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This thought experiment involves a friction-free snooker table, in a vacuum. The cue-ball is alone on the table, placed centrally on the balk cushion.
At t=0 the cue strikes it, sending it straight up the table at constant velocity, v, with constant momentum, p.
At t=1 it crosses the green spot. At t=2 it crosses the blue spot. At t=3 it arrives at the pink spot; at which point, time is reversed.
It crosses the blue and green spots at t=2 and t=1, respectively.
What happens to v and p, both are vectors, so at t=2 and t=1, in reversed time, the ball is travelling towards the balk cushion, but the vectors point away from it?
the green , blue and pink spots are not lined up with each other.
the 3 spots are not in a straight line so the ball would experience a change in velocity if it did cross the green spot and the blue spot and then it vectored to the pink spot.
however you can buy more pink spots and place another pink spot on the table lined up with the other 2 spots and then they would all be in a straight line.
or you could simply exchange the green spot with the brown spot in the OP if thats the way you do things.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
What happens to v and p, both are vectors, so at t=2 and t=1, in reversed time, the ball is travelling towards the balk cushion, but the vectors point away from it?
Now place yourself at the other far end bounce cushion and time is always running backwards according to you even when you are waiting to strike the ball ... you may need to think about it for a second
Time only goes the right way when the ball has bounced and is on it's way back.
The time evolution of the system is uniquely defined by Hamilton's equations
You have created a Hamiltonian description and it's just a mathematical description. The article even tells you how to deal with your vector descriptions and the physical meaning.
Want me to prove to you that your description is completely meaningless ... pick up the ball somewhere in it's travels.
So which way is your time running when I pick the ball up?
Last edited by Orac; 06/15/1602:37 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
Now place yourself at the other far end bounce cushion and time is always running backwards according to you even when you are waiting to strike the ball ... you may need to think about it for a second
I thought about it for a few seconds, but wherever I stand, time runs the same way.
Thanks for the link. I understand that Roger Penrose's father tought him calculus the evening before he started it at school. It would take me a lot longer, and I don't have the time; so if there is something there that would enlighten me, it will need to be simplified. Lots!
Quote:
So which way is your time running when I pick the ball up?
the reason Im asking is because if it were possible to reverse time then both v and p would be in the reversed direction.
my reasoning on this is that when the ball strikes the cue at the balk cushion its momentum would be transferred into the cue due to its v and mass.
if the experiment is only referencing time as in a frame by frame event such as a video that is stopped as the ball reaches the pink spot and then reversed frame by frame then in that case both v and p would still point the same way.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
Thanks for the link. I understand that Roger Penrose's father tought him calculus the evening before he started it at school. It would take me a lot longer, and I don't have the time; so if there is something there that would enlighten me, it will need to be simplified. Lots!
Instead of using the colors on the table make it a distance from the point you choose (you selected the cushion) and write the equation for speed and time.
The formula is straight forward: distance = speed ball hit at * time from ball strike
That is the hamiltonian you are describing in your thoughts. So select a table a length (say 2m), select a suitable speed say (0.25 m/sec) now write the distance for each of the 10 seconds following the ball strike.
Do you see the problem with your hamiltonian ... => time from ball strike only conceptually only goes forward then your distance can only ever get bigger. When the ball hits the time reversal pink spot the distance actually starts decreasing the weird behaviour you think is strange.
So what is required is to negate one of the terms in the hamiltonian at the point of reversal.
That can be done in one of TWO WAYS. 1.) Turn speed into a velocity one way being +ve the other -ve 2.) Invert time at the reversal point, notionally its zero at the reversal point so time has a +ve and -ve component
Surprised me but Paul correctly worked that out but he went for both, they don't both reverse you get to choose one.
The problem is there exists no selective process you can choose that tells you which is right or wrong or even if it has physically correct meaning.
What I was trying to get you to realize in your thought experiment was that your statement time reverses at the pink spot is totally SUBJECTIVE.
I can solve your problem in two other ways than your choice
1.) By simply putting time = 0 at the pink spot and it doesn't matter which way time runs the calculation will work. So time is zero at the pink spot and radiates out from that point. 2.) I can simply have an invisible bumper at the pink spot and the ball actually bounced inverting it's velocity.
