Deductive Logic on the subject of Time Travel.

[Mentat]

Originally posted by Royce
Mentat, remember way back in March when I first joined PF, you and I got in a discussion about time being a dimension, a real dimension?
I said that there is only one time and one time dimention that exists. The past, present and furture all exist along this dimension; but, as we are only 3 dimensional beings we cannot see or experience other than now; and we are compeled to travel along that dimention at whatever speed it is we are traveling and at whatever direction we are traveling.
Einstein showed that time is relative to the observer and interestingly time showed up negative in his relativity equations. If this has any significance or not I don't know; but, everybody including Einstein himself just ignored that fact.
In order for time travel to be possible in one universe then there must be one time in one (the 4th) dimension and all of time must exist at all times along that dimension. Time travel would then be traveling along that dimension; or, jumping out or off of our time line and jumping back in or on at another location. If this were possible then it would already be in our historic past whether known or not, or if would already be in our future history. Another facet of this one time idea is that to me it would make the universe determinate as our future already exists and we would be compelled to live it as it happens; but, others who believe this say that it doesn't, that we have, can and do exercise free will. This is illogical to me unless the future already includes our choices but then are we really choosing freely?
In one very real way we are all time travelers, traveling along our time line from our past to our future but always experiencing it as our present.

I disagree with only one point, Royce, and it's mainly to do with wording. Yes all events that happened in the past exist on the time line, but they do not exist "now", since now is the present. So, if I were to leave the time line (though I don't really see how you could, since it would take a certain amount of "time" to go in and out of the "line" wouldn't it?), I would not see infinite frames of the Universe at different points in time, but would see that the entire Universe (except, perhaps, tachyons and the like) are moving in one direction along this axis, at one speed or another. Therefore, our futures cannot be set, and our pasts are only set in that they are the past, and changing something is in the future tense (meaning that the idea of "changing" something, is the idea of taking something that exists now, and making it different; whereas the past has existed, and does not exist anymore, and can thus not be changed).

 

[Mr. Robin Parsons]

Originally posted by Sniper__1
And mr robin parsons i think time does not exist as again i have stated before.

Humm since in your profile it says you were born in 1989, and there was a British Scientist promoting this idea in the Early 90's (while you were still learning...) I would expect (false?/wrong?)your statement is simply one of your offer(ing) of 'your voice' (too) to the growing concensus, (?)

 

[Mentat]

Originally posted by Sniper__1
And mr robin parsons i think time does not exist as again i have stated before.

Are you sure you stated it "before", Sniper? If you stated it before the time of stating this post, then there is time. If there is no time, OTOH, there is a perfectly logical reason for Mr. Parsons to not have gotten your point to your satisfaction, you haven't said it yet, are still saying it, and have said it...all at the same time. I think I like the first scenario better .

 

[Mr. Robin Parsons]

Oh yes, BTW the past, the present and the future are all here/now as all of the atoms that were there in 1776 are still here and in use, just slightly altered, as are all of the other past particulate participants, and all of the Future ones too, right here, right now, just awaiting their chance to present themselves according to there "time"...atoms (and molecules) all.

 

[selfAdjoint]

Well, some of the uranium atoms have decayed into lighter atoms, and so forth, some of the hydrogen atoms have become helium too.

 

[Mr. Robin Parsons]

Originally posted by selfAdjoint
Well, some of the uranium atoms have decayed into lighter atoms, and so forth, some of the hydrogen atoms have become helium too.

O.K. but tell me something (perhaps) more important, has the total amount of energy in the entirety of the Universe changed, if so, how?, if not, why?

 

[Mentat]

Originally posted by Mr. Robin Parsons
Oh yes, BTW the past, the present and the future are all here/now as all of the atoms that were there in 1776 are still here and in use, just slightly altered, as are all of the other past particulate participants, and all of the Future ones too, right here, right now, just awaiting their chance to present themselves according to there "time"...atoms (and molecules) all.

Fine, but if they are "slightly altered", then there is a distinct difference between future, past, and present...future is when particles are "slightly altered" relative to past.

