This seems just to be some thinking on the subject of time travel and how the Universe may really be. The two papers are not together and are completely different, but then the subject of time is if it encompasses all?
And now to MIT's person's paper (sorry do not know name without looking at the paper again.)
VI. CONCLUSIONS
This paper reviewed quantum mechanical theories for
time travel, focusing on the theory of P-CTCs [17]. Our
purpose in presenting this work is to make precise the
similarities and differences between varying quantum theories
of time travel. We summarize our findings here.
We have extensively argued that P-CTCs are physically
inequivalent to Deutsch’s CTCs. In Sec. II we
showed that P-CTCs are compatible with the pathintegral
formulation of quantum mechanics. This formulation
is at the basis of most of the previous analysis
of quantum descriptions of closed time-like curves, since
it is particularly suited to calculations of quantum mechanics
in curved space time. P-CTCs are reminiscent of,
and consistent with, the two-state-vector and weak-value
formulation of quantum mechanics. It is important to
note, however, that P-CTCs do not in any sense require
such a formulation. Then, in Sec. III we extended our
analysis to general systems where the path-integral formulation
may not always be possible and derived a simple
prescription for the calculation of the CTC dynamics,
namely Eq. (9). In this way we have performed a complete
characterization of P-CTC in the most commonly
employed frameworks for quantum mechanics, with the
exception of algebraic methods (e.g. see [57]).
In Sec. IV we have argued that, as Wheeler’s picture
of positrons as electrons moving backwards in time suggests,
P-CTCs might also allow time travel in spacetimes
without general-relativistic closed timelike curves. If nature
somehow provides the nonlinear dynamics afforded
by final-state projection, then it is possible for particles
(and, in principle, people) to tunnel from the future to
the past.
Finally, in Sec. V we have seen that P-CTCs are computationally
very powerful, though less powerful than the
Aaronson-Watrous theory of Deutsch’s CTCs.
Our hope in elaborating the theory of P-CTCs is that
this theory may prove useful in formulating a quantum
theory of gravity, by providing new insight on one of the
most perplexing consequences of general relativity, i.e.,
the possibility of time-travel.
http://arxiv.org/PS_cache/arxiv/pdf/1007/1007.2615v2.pdf
http://www.physorg.com/news198948917.html
http://www.physorg.com/news199591806.html
http://arxiv.org/abs/1007.1750
Wun-Yi Shu
(Submitted on 11 Jul 2010)
Abstract: In the late 1990s, observations of Type Ia supernovae led to the astounding discovery that the universe is expanding at an accelerating rate. The explanation of this anomalous acceleration has been one of the great problems in physics since that discovery. In this article we propose cosmological models that can explain the cosmic acceleration without introducing a cosmological constant into the standard Einstein field equation, negating the necessity for the existence of dark energy. There are four distinguishing features of these models: 1) the speed of light and the gravitational "constant" are not constant, but vary with the evolution of the universe, 2) time has no beginning and no end, 3) the spatial section of the universe is a 3-sphere, and 4) the universe experiences phases of both acceleration and deceleration. One of these models is selected and tested against current cosmological observations of Type Ia supernovae, and is found to fit the redshift-luminosity distance data quite well.
---------------------------------------------------------------------------------
Doesn't the second paper sound like the Buddist religion or is that another religion where there is a cycle of expansion and regression every 80 billion years or so?
And what does the MIT paper really mean?
I am not sure if it means anything as of yet.
Although it does explain what I have read in other books about how to think about time travel and how it has to be self-consistent and can not change the past among other ideas.
--------------------------------------------
I am not really wound up sometimes, just trying to make the world better.
There is other News about the southern border and how some Sheriff's think with what is going on.
But then, perhaps another version will come out that is better than what I did with these versions, not that anyone really likes the Titor subject or anyone really has to like the songs.
It may depend on how much negativity anyone reads with any of the News or opinions of the days.
http://www.youtube.com/watch?v=KXkDneBKOmo
http://www.youtube.com/watch?v=ELBdIiPmfSk
But then anyone can also look up other videos.