So even if I could physically do your experiment and view it I would not in any way deduce time had reversed and it introduces no anomaly.
Originally Posted By: Bill S
Same way it was before you picked it up.
So now we take the other choice you didn't consider that when the ball reached the pink spot you the observer started going backward in time. If the pink ball is a point with a time reversal why can't the point you are observing from be one.
Picking up the ball is a metaphor for some event that is nothing to do with what is being observed but what the observer does or has done to them.
Your experiment assumes you the observer are GOD and know exactly what is actually happening .. an impossibility for us mere mortals.
Last edited by Orac; 06/17/1607:15 AM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
the reason Im asking is because if it were possible to reverse time then both v and p would be in the reversed direction.
For the sake of discussion, I'm accepting relativity. This means that t=2 (for example) is an immutable spacetime event. It cannot occur with v and p running R to L, then L to R.
Your experiment assumes you the observer are GOD and know exactly what is actually happening .. an impossibility for us mere mortals.
This is more-or-less my starting point. There are too many impossibilities to allow physical time reversal to work. Or are there? Do we impose the "impossibilities" through our own maths and physics.
BTW; I am "god"; so are you; but that's a whole different line of logic.
It's my thought experiment, but I got the idea from somewhere. I'll let you know if/when I remember where, because I'm fairly sure there were other time related issues there as well.
at first when I read that I pictured a fish swimming in a stream minding his own business carrying out his daily routine who was startled by a plopping sound as if something had been thrown into the stream ...
and I can see through the eyes of the fish as he swims over to the location where he heard the sound coming from ...
hes looking at a shinny bright metallic object with a big fat juicy worm dangling from it ...
the shinny metallic object and the big fat juicy worm then begin to jump up and down as if it ha been startled by the fish , and then the fish sees a tiny clear plastic line that is attached to the bright shinny object that leads up and out of the stream.
at first the fish was hungry but now hes curious so he quickly darts through the water following the plastic line then suddenly he is out of the water flying through the air and out of one of his eyes he sees a man standing on the bank holding a fishing rod and quickly tugging it up and down with a really big grin on his face ...
and standing just behind the man is a really huge grizzly bear who towers high above the mans head and to the right of the mans head is a brown blur that is quickly approaching the mans head the fish glances at the bears head , the bear has a really big grin on its face.
about that time the fish plops back into the stream and as he does he hears a extremely large splash and feels a jolt as he is swimming back to where the bright shinny metallic object was he notices that the plastic line is now laying flat on the bottom of the stream and the worm has crawled off of the bright shinny metallic object ...
the fish swims over to the worm and asks the worm if he would like to see the inside of his stomach and the worm said that was exactly what the man asked you when he saw you just before he tossed me into the stream.
as the fish is looking at the worm crawling away , the water is quickly changing to a bright shinny red color the next thing the fish feels is something hes never experienced before ... there is no water ... he cant breath .. then . he sees the bears teeth he both hears and feels a loud crunch and then darkness.
the moral of this story is that theres always something bigger than you are.
and of course the bait got away.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
if time could be reversed then the measurements would also be reversed.
t=2
time is a measurement and nothing else.
so its like using a measurement tape.
measured out to t=3 then back to t=2
why?
because if time were forwarded again at the blue spot
then history would repeat in the same order.
and the ball would once again approach the pink spot or t=3
else
if you advanced the time measurement to t=4 as the ball crosses the blue spot then time could not repeat if the time were forwarded at the blue spot because the next available time measurement would be t=5
and only 3 units of time would have occured.
t=1 t=2 and t=3
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
For the sake of discussion, I'm accepting relativity. This means that t=2 (for example) is an immutable spacetime event. It cannot occur with v and p running R to L, then L to R.
immutable spacetime event???? ... in relativity? Really?
Refresher ... Newtonian physics has immutable space and time events. Einstein wanted that feature in Relativity but he lost the argument and eventually worked it out that observers may see things differently.
To be blunt unless you are god you can't even identify that the ball didn't just go past t2 and keep sailing on and you started observing it go backward ... in a nutshell you have no way to know your observation is "absolute" or "real". This goes back to the time problem at the event horizon and you wanting to make it real.