 

[Mentat]

Originally posted by Mr. Robin Parsons
O.K. but tell me something (perhaps) more important, has the total amount of energy in the entirety of the Universe changed, if so, how?, if not, why?

The total amount of energy in the Universe should have a greater percentage that has been distributed as "random movement" (="heat"), as per the Second Law of Thermodynamics...right?

 

[Mr. Robin Parsons]

Originally posted by Mentat
The total amount of energy in the Universe should have a greater percentage that has been distributed as "random movement" (="heat"), as per the Second Law of Thermodynamics...right?

Why? hasn't lots of it become, well, you, me, the rest of all of the Fusioned productions of atoms that have gone on for how many billions of years now, in the Star's core(s)??

 

[Infomeantion]

--------------------------------------------------------
Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...
---------------------------------------------------------

Are you trying to prove that time travel is nonsensical or if your reasoning is? You have two contradictory statements. If those statements are the only information to go by, then both of them are meaningless. If you add more information to your speculation, you can come up with reasoning to support that it is sensical or nonsensical, either way. But in the limited context of those four statements, it's just contradictory.

What I tend to think of though, in addition to this, is that you might rephrase it the following (unless you are omniscient, which as I heartell from the crazy information theory people is possible because there is a finite amount of information in the universe):

One universe, possible:
1: I didn't know I existed in 1776.
2: I know I exist in the reality I'm in right now.
3: Then I went back in time to 1776.
4: Now, I know if I were to transport myself back to that old reality that I mentioned in 2, that I existed in 1776.

The point is that you as a person have less than total information about the universe. If you don't contradict that (which I'd be surprised if you wholeheartedly did), then the first statement as you state it would not have the full meaning of absolute truth, although I'm sure that you could probably get a lot of people to agree with you if that is the thing you are after. Not I, however...how do I know that you aren't some computer intelligence just posturing as a person? I'm not saying that I think any of these is likely to me (I am not running to the newspapers about a time-traveling machine intelligence), but I cannot wholeheartedly assert my absolute knowledge of anything. Maybe you can, and maybe you are omniscient too.

 

[Mentat]

Originally posted by Mr. Robin Parsons
Why? hasn't lots of it become, well, you, me, the rest of all of the Fusioned productions of atoms that have gone on for how many billions of years now, in the Star's core(s)??

Sure, lot's of it has. But for every congealed mass created in space (like stars and planets) a greater amount of heat is given off, than order is established.

[edit]"then" to "than"[/edit]

 

[Mentat]

Originally posted by Infomeantion
One universe, possible:
1: I didn't know I existed in 1776.
2: I know I exist in the reality I'm in right now.
3: Then I went back in time to 1776.
4: Now, I know if I were to transport myself back to that old reality that I mentioned in 2, that I existed in 1776.

The point is that you as a person have less than total information about the universe.

You forget that the time of my postulating that I didn't exist in 1776 is before the time of my changing that. I got into a time machine, after having existed in a reality wherein I didn't exist in 1776 (as per P2). Now, if I did exist in 1776, then that's fine, but that means that I already existed there, in spite of my never having gotten in a time machine (yet).

If you don't contradict that (which I'd be surprised if you wholeheartedly did), then the first statement as you state it would not have the full meaning of absolute truth, although I'm sure that you could probably get a lot of people to agree with you if that is the thing you are after.

I'm after a fuller understanding. I don't expect to be right about this particular deduction, since there are so many respected people who still believe it to be possible-in-principle to travel backward in time. I'm just waiting for this deduction to be refuted, not for it to be accepted.

Not I, however...how do I know that you aren't some computer intelligence just posturing as a person?

But I am a computer intelligence...so are you.

 

[Infomeantion]

Allow me to try to rephrase how I initially read this thread's first post, which is essentially one argument nested within another. One, which I'll call 'Argument A', is the internal consistency of your reasoning with P1, P2, P3 and C. You show plainly that the argument is self-contradicty, with C contradicting P1 and P2 (although I don't think it contradicts P3 but that doesn't really matter). The second argument can be shown as follows:

Premise: Argument A is contradictory.
Proposition: Time travel's possibility relies on Argument A not
being contradictory.
Conclusion: Time travel is not only impossible, but non-sensical.