:eek:
It has been hot though this year.
And no doubt more will be heard about that!
And now to MIT's person's paper (sorry do not know name without looking at the paper again.)
VI. CONCLUSIONS
This paper reviewed quantum mechanical theories for
time travel, focusing on the theory of P-CTCs [17]. Our
purpose in presenting this work is to make precise the
similarities and differences between varying quantum theories
of time travel. We summarize our findings here.
We have extensively argued that P-CTCs are physically
inequivalent to Deutsch’s CTCs. In Sec. II we
showed that P-CTCs are compatible with the pathintegral
formulation of quantum mechanics. This formulation
is at the basis of most of the previous analysis
of quantum descriptions of closed time-like curves, since
it is particularly suited to calculations of quantum mechanics
in curved space time. P-CTCs are reminiscent of,
and consistent with, the two-state-vector and weak-value
formulation of quantum mechanics. It is important to
note, however, that P-CTCs do not in any sense require
such a formulation. Then, in Sec. III we extended our
analysis to general systems where the path-integral formulation
may not always be possible and derived a simple
prescription for the calculation of the CTC dynamics,
namely Eq. (9). In this way we have performed a complete
characterization of P-CTC in the most commonly
employed frameworks for quantum mechanics, with the
exception of algebraic methods (e.g. see [57]).
In Sec. IV we have argued that, as Wheeler’s picture
of positrons as electrons moving backwards in time suggests,
P-CTCs might also allow time travel in spacetimes
without general-relativistic closed timelike curves. If nature
somehow provides the nonlinear dynamics afforded
by final-state projection, then it is possible for particles
(and, in principle, people) to tunnel from the future to
the past.
Finally, in Sec. V we have seen that P-CTCs are computationally
very powerful, though less powerful than the
Aaronson-Watrous theory of Deutsch’s CTCs.
Our hope in elaborating the theory of P-CTCs is that
this theory may prove useful in formulating a quantum
theory of gravity, by providing new insight on one of the
most perplexing consequences of general relativity, i.e.,
the possibility of time-travel.
http://arxiv.org/PS_cache/arxiv/pdf/1007/1007.2615v2.pdf
http://www.physorg.com/news198948917.html
http://www.physorg.com/news199591806.html
http://arxiv.org/abs/1007.1750
Wun-Yi Shu
(Submitted on 11 Jul 2010)
Abstract: In the late 1990s, observations of Type Ia supernovae led to the astounding discovery that the universe is expanding at an accelerating rate. The explanation of this anomalous acceleration has been one of the great problems in physics since that discovery. In this article we propose cosmological models that can explain the cosmic acceleration without introducing a cosmological constant into the standard Einstein field equation, negating the necessity for the existence of dark energy. There are four distinguishing features of these models: 1) the speed of light and the gravitational "constant" are not constant, but vary with the evolution of the universe, 2) time has no beginning and no end, 3) the spatial section of the universe is a 3-sphere, and 4) the universe experiences phases of both acceleration and deceleration. One of these models is selected and tested against current cosmological observations of Type Ia supernovae, and is found to fit the redshift-luminosity distance data quite well.
---------------------------------------------------------------------------------
Doesn't the second paper sound like the Buddist religion or is that another religion where there is a cycle of expansion and regression every 80 billion years or so?
And what does the MIT paper really mean?
I am not sure if it means anything as of yet.
Although it does explain what I have read in other books about how to think about time travel and how it has to be self-consistent and can not change the past among other ideas.
--------------------------------------------
I am not really wound up sometimes, just trying to make the world better.
There is other News about the southern border and how some Sheriff's think with what is going on.
But then, perhaps another version will come out that is better than what I did with these versions, not that anyone really likes the Titor subject or anyone really has to like the songs.
It may depend on how much negativity anyone reads with any of the News or opinions of the days.
http://www.youtube.com/watch?v=KXkDneBKOmo
http://www.youtube.com/watch?v=ELBdIiPmfSk
But then anyone can also look up other videos.
:eek:
It has been hot though this year.
And no doubt more will be heard about that!