In a message dated 9/21/00 12:13:53 PM Pacific Daylight Time,
samantha@objectent.com writes:
<< It is a pretty twisty notion as are most time-travel type paradoxes. It
would lead to the notion (among others) that any universe whose initial
conditions allow for the development of such Sentience and where
time-travel is possible and closed within the universe is largely the
creation of said Sentience. But that would conflate abilities to
transcend time and participate largely throughout its [the universe]
development with actual participation. And I don't see that such
participation necessarily could extend all the way to the actual birth
of that universe or to periods and more local conditions where no known
laws of physics would support intelligence or information or action.
The Sentience would have to be able to step outside the Universe to
exercise that level of control if it is possible at all. Admittedly
armchair blather but fun nonetheless. >>
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More armchair blather here, because there has been work by some scientists
regarding this subject. Certainly there has been the recent theortical work
by physicist, Neil Shulman, at Clarkson College in New York concerning time
reversing. Kurt Godel also pondered time-reversal, sideways lopps, and how to
best utilize causality, without violating it. Realistically how important is
this to our lives, does it have meaning for us? Possibly it does, but for
most logical positivists the answer is nyet. Deep in the future of spacetime,
it just might, long after we are gone, gone, gone, and then back again. Here
is another theorist's work.
==================================================
Here comes hypertime
Want to sidestep your future or rearrange your past? An extra time dimension
could be all you need, and it might even be the key to the theory of
everything
Space, it seems, is fair game. For years, physicists discontented with the
paltry three dimensions of space that our senses offer us have been merrily
adding extra ones to their equations. First there were four, then there were
nine. The best bet today appears to be ten dimensions of space, with seven of
them curled up so tightly that we can't see them.
Time, on the other hand, has been largely left alone by the theorists. One
time dimension is all you need, they say. Add any more and all hell will
break loose. But in the past couple of years all that has changed. One daring
physicist-Cumrun Vafa from Harvard-has discovered that an extra time
dimension could solve more problems than it creates.
But problems there certainly are. Where is this extra time? Is it just a
mathematical convenience or is it really out there? What will it do to our
notions of past and future, cause and effect? "We find ourselves floundering
around when there's more than one time," says theorist Michael Duff of Texas
A&M University. "It becomes very confusing."
The whole idea that extra dimensions can be useful stems from attempts to
unify the different forces of nature. Back in 1920, mathematicians found that
moving up to five dimensions, instead of the four dimensions of space-time,
helped them to reconcile electromagnetism with gravity. It was like climbing
a hill to look down on a two-dimensional battlefield. Suddenly, they could
see how all the parts of the battle plan fitted together.
In recent years, more dimensions have entered the fray. In 1984 came the
superstring revolution-the idea that the Universe is made up of
one-dimensional strings vibrating in a background of nine dimensions of space
and one of time. Then in 1995, Edward Witten of the Institute for Advanced
Study at Princeton, New Jersey, and Paul Townsend of the University of
Cambridge added a further space dimension to create M-theory. At a stroke,
this last addition seemed to unify the embarrassing plethora of string
theories that physicists had dreamt up ("Into the eleventh dimension", New
Scientist , 18 January, p 32)
Yet despite its great promise, M-theory has not ironed out all the
differences between the various string theories, which is where Vafa and his
"F-theory" comes in, upping the ante to 12 dimensions. The remaining problems
began to fall away with an extra dimension, and theorists eagerly welcomed
Vafa's equations. But the new dimension was one of time, and the
philosophical implications are rather more troubling.
"Most theorists would shun the idea of more than one time," says Duff, who
has himself dabbled with the idea of a 12th time-like dimension. "It brings
all sorts of headaches that we would rather do without." It's easy to see
why. If time is one-dimensional, like a straight line, every point on the
line is either before or after every other point. Future and past are well
defined. Every set of events has a unique sequence. But add another dimension
and the line becomes a plane. How do you define future and past now? How do
you link events-the whole game of physics-when the idea of effect following
cause has evaporated?
According to Duff that's not the end of it. Time dimensions differ
fundamentally from space dimensions in one important respect: when you insert
time into your equations it tends to come in with a negative rather than a
positive sign. If you start to mess around with extra time dimensions, all
sorts of nasties start to emerge-objects that travel faster than light,
photons with negative energy, events where the probabilities of all possible
outcomes don't add up to one.
Primitive tools
Admittedly, says Duff, the tools we use to understand the world may be at
fault. Perhaps the existing approaches are too primitive to describe multiple
times. But since these are the only tools around, the best approach seems to
be to treat Vafa's extra time dimension as a convenient device rather than a
real physical entity. Exploit the benefits it offers and finesse your way
around the disadvantages.
Indeed, Vafa's new time has some suspicious characteristics that could
justify this approach. For instance, while the 11 dimensions of M-theory obey
Einstein's relativity principle, which says that the laws of physics should
look the same to all observers, Vafa's 12 dimensions do not. This is one more
reason for physicists to discount the new dimension's physical reality. "It's
by no means on the same footing as ordinary time," says Frank Wilczek of the
Institute for Advanced Study. Duff agrees. Though it looks like time in some
limited ways, he says, "it's not a real, honest-to-goodness extra time
dimension."
Vafa admits that his extra dimension has many of the hallmarks of an abstract
mathematical device rather than a real physical entity. But this may not be
the case for much longer. "At this point, it's making the formalism look
nicer," he says. "Whenever that happens in the history of physics, there's
usually something behind it." Take quarks. A few decades ago, quarks were a
mathematical construction-a way of thinking about the make-up of particles
such as protons. According to the equations, quarks could never exist as
single individuals. They seemed to be theoretical conveniences. Now, says
Vafa, most physicists agree that quarks do exist in the physical world. The
same happy fate could await his mysterious extra time dimension.
But if it's really out there, why haven't we seen it? One possibility is
that, along with the seven "missing" space dimensions, the extra time
dimension is curled up so tightly that it's invisible to us. If so, the only
way to unwrap it would be to focus huge amounts of energy into a tiny volume.
This would have remarkable consequences.
"If the [extra] time dimension could be unleashed, objects would not have the
sensation of moving in time the way that we do," says Vafa. Think about it.
In space we have choices about how to move, forwards and backwards, up and
down, left and right. For time, our only choice appears to be forward into
the future-Hobson's choice. But with more than one time dimension, says
Wilczek, it might become possible to manoeuvre sideways in time, or
diagonally. If we saw an undesirable event looming in the "future" we might
even be able to sidestep it.
Perhaps it's just as well, then, that the prospects of releasing Vafa's
hidden dimension are actually rather remote. It is extremely unlikely that an
energy intense enough to activate the missing time exists anywhere in our
Universe-though some physicists speculate that it might happen in the centre
of a black hole. But that's not the end of the line for real-life multiple
times. After all, according to the latest cosmological theories there could
be plenty of other universes, each of which might have its own unique
combination of space and time dimensions.
What would it be like in a truly multi-time universe? "It would really be a
mind-stretcher," says Wilczek. "Is it impossible? No I don't think so. You
can write down the equations, but I have very little feeling for what the
solutions would be like to live in."
Gabrielle Walker
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