Time-loop computers ?

[dud...@gmail.com]

Some physicists believe in the possibility of instant time travels.
Let's assume hypothetically something much simpler and looking more
probable - that physics of four-dimensional spacetime we are living
in, allows for microscopic loops which include time dimension.
If they would have at least microseconds and we could amplify/measure
them (Heisenberg uncertainty principle...), we could send some
information back in time.

Observe that computers based on such loop could instantly find fixed
point of given function:
Let's take for example some NP-problem - we can quickly check if given
input is correct, but there is huge (but finite) number of possible
inputs.
So this computer can work:
- take input from the base of the loop,
- if it's correct, send back in time to the base of the loop the same
input, if not - send the next possible input (cyclically).
If there is correct input, it would be the fixed point of this time-
loop, if not - it should return some trash.
So we would only need to verify the output once again after all (out
of the loop).

Can such scenario be possible?
General relativity theory says that local time arrows are given by
solutions of some equations to the boundary conditions (big bang). CPT
symmetry conservation suggest that there shouldn't be large difference
between past and future. These arguments suggest so called eternalism/
block universe philosophical concepts - that spacetime is already
somehow created and we are 'only' going through it's time dimension.
I've recently made some calculations which gave new argument, that
such assumption actually gives quantum mechanics:
Pure mathematics (maximizing uncertainty) gives statistical property -
Bolzman's distribution - so it should be completely universal
statistics.
If we would use it to find distribution on constant time plane, we
would get stationary probability distribution rho(x)~exp(-V(x)).
If we would use it to create statistics among paths ending in this
moment, we would get rho(x)~psi(x) (quantum ground state).
If we would use it to create statistics among paths that doesn't end
in this moment, bu goes further into future, we would get rho(x)~psi^2
(x) - like in quantum mechanics.
So the only way to get QM-like statistical behavior is to threat
particles as their paths in four-dimensional spacetime.
So spacetime looks like four-dimensional jello - both 'tension' from
past and future influence the present.
http://www.scienceforums.net/forum/showthread.php?t=36034

It suggest that particles should for example somehow prepare before
they would be hit by a photon. The question is if this can be measured
(uncertainty principle)? If yes - are these times long enough to be
useful?
Observe that if the answer is yes, such computer could e.g. break RSA
in a moment. To make cryptosystems resistant to such attacks, they
should require long initialization (like based on Asymmetric Numeral
Systems).

[dud...@gmail.com]

There are plenty of interpretations of QM, and all of them are
controversial. Their problem can be that in opposite to GR, they try
to look at situation from the point of view of three dimensional
slices of the space. Statistics says that to understand QM we have to
think four-dimensional.

One way to make such time-loop I can imagine is that if we think about
for example electron-photon scattering, in four dimensions it would
have sharp edge. Physics doesn't like indifferentiability, so 4D field
should make it smooth - the electron should prepare before this
incident. But such effect would be rather week and short in time.
Maybe Mossbouer spectroscopy of the nucleus around which the electron
moves would spot something...

The other way could be by high energies - it's energetically
preferable for field solutions to propagate in time directions as
other solutions. But if they already have high energies, this
restriction weakens.

[dud...@gmail.com]

I though if we could reduce the required number of bits transferred
back in time, and it looks like one (B) should be enough (this
algorithm intuitively looks less stable?):
- if B then 'input' -> next possible 'input' (cyclically)
- if 'input' verify the problem
-- then transfer back in time B=false
-- else transfer back in time B=true.
If it could it should stabilize on B=false and some solution.

Such algorithm means that it uses input(B) from some physical process
which can predict for example if there will be photon absorbed and on
the end emits this photon or not.
If physics could stabilize this causality loop, it should be done. If
not - it would be stabilized by breaking it's weakest link - making
that the prediction would gave wrong answer.

I believe here has started discussion:
http://groups.google.com/group/sci.physics/browse_thread/thread/c5f055c9fc1f0efb

======================================= MODERATOR'S COMMENT:
That group is, perhaps, a better place for you; please wait for response in this group (s.p.f) before posting further addenda

[Ken S. Tucker]

On Dec 21, 8:15 am, duda...@gmail.com wrote:
> I though if we could reduce the required number of bits transferred
> back in time, and it looks like one (B) should be enough (this
> algorithm intuitively looks less stable?):
> - if B then 'input' -> next possible 'input' (cyclically)
> - if 'input' verify the problem
> -- then transfer back in time B=false
> -- else transfer back in time B=true.
> If it could it should stabilize on B=false and some solution.
>
> Such algorithm means that it uses input(B) from some physical process
> which can predict for example if there will be photon absorbed and on
> the end emits this photon or not.
> If physics could stabilize this causality loop, it should be done. If
> not - it would be stabilized by breaking it's weakest link - making
> that the prediction would gave wrong answer.
>

> I believe here has started discussion:http://groups.google.com/group/sci.physics/browse_thread/thread/c5f05...

>
> ======================================= MODERATOR'S COMMENT:
> That group is, perhaps, a better place for you; please wait for response in this group (s.p.f) before posting further addenda

Almost 3 decades ago I was involved in fiber optics
and notions of "photonic" computers that are now
evolving so I'm open minded on the subject, however,
at some point, a useful digital computer requires a
NAND gate - at least in theory.

Advanced Analog computers that can emulate the
highly advanced navigational skills of a house fly
and onward to humans are not "overtly" digital,
( it is hard to say if the human mind is sensitive at
the quantum level when shifting data between
neurons by electrical impulses).

Anyway, a demostration of an advanced algorithm
can usually be sim'd on available digital computers,
though slow, is able to provide a near proof.
Seasons Greetings
Ken S. Tucker

[dud...@gmail.com]

The verifier is completely classical computer, but when it is coupled
with some effect which can transfer data a few hundreds picoseconds
back in time, the physics should make that this couple create stable
causality loop. But it could only happen if it by the way solve given
NP problem (or e.g. find a keys so that decrypted message looks to
have significant correlations).

How to make such microscopic negative time bit transfer?
Mark L. Fergerson has written on the previous link I've gave:
'The reverse-time trajectory is not a problem, the accelerations
necessary to reverse temporal momentum at the beginning and end of the
trip can be though.'
They could be possible by using high energies or maybe even using that
field theory suggests that particles should know about an incident a
moment before.
Greetings
Jarek Duda

[Enrique Ferreyra (Pachu)]

If we are talking about a particle looping in time dimension, more
important, we are talking about a clean eternal source of energy, i
want a car with particle-looped engine! :-)

Pachu

[dud...@gmail.com]

Let's assume that we believe in CPT conservation, like most of
physicists (I think). Particle scattering is small enough to use this
symmetry - it strongly suggest that turning from proper time to
reverse time should be as difficult as backward - particles are just
some solutions of the field localized in some three dimensions and
long in the last one. They prefer their long dimension to be in
interior of local light cones and so they don't like to turn. They
don't distinguish between past and future. We are able to do it
because of boundary conditions with relatively small entropy (big
bang), which oriented these directions.

To understand physics we have to think four-dimensional. If particle
goes to the future and turns into past, it probably means that it was
particle-antiparticle annihilation. If it makes time-loop from the
perspective of our perception of time, this loop last only microscopic
range of time. So good luck with using it to fuel a car.

But we can use their causality. That assuming eternalism, all
causality loops/questions we will ask this way are already stabilized/
answered somewhere in four-dimesional spacetime.

We could make such loop purely spatial. It's much easier and they also
should want to stabilize, but not instantly only using some dynamics:
http://groups.google.com/group/sci.crypt/browse_thread/thread/736fd9f3e62132c2#