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#56049 - 06/14/16 08:56 PM Vectors and time reversal.
Bill S. Offline
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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?
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#56052 - 06/15/16 02:03 AM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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constant velocity?
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#56053 - 06/15/16 08:17 AM Re: Vectors and time reversal. [Re: paul]
paul Offline
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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.




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#56055 - 06/15/16 02:34 PM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Originally Posted By: Bill S.
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 smile

Time only goes the right way when the ball has bounced and is on it's way back.

Bill S new word for the day to learn about => Hamiltonian
https://en.wikipedia.org/wiki/Hamiltonian_mechanics

Quote:
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? laugh


Edited by Orac (06/15/16 02:37 PM)
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#56057 - 06/15/16 05:57 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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oh , Im on orachnids ignore list ... LOL




you may need to think about it for a second smile
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#56067 - 06/16/16 06:31 PM Re: Vectors and time reversal. [Re: Bill S.]
Bill S. Offline
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Quote:
At t=1 it crosses the green spot.


Of course, that should have been the brown spot!

Peter Ebdon plays snooker (very well) in spite of being colour blind; but even he would not put the green on that spot. smile
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#56068 - 06/16/16 07:42 PM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Quote:
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! smile

Quote:
So which way is your time running when I pick the ball up?


Same way it was before you picked it up.
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#56069 - 06/16/16 11:55 PM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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is this your thought experiment or someone elses?

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.

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#56071 - 06/17/16 03:23 AM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Originally Posted By: Bill S.
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! smile

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.


Edited by Orac (06/17/16 07:15 AM)
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#56072 - 06/17/16 12:10 PM Re: Vectors and time reversal. [Re: paul]
Bill S. Offline
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Quote:
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.
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#56073 - 06/17/16 12:19 PM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Quote:
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. smile
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#56074 - 06/17/16 12:26 PM Re: Vectors and time reversal. [Re: paul]
Bill S. Offline
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Quote:
is this your thought experiment or someone elses?


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.

Yes - you are "god", too. Feels good, doesn't it? smile
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#56075 - 06/17/16 01:40 PM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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well if its about "spacetime" then I personally dont care.

I just cant think of a valid reason to care.

right , thats it.
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#56076 - 06/17/16 02:37 PM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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Quote:
Yes - you are "god", too. Feels good, doesn't it?


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.
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#56077 - 06/17/16 08:29 PM Re: Vectors and time reversal. [Re: paul]
Bill S. Offline
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Loc: Essex, UK
OK, forget about spacetime, if you wish.

At t=2 the ball crosses the blue spot, R to L.

At t=3 it arrives at the pink spot; at which point, time is reversed.

At what time does the ball cross the blue spot, L to R?
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#56079 - 06/17/16 08:50 PM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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Registered: 03/21/06
Posts: 4136
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





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#56081 - 06/19/16 01:39 PM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Originally Posted By: Bill S.
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.


Edited by Orac (06/19/16 02:17 PM)
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#56082 - 06/19/16 01:55 PM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Registered: 05/20/11
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Loc: Currently Illinois, USA
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. 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 smile


Edited by Orac (06/19/16 02:26 PM)
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#56084 - 06/20/16 09:16 AM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Loc: Essex, UK
Quote:
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?
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#56085 - 06/20/16 09:26 AM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Registered: 08/20/10
Posts: 3570
Loc: Essex, UK
Quote:
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”. smile


Edited by Bill S. (06/20/16 09:27 AM)
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#56086 - 06/20/16 01:47 PM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Originally Posted By: Bill S.
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.


Edited by Orac (06/20/16 02:14 PM)
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#56088 - 06/20/16 03:46 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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Orac...

theres a no friction clause in the OP.

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.
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#56089 - 06/21/16 03:37 AM Re: Vectors and time reversal. [Re: paul]
Orac Offline
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Registered: 05/20/11
Posts: 2819
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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 smile

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.