I agree with the premise that Argument A is contradictory. Your conclusion definitely contradicts your first and second propositions. But the proposition above, that time travel relies on Argument A, I believe not to be true. By including your 'limited information' in your role of Argument A, I was trying to show you that it does not mean that your conclusion is necessarily false, but rather that your premise could have been false. Either way, Argument A is contradictory, but not necessarily applicable to the possibility of time travel. Does this make more sense?

 

[Mr. Robin Parsons]

Originally posted by Mentat
Sure, lot's of it has. But for every congealed mass created in space (like stars and planets) a greater amount of heat is given off, than order is established.

Humm, proof of that?

 

[Mentat]

Originally posted by Infomeantion
Allow me to try to rephrase how I initially read this thread's first post, which is essentially one argument nested within another. One, which I'll call 'Argument A', is the internal consistency of your reasoning with P1, P2, P3 and C. You show plainly that the argument is self-contradicty, with C contradicting P1 and P2 (although I don't think it contradicts P3 but that doesn't really matter). The second argument can be shown as follows:

Premise: Argument A is contradictory.
Proposition: Time travel's possibility relies on Argument A not
being contradictory.
Conclusion: Time travel is not only impossible, but non-sensical.

I agree with the premise that Argument A is contradictory. Your conclusion definitely contradicts your first and second propositions. But the proposition above, that time travel relies on Argument A, I believe not to be true. By including your 'limited information' in your role of Argument A, I was trying to show you that it does not mean that your conclusion is necessarily false, but rather that your premise could have been false. Either way, Argument A is contradictory, but not necessarily applicable to the possibility of time travel. Does this make more sense?

Indeed it does. However, could you please explain to me how time travel doesn't rely on its possibility being deductively valid?

 

[Mentat]

Originally posted by Mr. Robin Parsons
Humm, proof of that?

As much proof as I have that we there are planets orbiting other stars...I've been told, and I've read.

 

[Mr. Robin Parsons]

Originally posted by Mentat
As much proof as I have that we there are planets orbiting other stars...I've been told, and I've read.

Sorry but your first statement is a little confusing...(sp? possibly?) but to the second one, me too, but I don't believe everything that I have read, I have had many a years to both read, remember re-digest, think, and come to conclusions concerning an array of areas of knowledge.

So tell me then, what is "chaotic" about heat? how is it that the disspation of temperature is seen as a "chaotic event" overburdoning to the extent of overwhelming the very real increase in order that is going on inside stellar bodies, and then tell me how much heat a galaxy bleeds off in comparison to the Order generated within that structure...and more, when your ready...

 

[Mentat]

Originally posted by Mr. Robin Parsons
Sorry but your first statement is a little confusing...(sp? possibly?) but to the second one, me too, but I don't believe everything that I have read, I have had many a years to both read, remember re-digest, think, and come to conclusions concerning an array of areas of knowledge.

Well, I skip the "come to conclusions" part, since I like to remain open, but I agree that this is the typical method. It's "education", and is necessary.

As to the first statement, I was just saying that I have enough proof that heat, greater than the quantity of congealed mass, is released when said mass congeals.

So tell me then, what is "chaotic" about heat? how is it that the disspation of temperature is seen as a "chaotic event" overburdoning to the extent of overwhelming the very real increase in order that is going on inside stellar bodies, and then tell me how much heat a galaxy bleeds off in comparison to the Order generated within that structure...and more, when your ready...

I don't know how much heat "bleeds off", I've just read that it's greater than the amount of mass that congeals.

You ask "what's so chaotic about heat", my response is: The heat!

"Heat", by a physicist's definition is random movement of particles.

 

[Mr. Robin Parsons]

Originally posted by Mentat
(SNIP)[/color] "Heat", by a physicist's definition is random movement of particles. (SNoP)[/color][/B]

Oh, so then it is NOT "Ambient Energy Pressure" you know, what a thermometer reads...cause heat is something that occurs between atoms, the release of the atoms energy/EMR, and causes them to increase/decrease in motion relatively, cause and effect, just 'looks' "random" but follows all the rules like it is supposed to.