You need to stop making things "real" and "immutable" just because you observe them. Go and read Einsteins train thought experiment.
I can tell you from your setup I can't determine a thing, I don't have enough information.
Last edited by Orac; 06/19/1602:17 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
This is more-or-less my starting point. There are too many impossibilities to allow physical time reversal to work. Or are there? Do we impose the "impossibilities" through our own maths and physics.
In your experiment there is no way to sort forward from backward time in your experiment, you haven't given me enough to sort that out.
The biggest problem with your experiment is the result, which starts from an out there suggestion of a point at which time reverses.
So to make the "result fit" I am thinking what motions could happen to "observe that", and more direct out there results would be things like enter a worm hole and come out at the same entry point but going backwards. You are constructing the far out idea of a point at which time could reverse so I assume I am allowed to put a wormhole there as time is going backwards. So I believe in worm holes no but nor do I believe in points at which time reverses.
You need to have it clear in you mind when you talk of reversing time are you talking of really doing that or just reversing event order because the two things are not the same. Reversing event order is reasonably easy to do, reversing actual time not so much.
Paul correctly worked the LOGIC fail, that you can't be talking about real actual time as you won't go backwards because through the same section of space you initially were going forward. So why didn't you go backwards when coming thru the same section of space originally.
If this was your start point I think you need a new one
Last edited by Orac; 06/19/1602:26 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
To be blunt unless you are god you can't even identify that the ball didn't just go past t2 and keep sailing on and you started observing it go backward ... in a nutshell you have no way to know your observation is "absolute" or "real".
While this is all, undoubtedly, true; games of snooker are played, and they are subject to the laws of physics. If you apply your reasoning to the events of the macro-world, how would a player know what any ball was going to do?
If this was your start point I think you need a new one
A tourist in Ireland stopped his car and asked a local man: “Could you direct me to Ballynanty?” The man thought for a moment, then said: “Ah, to be sure, if I was going to Ballynanty, I’d not start from here”.
While this is all, undoubtedly, true; games of snooker are played, and they are subject to the laws of physics. If you apply your reasoning to the events of the macro-world, how would a player know what any ball was going to do?
Good pool players work out how balls will react by observing results and testing theories.
For example pool balls can be struck in such a way that you can put back spin on a ball and it would behave in the exact manner you describe ... Give your result to a pro pool player and the answer would involve no weird time reversing physics.
So you tell us there is a time reversal on the table and the result .. which does not differ from the ball had back spin on it. No pool player would ever arrive at your answer or agree with it because they don't need time reversal to arrive at the result.
Normally in a thought experiment you are supposed to either let me work through the problem, or show all the possible results. Instead you gave us some ridiculous result which actually can't possibly happen. It's a slightly strange way to setup a thought experiment.
Perhaps you might like to rephrased the question, and we provide the results we might expect rather than try and tell us an impossible answer.
The problem you need to address Paul identified for you
Quote:
because if time were forwarded again at the blue spot then history would repeat in the same order.
You can't be going both forward and backward in time at the blue spot unless time belongs only to an object and not globally. In which case we defer back to my answer you have no idea which way time is going for any given object as they are independent and it creates no problem ... one objects forward is another objects reverse.
Last edited by Orac; 06/20/1602:14 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
plus the starting position of the ball is on the balk cushion.
two reasons why a back spin cannot be applied to the ball.
but the main reason is the no friction clause.
we need to remember that Bill S has experienced a time change or at least he understood it to be a time change that he described in an earlier post that he made a while back.
perhaps we should discuss that event vs running around these diverse bushes beating them to see what comes out.
personally I think that he did not experience a time change event and his mind simply decided that a time change event was the only possible way that the event could have played out or occurred.
we have all experienced deja vu at one time or another and cannot quite put our finger on the reason or some other seemingly mystical event ... some more than others.
its best not to dwell on these things but it is healthy to try to find a physical reason if possible.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
Sorry I have never seen a pool table which doesn't have friction nor have I ever seen a point in space at which time reverses
I can however also produce the effect a number of other ways such as lift the end of the table, have a wind blowing and dozens of other cases. I only need a tiny amount of constant force going the opposite way to the ball movement to create the result. So Bill S needs to wave his fairy god wand and tell me no such forces exist in our thought experiment.