Edited by Orac (06/21/16 04:26 AM)
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#56090 - 06/21/16 06:38 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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Posts: 4136
its a thought experiment orakinovskivich.

have you ever seen a steam locomotive traveling in space?

ie...



"But it is the only reasonable transformation
that ((((( preserves light speed ))))) ... prop.

it shrinks objects ...
it slows down clocks ...

what percentage of the laws of physics do the above
two claims ignore?

100%

how much energy would be required to shrink an object?
where does the required energy come from?

where does the required energy to slow down a clock come from?

the einstein theories do not belong in physics they dont even
belong in science at all.


Quote:
You need to stop making things "real" and "immutable" just because you observe them. Go and read Einsteins train thought experiment.


if you observe something then the observance is real to you
perhaps not to anyone else , none the less to you it is
real and immutable.

you just cant explain it with the tools that you have to
work with ... and thats not our fault.

your tools in your tool box are designed for a special purpose
and cannot be used to examine anything real.

you could just as well label the tool box "dungeons and dragons"

because its all in your mind and in the minds of like minded
D&D players.




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#56091 - 06/21/16 10:14 PM Re: Vectors and time reversal. [Re: paul]
Bill S. Offline
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Quote:

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.
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#56092 - 06/21/16 11:05 PM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Quote:
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


Which answer was that?
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#56093 - 06/22/16 07:32 AM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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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 smile
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.


Edited by Orac (06/22/16 08:23 AM)
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#56094 - 06/22/16 02:19 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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Registered: 03/21/06
Posts: 4136
Orinkadink ifyoucouldthink thenyouwouldsee thewholethingstinks

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.
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3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#56095 - 06/22/16 02:39 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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Registered: 03/21/06
Posts: 4136
meanwhile theres this.

a photon travels at the speed of light.

light has been slowed down.

did the photon become massively larger because the
light was slowed down?

NO

so this is empirical evidence that the einstein theory
is incorrect.

because if an object were to shrink due to the einstein
theory then a photon is already shrunk.

when it is slowed down it should regain its uneinstein size.

AND IT HASNT!!!



_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#56096 - 06/22/16 03:03 PM Re: Vectors and time reversal. [Re: paul]
Orac Offline
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Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
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 laugh


Edited by Orac (06/22/16 03:33 PM)
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#56098 - 06/22/16 09:43 PM Re: Vectors and time reversal. [Re: Orac]
Bill S. Offline
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Registered: 08/20/10
Posts: 3570
Loc: Essex, UK
Quote:
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.
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There never was nothing.

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#56099 - 06/22/16 10:04 PM Re: Vectors and time reversal. [Re: Orac]
paul Offline
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Registered: 03/21/06
Posts: 4136
just how many times are you going to ignore me orIcantsoIbiach?

you cant claim that you are ignoring someone if you continue
to reply to them.

so stop replying to my post.




_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

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#56102 - 06/23/16 03:44 AM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: Bill S.
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.


Edited by Orac (06/23/16 06:19 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

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#56104 - 06/23/16 02:07 PM Re: Vectors and time reversal. [Re: Bill S.]
Bill S. Offline
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Registered: 08/20/10
Posts: 3570
Loc: Essex, UK

Paul asked:
Quote:
is this your thought experiment or someone elses?

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.
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There never was nothing.

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#56106 - 06/23/16 03:02 PM Re: Vectors and time reversal. [Re: Bill S.]
paul Offline
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Registered: 03/21/06
Posts: 4136
http://www.pdf-archive.com/2014/07/24/from-eternity-to-here/from-eternity-to-here.pdf
pg 132
BOX OF GAS REDUX

Quote:
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.

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#56109 - 06/23/16 06:24 PM Re: Vectors and time reversal. [Re: Bill S.]
Orac Offline
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Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: Bill S.
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.

If you assume the LIGO result is correct you should probably start here: https://en.wikipedia.org/wiki/Absolute_horizon

I will add one other quote for you to ponder: "The LIGO results provide the first experimental observation of the uniqueness or no-hair theorem"


Edited by Orac (06/23/16 07:11 PM)
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