 

[Mr. Robin Parsons]

Originally posted by Mentat
(SNIP)[/color] As to the first statement, I was just saying that I have enough proof that heat, greater than the quantity of congealed mass, is released when said mass congeals. (SNoP)[/color]

Humm, let's see, debating tactics, distract your opponents attention by diverting from subject matter in an innocent looking enough manner...we had been talking (least I was) about the Fusion reactions going on inside "stellar bodies" remember that?, not congealing masses that are releasing heat, aside, have you proof of that "Heat V Order" relativity in/concerning a galaxy?

 

[Mentat]

Originally posted by Mr. Robin Parsons
Oh, so then it is NOT "Ambient Energy Pressure" you know, what a thermometer reads...cause heat is something that occurs between atoms, the release of the atoms energy/EMR, and causes them to increase/decrease in motion relatively, cause and effect, just 'looks' "random" but follows all the rules like it is supposed to.

Rules?

Besides, what exactly are you getting at with this post?

 

[SmarterThanGod]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

You could go by a predestination assumption, in which case, you would have existed in P1 and P2 before you were even born, because in the future, you will travel back to 1776, and since this must have already happened before you were even born, P1 would be false before you traveled back to 1776, and therefore, the present reality would include the events that happened to you in 1776, though you may not remember them, they are technically your past AND future. The main assumption here is that all events in the universe are predestined, and therefore that you cannot change the future because it is included in your present. Anythign you do while in 1776 will ALREADY be included in the present universe, so the outcome will never change.
This may have been mentioned already in another reply, but I am tired, and have only read the first post, so sorry if I am redundant

 

[Mr. Robin Parsons]

Originally posted by Mentat, on page 5
The total amount of energy in the Universe should have a greater percentage that has been distributed as "random movement" (="heat"), as per the Second Law of Thermodynamics...right?

Originally posted by Mentat
Rules? Yes rules, heat a gas, and it expands, yes! rules!
chemistry and physics are all about "The Rules" and we don't really "write" them...[/color]
Besides, what exactly are you getting at with this post?

To the [ b]'d See the above, your question, and what (it) followed it...

 

[hey.like]

One mean of Time travel is movement in time dimension

Time system is not in future past and nowonly , but in space time , it is exist in a semi-dimension. to move in this semi-dimension and take the university strong power, it is ony way to exceed the light to travel. as the time system is one only. it isn't in time value travel but in dimension and to borrow the space-time unit action to arive a far away distance.

 

[hey.like]

Why the travel is not to go some distance?

Why the time travel is to go in time , it is semi-dimension as the first event. to return , first to face the first event. it is no mean.
If to take the mass system time help, it is enable and the time is in some progress only. but the livethings to front is in the right time direction . it is hard to fact the against time direction.

 

[Silverious]

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

I was wondering, why you would assume you did not exist in 1776.

But, assuming P1 and P2 are correct. P3 could never have happened.

But assuming P3 DID take place, C is correct, P1 is false, and P2 would have to be modified. Because, at every time interval before P3, P1 and P2 are entirely correct. But once P3 takes place, you exist now in 1776.

I think you assumed too much, which is the main cause of the contradiction. But what do I know?

 

[olde drunk]

slightly different view

let's approach with a 'reasonable' basis.

a)i exist in 2004
b)i existed in 1950
c) i can travel back to 1950

hmmmm? how many times have you seen two family members talk about a past event? dick and jane were married on a saturday; the weather was misty, friend Spot attended.

now, when dick and jane discuss that day/event, they have two different views of events. regardless of the circumstances they vehementally disagree.

i submit that they each are traveling back to a 'probable past'. each is revisting the past that they experienced. i further submit, that when we can accept this possibility, we will get closer to actual time travel.

imho, all pasts, presents and futures exist as probablities or potential experiences. it is because we narrow our focus into a very fine 'present' that we negate our ability to visit the past or future. we see clues when we dream of of a future and it becomes a reality to be experienced.

in my construct, the past and future are there for us to visit when we develop full powers and prepare the human awareness for the experience. anyone who said they did today would be labled as a nut. also, are dreams a less valid reality?? are my rememberances of a past event lass valid than my conscious present?


peace,

 

[Sikz]

The thing with time travel is definitions.

