From: Dace (firstname.lastname@example.org)
Date: Sun 21 May 2006 - 01:34:02 GMT
> From: Robin Faichney <email@example.com>
> Subject: Re: RS
> Monday, May 15, 2006, 7:55:08 PM, Ted wrote:
> > Robin writes:
> >> Physical information is basically just any and all form/structure, and
> >> is a very powerful concept. The usual concept of information is
> >> intentional information, and all intentional info is encoded in
> > info.
> > The problem with equating information with structure is that the word
> > "information" no longer has meaning, i.e., it carries no information.
> > not simply drop this term and refer to structure instead?
> What you consider to be essential to the concept of information is
> missing from physical information, but what others consider to be
> extremely important is present. In particular, physicists NEED (and I
> do mean "need") to apply concepts and techniques from information
> theory to physical entities and processes. As an example there's the
> issue of conservation of physical information inside black holes.
> Stephen Hawking made a bet with John Preskill,
> another physicist. I don't claim to fully understand the matter, but
> Hawking conceded he'd lost a year or two ago when he accepted that all
> of the information that enters a black hole eventually escapes again.
> Of course, structure, generally speaking, is destroyed on entering a
> black hole, so the information that escapes is not the same as that
> which entered, but it is the outcome of a lawful transformation, so
> that the black hole behaves like a computer in the sense that it's an
> information processor. We could say that the input information is
> ENCODED in the output information. And this isn't just woolly
> conceptualisation -- physicists actually apply mathematical techniques
> that originated in communications theory to such problems. And the
> concept of conservation of information is arguably as important as
> conservation of matter and energy.
I see your point. Thank you. Here's another example of the role of
information in physics, from the World Science website:
Light's most exotic trick yet: so fast it goes backwards?
May 12, 2006
Courtesy University of Rochester
and World Science staff
In the past few years, physicists have found ways to make light go both
faster and slower than its usual speed limit. Now researchers say they've
gone a step further: pushing light into reverse.
As if to defy common sense, they say, the backward-moving pulse of light
travels faster than light.
Confused? You're not alone.
"I've had some of the world's experts scratching their heads over this one,"
said Robert Boyd of the University of Rochester in Rochester, N.Y., one of
the researchers. "It's weird stuff."
"Theory predicted that we could send light backwards, but nobody knew if the
theory would hold up or even if it could be observed in laboratory
Einstein determined that nothing can be accelerated to a speed greater than
that of light in a vacuum. That's about 300,000 kilometers (190,000 miles)
If something broke that limit, then some observers could see it reach its
destination before it left, violating a universal law of causality.
But physicists in recent years have reported finding tricks to slow light to
a near-standstill, or even speed it up in apparent violation of Einstein's
Now, Boyd said, he's taken what was once just a mathematical oddity-negative
speed-and shown it working in the real world. The findings are published in
the May 12 issue of the research journal Science.
Boyd and colleagues sent bursts of laser light through an optical fiber
laced with the element erbium. An optical fiber is a thin, transparent tube
that transmits light by letting it bounce along its interior.
"The pulse of light is shaped like a hump with a peak," Boyd explained. "We
sent a pulse through an optical fiber, and before its peak even entered the
fiber, it was exiting the other end. Through experiments we were able to see
that the pulse inside the fiber was actually moving backward."
To understand how light's speed can be manipulated, think of a funhouse
mirror that makes you look fatter. As you first walk by the mirror, you look
normal. But as you pass the curved portion in the center, your reflection
stretches. The far edge seems to leap ahead of you momentarily.
In the same way, a pulse of light fired through a special material may move
at normal speed until it hits the substance, where it is stretched out to
reach and exit the material's other side.
Conversely, if the funhouse mirror were the type that made you look skinny,
your reflection would appear to suddenly squish together, with the leading
edge of your reflection slowing as you passed the curved section. Similarly,
a light pulse can be made to contract and slow inside a material, exiting
the other side later than it naturally would.
To visualize the backward-moving light pulse reported by Boyd, replace the
mirror with a TV and video camera. As you may have noticed when passing such
a display in an electronics store window, as you walk past the camera, your
on-screen image appears on the opposite side of the TV. The image walks in
the direction opposite to yours, and thus toward you. It passes you in the
middle, and continues until it exits the other side of the screen.
A negative-speed pulse of light would act similarly. As the pulse enters the
material, a second pulse appears on the far end of the fiber and flows
backward. The reversed pulse not only propagates backward, but releases a
forward pulse out the far end of the fiber. In this way, the pulse that
enters the front of the fiber appears out the end almost instantly,
apparently beating light's regular speed.
It's as if you walked by the shop window, saw your image stepping toward you
from the opposite edge of the TV screen, and that TV image of you created a
clone at that far edge, walking in the same direction as you, several paces
Wouldn't Einstein shake a finger at all these strange goings-on? Not
necessarily, Boyd said, because Einstein's speed limit applies only to
effects that carry some sort of information.
"In this case, as with all fast-light experiments, no information is truly
moving faster than light," said Boyd.
The hump-like pulse has long leading and trailing edges, Boyd explained.
"The leading edge carries with it all the information about the pulse and enters the fiber first. By the time the peak enters the fiber, the leading edge is already well ahead, exiting. From the information in that leading edge, the fiber essentially 'reconstructs' the pulse at the far end, sending one version out the fiber, and another backward toward the beginning of the fiber."
Boyd said he's working on ways to see what will happen if he can design a
pulse without a leading edge. Einstein says the entire faster-than-light and
reverse-light phenomena should disappear. Boyd is eager to put Einstein to
It seems the information for the entire pulse is contained in its leading
edge. This leads me to wonder if information has primacy over tangible
things such as light and matter, which we might refer to as "exformation."
> > The traditional meaning of information includes representation. Yet
> > no representation within a physical structure itself but only in the
> > interpretation of that structure. We can say representational
> > is encoded in a structure, but the structure doesn't know that. A
> > is simply a structure, no more and no less. Only in the mind of the
> > interpreter does it encode information.
> That's true of any en/decoding scenario. The encoded information only
> exists if the appropriate decoder is available
The difference is that in the case of physical information, the effect is
automatic. The end of the optical fiber doesn't have to represent the light
pulse in order for it to be reconstructed. The process follows
automatically from the principles of physics. Only with the intervention of
reflective consciousness is there representation, which is wholly
antithetical to physical reality (A = B instead of A). In physics, the
identity principle rules: a thing is never more or less than itself. It's
all about presentation, not re-presentation.
> > "Meaning" is not a physically meaningful concept. At no point has
> > ever located meaning in a physical system, nestled among matter, energy,
> > space, field, force, pressure, momentum, etc. No meaning or
> > Yet these concepts become attached to physics when we use the term
> > "information" in regard to physical processes. Because we traditionally
> > associate information with representation, we assume that physical
> > information contains representation as well. The physical existence of
> > representation never has to be demonstrated, instead being smuggled in
> > through the back door. This isn't so much science as a trick of the
> Absolutely not. That's all in your mind. You project your own
> confusion onto everyone else. No physicist, nor anyone with a serious
> interest in it, would see representation in physical information.
That's exactly my point. When you think about it, physical information
cannot include representation. The problem is that we don't always think
about it. Since we associate meaning with information, and we now have a
concept of physical information, we imagine that meaning exists physically,
including in such objects as books, computers and brains.
Incidentally, confusion is a fine example of a mental phenomenon that cannot
be transposed onto the physical. A thing cannot be "confused" any more than
it can be "clear." You or I may be confused at times, but our brains are
just doing their thing, as always. Only when you step back from physical
reality can you experience confusion or bridge the gap via truth.
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