Given the magic wand has acted then I can sort of guess how a pool table without friction would work by extending the laws of physics. If I extend the physics of a point in space with time reversing, the entire universe collapses in on the point for exactly the logic you worked out with the blue spot. Bluntly there is no way to stop the collapse unless you create a time horizon (relative, absolute or event horizon) but the result of the ball then differs completely to what Bill S gives as the answer.
I can't construct the result within the thought experiment and the fairy god wand and so all I can do is say to Bill S that his answer is impossible, which you also worked out.
Now I have no intention of starting another stupid conversation with you, and so I will leave you and Bill S to sort out the physics of time reversing points in your own special physics. Engaging ignore factor warp 10.
Last edited by Orac; 06/21/1604:26 AM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
personally I think that he did not experience a time change event and his mind simply decided that a time change event was the only possible way that the event could have played out or occurred.
we have all experienced deja vu at one time or another and cannot quite put our finger on the reason or some other seemingly mystical event ... some more than others.
If you mean the “stone tape” experience I talked about, then I think you are absolutely right; it was not a “time change event”. There was not really “déjà vu” involved, either. I would not attempt to place any interpretation on it other than that it seems to indicate that there may be aspects of life that science has not yet found a satisfactory answer for.
Sorry I have never seen a pool table which doesn't have friction nor have I ever seen a point in space at which time reverses
Would you say that Einstein’s thought experiment with light was invalid because you have never seen anyone travelling at c beside a beam of light?
Terry Pratchett described a thought experiment as “One that you can’t do, and which won’t work”. Be that as it may, is one of us missing something about the nature of thought experiments?
Of course, all this is really irrelevant because you are so far from the OP that I find myself wondering if you actually read it; or if you are suffering from fixation amnesia?
I didn’t say that time could be reversed. I didn’t say I thought that time could be reversed. I did try to investigate one of the factors that seemed to me to be an argument against time reversal.
Quote:
I can't construct the result within the thought experiment and the fairy god wand and so all I can do is say to Bill S that his answer is impossible
Why do you two keep referring this rubbish back to me, I don't do philosophy. Your thought experiment is a philosophical one to me.
Originally Posted By: https://en.wikipedia.org/wiki/Thought_experiment
USES: .. In thought experiments we gain new information by rearranging or reorganizing already known empirical data in a new way and drawing new (a priori) inferences from them or by looking at these data from a different and unusual perspective.
IN SCIENCE: Scientists tend to use thought experiments in the form of imaginary, "proxy" experiments which they conduct prior to a real, "physical" experiment (Ernst Mach always argued that these gedankenexperiments were "a necessary precondition for physical experiment"). In these cases, the result of the "proxy" experiment will often be so clear that there will be no need to conduct a physical experiment at all.
You ignore all the prior physics and data.
Your experiment doesn't take the form of Einsteins which leaves all normal physics working ... you violate just about everything (even Paul could see the basic problem). It's completely meaningless to me, it's like putting GOD in a science thought experiment. I have tried to explain why but if you don't get it by now, then sorry but I can't be anymore clear.
You two want to argue that it's a science thought experiment, well fine ... I give in its a science thought experiment. I can see the logic it's sort of got some layman science in it, so you got me I agree, just don't ask me to care about it.
Sorry I understand you guys now .. you never said it and it never happened
Originally Posted By: OP from Bill S
At t=3 it arrives at the pink spot; at which point, time is reversed.
It crosses the blue and green spots at t=2 and t=1, respectively.
What happens to v and p, both are vectors, so at t=2 and t=1, in reversed time, the ball is travelling towards the balk cushion, but the vectors point away from it?
Feel free to discuss it together but leave me out, I have had my fill of invent-a-physics this week and my care-o-meter is on empty.
Last edited by Orac; 06/22/1608:23 AM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
I have a serious question to ask you about the einstein shrinking objects bit.
suppose one of earths space steam locomotives were traveling away from the earth just fast enough so that it would begin to shrink!
lets say that the space train continues to gain acceleration as it travels and it shrinks by 50% of its normal size .... it then returns to the earth then upon arrival back at earth
1) would the earth then shrink by 50% its normal size in order to preserve the effects of light speed upon its arrival?
