,751	Orbital, you are right that, working backwards, there is no finite time in which we could complete the series (on a bunch of assumptions). This would be a problem if the infinite-past model claimed that this had been done "frontwards" -- that the series had been traversed in a finite time. But it doesn't. It says only that before each event there was a previous one. So working backwards you'd find that, after each event, there's a next one. No problem.

01-30-2002, 09:23 AM	#17
Clutch Veteran Member Join Date: Oct 2001 Location: Canada Posts: 3,751	Cardinalman, thanks. Yep, I had that backwards. Franc, my first post was simply a reply to the thread-starter. Indeed, many things that I write are not intended as replies to you -- typically, the ones that make no mention of you. Yours hadn't appeared when I started composing. This explains why mine might seem a bit non-sequitur-ish, as a refutation of your claim.

01-30-2002, 10:26 AM	#18
Theophage Senior Member Join Date: Jun 2000 Location: Tucson, AZ USA Posts: 966	Quoted material by Ism Schism. will be in bold: There may be a slight differance between infinite and permanant. I currently know next to nothing about physics but this seems to be a question only physics can answer. Given that nothingness can not exist -- the universe is permanant (in a sense infinite if time is the measurement). The way I like to say it is that the universe has always existed and always will exist. Here, the word "always" is used as meaning "at every possible place and time". This means that the age of the universe is not necessarily infinite (I think it is quite finite), just that it has been around ever since it has been possible for it to be around. (Since you cannot have time before time begins, etc.) If the eventual "burn out" from the expanding Universe theory happens, what happens to all of that energy -- is it just so dispersed that it becomes a non-factor? If I am not mistaken energy and/or mass can not be created or destroyed -- it remains constant in a closed system. That is correct, the energy in the universe doesn't disappear or get destroyed, it just spreads out and becomes useless. In physics terms, energy which is useless (or cannot be used to perform work) is called "entropy". The reason the energy becomes useless is that to perform work there must be a transfer of energy from a higher to a lower state. Once the universe spreads out and dies of "heat death", everything will be at the lowest energy state, and thus nothing can go from higher to lower to do work. Daniel "Theophage" Clark [ January 30, 2002: Message edited by: Theophage ]</p>

01-30-2002, 11:04 AM	#19
Francois Tremblay Banned Join Date: Sep 2000 Location: Montreal, QC Canada Posts: 876	It's ok Clutch, I wasn't assuming that you were answering me. But I still asked you a question though

01-30-2002, 11:13 AM	#20
Draygomb Veteran Member Join Date: Jan 2002 Location: Harrisburg, Pa Posts: 3,251	If there is a finite amount of energy then there is a finite amount of matter and space and a finite number of possible combinations of matter in space. Tf each combination is a unique moment in time and time must continue then eventually some combination must be repeated. This means that if energy is finite then time looops around and starts its self.

Freethought & Rationalism Archive

The archives are read only.