"P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ..."

The contraversy here is the definition of "I". Is the you who goes back the same you who is there? This is why there is not as yet (to my knowledge) any undeniable logical proof against time travel- they are all based on contraversial axioms.

 

[Mentat]

Originally posted by SmarterThanGod
You could go by a predestination assumption, in which case, you would have existed in P1 and P2 before you were even born, because in the future, you will travel back to 1776, and since this must have already happened before you were even born, P1 would be false before you traveled back to 1776, and therefore, the present reality would include the events that happened to you in 1776, though you may not remember them, they are technically your past AND future. The main assumption here is that all events in the universe are predestined, and therefore that you cannot change the future because it is included in your present. Anythign you do while in 1776 will ALREADY be included in the present universe, so the outcome will never change.
This may have been mentioned already in another reply, but I am tired, and have only read the first post, so sorry if I am redundant

No, yours is a very good point. However, the real question is: If P1 and P2 are true, then is it possible to travel backward in time?

 

[Mentat]

Originally posted by Sikz
The thing with time travel is definitions.

"P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ..."

The contraversy here is the definition of "I". Is the you who goes back the same you who is there? This is why there is not as yet (to my knowledge) any undeniable logical proof against time travel- they are all based on contraversial axioms.

There can be only one "I", as that is what the whole semantic purpose of the term "I" is, ITFP.

 

[Mentat]

Originally posted by Silverious
I was wondering, why you would assume you did not exist in 1776.

But, assuming P1 and P2 are correct. P3 could never have happened.

But assuming P3 DID take place, C is correct, P1 is false, and P2 would have to be modified. Because, at every time interval before P3, P1 and P2 are entirely correct. But once P3 takes place, you exist now in 1776.

I think you assumed too much, which is the main cause of the contradiction. But what do I know?

I may have assumed "too much", but I may have assumed "just enough". You see, if I existed in 1776, then I am predestined to travel there, and thus there is no contradiction, as SmarterthanGod has pointed out. However, with the assumptions as stated, I have to assume your last paragraph is flawed. The reason I say this is: If P1 is true before P3 takes place, then P3 cannot take place (logically). Thus, if P1 is ever true, P3 is never true.

 

[confutatis]

"Time" is just the way we think

Originally posted by Mentat
When I say "Time Travel" in the title, I'm referring to traveling into the past. I just wanted to see if I could establish deductive validity for my assumption that it is not just impossible, but non-sensical, to travel backward in time.

("P" stands for "Proposition" and "C" stands for "Conclusion")

Here we go:
P1: I did not exist in 1776.
P2: I exist now in a reality that includes P1 as being true.
P3: I go back in time (using whatever means) to 1776.
C: I did exist in 1776! ...

But, then, I have invalidated P1 and P2, and even (by extension) P3, so my conclusion violates all the propositions...is this logically sound?

Any and all helpful criticism is appreciated.

The problem with this issue is that you can't say something cannot happen because it's illogical. In fact, history is full of episodes when actual observation contradicted the logic of the time. The key point here, unseen by many people, is that logic does not apply to reality, it only applies to the way we think about reality. People who believe time travel may be possible are not entirely wrong; however, if what we loosely think of today as "time travel" turns out to be possible, then the skeptics will prove their point: whatever it is, it can't be called "time travel".

Mentat, I suggest your approach to the problem is slightly wrong, because you are not fully taking into account the way we think. Here's how I see the problem:

At any given point in time, I am aware of a certain amount of historical knowledge. One such piece of knowledge is "I did not exist in 1776". This is very much what you say in P1 and P2, with an important difference: the emphasis on "what I know" as opposed to "what is true".

Now suppose "something" happens (let's leave that undefined for now), and suddenly you acquire a new piece of knowledge that says "I did exist in 1776". You have a problem now, because two pieces of knowledge contradict each other. By the way, this is an extremely common occurrence in our daily lives, so the solution shouldn't be that difficult.