2) would the space train simply be 50% smaller.
Quote:
I have had my fill of invent-a-physics this week and my care-o-meter is on empty.
so Im going to guess know that somewhere in the first hour of every new week as you begin to wake up from your more realistic dream state that upon awakening on the first day of every new week you quickly reach your "fill of invent-a-physics"
............
and your thinking ... oh man that dream was realistic ... but it was just a dream as you comfort yourself in your knowing that reality is all in the mind ... and that you have one ... so what you know in your mind is reality to you , not to everyone else , only to you and to like minded D&D players.
Im thinking up a really good thought experiment using the einsteinstonedians theories that I will post later.
it will be revealing.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
Now it is obvious this is just another attempt to get a blatantly religion inspired stupid argument going, just by the way you address me in your posts. Sorry my little religious whackjob I am not buying.
Why even ask me ... your a religious nutter so ask your GOD which supposedly has all the answers. What GOD can't answer this basic physics stuff?
You really are like Marosz even down to the attention seeking behaviour to discuss utter stupidity.
So for the final time I don't care what Marosz and you believe, it isn't my problem and I am happy just to ignore you both. I see your other mate Samwik, finally worked out to just ignore you.
Now I have taken notifications off this thread ... start posting to yourself that is what Marosz has to do next
Last edited by Orac; 06/22/1603:33 PM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
Why do you two keep referring this rubbish back to me
Orac, let’s have some clarity. Look at the OP; I didn’t refer it to you; and unless you believe you are the only poster on SAGG who can answer a question, I see no reason why you would assume it was addressed to you.
The choice to respond was yours. Are you suggesting I should have ignored your response?
If you chose to misinterpret what I say, and berate me for what you wrongly impute to me, there seems little point attempting discussions.
Orac, let’s have some clarity. Look at the OP; I didn’t refer it to you; and unless you believe you are the only poster on SAGG who can answer a question, I see no reason why you would assume it was addressed to you.
I agree the OP was not directed to me but your responses above clearly are (they quote me), even after I asked not to be involved because I don't consider it a valid science thought experiment. Then you want to argue what I should think a valid science thought experiment to be.
Originally Posted By: Bill S.
The choice to respond was yours. Are you suggesting I should have ignored your response?
Yes I make the choice to reply or not as I feel, as I do with nutcases like Paul and Marosz. I answered it to explain you have gone into an area of philosophy which I am not interested in. Whether you consider it philosophy or science is not under question here, nor relevant.
Originally Posted By: Bill S.
If you chose to misinterpret what I say, and berate me for what you wrongly impute to me, there seems little point attempting discussions.
I highlight in red your exact words in the OP, which you say I misinterpret ... ok then must be that english thing again. I am not berating you for anything, I just set some solid hard limits on this discussion which if you cross I am not interested in. To me in your response, you then not only ignored the limits I set but want to argue I shouldn't have those limits.
So I am not berating you when I say, I am not interested in discussing what you consider a science thought experiment, it isn't remotely relevant to me. I have a definition of science thought experiment it differs from yours and it sets the limits to which I am willing to discuss things. As I said it stops me putting a GOD in a science thought experiment. That is exactly what your thought experiment does (replace your time reverse point with GOD deciding to reverse time when the ball gets to the point... same thing ... no consideration for if it's possible). However I now get you don't see it like that, so lets just leave it. I tried to get you to adjust the question so I could discuss it. You don't want to, so fine I will leave it, not a problem to me.
On any actual real science forum you would simply have got a warning from moderator the thought experiment isn't scientific and they would generally lock the thread. They wouldn't let you argue it either because it's not up to them to define such things. It is a little more problematic on this loose forum and I have to tell you when you drift to far for me.
However when I tell you that you have strayed out of what I call science, I would appreciate if you do not try and argue what I call science. What you or others choose to call science may differ and it isn't relevant to me as my definition is inflexible and not up for discussion by you. You have seen that Rev K tries to say his stuff is scientific and I won't discuss that either, and I don't care if he calls it science it doesn't change anything to me as it fails the basic rules.
So again I say to you, your OP is not a valid or suitable post for a science forum it fails the basic rules. I am not the moderator on this pseudo science forum AR2 is, so I can only ask and you may well select to ignore me and say it is science and I will ignore the thread like the other stuff here I find as not science.
Last edited by Orac; 06/23/1606:19 AM.
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
I have now sorted out where the idea came from. It was Sean Carroll’s “From Eternity to Here” (P132). Possibly you consider Sean’s science to be inferior to yours, but we mere amateurs have to question everything, indiscriminately, if we are to have any hope of reaching an understanding.
Originally Posted By: Orac
However when I tell you that you have strayed out of what I call science, I would appreciate if you do not try and argue what I call science.
I would not presume to argue with your views/beliefs. If my attempts to work out how your expression of those views/beliefs might relate to my question make you uncomfortable, that is unfortunate, but I cannot, and will not pretend to understand a connection I cannot see, just to protect another's delicate sensativity.
Originally Posted By: Orac
So again I say to you, your OP is not a valid or suitable post for a science forum it fails the basic rules. I am not the moderator on this pseudo science forum AR2 is, so I can only ask and you may well select to ignore me and say it is science and I will ignore the thread like the other stuff here I find as not science.
Perhaps I should take the OP to another science forum and see what the response is.
Originally Posted By: Bill S
This is more-or-less my starting point. There are too many impossibilities to allow physical time reversal to work.
Could this be clearer?
Perhaps I should have highlighted that latter sentence. I didn't because I prefer to do my fellow posters the courtesy of assuming they can understand without being "shouted" at.
So this is the origin of the arrow of time, according to Boltzmann and his friends. We start with a set of microscopic laws of physics that are time-reversal invariant: They don’t distinguish between past and future.
this states that the set of microscopic laws of physics do not vary with time nor do the laws distinguish between past and future.
so the laws can be applied in a time reversal scenario such as your OP because the laws do not recognize a direction of time as in past or future.
ie... you can choose any direction you want for time and the laws simply overlook the chosen direction as the laws do not recognize a direction of time.
so when time reverses in your OP then p and v both reverse with the time reversal and the arrows of p and v will reverse.
so this is in line with my thoughts on the matter
unless I perceive the wording incorrectly.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.
Possibly you consider Sean’s science to be inferior to yours
Sean definitely gets out to the extremes where at times I would call his work not science. Over the years I would not be alone to say that. Read his discussions on Quantum Bayesian (QBSim) if you want a real eye opener. In general he is a reasonable scientist who I don't mind reading but I would never take anything he says as gospel and I would never blindly accept his opinion.
He is an interesting character who likes to push the limits (sometimes a bit far) but writes well and I know why people like his books.
His science is sometimes different to mine but inferior requires a grading which would be subjective. Will you accept different at times rather than inferior?
Originally Posted By: Bill S
Perhaps I should take the OP to another science forum and see what the response is.
Please do .. I can tell you why it will get canned in a simple description .. they will say it is ad-hoc.
Science requires you to consider the prior understanding as the default. I can not for example create a valid science experiment in which I consider there is a point on earth that gravity doesn't exist. Do you see why, because I have no description of physics that allows that it is totally ad-hoc. So you want me to allow something science says can't happen and then discuss it using science ... LOGIC FAIL 101.
Any good science forum will kick you, they will initially give you a nice response and try to send you off but they definitely won't let you discuss it in that form.
Originally Posted By: Bill S
This is more-or-less my starting point. There are too many impossibilities to allow physical time reversal to work.
That isn't true a black hole could possibly have time reversal in it as it causes no problems to our normal physics. Wormhole physics are another classical case of following that line.
That was the bit I was trying to get you to realize that your question as posed was ad-hoc but you could turn it to an area with a horizon (an interface) between forward and backward time. The key point you needed to get clear is why your situation requires a horizon of some form otherwise you get inconsistent logic which you seemed to have realized. Once I put a horizon of all the different options in place none of the results give your OP answer they all give different and sometimes weird answers.
So if you turn your thought experiment to an area with a horizon you would be able to ask it on a physics forum. You can then discuss what features the horizon might have and take on. Those horizon features will determine the answer you deduce in your thought experiment.
Final comment, you can't bring the horizon area down to a point, all the physics will blow up in your face in a singularity. You must keep the horizon as a finite area or surface so that you can formally describe the interface.