Let's examine a somewhat similar situation: At some point in your life, the statement "I have never been to Atlanta" was true. Then another "something" happened, and the statement "I have been to Atlanta" becomes true. Do you have a problem now? Replace "have been" with "existed" and think about the difference between Atlanta and 1776. Particularly why it's possible to be and not to be in Atlanta, while the same cannot be said about 1776. It's very interesting if you approach it from a particular perspective, as it reveals something about time.

The reason you can be and not be in Atlanta, the reason the two pieces of knowledge do not seem paradoxical to you, is because you already know the solution to situations like that. And the solution involves a concept called... time! "Time" is what allows two apparently contradictory statements to be true.

Back to time travel. Can it be possible? I say it can, only not the way you think about it. In order to explain how you can be and not be in 1776, you need the same concept you use to explain how you can be and not be in Atlanta: you need "time". So time travel is possible if you can "travel" through "time 1" using "time 2". In other words, time travel is perfectly possible as long as there are two or more time dimensions.

I suspect a question still remains: can we prove time travel is impossible if there is only one time dimension? And here the answer sounds too obvious to me: if there is only one dimension of time, then you can only travel from 2004 to 1776 by going through every single moment in between. You can't jump from 2004 to 1776 without first going through 2003, 2002, 2001, and so on. Now what happens when you go back through those years? If there's only one dimension of time, you already know the answer.

 

[Mentat]

Originally posted by confutatis
The problem with this issue is that you can't say something cannot happen because it's illogical. In fact, history is full of episodes when actual observation contradicted the logic of the time. The key point here, unseen by many people, is that logic does not apply to reality, it only applies to the way we think about reality. People who believe time travel may be possible are not entirely wrong; however, if what we loosely think of today as "time travel" turns out to be possible, then the skeptics will prove their point: whatever it is, it can't be called "time travel".

Mentat, I suggest your approach to the problem is slightly wrong, because you are not fully taking into account the way we think. Here's how I see the problem:

At any given point in time, I am aware of a certain amount of historical knowledge. One such piece of knowledge is "I did not exist in 1776". This is very much what you say in P1 and P2, with an important difference: the emphasis on "what I know" as opposed to "what is true".

But I didn't say that I knew I didn't exist in 1776, merely that I didn't. There's a difference. And as to reality contradicting logic, that is not true, and literally cannot be. You see, for anything that takes place, there is a logical framework that allows it.

The reason you can be and not be in Atlanta, the reason the two pieces of knowledge do not seem paradoxical to you, is because you already know the solution to situations like that. And the solution involves a concept called... time! "Time" is what allows two apparently contradictory statements to be true.

Back to time travel. Can it be possible? I say it can, only not the way you think about it. In order to explain how you can be and not be in 1776, you need the same concept you use to explain how you can be and not be in Atlanta: you need "time". So time travel is possible if you can "travel" through "time 1" using "time 2". In other words, time travel is perfectly possible as long as there are two or more time dimensions.

I suspect a question still remains: can we prove time travel is impossible if there is only one time dimension? And here the answer sounds too obvious to me: if there is only one dimension of time, then you can only travel from 2004 to 1776 by going through every single moment in between. You can't jump from 2004 to 1776 without first going through 2003, 2002, 2001, and so on. Now what happens when you go back through those years? If there's only one dimension of time, you already know the answer.

Yeah, I'd considered the dual time-dimension idea (btw, Kudos on your explanation, it was really good...I hadn't looked at in quite the same manner before), but disqualified it for reasons of Occam's Razor and my own distaste for ad hoc arguments.

Finally, in that last paragraph you seem to be describing a regressive type of time travel, wherein everything - including the Time Traveller - regress to former states. You are right, of course, that this is both impossible and non-sensical (especially since, if the time traveller goes back to any time before the time that he started going back, he is no longer going back, but forward as always), but I was also hoping to show that, even if we make the Traveller immune to the consequences of regressive time, it is still impossible and non-sensical to postulate backward time travel.